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Gear / Technical Help => Recording Gear => Topic started by: pjdavep on June 29, 2009, 02:29:44 PM

Title: Edirol R-09 low cut frequency curve?
Post by: pjdavep on June 29, 2009, 02:29:44 PM

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

Title: Re: Edirol R-09 low cut frequency curve?
Post by: aaronji on June 29, 2009, 06:36:32 PM

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)...

Title: Re: Edirol R-09 low cut frequency curve?
Post by: Xontar on June 29, 2009, 10:03:25 PM

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.

Title: Re: Edirol R-09 low cut frequency curve?
Post by: pjdavep on June 30, 2009, 09:30:42 AM

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