AW: [sdiy] Crazy idea to improve transient response?

[Nils Pipenbrinck]

Glen wrote:

> I have an idea for improving transient response of a few things. For
> example, let's say you have a condenser mic with excellent transient
> response, but a very poor S/N ratio. At the same time, you have a dynamic
> mic with poor transient response, but a *much* better S/N ratio than the
< condenser mic. Why not use both mics, and let a circuit rapidly crossfade
> from the dynamic signal to the condenser signal on loud signals (ie,
< transients) only? (This assumes that both mics are placed in perfect
> physical alignment, and offer the same phase response to your incoming
< signal of interest.) I'm thinking of something that would operate very
> quickly and "crossfade" in and back out again--even on a single waveform
> peak, if that peak exceeded a certain threshold.

I think this wouldn't work. The mics will pickup the signal with a slightly
different phase (due to placement, the cable, the preamp ect. all this adds
to the phase-response. Furthermore the moving parts within the mic itself
have their characteristic resonance peaks. You can pickup something with two
identical mics and identical equipment, but the result will never be the
same signal.

You can try it out and simply mix two mics together. Some fixed frequencies
will cancel out and add, just like a static phasing effect (that does not
mean it has to sound bad. Infact there are a lot of sweet spots where the
phasing gives you a great tone. A lot of guitar-tones are done this way. On
the other hand you can get really bad recordings. Might be one of the
reasons why microphone placement is an art).

Anyways, if you fade between two inputs based on one input signal you'll
call for trouble. The notches will start to move around. What you do is to
mix two amplitude modulated, phase-shifted signals together. This will give
distortion.


(OTOH I might be completely wrong)

  Nils