Marik
Pro Microphone Design
<I don't follow this, Marik. You can put the front end FET in a feedback loop by using a source follower circuit, which most will, but that only eliminates the FET distortions. I know of no way to put the physical capsule in a feedback loop and I'm puzzled by your statement that cleaning it up would make it sound like crap.>
Bob,
I don't know the way to put negative feedback around the capsule either. What I meant is a global feedback around preamp part of circuit. Yes, it will clean up the sound, but will make it sound very different, in a way I personally don't like in a microphone.
<BTW, harmonic and intermodulation distortion are two sides of the same coin. Any non-linearity that causes one will also cause the other. The nature of the non-linearity will affect the spectral distribution of the distortion products but you can't have one form of distortion without the other. There are types of non-linearities that make the harmonic distortion more or less benign but the IM distortion that results will still be offensive regardless of the nature of the harmonic distortion. Their magnitudes are pretty much proportional to commom factors but the harmonic can be clustered at frequencies relative to the fundamental that are less offensive. No such property exists for IM.>
It seems that people often use harmonic and IM distortions interchangably. Harmonic ones measure added tones or harmonics of single sinusoidal tone. The major consequence of non linearity is not the production of harmonics, but the production of intermodulation products--when two or more tones are present. But once again, I cannot tell which is which by ears.
<One big exception to this is the differrence between electrically and electret polarized designs and the electret is the winner in this regard. >
IMO high resistance graphite coated diaphragms, I was talking before, have the same properties, with two major advantages--1) weight of coating is absoulutely negligible, 2)the coating doesn't age.
Bob,
I don't know the way to put negative feedback around the capsule either. What I meant is a global feedback around preamp part of circuit. Yes, it will clean up the sound, but will make it sound very different, in a way I personally don't like in a microphone.
<BTW, harmonic and intermodulation distortion are two sides of the same coin. Any non-linearity that causes one will also cause the other. The nature of the non-linearity will affect the spectral distribution of the distortion products but you can't have one form of distortion without the other. There are types of non-linearities that make the harmonic distortion more or less benign but the IM distortion that results will still be offensive regardless of the nature of the harmonic distortion. Their magnitudes are pretty much proportional to commom factors but the harmonic can be clustered at frequencies relative to the fundamental that are less offensive. No such property exists for IM.>
It seems that people often use harmonic and IM distortions interchangably. Harmonic ones measure added tones or harmonics of single sinusoidal tone. The major consequence of non linearity is not the production of harmonics, but the production of intermodulation products--when two or more tones are present. But once again, I cannot tell which is which by ears.
<One big exception to this is the differrence between electrically and electret polarized designs and the electret is the winner in this regard. >
IMO high resistance graphite coated diaphragms, I was talking before, have the same properties, with two major advantages--1) weight of coating is absoulutely negligible, 2)the coating doesn't age.
