How do I measure the quality of a pre-amp?

David W. Jones said:
I use my dog for that kind of testing. ;)

Bark once if it sounds good, twice if it sounds bad.
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Unfortunately I've not been able to train our dog to do this... yet... however, she is pretty good at identifying 'dog barks' under several layers of Sound FX. She also seems to on occasion bark at the character who eventually is shown to be 'The Bad Guy'... And then there are four legged animals which get barks, especially horses and of course dogs...

But unfortunately she doesn't seem to be able to pick out TV shows that will be the most popular during the season... but then... we don't watch over-the-air broadcasts, nor cable TV... so, perhaps that's an unknown talent.

As it is, the Wife is pretty good at determining whether a sound system is any good... I have to turn up the volume so loud for her to hear, that any 'defect' is readily apparent...
 
TheDingo said:
...But what if what you are trying to find out is beyond the limits of your own hearing?
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This comes back to the "you pay for what you get" statement. I know a sound devices recorder is going to be much quieter than a zoom. When it comes to anything with A/D converters or pre-amps, you can't cut corners. The good stuff still costs good money. Even then, all you really need to do is look at a spec sheet to get this info, assuming the manufacturer has published these specs.
 
davefisk said:
Even then, all you really need to do is look at a spec sheet to get this info, assuming the manufacturer has published these specs.
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I find that spec sheets and reality often don't mesh, where things look great on paper but don't perform that way in real world situations.

For example, the compact Sony PCM-M10 recorder has a great reputation on the web, where it has almost a cult following on the TapersSection.com website. So I bought one to give it a try, and was pretty disappointed by the noise-level of the mic pre-amp when I tested it...

Sony PCM-M10

RMS MIC NOISE FLOOR

MIC LEVEL 2 : -75 dB
MIC LEVEL 4 : -72 dB
MIC LEVEL 6 : -60 dB
MIC LEVEL 8 : -51 dB
MIC LEVEL 10 : -49 dB

I consider an RMS noise-floor of -60 dB to be the absolute minimum you can get away with and still make a noise-free recording, and the PCM-M10 is barely able to reach -60 dB at the half-way point with it's mic pre-amp. ( it holds steady at -75 dB when recording LINE level audio )

Now I'm sure if I check the Sony specs for this recorder, it won't give me any indication that this recorder will start to sound noisy at the half-way point of it's mic pre-amp.

The Tascam DR-100 has the same story when it's mic pre-amp gain is set to the HIGH setting. It's not as noisy as the Sony PCM-M10, but it's not far behind.

Tascam DR-100 MK2

RMS MIC NOISE FLOOR : MIC GAIN = LOW

MIC LEVEL 2 : -83 dB
MIC LEVEL 4 : -84 dB
MIC LEVEL 6 : -84 dB
MIC LEVEL 8 : -83 dB
MIC LEVEL 10 : -84 dB

RMS MIC NOISE FLOOR : MIC GAIN = MED

MIC LEVEL 2 : -83 dB
MIC LEVEL 4 : -83 dB
MIC LEVEL 6 : -83 dB
MIC LEVEL 8 : -80 dB
MIC LEVEL 10 : -79 dB

RMS MIC NOISE FLOOR : MIC GAIN = HIGH

MIC LEVEL 2 : -79 dB
MIC LEVEL 4 : -72 dB
MIC LEVEL 6 : -63 dB
MIC LEVEL 8 : -55 dB
MIC LEVEL 10 : -53 dB

...So based upon RMS noise-floor tests, I would only use the Sony PCM-M10 recorder for LINE level work, and the Tascam DR-100 MK2 is very quiet as long as you stay away from the HIGH gain setting.

Going just by the specs I would have no idea of the real limitations of these two recorders, or how to get the best out of them.

I don't trust any specs that I can't verify for myself, as there are too many companies that fib about the details. :-)
 
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