Does anyone know the curve that the Edirol R-09 "low cut" switch removes? The most I could find was GuySonic's review that stated it was a steep curve that started at 185Hz.
I accidentally recorded a show with this switch engaged and I'd like to try to apply an EQ curve to attempt to get some of the "oomph" back. Even though it was an acoustic/solo show, it still sounds pretty thin.
I can't beleive that this hasn't been asked before, but after an hour searching here and google, I found nothing. If no one knows, I'll try to get the info from Edirol.
Later,
pjdavep
I am guessing that you could estimate this. Make a file with a bunch of test tones at a variety of frequencies, and feed it into your recorder, once with the HPF and once without. Then look at the dB difference at each frequency; maybe a plot would make it easier to see. Using the difference should account for any baseline non-linearity in frequency response. The graph should be flat above the corner frequency and sloped below. I think that for the sloped part to be a straight line, the graph would have to be plotted such that each interval along the frequency axis corresponded to a halving of the frequency. The intersection of the flat and sloped parts of the graph should be the corner frequency.
All of that's assuming that the rolloff is a sufficiently linear number of dB per octave. By selecting additional frequencies to test, you could refine your estimate of the corner frequency.
I think...I might be wrong about the whole thing, though! :D If I am, maybe one of the gurus can help us (I am interested in figuring this out, too)...
Can't he just feed white noise into the recorder with the switch off then on? Then he'd just make a spectral plot of each and take the difference.
I ended up calling Edirol support to save myself some time and the first thing the guy said was "oh, I can find anything, hang on". After 5 minutes on hold he comes back to say "well, I wasn't able to find that info. But I'm pretty sure it starts somewhere between 100-200Hz and is a second order slope (12db per octave)."
He offered to send an email off to the engineers in Japan, but followed it up with "we'd never get a response" ::)
So if I'm not mistaken, if it does start at 185Hz and is a second order slope, then at approximately 90Hz there is 12db reduction, and at 45Hz there is 24db reduction. Can someone confirm?
Thanks,
pjdavep