[quote title=Klaus Heyne wrote on Tue, 07 March 2006 02:26]Three considerations to add to the discussion:
Hi Klaus,
"1....Serious capsule distortion sets in very late, at very high volume levels…."
I came here asking what to expect in terms of max and min “rest” capacitance (no sound),
And what to expect the variations in C (capacitance) to be. I do not know what “very late” means (for me, late is a term I use for time related issues). I assume for now that you mean very loud. Yes, the louder, the more non linearity, but I would not “write is off” so fast. Yes, with say 50pf +/-10pf you get huge distortions, but at 50pf+/-1pf you get pretty high distortions also. What is high? Say high compared to mic pre’s power amps, converters… most gear.
"2. If distortion cannot be heard, but measured, is it relevant in microphone applications?"
A distortion will not be heard when it is a very low amplitude distortion. It can not be heard when it is in a frequency range we can not hear.
The distortion mechanism I am addressing is high enough amplitude, and certainly at hearing frequencies (second, third, forth….). Of course “distortion being heard” is all in reference (comparison) to the original sound, just before it came into the microphone.
"3. Is a distortion-free microphone automatically preferable to the listener to one with, let's say, 0.5% or 1% THD?"
That is a subjective issue. Some people like tube sound because they like that specific distortion sound.
Personally I am into minimal distortions, I like to have the ability to capture the sound (air vibrations) in the performance space as close as possible, and play it exactly the same (as much as possible) in my living room - the exact same air vibrations. That means 0 distortions. Of course I accept the fact that mastering and recording engineers add sonic alterations (EQ, compression reverb....) but such alterations are DELIBERATE ARTISTIC DECISION that vary from song to song... I personally do not like to be "stuck" with some given distortions, because while one can add distortions, taking them out is not even possible.
But the question you raise is regarding distortion that is “preferable to the listener to one with, let's say, 0.5% or 1% THD”. The question is too open ended, because there are INFINITE POSSIBILITIES to have 1% distortions. One can have 1% at 20KHz, or 1% at 3KHz, you will hear the later much more. One can have 1% spared over all the harmonics, with all sorts of “patterns”.
Here I am talking about a specific type of distortion, all the harmonics are there and they decay linearly, a rather unique sonic “signature” of a condenser mic.
At this point, all I am saying is: The condensers, right from the start (the concept, the operating principle) has a specific sonic signature. I most often use condensers for my music band. I do not have better options. I did not analyze dynamics. My guess is that they have their own mechanism yielding a unique sonic signature.
I do not think there is such a thing as “distortion free mic”. I am just talking about a fundamental distortion mechanism that is directly related to condensers. Knowing and understanding the operating principles is the first step towards lowering the distortions.
Do you want lower distortions? Do you like the sonic signature of a condenser? That I can not answer. But is you wish to “check it out”, you could try some comparisons with and without some small fixed capacitor in parallel, a tradeoff between amplitude and linearity. If you do, please let us know your opinion.
If you are really interested in experimenting, I will be glad to contribute a LavryBlue micpre, a very low distortion (and noise) unit, thus ideal for such tests
Regards
Dan Lavry
www.lavryengineering.com