Topic: Nady DMP-2?

[gossling]

Would estimate it to be more or less noisy than the Zoom H4 or Microtrack preamps? Basically, would I be better off (in terms of noise) with:
Microphones -> Nady DMP-2 -> Recorder's line input
Microphones -> Zoom H4 XLR microphone input

Also, how much better do you think the ART USB Dual Pre is than the Nady DMP-2? The ART USB has signal-to-noise ratio "greater than 90 dB" according to its spec sheet.  Is this a good rating? Should I trust it?

Thanks (check PM beeco)

[taperwheeler]

Gossling,

I've noticed from your comments that you have yet to purchase external mics.  Mics are the most important element in how your recording will sound (location IMO is 2nd).  Have you considered mini condensers that only require 9v?  Church Audio and the Sound Professionals make great quality, fairly inexpensive mini mics that have a lot of functionality.  They also make low noise preamps that help to circumvent any shortfalls in on-board pre's. 
Don't rush your purchasing decisions.  This hobby/habit/lifestyle can get very costly, especially when you make uninformed and under researched buys (i've made my share!)  This place is great for advice and info and the live music archive is a great source to hear how diff equipment performs and sounds together.  Remember, there is give and take with all gear.  What matters is that you're happy with the end result.
Enjoy and good luck!

[nameloc01]

What kind of stuff are you going to (primarily) be recording? And what kind of mics are you planning on purchasing? If you are (primarily) planning on recording amplified music then-and while it wouldn't hurt- you probably wouldn't even *need* a preamp, if you're gonna be doing soft (acoustic) stuff, then sure, you may want one. Like someone said, you need to focus on the mics and- I see you mentioned phantom power- a quality portable power supply. A pre is not necessarily a "must-have", however, quality mics are.

[gossling]

Ok, I just ordered a pair of CAD M179 new off ebay (with a good return policy, of course).  They require either 24v or 48v of phantom power, but it says the phantom power needs to be "capable of delivering at least 8 mA."  Not sure what this 8mA means...

It is a large dual diaphragm microphone, so it should be relatively quiet (I've read it's quieter than the AKG 414...).  Here are the noise specifications:
# Signal to Noise Ratio: 85 dBA
# Self Noise: 10 dBA
# Maximum SPL: 148 dB

I'll be recording quiet music, mostly classical/jazz chamber.  So yeah, noise is definitely going to be an issue.  I will be recording in halls or churches with good acoustics, so I want some room sound, but overall, I'd like a more intimate sound (as the composer probably intended).  I am not exactly going to "close mic" the ensemble, but I don't want a third row audience's perspective either.

I linked a lute recording at the bottom of this post, just to show you what I'm after.  I'm perfectly fine with that much noise (skip to the end to hear some silence).  Am I looking at more or less noise with each of the various setups below? This is also the kind of sound I'm after (you can hear the reverb, but it's still intimate).  In general, I'm more concerned with depth and detail than noise, as long as the noise doesn't get in the way.  And I realize that "get in the way" is subjective, but to me, the noise in the lute recording, while audible, doesn't "get in the way" at all.  After all, hundreds of thousands of people have spent good money on Pablo Casals' recording of the Bach Cello suites (which I plan to record). 

1. M179 -> Rolls PB224 -> Tascam DR-1
2. M179 -> Nady DMP-2 / Art USB Dual Pre -> Tascam DR-1
3. M179 -> Zoom H4

I'm almost tempted to just go with option 3 and be done with it.  But I may need a preamplifier for live sound reinforcement anyway, so I might as well hit two birds with one stone (I apologize for the political incorrectness). 

Just a reminder, the Art USB Dual Pre has "greater than 90dB signal-to-noise ratio" according to their website and spec sheet, but I'm also looking at quite a bit of gain for this low-level classical music. 

Thanks

http://www.2shared.com/file/4466186/ce65b654/11_Konrad_Junghnel_-_Prludium_in_C_Monir_BWV999.html
(download by pressing "click here" at the bottom under the file url, next to "Save file to your PC:")

[nameloc01]

Milli-amp

[DSatz]

gossling, the Neumann KM 184 requires standard 48-Volt phantom powering, which has a tolerance (open-circuit) of +/- 4 Volts. In other words, if you measure at the XLR socket with no microphone connected, the allowable voltage range is 44 to 52.

The present-day version of the KM 184 draws 3.2 mA per microphone; the original version only drew 2.3 mA, but the present-day version is about 3 dB quieter so you get what you pay for.

The KM 184 uses a DC/DC converter to step up the supply voltage to around 60 Volts to charge the capsule. This DC/DC converter is based on an oscillator that puts out an AC voltage with a fundamental frequency well above the audible range under normal operating conditions. However, if you under-power the microphone, this oscillator's frequency will dip, and if the supply voltage is very low, it will fall into the audio range. The filtering within the microphone is of course designed to keep the oscillator's normal operating frequency out of the audio; it's far less adept at blocking lower frequencies. So if your powering falls severely below spec, the oscillator's whine can definitely become audible.

You can get a whiff of this if you shut off the phantom powering while leaving the gain turned up with one of this type of microphone connected--it's interesting, but it isn't pretty. Don't cut corners with microphone powering; every microphone has a particular powering method that it was designed for, and it strikes me as rather insane to pay top dollar for good microphones and then nickel-and-dime oneself out of getting the best performance that they're capable of.

--best regards

P.S.: Signal-to-noise specifications for microphone preamps are generally dynamic range specifications--they tell you the amount of residual noise that you'd expect to find in a signal at the full maximum output level of the preamp. A 90 dB signal-to-noise ratio for a microphone preamp is a strikingly poor specification.

P.P.S.: Most small, portable preamps and phantom power supplies that I've tested are NOT capable of reliably powering a pair of condenser microphones that draw 8 mA apiece. It's true that the IEC standard gives 10 mA as the maximum allowable current per microphone, but most professional condenser microphones consume 5 mA or less, and even that is beyond the capacity of quite a few portable power supplies, preamps and recorders I've tested. For many years the maximum current was specified at only 2 mA per microphone, and there's a lot of equipment that can barely keep up with that amount.

[gossling]

So I probably shouldn't use the CAD M179 for portable field recording without wall power? Should I simply avoid phantom power requiring microphones in general and go straight into the Tascam DR-1/GT-R1? The thing is, most low-end (<$400 for a pair) microphones I've read about that are good with bowed strings are condensers that require 48v.  I have read that the MXL 603s works with the Zoom H4, so I'm guessing its power specifications aren't dreadfully high. 

If 90dB is poor, what's a solid budget spec for signal-to-noise in preamps? Remember, depth and detail are more important to me than noise floor.  Just so you know, the spec is "greater than 90 dB (Ref 0 dBu)."

Not at 10dBA, it won't be.  Ambient noise, however, you must always deal with; that depends on the venue and whether or not there is an audience.

What do you mean? Sorry, I'm still pretty clueless...

Ok, so I did some research regarding the USB Dual Pre...correct me if I'm wrong:
current (mA) = voltage (v) / resistance (k ohms)
12mA       = 48v / 4k ohms
So, in theory, the Art USB Dual Pre should deliver 12 mA, right? But this is relying on their own spec sheet, which should not necessarily be trusted. 

So I did a little more work:
It can be run with 100% efficiency on a 9v battery (~500 mAh capacity), and the battery lasts approximately 20 hours with phantom power (according to their specs). 
Battery capacity (mAh) = time * draw (mA)
500mAh / 20 hours = 25mA draw

Is 25mA enough to power two microphones and amplify their signal? If 18mA is being used to just power the microphones, that only leaves 7mA for whatever else it has to do.

Is there any way to tell if your microphone is running optimally? mshillarious mentioned that a microphone may work, but not to its potential under less-than-optimal conditions.  Is there any way to detect whether or not the microphone is just getting by? I'm afraid that when I test the CAD M179s with a given preamp, they may work, but I may never know that they could sound better with adequate power.  I really think that the CAD M179s are the best microphones sound-wise for my situation, but if they require too much power, I guess I won't be able to use them.

Thanks for all your help.

[DSatz]

gossling, I mainly use a kind of condenser microphone that draws more current than some others do. It's only half as much as your CADs, but I still can't plug them into a fair number--perhaps the majority--of small, portable preamps and recorders that are out there. I always need to test ahead of time to make sure.

If you really like your CAD microphones then I think you're in the same boat, only more so. I haven't tried them myself, but I can sympathize completely with feeling that you've found the mikes that you want to use for the foreseeable future, and that if there are technical obstacles, well, then, you'll just deal with them as they come.

In this case the problems aren't insurmountable or even very complex, but some extra care and attention will be required.

--best regards

P.S.: As for signal to noise ratio, I think you'll find that most professional microphone preamps aren't specified the way most domestic hi-fi, public address and musical instrument gear is specified. To some extent, the fact that you're quoting signal-to-noise ratios is symptomatic of looking at equipment that isn't professional audio equipment in the first place.

[gossling]

mshillarious mentioned that it may work better in 24v mode.  How does this work? Would this be a possibility for me?

Here's a quote from another forum:
"I bought [the H4] for the XLR inputs and plugging in a CAD M179 for vocals and using the pickup through a Baggs PADI worked very well."  Worked for him...but maybe it wasn't working optimally and he didn't even know it?

I really want this microphone to work.  Are there any options I'm overlooking?
Thanks

[DSatz]

gossling, 24-Volt phantom powering exists only in a netherworld or even a non-world. By the time it was first described in the IEC standard, 12- and 48-Volt powering had already been established for decades. Only a few microphones were ever built that could take advantage of it; even that support was always as a "plan B" type of thing as your case illustrates, since no commercially available preamps, mixers or recorders ever offered it (to my knowledge). There was simply no incentive to add the extra switch and circuitry, or for engineers to deal with the added complexity.

The whole idea of standardized phantom powering was to do away with the bad old days in which a U 47 required its own special power supply and cable while the M 49 required a different supply and cable, and a U 67 had a different supply and cable from either one of those--and finally all the KM 54s and 56s and 64s and 66s and M 221 Bs used the same cables and supplies as each other, but those were still different from the other three types. Last I heard, 24-Volt phantom will be eliminated from the standard, except as a historical footnote.

Upshot is, you could build (or get someone to build) a 24-Volt phantom power supply for your microphones. That's easier than building a heavyweight 48-Volt supply, and might be a good solution for you in the short term--just think of it as a dedicated power supply for those particular microphones, as if they were U 67s.

--best regards

[gossling]

What I think he meant was that the H4 may be able to power the CAD M179 better in 24v mode (which the recorder has for some reason).  The CAD M179 are relatively quiet microphones, so I may be able to tolerate the somewhat noisy preamps of the H4. 

[stantheman1976]

http://www.mbbchurch.com/mbbcmedia/Tis_So_Sweet_To_Trust_In_Jesus(8-1-2007).mp3

This song is a SBD+MIC mix.  It was JM27's>Nady DMP-2<Hosa adapters>laptop.

I don't have the individual tracks anymore. 

This was in a large church with the mics on stage about 5' high at about 6-8' in front of the performers in DINish config.  There is also added reverb on the SBD track.