Topic: Portable Larvy AD10?

[mblindsey]

The latest TapeOP magazine has a “Behind The Gear” article on Dan Lavry and the AD10 A/D converter.  It caught my eye because it has ability to color sound from “clear” to “tube”, “transformer”, or “complex” (both).  That sounded like something I’d like to have in my arsenal (not to mention the creator's resume seemed impressive).  So, I promptly went to the company website to check this thing out, only to find out that it runs on AC.

I decided to email the company to see if they might ever release this item in something that was more friendly for recording in the field, and possibly with pres built in.  Dan Lavry emailed back and said he would consider it.  At his direction, I’m posting here, as he wishes to “post some comments regarding some of the issues and compromises that take place when designing portable gear.”   

Dan, the stage is all yours.

Mods, I apologize if this discussion is more suited for the “retail” section.  Since, the product I inquired about doesn’t actually exist, and I have no relation to the vendor, I thought posting here would be okay.

[muj]

remember apogee ad-1000? Dan was involved designing that thing

[BC]

This was also reviewed in Pro Audio Review recently. I recall the reviewer was not so hot on the processed modes, FWIW. But he really liked the AD10 overall.

I was looking but I don't think they have put up the review on their website yet. Subscriptions are free so maybe if you register you can search through the old digital issues?

http://www.proaudioreview.com/

[BC]

I decided to email the company to see if they might ever release this item in something that was more friendly for recording in the field, and possibly with pres built in.  Dan Lavry emailed back and said he would consider it.  At his direction, I’m posting here, as he wishes to “post some comments regarding some of the issues and compromises that take place when designing portable gear.”   

I'll put in my 2 cents (not in any particular order)

1) Form factor. I personally think the V3/AD2K type boxes are well sized.
2) large easy-to-adjust controls (a la V3)
3) Metering that goes down to -30dB or so, with functional increments.
4) Switchable -15db pad would be nice for taking SBD feeds.
5) HPF possibly, for super bassy shows, wind and LF rumble

[Dan Lavry]

The latest TapeOP magazine has a “Behind The Gear” article on Dan Lavry and the AD10 A/D converter.  It caught my eye because it has ability to color sound from “clear” to “tube”, “transformer”, or “complex” (both).  That sounded like something I’d like to have in my arsenal (not to mention the creator's resume seemed impressive).  So, I promptly went to the company website to check this thing out, only to find out that it runs on AC.

I decided to email the company to see if they might ever release this item in something that was more friendly for recording in the field, and possibly with pres built in.  Dan Lavry emailed back and said he would consider it.  At his direction, I’m posting here, as he wishes to “post some comments regarding some of the issues and compromises that take place when designing portable gear.”   

Dan, the stage is all yours.

Mods, I apologize if this discussion is more suited for the “retail” section.  Since, the product I inquired about doesn’t actually exist, and I have no relation to the vendor, I thought posting here would be okay.

Hi Michael and all,

Michael Lindsey wanted to know if the LavryBlack AD converter “AD10 will ever be released as a unit that can be used in the field on battery power”. The other question was about including a built in microphone amplifier (micpre) with the capability of supplying phantom power for condenser mics.

A as a designer, I am aware of the commonly encountered tradeoffs associated with battery powered gear. As a rule, when designing equipment to be powered by AC line energy, a few more watts is not much of an issue. The limiting factor for power level is most often heat, but given large enough physical size, one can get top notch performance without overheating. The AD10 is ½ rack wide, and  it runs relatively cool.

But designing portable battery operated equipment calls for a serious focus regarding the usage of power. The power consideration gets magnified when small size is desirable, because a while given amount of power may not heat up a large chassis, the same amount of power can cause very high temperatures in a small case. In addition, when using battery operated gear, some of the space is reserved for the battery itself, leaving less space for the electronics.

It is not wise to lump all battery operated gear together. Laptop technology is pretty impressive, enabling a few hours of operation at power levels of tenth of watts. Achieving such high performance is a result of much technological evolution for a true mass production product line. Progress in battery technology is still being made, to provide more power for longer operation. But the focus of such progress is towards mass production laptops, hybrid cars and alike.

High end portable audio recording is not a mass production market. Most often, the designs relay less on increasing battery capability, and more on reducing the power required to operate the gear. There is a whole “family” of semiconductors designed specifically for low power applications, for portable equipment. In most cases, such portable components are made to work at very low voltages (such as single 3V-5V range) and draw as little power as possible. Such devices is what makes the major portion of portable recording gear. Much of the portable recording market is driven by mass production low cost device, where performance is not the driving consideration. 

For those interested in technology, digital has been going to lower and lower voltages (the currents are still high for high performance) and that is the best path for digital. But analog for audio is “being dragged down” by the mass production computer, cell phone and similar technology. Lower voltage and high performance audio are opposite… 

When using circuits and devices with low power and low voltage, one compromises performance. Say my goal is to have 120dB dynamic range, with a 3V supply. The electron motion inside a single 3.5KOhm resistor at room temperature generates noise at 120dB below a 3V signal…  While some of the technological limitations may be temporary, there are a number of fundamental physical principles at play, that are here to stay. That is why the highest end gear ends up using higher power (higher voltage and higher currents).

When it comes to low power operation, the big question is the level of compromise in performance vs. the amount of power. In most cases, small, light, long battery life (or time between charges) and product price seems to outweigh the quality and performance.
Portability and low power and not exactly the same thing. One can “settle for” a heavier, bigger device (with a battery) that performs much better.

Clearly, I can make a version of the AD10 that is more portable. I can go for a different, less power consuming display and do what can be done to reduce power, which was not much of a consideration fro the present AD10. But at some point, one faces the decision of performance and quality vs. portability. Say you want 48V phantom stereo power. There goes a watt… Much portable gear offers lower phantom voltage, say 12V or even less. That is an example of compromise. Then come the monitoring question. Do you want to be able to listen to the OUTPUT through your choice of quality headphones? That would call for a quality DA plus heavy duty headphone driver – more power…

My very new AD10 is gaining much respect at music production facilities, a market that I am familiar with. At this point, I do not know how much need there is for the performance level of my products in the portable market. Clearly I am not going to recommend that people carry a 12V car battery with 115V 60Hz inverter to the field. I can alter the product to yield similar performance with increased portability. I can not make an AD10 fit in a pocket, but I can make it portable enough. I just do not know how many people with portable recording applications have a requirement for the highest sound quality.

Regards
Dan Lavry
www.lavryengineering.com







 

[carlbeck]

Dan thank you for your insight & for joining our forum, we appreciate your time here. With that being said you don't necessarily need to provide on-board battery power. We are a crafty bunch, if you can make it powered by 12 volts drawing an amp or two per hour we will figure out how to power it. In our circles, if you make it they will come. We take great pride in what we do & go through great lengths to support a company that we feels supports us. Our market may be small but some of us are fiercely loyal to those who feel have our interests in mind.

[mblindsey]

I can not make an AD10 fit in a pocket, but I can make it portable enough. I just do not know how many people with portable recording applications have a requirement for the highest sound quality.

The short answer is that most of us here strive for the highest sound quality.  It's not easy to make high quality recordings in a hostile environment that one often has very little control over.  However, that is a small part of what makes this hobby fun.  The gear we use is one of the variables that we have complete control over.

Let me further answer that with a very short list examples of manufacturer's that people have been known to use around here:

Mics:  Schoeps, Nuemann, DPA, AKG, MBHO, Microtech Gefell, etc

Pres/AD's/Both & More:  Neve Portico, Apogee, Grace Designs, Sound Devices, Sonosax, etc

I purposely picked those because they are on the more expensive side (and I know I've left some off in my haste).  The point is, if people see value in the quality of your product, and it fits a need - they will pay for it.  And, based on the gear list above, people here do.  It's also worth pointing out that some spend hundreds on bags, shock mounts, stereo bars, stands, cables, batteries, etc., all in the pursuit of quality.   

--Michael

Note:  I'm not trying to correlate price and sound quality, as we all know, that doesn't fit.  Some outrageously good recordings have been made with gear priced on the lower end of the spectrum.

[Dan Lavry]

Dan thank you for your insight & for joining our forum, we appreciate your time here. With that being said you don't necessarily need to provide on-board battery power. We are a crafty bunch, if you can make it powered by 12 volts drawing an amp or two per hour we will figure out how to power it. In our circles, if you make it they will come. We take great pride in what we do & go through great lengths to support a company that we feels supports us. Our market may be small but some of us are fiercely loyal to those who feel have our interests in mind.

Reading your post made me wonder about a couple of points.

Is there one or more commonly "battery packs" used by the "portable recording community"? What are the type plugs and jacks are  used to connect the battery to a unit (converter, micpre and alike)?
What is the prefered "storage" for the recorded music? Is it a laptop hard drive? Is there a preference for a
Mac vs. PC?

Thanks in advance to answers to my questions.

Regards
Dan Lavry
     

[JasonSobel]

Dan thank you for your insight & for joining our forum, we appreciate your time here. With that being said you don't necessarily need to provide on-board battery power. We are a crafty bunch, if you can make it powered by 12 volts drawing an amp or two per hour we will figure out how to power it. In our circles, if you make it they will come. We take great pride in what we do & go through great lengths to support a company that we feels supports us. Our market may be small but some of us are fiercely loyal to those who feel have our interests in mind.

Reading your post made me wonder about a couple of points.

Is there one or more commonly "battery packs" used by the "portable recording community"? What are the type plugs and jacks are  used to connect the battery to a unit (converter, micpre and alike)?
What is the prefered "storage" for the recorded music? Is it a laptop hard drive? Is there a preference for a
Mac vs. PC?

Thanks in advance to answers to my questions.

Regards
Dan Lavry

Dan,

the battery packs that most people use a varied.  It used to be sealed lead-acid batteries (SLA) were the norm.  Now, most people prefer to use NiMH or L-Ion battery packs, because they are lighter when lugging around our gear.  Generally speaking, the gear that we use runs on either 6V DC or 12V DC, and some pieces of gear can run on anything from 6-12V.  Having that flexibility is nice.  There are a lot of L-Ion batteries that are made for portable DVD players or whatnot, that output 9V.  Those are popular here.  Many people make their own battery packs by purchasing batteries meant for other purposes, hacking off whatever connector comes with the battery, and then soldering on whatever sort of connecter they need.  Regarding a connection.  If there's room on the unit, a 4-pin XLR is great (the Grace Design V2 and the Benchmark AD2402-96 (aka AD2K+) both use a 4-pin XLR for power).  However, as gear is getting smaller and smaller, it seems like these connectors are being used less frequently because they take up too much space.  Most gear that we use make use of standard barrel power plugs (the kind of plugs you can get from radio shack).  There are even a few barrel plug models that provide a locking connection as well, which is nice.  Basically, if its a standard connector that people can buy easily and relatively cheaply, and is secure, it's a good connector to use. 

in regards to recording devices, laptops are no longer the preferred way to record.  too many variable and they're too fragile for the kind of environments many of us record in (loud bars with drunken people surrounding us).  These days, most people have dedicated hard drive or flash card recorders.  Sound Devices 722, Tascam HD-P2, Marantz PMD-671, M-Audio Microtrack, etc, etc.  there are a number of other smaller flash card recorders that are also popular because they're small, but many lack a digital input.
These HD and flash card recorders are nice, because you just turn it on and hit record (a lot less to worry about relative to a laptop), and then its easy to copy the show to your computer (either PC or mac) at home via USB or firewire.

thanks for taking an interest in our community.
- Jason

[Dan Lavry]

I can not make an AD10 fit in a pocket, but I can make it portable enough. I just do not know how many people with portable recording applications have a requirement for the highest sound quality.

The short answer is that most of us here strive for the highest sound quality.  It's not easy to make high quality recordings in a hostile environment that one often has very little control over.  However, that is a small part of what makes this hobby fun.  The gear we use is one of the variables that we have complete control over.

Let me further answer that with a very short list examples of manufacturer's that people have been known to use around here:

Mics:  Schoeps, Nuemann, DPA, AKG, MBHO, Microtech Gefell, etc

Pres/AD's/Both & More:  Neve Portico, Apogee, Grace Designs, Sound Devices, Sonosax, etc

I purposely picked those because they are on the more expensive side (and I know I've left some off in my haste).  The point is, if people see value in the quality of your product, and it fits a need - they will pay for it.  And, based on the gear list above, people here do.  It's also worth pointing out that some spend hundreds on bags, shock mounts, stereo bars, stands, cables, batteries, etc., all in the pursuit of quality.   

--Michael

Note:  I'm not trying to correlate price and sound quality, as we all know, that doesn't fit.  Some outrageously good recordings have been made with gear priced on the lower end of the spectrum.

Thanks for the comments.
Am I correct to assume that most of the portable recordings is does via stereo and sorround is the exception?

I like your comment regarding the "pursuit of quality". I agree that no matter how good the gear is, if the music itself is not good, the end result will not be good. Great music on lesser gear can be wonderful. The best is of course when recording great music with great gear...

Regards
Dan Lavry

[mblindsey]

Am I correct to assume that most of the portable recordings is does via stereo and surround is the exception?

I think that is a fair statement.  I think some people are doing surround with Soundfield gear, and then there is also the TetraMic from Core Sound.  Someone else here might be able to provide a better answer.

I think running four channel recorders seem to be becoming more popular (cards + omini or cards/omnis + sbd).  Four channels will be my next step (Edirol R-44, not yet released).

[Brian]

4 track recordings have become popular of late with recorders like the sound devices 744t and edirol R4.

most use the onboard ADC of the recorders when going four channel though. tapers are a funny bunch.  if there was a four channel outboard ADC that could be run on DC power and not cost a mint,  we'd buy it for sure   that is of course if it sounded better than the onboard ADC of the recorders.  I personally think the ADC's in HD/flash based recorders are always getting better.

edit to clarify:  not to say they are getting better than dedicated outboard ADC's.  just that the onboard ADC's on recorders coming out today sound much better than they did, say, 3-5 years ago

[aegert]

Dan
First off thanks for stepping in +t...

Headphone would not really be necessary as most all of us have that on the bit bucket we use... The battery issues were covered very well as was dc connectors...

It is important to have a very flexible pre capable of being fairly transparent with HPF and padding. The HPF with choices of slope and freq! Your gear is world class and will be very prised in our world for sure. I think having features that support the film industry woudl probably be the best marketing and sales promoting for a new product. Looking at the wendt, sd and sure pre/mix pre products with your world class a/d would be a very very hot product for that market...

Personally metering is very important for my needs. I find that  many of the pre/ a/d's don't have a very readable and usable meter. Some  better intuitive peak detection ala a programmable led for personal level set would be great... ie setting it of -2 or -1 db not just a last led before 0 as -3db.

It is great you came over here. It is so refreshing to see manufacturers reaching out to users and having open dialog. Thanks again

A

[it-goes-to-eleven]

I just took a look at the specs of the AD10 and it appears to draw only 0.1 amps at 90+ volts. Assuming 0.1 amps at 110 volts, that's only 11 watts.

I currently power my DAV BG1 with an exeltech inverter. It uses about 20 watts.  Others are using a/c powered tube pre-amps in the field.  Where there is a will, there is a way...

[Dan Lavry]

I just took a look at the specs of the AD10 and it appears to draw only 0.1 amps at 90+ volts. Assuming 0.1 amps at 110 volts, that's only 11 watts.

I currently power my DAV BG1 with an exeltech inverter. It uses about 20 watts.  Others are using a/c powered tube pre-amps in the field.  Where there is a will, there is a way...

Yes, I was wondering about that inverter business. When I found out that my alarm battery backup (power failure here are not uncommon) is only good for 48 hours maximum, and that the alarm company has no solutions, I looked around, and ended up with a couple of very heavy duty batteries and a Tripp-lite inverter, the type that gives good "switch-over", protection, regulation... I do not recall off hand what the outcome was, but I believe I am getting around .1A for almost 2 weeks. I tested it with a "dummy load" for that long...
Clearly, I would not call that system portable, and it does not need to be. But when I heard 1Amp for 2 hours, it almost sounds like a high efficiency inverter and a battery can go a long way.

Still, I think that when it comes top portability, it would be good to have all the desired features in one reasonable size case, and that the design should be done with a lot of emphasis on power consumption. Of course, I will look into a design that includes the appropriate DC to DC converter.

Here is a question:
Of course, most pro recordings use condensers. Condensers are great, but they also have some "issues", relative to dynamic mics. First, dynamics are more robust, and many condensers are relatively fragile. Second, with condensers, one needs to be careful regarding mechanical motion of the cables (such as tapping on the cable), to avoid "thump" sounds. That is because a cable has capacitance, and when charged to 48VDC, you tap it, the capacitance changes for a moment, which generates a voltage "spike".
The above weaknesses seem to me to be more of an issue for portable applications, while dynamics offer robust operation with fewer issues. Yes, of course the condenser yields more output, and very often better response, but there are a few dynamics out there that are pretty nice. So is the majority using condensers? That would be my guess, but I do not really know.

Regards
Dan Lavry

[carlbeck]

Dan I would say almost if not all of us are using condensers, you are correct.

[it-goes-to-eleven]

Since we are on the topic of powering a/c audio gear via an inverter, it is worth mentioning that the common modified sine wave units are far from ideal. The Exeltech is a true sinewave.  The spectrogram of a preamp's noisefloor is dramatically different on wall a/c vs. a modified sinewave inverter:

http://taperssection.com/index.php/topic,71722.msg960770.html#msg960770

[Dan Lavry]

Since we are on the topic of powering a/c audio gear via an inverter, it is worth mentioning that the common modified sine wave units are far from ideal. The Exeltech is a true sinewave.  The spectrogram of a preamp's noisefloor is dramatically different on wall a/c vs. a modified sinewave inverter:

http://taperssection.com/index.php/topic,71722.msg960770.html#msg960770

The Tripp-lite inverter I used for my alarm backup is not required to be particularly clean. Of course I can see potential problems with dirty inverters used for audio, especially when the waveform has significant amount of high frequency content, which can find its way into the signal path, by one of a number of mechanisms of interference.

You said: "The spectrogram of a preamp's noise floor is dramatically different on wall a/c vs. a modified sine wave inverter", but while you can show it to be the case, it is worthwhile to note that different preamps may be impacted very differently to various disturbances. In fact, I stand by that statement for virtually all analog gear.

Take a single OP amp, or a discrete stage or what not. You can measure it , or you can often look at data sheets of opamps and alike... The terminology is PSRR (power supply rejection ratio). The rejection (commonly expressed in dB) is very much a function of frequency content, and tends to be worse at higher frequencies... So you start with the power source, then you figure the rejection of the power supply, then you figure the rejection of the circuits... It is the combined rejection which counts. Some micpres will have fantastic rejection, others will have poor rejection... Same is true for other gear...

Having said it, I do agree that micpres are inherently extra sensitive at the front end circuitry, because whatever gets in there, even a small amount of garbage, will be amplified right along with the signal.

Regards
Dan Lavry

[mblindsey]

Here is a question:
Of course, most pro recordings use condensers. Condensers are great, but they also have some "issues", relative to dynamic mics. First, dynamics are more robust, and many condensers are relatively fragile. Second, with condensers, one needs to be careful regarding mechanical motion of the cables (such as tapping on the cable), to avoid "thump" sounds. That is because a cable has capacitance, and when charged to 48VDC, you tap it, the capacitance changes for a moment, which generates a voltage "spike".
The above weaknesses seem to me to be more of an issue for portable applications, while dynamics offer robust operation with fewer issues. Yes, of course the condenser yields more output, and very often better response, but there are a few dynamics out there that are pretty nice. So is the majority using condensers? That would be my guess, but I do not really know.

Regards
Dan Lavry

Dan:

I think you are correct on the "more output, and very often better response" observation.  Although, I have seen some good recordings made with dynamics.

When I stepped into this hobby I took a completely non-technical approach to my choice in mics.  I listened to a bunch of recordings made with many different mics, and picked out something that sounded good to my ears.  I think that's the way a lot of people here choose gear.  Over several decades I think this community has gravitated to certain brands/models because they've heard great recordings made with them.  Simple as that.  If it sounds good, it is good...and we'll lug a bigger battery around for phantom to get that sound we're looking for.

Shock mounts go a long way towards reducing the thumps that you mentioned.  I've had drunks grab my mic stand to catch their balance and never heard it on play back (Sabra's SSM-1).

--Michael

[Weirdness]

Wow!!!
    Very exiting to have a great designer on the forum.  Funny too, I had recently noticed the new Lavry ADC online and the A/C only thing made me quickly erase the whole thing from memory.  I for one think that a high quality portable ADC would sell and this is precicely the reason that I have not sold off my V2 as yet.  If the unit were around the same physical size as a V2 and could run off of a 6v battery, it would be a killer piece in the field.  The metering on the AD10 looks great too and having adjustable gain is definitely a must.  I ran a friends Benchmark AD2K+ for awhile and not having continually adjustible gain was something that was a minus on that unit.   I woud say that the Apogee AD500 was a real treat to use, adjustable gain, no 48v or headphone out or DAC required.  The only drawbacks with that piece were really that it was a bit big in size and the 12v battery was a pain to lug around.           

Otherwise, I have heard such great things about Lavry products in general there is no doubt that a portable AD10 would be a winner.  Hopefully sometime in the near future I'll have a DA10 running in my playback system as well, I've wanted to have a listen to that piece for some time and have heard nothing but good things about it.  Anyways, count me in on this one, if you can come up with a great sounding portable ADC I'm in for sure...

[Dan Lavry]

Here is a question:
Of course, most pro recordings use condensers. Condensers are great, but they also have some "issues", relative to dynamic mics. First, dynamics are more robust, and many condensers are relatively fragile. Second, with condensers, one needs to be careful regarding mechanical motion of the cables (such as tapping on the cable), to avoid "thump" sounds. That is because a cable has capacitance, and when charged to 48VDC, you tap it, the capacitance changes for a moment, which generates a voltage "spike".
The above weaknesses seem to me to be more of an issue for portable applications, while dynamics offer robust operation with fewer issues. Yes, of course the condenser yields more output, and very often better response, but there are a few dynamics out there that are pretty nice. So is the majority using condensers? That would be my guess, but I do not really know.

Regards
Dan Lavry

Dan:

I think you are correct on the "more output, and very often better response" observation.  Although, I have seen some good recordings made with dynamics.

When I stepped into this hobby I took a completely non-technical approach to my choice in mics.  I listened to a bunch of recordings made with many different mics, and picked out something that sounded good to my ears.  I think that's the way a lot of people here choose gear.  Over several decades I think this community has gravitated to certain brands/models because they've heard great recordings made with them.  Simple as that.  If it sounds good, it is good...and we'll lug a bigger battery around for phantom to get that sound we're looking for.

Shock mounts go a long way towards reducing the thumps that you mentioned.  I've had drunks grab my mic stand to catch their balance and never heard it on play back (Sabra's SSM-1).

--Michael

Am not "for" or "against" condensers. dynamic or ribbons. My post was an inquiry of what is being most used in portable settings. The more "stationary" applications is almost completely based on condensers, and I suspect that the main reason for it (not the only reason) is the higher output level. Of course it does not come "free", because the condenser requires an energy source (other then the sound air vibrations) . The dynamic and ribbon mics do not, so I thought it possible that people will use dynamic mics more often for portable applications. The ribbon yields the weakest output, yet it has been getting a bit more popular lately, especially for solo piano, acoustic guitar...

Yes, a lot of people use their ears, and I am all for it. I am a musician (I play piano and accordion), and I use my ears. After all, music is for the ears :-) 

In my opinion, there is too much of a gap between "ear people" and "technical people". The ear people insist that the ear is all that matters. So very often I see someone listening to something and mistakingly expanding their conclusions with far overreaching generalizations. I see technical people look at specs, not realizing that one can have an inaudible 1% distortion and an irritating .01% distortion...

On one side of the equation, one can not do everything by ear. A designer can, and should verify how a product sounds. But getting to an end result that sounds great is not done by ear. It is done by engineering. Say you have a disturbing 7KHz tone. The ear can hear it, but it can not tell you if it is due to radio interference, power supply noise, circuit oscillations, aliasing of high frequency energy, intermediation... The ear is no substitute for an ohm meter, scope, audio test system...
On the other side, the designer should be very aware of the ear, and that is not at all an easy task. The ear is NOT an FFT, the ear is NOT an oscilloscope, though it does share some "elements" of an FFT and a scope.

The "difficult part" happens when people have different SUBJECTIVE tastes. When I started designing for audio I realized very quickly that I need to separate the objective from the subjective. I decided to stay with what is OBJECTIVLY good, and get as far as I can from what is SUBJECTIVE. In order to do it, I separated all the audio gear (generically) into 2 lists:

1. Gear that needs to be transparent.
2. Gear that is designed to alter the sound.

We do not want our speaker wires to do EQ. We do not want the amplifiers to compress the sound. We do not want the power amplifier to yield reverb... In fact, ideally, we would be doing great if we can have a perfect reproduction of the acoustic performance, and for that, one needs all the elements in the chain to be as transparent as possible.

At the same time, the music production person (recording, mixing, mastering...) may choose to alter the sound, and for that we have equipment such as EQ, compressors, reverb, limiters...

If the micpre, converters, amplifiers, mixers, speakers and more color the sound, there is no good way to take the coloration out. The music production person is being controlled by the gear. However, if the gear is as transparent as possible, one can alter it as they wish with tools designed for alteration. One may like the coloration of some gear, but the same coloration over and over? I like salt in my soup but not on my desert. One may enjoy seeing the world through pink tinted glasses, but there are times that blue tint works better, or no tint at all. The first real life test of my first Lavry Engineering AD (AD122) was to record YoYo Ma. I did not want to alter his Stradivarius cello sound... One may love tubes, but you leave YoYo alone... At minimum you want to record it as accurately as you can, and alter it later...

So now you know what I think :-)

Regards
Dan Lavry

   

[scb]

transparency is the name of the game!

Over the years, i've owned portable ADC's from Graham Patten (ADC-20, too digital and artificial sounding), Benchmark (Sonic AD2k+, aka the ad2402, very transparent and awesome at 24 bit, a little thin at 16 bit), apogee (mini-me, a little too colored for my taste), grace design (lunatec v3...I can't really put my finger on what I disliked about the ADC except to say I simply prefer the sound of my current ADC), and the Mytek Stereo 192.  The Mytek is my current box and the one that i've run for the last 3 years or so.  It's the only portable box that Mytek makes, and it runs off of 7 or 8+ volts.  I think Michal said it needs a minimum of 7 volts, but I'm forgetting his exact words that he told me when I bought the box in 2004.  I've been running it off of a 9 volt lithium battery pack with no issues, and have routinely run it for over 3 hours with juice to spare on a 9v, 5400mAH battery.  It doesn't get too hot at 9V, though if you give it 12, that extra juice can definitely be felt in the form of heat

Anyway, if there were a portable Lavry unit, it's definitely something I'd look into...

[mblindsey]

So now you know what I think :-)

Regards
Dan Lavry

No disagreements here. 

I hope though this forum exchange we've opened another potential market for your products.  Please keep us updated if you decide to enter the field recording market, as I'm sure there is no shortage of people in this forum who would be willing to tell you exactly what feature sets in a product would be important to this group of potential customers.

Thanks again for posting here.  It is wonderful to have industry experts drop by and interact.

Regards,
Michael Lindsey

[Dan Lavry]

So now you know what I think :-)

Regards
Dan Lavry

No disagreements here. 

I hope though this forum exchange we've opened another potential market for your products.  Please keep us updated if you decide to enter the field recording market, as I'm sure there is no shortage of people in this forum who would be willing to tell you exactly what feature sets in a product would be important to this group of potential customers.

Thanks again for posting here.  It is wonderful to have industry experts drop by and interact.

Regards,
Michael Lindsey

Thank You Michael,

I am trying to figure out what the needs are for a portable unit, and it is not always as easy as it seems.
For example, I was thinking about a stereo unit, but reading some comments, there may be some preference for a 4 channel unit, which will obviosly must be bigger (more XLR connectors, more circuits...) , will require more power, will cost more... Then there is the question of the prefered memory: based on the posts, my guess was incorrect, laptops are not the prefered choice...

I appreciate the various comment but I still have much to learn regarding "the most desirable features" in portable recording, on top of best sound and product reliability.

Regards
Dan Lavry 

[sygdwm]

i would think that a dc powered 2 channel analog pre would suffice for the larger part of the demographic here

[Dan Lavry]

i would think that a dc powered 2 channel analog pre would suffice for the larger part of the demographic here

2 Channel micpre without an AD? I was thinking about a combination of Pre and AD, while trying to figure out the best memory storage. The reason? It would be easier to handle fewer pieces, less interconnecting cables between various units and less interconnections to the battery. But I can also see some very good reasons to having a separate micpre.

Is there a general preference for separate pieces (pre, AD, memory...)? Is there a preference for "multi function gear"?

Regards
Dan Lavry
www.lavryengineering.com

[mblindsey]

Off the top of my head, I would vote for:

1.  Able to be powered by 6-12V DC
2.  2 x Good Pre's
3.  Good AD
4.  S/PDIF out
5.  Analog out
6.  Provides phantom
7.  Rugged, yet small-ish enclosure (~6-9”L x ~6-9”W x ~2-3”H)
8.  Priced between $1-2K

--Michael

[mblindsey]

Is there a general preference for separate pieces (pre, AD, memory...)? Is there a preference for "multi function gear"?

Regards
Dan Lavry
www.lavryengineering.com

My personal preference is to just get a S/PDIF signal and use the "bit bucket" of my choice (in the field).  However, there are a lot of people here that like all the conveniences that come with all-in-one solutions. 

Like my Grace Designs Lunatec V3, I want another device that is at home in the field and in my rookie basement project studio.  But, one that is different enough to justify owning both (like a “clear, tube, transformer, or complex” feature).

--Michael

[JasonSobel]

Is there a general preference for separate pieces (pre, AD, memory...)? Is there a preference for "multi function gear"?

in general, the preference of most is "multi function gear".  many people use something like the Grace V3 or the Apoogee MiniMe for both the pre and A/D.  Just about everyone I know of who uses a Sound Devices 722 uses it for both A/D and storage (obviously).  And many people, for convenience, will run mics straight into the Sound Devices units and utilize the on-board mic pres, A/D, and storage.

on the other hand, there are also many people who think that a piece of gear designed for a specific function will perform that one function better than the "multi function" pieces of gear.  So you still get people running seperate pre-amps, seperate A/D's, and seperate recording decks.  but the general trend is combining functions into a single piece of gear.

[easy jim]

Off the top of my head, I would vote for:

1.  Able to be powered by 6-12V DC
2.  2 x Good Pre's
3.  Good AD
4.  S/PDIF out
5.  Analog out
6.  Provides phantom
7.  Rugged, yet small-ish enclosure (~6-9”L x ~6-9”W x ~2-3”H)
8.  Priced between $1-2K

--Michael

add to that:

-AES/EBU out (nice to have in addition to s/pdif, and more rugged)
-wordclock in/out for syncing with other devices
-field-functional metering

[Todd R]

Yep, echoing the sentiment that its great to see gear designers here!

In terms of needs, I'd agree that 4ch is probably not necessary.  Overall, there aren't nearly as many concert tapers doing 4ch, and those that do are often using a 4ch recorder.  However, to help with this, a word clock in (and/or word clock out) would be helpful.  Perhaps better still the ability to clock to an incoming spdif data stream, not just a word clock stream.

In terms of outputs, coax/rca spdif for sure, but an optical output would be helpful as some of the available recorders only have optical input, not coax (e.g., Sony D50).

[scb]

I am trying to figure out what the needs are for a portable unit, and it is not always as easy as it seems.
For example, I was thinking about a stereo unit, but reading some comments, there may be some preference for a 4 channel unit, which will obviosly must be bigger (more XLR connectors, more circuits...) , will require more power, will cost more... Then there is the question of the prefered memory: based on the posts, my guess was incorrect, laptops are not the prefered choice...

I appreciate the various comment but I still have much to learn regarding "the most desirable features" in portable recording, on top of best sound and product reliability.

Regards
Dan Lavry 

-Stereo unit
-dc power somewhere in the neighborhood of 6-12 volts
-lavry adc (the reason we're interested )
-with or without mic preamp .  obviously if it has a pre, that makes it more functional, but it would also drive cost/price up, drive power requirements up, and take up more space in the box.  if it sounded good enough and only was an a/d, you'd get some users, but a pre would probably get more interest from our "community" just because its 1 less box to carry around.  if there was a preamp, but the box also had the option to run line-in and bypass the preamp, this would probably be the ideal solution (though maybe not most practical).  i apologize for rambling...
-digital output (rca/xlr)
-balanced xlr input
-form factor around the same size of the grace v3, sound devices 722,  or mytek stereo 192 units

i'm sure i'm forgetting stuff, but these would be "the basics" in my opinion

[Dan Lavry]

I am trying to figure out what the needs are for a portable unit, and it is not always as easy as it seems.
For example, I was thinking about a stereo unit, but reading some comments, there may be some preference for a 4 channel unit, which will obviosly must be bigger (more XLR connectors, more circuits...) , will require more power, will cost more... Then there is the question of the prefered memory: based on the posts, my guess was incorrect, laptops are not the prefered choice...

I appreciate the various comment but I still have much to learn regarding "the most desirable features" in portable recording, on top of best sound and product reliability.

Regards
Dan Lavry 

-Stereo unit
-dc power somewhere in the neighborhood of 6-12 volts
-lavry adc (the reason we're interested )
-with or without mic preamp .  obviously if it has a pre, that makes it more functional, but it would also drive cost/price up, drive power requirements up, and take up more space in the box.  if it sounded good enough and only was an a/d, you'd get some users, but a pre would probably get more interest from our "community" just because its 1 less box to carry around.  if there was a preamp, but the box also had the option to run line-in and bypass the preamp, this would probably be the ideal solution (though maybe not most practical).  i apologize for rambling...
-digital output (rca/xlr)
-balanced xlr input
-form factor around the same size of the grace v3, sound devices 722,  or mytek stereo 192 units

i'm sure i'm forgetting stuff, but these would be "the basics" in my opinion

Thank you all for the inputs.

Does anyone use rca connectors? I like the robust XLR's which lock into place, and the XLR signal power level is at least 25 times stronger then SPDIF...

Any comments regarding the preferred memory technology would be appreciated. Are there problems with the robustness of hard drives in portable applications? (I tend to be very "protective" of my laptop, mostly the hard drive).   

Regards
Dan Lavry

[Colin Liston]

Any comments regarding the preferred memory technology would be appreciated. Are there problems with the robustness of hard drives in portable applications? (I tend to be very "protective" of my laptop, mostly the hard drive).   

Regards
Dan Lavry

Memory?  Are you considering making this a recording device also?  An all in one, preamp, AD converter and recorder?
If so, either CF (compact flash) or SD card would be my vote.

[easy jim]

Thank you all for the inputs.

Does anyone use rca connectors? I like the robust XLR's which lock into place, and the XLR signal power level is at least 25 times stronger then SPDIF...

Any comments regarding the preferred memory technology would be appreciated. Are there problems with the robustness of hard drives in portable applications? (I tend to be very "protective" of my laptop, mostly the hard drive).   

Regards
Dan Lavry

I also prefer XLR connectors over RCA, or BNC over RCA for s/pdif.  Adapter cables are not too hard to come by/make/have made, and robustness and durability are key values for field use.

Regarding memory technology, I use a 4 track hard drive recorder.  Most folks on here, I believe are using newer flash media (CF and SD cards) or dedicated hard drive recorders.  The Sound Devices 7xx series seems the benchmark/new standard for most, with the recorders (excepting the 702) all having both internal hard drives and CF card recording ability).  

The issue with the robustness of hard drives, especially with laptops, seems mostly a function of speed/cache, fragmentation, quality of internal shockmounting, and how much other crap (like Winblows OS, etc.) is also running that may cause the processor to run up against its limits and/or have write errors.  Couple this with recording loud amplified music, often in smaller venues with pumping subwoofers, lots of vibrations, and the potential for being bumped and spilled on by drunk attendees.

I use(d) a laptop for field multitrack recording, and now avoid it if at all possible.  I'll only go through what I view as the additional risk and hassle if I really need more than 4 tracks - which I've found is very often not the case for what I'm trying to do (represent the show more or less as it went down with the full ambience of at least one pair of open mics vs. a studio-like, polished-sounding full blown multitrack).  

[Dan Lavry]

Any comments regarding the preferred memory technology would be appreciated. Are there problems with the robustness of hard drives in portable applications? (I tend to be very "protective" of my laptop, mostly the hard drive).   

Regards
Dan Lavry

Memory?  Are you considering making this a recording device also?  An all in one, preamp, AD converter and recorder?

If so, either CF (compact flash) or SD card would be my vote.

I am very disapointed with the state of computer interfaces to audio. The new mac computers do have optical in and out, both are stereo spdif, and that is very cool. But most of the firewire and usb leaves a lot to be desired, with tons of issues regarding compatibility between various devices and operating systems... It is a mess! So I was very gld to read that CF and CD is being used here. The trouble is not about transfering data. The computer world is doing fine with data transfers, and the internet world does also does well at it. The mess is when trying to transfer data in real time, especialy with more channels.

My AD10 phisical outputs are XLR and optical (toslink), and I provide an adapter for users of rca connectors (XLR to RCA), but might as well consider a CF. How much capacity for stereo? I assume 24 bits and 16 bits are most common. Is 44.1KHz most common? Is 96KHz used alot in portable recording?

Regards
Dan Lavry 

   

[easy jim]

I assume 24 bits and 16 bits are most common. Is 44.1KHz most common? Is 96KHz used alot in portable recording?

Most of us here are recording 24 bits now, though some are still doing 16 bit considering that we are often recording PAs in substandard acoustical environments.

I personally run 24bit/48KHz most of the time, in part because I often record with HD video guys.  44.1, 48, 88.2, and 96KHz are all utilized by many of us.  Many, like myself, run at 24/48 or 24/44.1 most of the time, while others maximize the potential of their devices and run 24/96 (or 1bit/2.8 or 5.6MHz DSD format using the Korg MR-1 or MR-1000).

For those transferring old analog masters, with many looking at having high-end A>D converters in their signal chain, the ability to go up to 96KHz may be an important consideration (or 192KHz, or even DSD with the Korg devices).  With the FAT32 file size limitations, it is important - of course - that any device that offers the higher sample rates be able to 'seamlessly' split/create new files either at or near the 2GB point, or at some selectable, smaller file size.  3 hour long sets are not unheard of for some bands, and no one here wants to have a cut in their recording from having to swap out or manually start a new file on a flash card.

I'm sure I'm speaking for many in saying that we'd truly love to see a Lavry Pre/A>D device that would also record to high capacity flash media.  Many have been hoping to see that same thing from Grace Designs vis-a-vis their V3 Pre/A>D.

[Colin Liston]

I'm sure I'm speaking for many in saying that we'd truly love to see a Lavry Pre/A>D device that would also record to high capacity flash media.  Many have been hoping to see that same thing from Grace Designs vis-a-vis their V3 Pre/A>D.

Yeah, what he said.

[scb]

I am very disapointed with the state of computer interfaces to audio.

I gave up on computer interfaces when I got my Sound Devices 722 3 years ago.  I realized that the Sound Devices box did everything I needed it to (get 2 tracks to disk, via analog line in, microphone in, or spdif in) and the firewire transfer moves it right over to the computer.  It definitely saved the hassle of needing an actual computer, and has been much more reliable than any firewire or USB interface I ever owned

My AD10 phisical outputs are XLR and optical (toslink), and I provide an adapter for users of rca connectors (XLR to RCA), but might as well consider a CF. How much capacity for stereo? I assume 24 bits and 16 bits are most common. Is 44.1KHz most common? Is 96KHz used alot in portable recording?

Regards
Dan Lavry 

I think people record at 96khz simply because they can now.  If the box does it, why not record at the "best" (subjective, I know) possible rate?  It's at rates higher than 96hz that I think the reality of space vs sonic improvement sets in for many of us.  I can currently record at 192khz, but it just doesn't make much sense.  I usually stick to 88.2 or 96.  But portable boxes that do 96khz are commonplace, now

[mblindsey]

How much capacity for stereo?

Regards
Dan Lavry 

Credit to Rick in another thread for posting:

Recording Time using 8 GB SDHC card   
16 bit/44.1kHz : 755 minutes (Stereo), 377 minutes (4ch)
16 bit/48kHz : 694 minutes (Stereo), 347 minutes (4ch)
24 bit/48kHz : 462 minutes (Stereo), 231 minutes (4ch)
24 bit/96kHz : 231 minutes (Stereo), 115 minutes (4ch)
24 bit/192kHz : 115 minutes (Stereo)

http://taperssection.com/index.php/topic,97214.msg1342757.html#msg1342757

--Michael

[mblindsey]

I'm sure I'm speaking for many in saying that we'd truly love to see a Lavry Pre/A>D device that would also record to high capacity flash media.  Many have been hoping to see that same thing from Grace Designs vis-a-vis their V3 Pre/A>D.

Yeah, what he said.

I like where this is going....

[spcyrfc]

I'm sure I'm speaking for many in saying that we'd truly love to see a Lavry Pre/A>D device that would also record to high capacity flash media.  Many have been hoping to see that same thing from Grace Designs vis-a-vis their V3 Pre/A>D.

Yeah, what he said.

I like where this is going....

yep

[bgalizio]

I think the feature set of the SD7XX recorders is near ideal for our uses (wrt size as well) as far as all-in-one boxes go.

Just wanted to say that I enjoyed the interview in the newest TapeOP magazine!

[JWard]

When all I'm going to do is set up a stereo pair of microphones, I want nothing less than an all in one box.  Second best to that would be a preamp w/ADC and a reliable and cheap "bit-bucket."  The 702, to me, seems like the best machine out there. 

I think word clock I/O is highly functional, and allows the expansion of a 2-track recording device to a 4-track aggregate, thus I don't think a 4-track device is necessarily required.

I generally record at 24/48, although I think I may start doing more at 24/88.2

What I would want:
2 channels of preamplifier with phantom power, switchable to line level
AES/EBU I/O on XLR
S/PDIF I/O on RCA or BNC
balanced 1/4" analog outs
word clock I/O on BNC
records to compact flash
good metering
headphone amplifier that isn't lacking

[Dan Lavry]

When all I'm going to do is set up a stereo pair of microphones, I want nothing less than an all in one box.  Second best to that would be a preamp w/ADC and a reliable and cheap "bit-bucket."  The 702, to me, seems like the best machine out there. 

I think word clock I/O is highly functional, and allows the expansion of a 2-track recording device to a 4-track aggregate, thus I don't think a 4-track device is necessarily required.

I generally record at 24/48, although I think I may start doing more at 24/88.2

What I would want:
2 channels of preamplifier with phantom power, switchable to line level
AES/EBU I/O on XLR
S/PDIF I/O on RCA or BNC
balanced 1/4" analog outs
word clock I/O on BNC
records to compact flash
good metering
headphone amplifier that isn't lacking

Thanks for all the comments. I am looking at the many details mentioned here. I appreciate all the inputs.


Regards
Dan Lavry

[rowjimmy]

Dan,
The folks here have more than covered my sentiments but I did want to add that I, too, appreciate your taking the time to hear out the needs of our community.

Thanks.
jmh

[Dan Lavry]

Dan,
The folks here have more than covered my sentiments but I did want to add that I, too, appreciate your taking the time to hear out the needs of our community.

Thanks.
jmh

Thanks for the kind words. I am pretty sure I will have more questions. For now, I have more then enough to look up. It all takes time, but I would like to make some real high performance real robust unit, stereo micpre (with very clean phantom), AD and some memory.

Regards
Dan Lavry

[carlbeck]

Dan,
The folks here have more than covered my sentiments but I did want to add that I, too, appreciate your taking the time to hear out the needs of our community.

Thanks.
jmh

Thanks for the kind words. I am pretty sure I will have more questions. For now, I have more then enough to look up. It all takes time, but I would like to make some real high performance real robust unit, stereo micpre (with very clean phantom), AD and some memory.

Regards
Dan Lavry

AWESOME!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Build it & they will come

[MattD]

AWESOME!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Build it & they will come

In that vein, I'm tagging this thread. Dan has always been helpful with answering my questions in other forums. It's nice to see him here and to see everyone welcome him with open arms.

P.S. Mods - can we get a "subscribe to thread" option?

[muj]

please add a analog saturation effect..to round of digital overs/ clipping

[Gutbucket]

...In my opinion, there is too much of a gap between "ear people" and "technical people". The ear people insist that the ear is all that matters. So very often I see someone listening to something and mistakingly expanding their conclusions with far overreaching generalizations. I see technical people look at specs, not realizing that one can have an inaudible 1% distortion and an irritating .01% distortion...

So now you know what I think :-)

Another subscribing to the thread and expressing gratitude and thanks for your expertice, quality grear, attention to the needs of your customers and reasonable design philosophy, Dan!

There has been a good summary of the features desired by our needs outlined so far.  I will only add that if this product does end up including memory to act as an all-in-one phantom>preamp>ADC>recorder (SDHC support of 32 gig cards would be welcome), the ability to link a second unit in a master/slave arrangement so that one machine controls the recording functions as well as providing clock would be ideal.  That would provide an easy and attractive upgrade path for users starting with two track recording and adding the capability to run either two seperate identical 2-track rigs or link them for use as a 4-track rig.  Just control and clock data need pass between the two machines, each could record to their own media card.  That sould also be attractive to the sound for video and film guys that are the usual target market for most of this type of gear.

...Yes, a lot of people use their ears, and I am all for it. I am a musician (I play piano and accordion), and I use my ears. After all, music is for the ears :-)

Hear the one about the accoridan player who left his instrument locked in the back seat of his car and to his horror, returned to find the back window broken and his worst fears confirmed?

Two accordians in the back seat.

Regards and welcome to the forum.

[Javier Cinakowski]

If he builds the device that is described here, I think it will sell very, very well.....

[lek]

Interesting
I use a lavry blue ad and da for my studio, and I was thinking about adding the mic pre module and then sending it spdif to an m audio microtrack - of course the lavry would have to be connected to a wall outlet (though it's for recording my own band so I could probably handle that). The lavry blue is amazing, my favorite so far compared to mytek, crane song, apogee, benchmark. If it could be done in a small portable package combined with a flash recorder that would be great - at least until I can afford to roll my ampex atr102 to a gig!

[Dan Lavry]

Hear the one about the accoridan player who left his instrument locked in the back seat of his car and to his horror, returned to find the back window broken and his worst fears confirmed?

Two accordians in the back seat.

Regards and welcome to the forum.

As an accordion player (and piano), here is my favorite:

"Welcome to hell, here is your accordion..."

Regards
Dan Lavry

[Dan Lavry]

I checked the possibility of puting audio data on "memory sticks", and sadly enough, those devices are too slow for recording data in. A few of them are fast enough for an uncompressed playback at CD speed... 
Flash ram is great, but it does have it's limitations. Writing in (recording) must be preceeded by a process of earsing, which slows the whole thing down a lot...

That leaves us with other memory types. Looking at CF memory, I wonder what are the most popular formats for "putting audio" such on CF memory for use in portable gear? Does ALL the gear that comes with CF require the use of specific software to be installed on the computer? Is there some "generic" software driver for downloading the audio from CF to the computer? Clearly, one needs to know the sample rate and the bit length of the data...

I would appreciate answers to the question.

Regards
Dan Lavry

[carlbeck]

You do not need a driver or software to pull the "data" off the CF card since the recorder creates the wav file. Windows will recognize it as a .wav file & allow you to drag it on to your desktop, then you use what editing software you prefer.

[Gutbucket]

Most flash based recorders use either Compact Flash or SDHC card media with a FAT32 file format and write standard linear PCM files to the card as WAV extension files or BWF extension files (a broadcast wave format popular with news organizations and I suppose film & video people).  The exception is Sony which rope people into using their proprietary Memory Stick flash card format.  The cards can be removed and the data transferred to a computer via flash card reader like you would use for a digital camera.  Most if not all of the recorders feature a USB port which allows the recorder to act as a simple USB storage device when connected to a computer - basically a simple card reader to transfer files only, they do not function as a 'recorder' in USB transfer mode.  A few also use that USB connection to act as a 'real time' audio interface to the computer, but that is the exception to the rule. 

In general, people like non-proprietary formats-

• Compact Flash or SDHC media (preference usually depends on what cards the user already has for previous gear, SDHC is physically smaller)
  
• FAT32 file format for the media, which allows it to be read by any computer
• If the unit includes battery power, standard AA size Alkaline or rechargeable NiMH batteries are popular over internal Li-ion packs because they can be swapped in the field and bought at the corner store if needed.  If more or longer term power is needed, the appropriate DC-in jack for an external battery pack(s) allows the user to roll their own power depending on run-time requirements.
  

[modmike]

If FAT32 -- gapless 2GB splits Please

[Dan Lavry]

Thanks for the replies.

Using WAV files is fine with me, and USB is great for data transfer.
I also like non proprietary formats.

With real time transfer, I was under the impression that unless one is clever enough, Windows defaults to 16 bits. This is not exactly my area of expertise... But here we are just copying files so I would want to provide up to 24 bits, at sample rates from 44.1 to 96KHz. Of course, the user would have to know the bit depth and sample rate. Where is that information stored? Is it in the WAV file itself? I would hope such is the case. Or does the user "just knows" how the recorder was set up?
There is much here for me to be learned...

Regards

Dan Lavry

[mblindsey]

I've often wondered how difficult it would be for a manufacturer of a pre/ad to add the "storage" component to an existing device.  I mean, there are already companies building very small embedded Linux devices.  Here is one:

http://gumstix.com/platforms.html

Slap on the screen, expansion board for storage and some buttons.  It's making the leap from the output of the internal AD to something like the gumstix is where I get lost. 

The Rockbox folks have probably already written the code to write all the important file types, as well as, handle most all the other functions we care about.  I haven't gone through it, but it's here: http://build.rockbox.org/. 

inside one small case => {nice pre's > Larvy AD > gumstix running modified rockbox > flash}

Does this sound far fetched? 

--Michael

[Javier Cinakowski]

Of course, the user would have to know the bit depth and sample rate. Where is that information stored? Is it in the WAV file itself? I would hope such is the case.

yep, the wav file has a header that indicates bit depth and sample rate....  Whatever you record on your device will transfer to windows without problems

[Gutbucket]

Of course, the user would have to know the bit depth and sample rate. Where is that information stored? Is it in the WAV file itself? I would hope such is the case.

yep, the wav file has a header that indicates bit depth and sample rate....  Whatever you record on your device will transfer to windows without problems

and that file is transfered like any other data at a rate determined by the memory read & bus speed.  But only after it has been recorded in the WAV format with proper header info. Not in real time.

[it-goes-to-eleven]

Slap on the screen, expansion board for storage and some buttons.  It's making the leap from the output of the internal AD to something like the gumstix is where I get lost.

Yeah, so does M-audio.

[mblindsey]

Slap on the screen, expansion board for storage and some buttons.  It's making the leap from the output of the internal AD to something like the gumstix is where I get lost.

Yeah, so does M-audio.

+T

I forgot to mention that QNX is probably suitable for building the type of device I was mentioning:

http://www.qnx.com/products/middleware/multimedia.html

--Michael

[Dan Lavry]

I've often wondered how difficult it would be for a manufacturer of a pre/ad to add the "storage" component to an existing device.  I mean, there are already companies building very small embedded Linux devices.  Here is one:

http://gumstix.com/platforms.html

Slap on the screen, expansion board for storage and some buttons.  It's making the leap from the output of the internal AD to something like the gumstix is where I get lost. 

The Rockbox folks have probably already written the code to write all the important file types, as well as, handle most all the other functions we care about.  I haven't gone through it, but it's here: http://build.rockbox.org/. 

inside one small case => {nice pre's > Larvy AD > gumstix running modified rockbox > flash}

Does this sound far fetched? 

--Michael

Thanks for the post. Here are my initial thoughts:

The modules you point out seem to be aimed at very high speeds, at lower capacity. For audio storage, the speed for say 96KH stereo at 24 bits (which is really 6 bytes in "computer language") is near 600KB/sec. Given that one wants some margin, I would want at least 1MB/sec write speed. There is no need for 400MHz clock speed...
Also, there are all sorts of memory types. Most of the modules oriented for computer applications are volatile RAM. Volatile means the data is lost when you turn the power off, which is not good for a recorder. RAM means "random access memory", which is not needed for audio, because we "park the data" sequentially ("first come first served").
The type of memory needed is non volatile and sequential. The memory size of a standard CD (16 bits stereo at 44.1KHz) is around 650MB. So for the same CD length of time, at 24 bits you need 1/3 more, and for 96KHz 24bits you need around 2.5 times more memory... you are quickly approaching 2GB capacity...

Hard drives have huge capacity, but they tend to have limited life, and are a bit on the fragile side, though things have been improving a lot due to advancements in laptops. I like memory sticks and other flash memory technology, though they have their issues as well. With most memories, one can simply re write new data over the old data. But with flash, one needs to first erase the intended area (sort of like formatting the old floppy).

There are many other issues under consideration. It is not all that simple to design a digital device inside analog circuits.

It is always a challenge to put digital circuits near sensitive analog circuits, and with a mic pre, the challenge is the greatest. The electrical "environment" has to be extremely free of electrical interference.   
As a rule, digital circuits are "noise machines", which is not an issue for all digital gear, such as computers.
But it is an issue for converters and even more so for micpre's. When your micpre is set to say 60dB gain, an input signal of 1mV (from the mic) will be amplified by 1000  (you get 1V). Clearly a 1mV digital noise getting in to the input will yield a 1V of unwanted noise... It is always a challenge to put digital circuits near sensitive analog circuits, and with a mic pre, the challenge is the greatest.

There are many more considerations and issue, but the post is getting pretty long. As you probably expected, some of the issues have known solutions, others require innovation and/or a lot of care.

Regards
Dan Lavry     
www.lavryengineering.com

[Dan Lavry]

Of course, the user would have to know the bit depth and sample rate. Where is that information stored? Is it in the WAV file itself? I would hope such is the case.

yep, the wav file has a header that indicates bit depth and sample rate....  Whatever you record on your device will transfer to windows without problems

Thank you.

That is good news. I will look into the details of the format.

Does anyone use the Mac format (AIFF)? Does the Mac accept WAV files?

Dan Lavry
www.lavryengineering.com

[bgalizio]

Of course, the user would have to know the bit depth and sample rate. Where is that information stored? Is it in the WAV file itself? I would hope such is the case.

yep, the wav file has a header that indicates bit depth and sample rate....  Whatever you record on your device will transfer to windows without problems

Thank you.

That is good news. I will look into the details of the format.

Does anyone use the Mac format (AIFF)? Does the Mac accept WAV files?

Dan Lavry
www.lavryengineering.com

Mac audio editing software will accept WAV files.

[mblindsey]

Also, there are all sorts of memory types. Most of the modules oriented for computer applications are volatile RAM. Volatile means the data is lost when you turn the power off, which is not good for a recorder. RAM means "random access memory", which is not needed for audio, because we "park the data" sequentially ("first come first served").
The type of memory needed is non volatile and sequential. The memory size of a standard CD (16 bits stereo at 44.1KHz) is around 650MB. So for the same CD length of time, at 24 bits you need 1/3 more, and for 96KHz 24bits you need around 2.5 times more memory... you are quickly approaching 2GB capacity...

I was thinking that you would need both RAM and flash.  A small Operating System of some sort on EEPROM/flash (like on most portable multimedia devices...iPod, M-Audio Mircrotrack, Edirol R-09) that runs in RAM, and removable Flash to write the *.wav file to.  You'll need some form of an OS to display of recording time to a screen, start/stop writing of files, let user delete files, etc.

With most memories, one can simply re write new data over the old data. But with flash, one needs to first erase the intended area (sort of like formatting the old floppy).

Are you referring to the wear-leveling algorithms built into flash memory?  Most flash memory sectors can be written to a finite amount of times.  This causes problems for things like file allocation tables that get written to frequently.  Most of these devices act like they are normal IDE/ATA devices, and they abstract the fact that they are using a wear-leveling algorithm to write data evenly across the whole device.  I don't think you have to erase before you write. 

Side Note:  This has big implications for forensics on these types of devices as you may think you are overwriting a file when in reality the wear-leveling algorithm is writing your bits somewhere else on the drive...thus, leaving data you thought was overwritten still around for investigators to find. 

--Michael

[Dan Lavry]

Also, there are all sorts of memory types. Most of the modules oriented for computer applications are volatile RAM. Volatile means the data is lost when you turn the power off, which is not good for a recorder. RAM means "random access memory", which is not needed for audio, because we "park the data" sequentially ("first come first served").
The type of memory needed is non volatile and sequential. The memory size of a standard CD (16 bits stereo at 44.1KHz) is around 650MB. So for the same CD length of time, at 24 bits you need 1/3 more, and for 96KHz 24bits you need around 2.5 times more memory... you are quickly approaching 2GB capacity...

I was thinking that you would need both RAM and flash.  A small Operating System of some sort on EEPROM/flash (like on most portable multimedia devices...iPod, M-Audio Mircrotrack, Edirol R-09) that runs in RAM, and removable Flash to write the *.wav file to.  You'll need some form of an OS to display of recording time to a screen, start/stop writing of files, let user delete files, etc.

With most memories, one can simply re write new data over the old data. But with flash, one needs to first erase the intended area (sort of like formatting the old floppy).

Are you referring to the wear-leveling algorithms built into flash memory?  Most flash memory sectors can be written to a finite amount of times.  This causes problems for things like file allocation tables that get written to frequently.  Most of these devices act like they are normal IDE/ATA devices, and they abstract the fact that they are using a wear-leveling algorithm to write data evenly across the whole device.  I don't think you have to erase before you write. 

Side Note:  This has big implications for forensics on these types of devices as you may think you are overwriting a file when in reality the wear-leveling algorithm is writing your bits somewhere else on the drive...thus, leaving data you thought was overwritten still around for investigators to find. 

--Michael

I have designed with all sorts of RAM and various types of ROM in the last 30 years, but my experience with flash is limited. I do use flash memory inside my Altera CPLD to store operating parameters, which are user settable, and one does need to erase a whole sector before writing anything (even a single bit). You can alter a single 0 into 1, but can not alter a single 1 into a 0 (I may have it upside down but that does not matter). You must "reset" a whole sector to all 1's (or maybe it is all 0's) before you write into it.

Yes, there are limitations regarding the number of times you can re write. I believe the specific hardware I use allows over 10000 writes, and that is plenty good for parameter settings such as how many bits, what sample rate you use... You can change it 3 times a day for 100 years.... But such devices with so many cycles offer very tiny amount of memory, and are also very slow. Many of the larger capacity devices have far fewer cycles, and recording music may be done much more often then altering a converter setting such as - to turn on or off a "peak hold" function, an internal/external clock mode....

That "wear leveling" may be good when you have a lot of memory, and use only some of it at a time. But say you have 2GB and you use 24bit/96KHz stereo for an hour. You used half the space, and the next time you get to use the other half... The third time you are already rewriting...

So why not go for say 20GB with "wear leveling"? It may be great but there are tradeoffs - First, it would increase cost a lot, and second, it may increase power consumption, which is not ideal for battery operated gear. I am not making final decisions here, because I still have a lot to learn here, and the flash technology is evolving very fast.

I really like the little portable memory sticks. I can backup whole projects, stick the device in a usb port, and there it is, ready to work with… The cost of a 2-4GB device has gone way down in the last couple of years. Too bad that they are too slow for uncompressed music.

I also often work with other type novram (non voltile ram) that does not require pre erasing and offers almost endless cycles, at tiny power and good enough speed. There is tons of such stuff on the market, But the memory capacity is way too tiny.   

Regards
Dan Lavry   

[mblindsey]

What's your opinion of building a device that uses the QNX real time OS?

http://www.qnx.com/products/middleware/multimedia.html


--Michael

[scb]

But here we are just copying files so I would want to provide up to 24 bits, at sample rates from 44.1 to 96KHz. Of course, the user would have to know the bit depth and sample rate. Where is that information stored? Is it in the WAV file itself? I would hope such is the case.

the wav format stores bit depth and sample rate in the header info

check this site for info on the header format:

http://ccrma.stanford.edu/CCRMA/Courses/422/projects/WaveFormat/

[Dan Lavry]

What's your opinion of building a device that uses the QNX real time OS?

http://www.qnx.com/products/middleware/multimedia.html


--Michael

I do not know much about QNX.

I rather use some "plug in" portable small device, and whatever it may be, it should take the data in at "real time". I would like WAV (and possibly AIFF for the Mac), since it does not require special drivers to be installed.  When transferring the data from memory to computer, real time is not needed. In fact it would be best to go as fast as possible, as long as the transfer is reliable (that is a whole other issue).

Do you think the QNX offers something that I missed?

Regards
Dan Lavry

[mblindsey]

What's your opinion of building a device that uses the QNX real time OS?

http://www.qnx.com/products/middleware/multimedia.html


--Michael

I do not know much about QNX.

I rather use some "plug in" portable small device, and whatever it may be, it should take the data in at "real time". I would like WAV (and possibly AIFF for the Mac), since it does not require special drivers to be installed.  When transferring the data from memory to computer, real time is not needed. In fact it would be best to go as fast as possible, as long as the transfer is reliable (that is a whole other issue).

Do you think the QNX offers something that I missed?

Regards
Dan Lavry

I guess what I see are two possible options:

1.  Build a device that outputs both analog and digital out in the ways people have expressed they would like to get their output in this thread.  Your device would pretty much be in direct competition with the Grace Designs Lunatec V3 and Apogee's MiniMe (some others).  In this scenario, you wouldn't have to worry about providing storage, and I assume, would be quicker to market.  Buyer's would purchase a recording device that has either S/PDIF in or Line In that would write the file to removable media.  Most here have that already.

2.  Try to build a device that incorporates storage in addition to the pre's and AD.  I think this is more difficult.  I'm not an expert in this area, but I think you would have to incorporate some type of OS, be it embedded Linux, something custom, or something like QNX.  The embedded OS would be responsible for displaying things to a screen, play/stop/record/pause/ff/rw, writing files to a removable media, allowing a user to delete files, keeping track of/displaying time, possibly displaying levels, etc.  A device like this would possibly compete with the Edirol R-4/R-44/R-09, M-Audio Microtrack, Sound Devices 7xx, Korg MR-1, Marantz PMD 660, Fostex FR2-le, Tascam HD-P2/DR 1, and a host of others.  If you build the device in option number one, it would go in front of a device like those mentioned in the previous sentence to provide boutique pre's and/or AD.

I mentioned QNX because I know it to be a small, fast, extremely reliable OS that is used in critical commercial applications, and it looks like they are now branching into audio.  If I were building a recording device, I would look to something like QNX to keep development time to a minimum.

I don't want to discourage building an "all in one" solution, but if you want to use some "plug in" portable small device, and whatever it may be, it should take the data in at "real time"...you can do that by building a quality device that provides both analog and digital outs.  There are devices in the market that will take the feed and write the file in multiple formats to removable media in real time (see those in option #2).  I'm guessing that both option #1 and option #2 will probably sell well here.  I think people would be more excited about a quality "all in one" solution, though. <- warning!, opinion.

I'm not the only customer here, though...so, team..chime in and correct me where I've misspoken.

--Michael

p.s.  I'm no E.E/C.E, so I may be missing an obvious option that doesn't involve an OS, per se....well, this is where I get that free Internet education    

[taylordb]

Topping this just to keep my hopes up 

[eric.B]

code to write all the important file types, as well as, handle most all the other functions we care about.  I haven't gone through it, but it's here: http://build.rockbox.org/. 

inside one small case => {nice pre's > Larvy AD > gumstix running modified rockbox > flash}

Does this sound far fetched? 

--Michael

Thanks for the post. Here are my initial thoughts:

The modules you point out seem to be aimed at very high speeds, at lower capacity. For audio storage, the speed for say 96KH stereo at 24 bits (which is really 6 bytes in "computer language") is near 600KB/sec. Given that one wants some margin, I would want at least 1MB/sec write speed. There is no need for 400MHz clock speed...
Also, there are all sorts of memory types. Most of the modules oriented for computer applications are volatile RAM. Volatile means the data is lost when you turn the power off, which is not good for a recorder. RAM means "random access memory", which is not needed for audio, because we "park the data" sequentially ("first come first served").
The type of memory needed is non volatile and sequential. The memory size of a standard CD (16 bits stereo at 44.1KHz) is around 650MB. So for the same CD length of time, at 24 bits you need 1/3 more, and for 96KHz 24bits you need around 2.5 times more memory... you are quickly approaching 2GB capacity...

Hard drives have huge capacity, but they tend to have limited life, and are a bit on the fragile side, though things have been improving a lot due to advancements in laptops. I like memory sticks and other flash memory technology, though they have their issues as well. With most memories, one can simply re write new data over the old data. But with flash, one needs to first erase the intended area (sort of like formatting the old floppy).

There are many other issues under consideration. It is not all that simple to design a digital device inside analog circuits.

It is always a challenge to put digital circuits near sensitive analog circuits, and with a mic pre, the challenge is the greatest. The electrical "environment" has to be extremely free of electrical interference.   
As a rule, digital circuits are "noise machines", which is not an issue for all digital gear, such as computers.
But it is an issue for converters and even more so for micpre's. When your micpre is set to say 60dB gain, an input signal of 1mV (from the mic) will be amplified by 1000  (you get 1V). Clearly a 1mV digital noise getting in to the input will yield a 1V of unwanted noise... It is always a challenge to put digital circuits near sensitive analog circuits, and with a mic pre, the challenge is the greatest.

There are many more considerations and issue, but the post is getting pretty long. As you probably expected, some of the issues have known solutions, others require innovation and/or a lot of care.

Regards
Dan Lavry     
www.lavryengineering.com

[/quote]

great post.. thanks! 

[Colin Liston]

Bump to the top.

[anechoic]

I just do not know how many people with portable recording applications have a requirement for the highest sound quality.

film sound effects, ENG, video, etc.
I'd say the market is there and growing weekly as evidenced by the amount of portable digital recorders coming to market

[jerryfreak]

keep in mind that 8gb SDHC is like $10, and 16 and 32 gb  are cheap and common these days, so double or x4 those times for most users

sdhc is small, cheap, and efficient, is currently my media of choice (16GB in the size of a postage stamp, for $50 , and falling every day, are you kidding?!?) we dreamed about this years ago!

im sure sdhc is much cheaper to implement than a hard-drive that sucks power and creates heat.

a lot of people love the sound devices unit, but imo that unit could be improved if the cost savings from eliminating features like the (redundant) hard drive setup could be used toward better sounding conveters and pres. I'm big on simple, clean sound with LESS bells and whistles. 

How much capacity for stereo?

Regards
Dan Lavry 

Credit to Rick in another thread for posting:

Recording Time using 8 GB SDHC card   
16 bit/44.1kHz : 755 minutes (Stereo), 377 minutes (4ch)
16 bit/48kHz : 694 minutes (Stereo), 347 minutes (4ch)
24 bit/48kHz : 462 minutes (Stereo), 231 minutes (4ch)
24 bit/96kHz : 231 minutes (Stereo), 115 minutes (4ch)
24 bit/192kHz : 115 minutes (Stereo)

http://taperssection.com/index.php/topic,97214.msg1342757.html#msg1342757

--Michael

[jerryfreak]

most sdhc out there is typically 'class 4' or 'class 6' (4-6MB/sec minimum speed),

so with some buffering, they handle all commmon audio data streams fine

16/44.1 @ 2channel = 1411 kbit/sec= 1.411 mbit/sec = 0.176 MB/sec
24/26 @ 4-channel = 9216 kbit/sec= 9.216 mbit/sec = 1.15 MB/sec

SDHC is smaller and cheaper than compact flash, is plenty fast, and becoming more common every day

I checked the possibility of puting audio data on "memory sticks", and sadly enough, those devices are too slow for recording data in. A few of them are fast enough for an uncompressed playback at CD speed... 
Flash ram is great, but it does have it's limitations. Writing in (recording) must be preceeded by a process of earsing, which slows the whole thing down a lot...

That leaves us with other memory types. Looking at CF memory, I wonder what are the most popular formats for "putting audio" such on CF memory for use in portable gear? Does ALL the gear that comes with CF require the use of specific software to be installed on the computer? Is there some "generic" software driver for downloading the audio from CF to the computer? Clearly, one needs to know the sample rate and the bit length of the data...

I would appreciate answers to the question.

Regards
Dan Lavry

[jerryfreak]

well ideally, you are transferring the recorded wav file as a file, not real time. there is no resampling, reclocking, etc. if your device records 24/96, that is stored in the wav header, and its just a file copied via usb2 speeds. i dont know anybody that uses real-time playback to transfer from flash-based recorders.

in regard to developing software for writing datastreams, gordon needs to enter this thread.

Thanks for the replies.

Using WAV files is fine with me, and USB is great for data transfer.
I also like non proprietary formats.

With real time transfer, I was under the impression that unless one is clever enough, Windows defaults to 16 bits. This is not exactly my area of expertise... But here we are just copying files so I would want to provide up to 24 bits, at sample rates from 44.1 to 96KHz. Of course, the user would have to know the bit depth and sample rate. Where is that information stored? Is it in the WAV file itself? I would hope such is the case. Or does the user "just knows" how the recorder was set up?
There is much here for me to be learned...

Regards

Dan Lavry

[live2496]

On pocket pc's it has been my experience that CF cards and SD cards are both adequate. We have had problems sustaining 24/96 to CF cards, but I think this was largely due to the requirement of passing the data through a 16-bit PCMCIA interface to get the data to the storage device. (SoundDevice's recorders use CF cards.) 

On newer machines we have used 150x SD media with excellent results.

How does the user preference of sampling rate, etc get passed from the mic A>D to application software?
In our case it was a question of transmission over SPDIF. You can auto-detect the rate from the SPDIF stream (SPDIF receiver chips can do that), or you can let the user set it to whatever they want and require that the transmission rate and SPDIF receiver's rate match. I made a design choice to implement both. The user can lock onto the sampling rate of the transmitting chip or set it to a specific rate. If the application is expecting a specific rate and it's something different you get an error.