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Author Topic: Question On Specs  (Read 3347 times)

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stevetoney

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Question On Specs
« on: December 09, 2014, 02:00:21 PM »
I'm not a wiz-bang on gear specs...in fact they're damn confusing to me.  I was recently asked a question that I feel like I should know the answer to, but I don't.  The question wasn't exactly, but went basically like this...

So, I have two preamps and two recorders.  The preamps are a Sonosax and Tinybox (latest version) and the recorders are an XLR-based four channel Tascam DR70D and a handheld Sony m10 which of course has 1/8 inch line in and mic in jacks.  Assuming the same mics for both rigs, if I were to set the two preamps to the same setting and go 'line in' on either of the recorders, would I expect to see similar levels on the recorders no matter which preamp is used?   
« Last Edit: December 09, 2014, 02:27:50 PM by tonedeaf »

Offline DSatz

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Re: Question On Specs
« Reply #1 on: December 09, 2014, 07:45:01 PM »
tonedeaf, if both preamps receive identical microphone signals at their inputs, and are both set for the same voltage gain (in decibels), then the same voltage levels should appear at both of their outputs. That part of the puzzle is fairly straightforward.

But any two different recorders will almost certainly differ in the sensitivity of their inputs, unless you purposely set their recording level controls so as to make their sensitivities the same. You could take a tone generator that's putting out a certain fixed voltage, and connect it first to the inputs of one recorder, then the other recorder, and on both recorders adjust the record level knobs so that they both register the same level on their meters when the tone generator is feeding them, e.g. 3 dB below full scale (assuming that both recorders have true peak-reading meters, or meters with other characteristics as long as they're both the same).

The thing is, it's unlikely that you'd want to set your record level controls that way in an ordinary recording situation. You'd do it if you were conducting a experiment in which you needed the same recording levels on both recorders--but after lining up the sensitivities of the two recorders with the tone generator, you might find that one of their record level knobs was set near the middle of its range while the other knob was set close to one extreme or the other--not a good situation to be in. This is because in the world of consumer electronics, there's no standard voltage, at the mike or line input of a recorder, that everyone agrees should drive that recorder to any particular level in terms of dB-below-0 on the meter.

Does this make sense, and does it answer your question(s)?

--best regards
« Last Edit: December 09, 2014, 07:50:28 PM by DSatz »
music > microphones > a recorder of some sort

stevetoney

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Re: Question On Specs
« Reply #2 on: December 09, 2014, 09:33:27 PM »
Does this make sense, and does it answer your question(s)?
It does make sense.  Thank you!

Offline F.O.Bean

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Re: Question On Specs
« Reply #3 on: December 10, 2014, 02:59:23 AM »
Tonedeaf, I'm in the same boat! I even went to Electronics school back in 2001/2002, and technical specs still confuse the hell out of me ;) But if you give me any gear, I'll make it work 8) I wish I did know more about specs and whatnot! I'm starting to learn ohms law all over again since I NEED to know it with regards to my vaping hobby and building my own microcoil with kanthal!!! As always, DSatz helped explain it in layman's terms!!!
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stevetoney

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Re: Question On Specs
« Reply #4 on: December 10, 2014, 09:08:56 AM »
The thing is, it's unlikely that you'd want to set your record level controls that way in an ordinary recording situation. You'd do it if you were conducting a experiment in which you needed the same recording levels on both recorders--but after lining up the sensitivities of the two recorders with the tone generator, you might find that one of their record level knobs was set near the middle of its range while the other knob was set close to one extreme or the other--not a good situation to be in.

FWIW, the reason I asked this question is that I've had a fairly lengthy conversation going on with another ts.com member who's undergoing some gear changes.  He got a new DR70d and was confused why his levels, all things equal, were wildly different than the levels he was getting on his m10.  My initial answer was that isn't unusual and it's not a surprise, but I couldn't explain why even though I knew the answer lies in understanding recorder specs. 

The technical parts of my brain wants additional detail on how to interpret recorder specs in the context of the above, but honestly you answered the question so please don't go there unless you feel like killing some time.

Thanks again for your help.

Offline bombdiggity

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Re: Question On Specs
« Reply #5 on: December 10, 2014, 12:15:53 PM »
Theoretical physics  ???

The results may have practical import but as noted differences in circuits and construction and nominal scales will mean there isn't comparability between manufacturers in this stuff.  As noted in other threads from time to time "line-in" does not even necessarily mean a straight unprocessed signal.  Most of those cross the pre-amp circuitry too. 

Gear:
Audio:
Schoeps MK4V
Nak CM-100/CM-300 w/ CP-1's or CP-4's
SP-CMC-25
>
Oade C mod R-44  OR
Tinybox > Sony PCM-M10 (formerly Roland R-05) 
Video: Varied, with various outboard mics depending on the situation

stevetoney

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Re: Question On Specs
« Reply #6 on: December 10, 2014, 01:59:31 PM »
As noted in other threads from time to time "line-in" does not even necessarily mean a straight unprocessed signal.  Most of those cross the pre-amp circuitry too.

I was really surprised when I read a ts.com post that someone's inquiry directly to Sound Devices confirmed that the line-in setting on the Sound Devices 7XX series doesn't bypass the pre-amps.   

Offline Gutbucket

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Re: Question On Specs
« Reply #7 on: December 10, 2014, 03:54:41 PM »
Theoretical physics  ???

Nah, just straight design engineering.  The problem is the published specs, user documentation, and actual unit markings on the machines are more often handled by the sales & marketing departments.  Actually the real source of the problem is that the target customer for these devices doesn't care what the actual specs are.  They just want an inexpensive recorder which fits their mental concept of "good", sounds decent and works reliably, whether it's actually measurably good or not.  And there's nothing wrong with that.

Specs for gear marketed to professionals is usually much better documented, or you can at least contact them and actually find out what ever you need to know.  But determining the usage specs for gear sold to the prosumer or enthusiast market or whatever one cares to call it more often than not comes down to someone with decent test gear getting a hold of the recorder, bench-testing it, and posting the applicable specs here or on some other website.

In general, we as tapers land somewhere between the pro users and the point-n-shoot commercial users, both in the specifications useful to us and in our understanding of them!

As noted in other threads from time to time "line-in" does not even necessarily mean a straight unprocessed signal.  Most of those cross the pre-amp circuitry too.
I was really surprised when I read a ts.com post that someone's inquiry directly to Sound Devices confirmed that the line-in setting on the Sound Devices 7XX series doesn't bypass the pre-amps.

What is a "straight unprocessed signal"? a direct pin-in to the ADC? 
Refer to it as an "input buffer with gain" rather than a "preamp section" if that makes you feel better about it.

When I see "line-in"  that says to me, "an input which does not provide any sort of microphone powering, typically for a source with an output level that can be higher than a typical microphone level input".  To figure out how hot that input signal can be, or where the input noise floor is, or how the input sensitivity relates to another piece of equipment, I need the specs.  I don't care what's inside, only it's parameters, how it sounds, its reliability, etc.

It's is actually an ironic confirmation of all this stuff.  What truly maters for us as end users is the actual performance specs, partly just for proper interfacing of gear, but those things are described by numbers and terminology which many end users don't  know how to interpret.  What doesn't really matter at all very much is how it's achieved- the engineering stuff and whatever labels describe the circuitry inside.  So what if it bypasses preamps, uses discrete transistors, thermionic valves, magnetic core memory, trained circus fleas on miniature hamster-wheels or whatever.  Well, the design engineers care, the circuit-geeks do, the recorder company accountants do, but the end user shouldn't really give much of a hoot as as long as the thing works to specification, sounds good, and is reliable.  It quickly degrades in to audiophile bs of what people think is important when it isn't necessarily- "this one uses such-and-such a chip, with a discrete "blah, blah, blah" wired with pure-silver twisted unicorn hair insulated whatevers. 

Eh, whatever.  I guess I'm just not a very good gearslut at heart.  I dig the recordings way more than the gear.  Measure it, listen to it, beat it up.  If it does the job well, reliably, and predictably who cares what's inside?
« Last Edit: December 10, 2014, 03:57:01 PM by Gutbucket »
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<<

Offline 2manyrocks

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Re: Question On Specs
« Reply #8 on: December 10, 2014, 05:56:57 PM »
I'm okay with whatever internal electronics might be used, but could we please skip the trained circus fleas? 

Offline bombdiggity

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Re: Question On Specs
« Reply #9 on: December 10, 2014, 07:28:25 PM »
While I agree in the end it can become pure silver twisted unicorn fur insulation I've learned in trying to better understand what the specs are and what they mean.  I don't fully understand most of it and I don't record in a conventional manner relative to the most widely adopted practices (such as they may be) but I nearly always like what I get and that is a lot better than what I got before I started reading here (though some YS gear may be a bigger driver in that than most other factors!).  The gear I bought based on my hearing of the results.  The recording I do is based on my expectation of what I'll hear in the results.  So in the end it comes to one's own taste and ears.  Some differences of specs we can hear, others we can't...  I'm happy if I can get there and roll from where I want to. 
Gear:
Audio:
Schoeps MK4V
Nak CM-100/CM-300 w/ CP-1's or CP-4's
SP-CMC-25
>
Oade C mod R-44  OR
Tinybox > Sony PCM-M10 (formerly Roland R-05) 
Video: Varied, with various outboard mics depending on the situation

Offline Gutbucket

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Re: Question On Specs
« Reply #10 on: December 10, 2014, 11:38:21 PM »
Heavens no, we need those fleas! The magic manifests through strongly regimented gymnastic flea training.

It used to be minute carny knat dropouts toiling away in analog portable decks imparting spitty grunge, eating ferrous oxide dipped corndogs while operating the steeple-chase ride tape-guide. Substitution of cold digital highly-trained surface-mounted circus fleas introduced warmth and air via their dynamic high sample-rate flatulent gas saturating the excess headroom. Cue the circus flea drum roll.. "pbpbpbplt!"  Digit?

[edit- my apologies, it's been a rather odd day.  Thankfully there are members here who are able and willing to enlighten our  flea-brains by helping to interpret the Greek of specs when we need help.  Major thanks to each of them!]
« Last Edit: December 10, 2014, 11:51:58 PM by Gutbucket »
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<<

stevetoney

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Re: Question On Specs
« Reply #11 on: December 11, 2014, 12:30:36 PM »
The Who's from Whoville would be pissed that people give all the credit to fleas, except they're Who's and they don't get pissed about anything. 
« Last Edit: December 11, 2014, 12:32:31 PM by tonedeaf »

stevetoney

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Re: Question On Specs
« Reply #12 on: December 11, 2014, 03:41:55 PM »
^ Amazing response.  Thank you so much Jon. 

When you say 'maximum signal the unit can handle' just means that the output won't be a clean sound?

 

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