Re: Pink noise filtering
Re: Pink noise filtering
- Subject: Re: Pink noise filtering
- From: "James Chandler Jr" <email@hidden>
- Date: Fri, 17 Nov 2006 09:06:28 -0500
It used to be difficult to make a good, quiet phono preamp for a few bucks of
parts. Maybe that has recently changed, dunno. In the past it was pretty common
for cheap phono preamps in such items as Radio Shack 'brick' phono preamps or DJ
mixers, so noisy they sound like a waterfall.
If it is noisy electronics in your preamp- semiconductor and resistor noise-
then removing the RIAA EQ would probably only get you white noise rather than
pink noise. Removing the RIAA EQ could be difficult. Often the EQ is an integral
part of the preamp circuit design, rather than an add-on stage.
As Herbie said, you could try some kind of software noise gate. A 'downward
expander' dynamics processor.
Or maybe a software 'burwen' single-ended noise reduction. The sliding lowpass
filter in a burwen only passes high-frequencies when there is sufficient
high-freq content in the signal to hopefully mask the noise. A burwen is a
downward expander which modulates low-pass filter cutoff frequency rather than
broadband amplitude.
Perhaps spectral noise reduction would work better. Spectral noise reduction is
more cpu-intensive, and won't necessarily sound better than a simple noise gate.
Spectral noise reduction can work near-miracles if the noise is not very loud.
But if the noise is too loud, spectral noise reduction can make a chirpy mess
that is worse than the original noisy signal. You could look for a spectral
noise reduction plugin to test against your recordings.
I once wrote a phono de-click plugin which has optional software RIAA EQ, and
found that the mic/line preamps in some of the inexpensive desktop mixers, such
as Mackie or Behringer, can have better noise characteristics than cheap phono
preamps. It depends on how well the impedance of the mixer preamp gets along
with the impedance of your turntable, which is the 'luck of the draw'.
If your usb interface also has line inputs, perhaps running the turntable thru a
cheap mixer preamp, and applying software RIAA EQ, MIGHT improve the results.
JCJR
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