Long shot. Pultec passive circuit subbed in for PM1K eq?

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JW

Well-known member
Joined
Jun 8, 2005
Messages
1,100
Location
Portland USA
Hey guys,

I have a full Yamaha PM1000 board. I was wondering if it might be possible to just sub in the passive Pultec circuit into the PM1K channels after C10. After the Pultec, it would come back into the circuit at the top of R47 (the fader pot)

Between those two points it appears that the PM1K circuit is essentially passive anyway.

I wonder if the resistance would be low enough at this point for the pultec input, and whether there is enough makeup gain.

I'm potentially sounding like a total newbie because I know little about the connotations of doing this, but it occurred to me while trying to figure out how to bypass the eq that it might be pretty easy and affordable to add a bunch of pretty nice eq's here.

???

Edit: oops, forgot to post the schematic. It can be found on page 11 of this document:
http://www2.yamaha.co.jp/manual/pdf/pa/english/mixers/PM1000E_2.pdf
 
I have heard that you can mod the frequency points on the PM1k pretty easily, I am sure there a few people on this forum who could chime in with some info on how to do that.
 
(concerning the PM1K eq. I have modified it. I still don't find it very useful)

Okay, since I had the resources to just go ahead and try it, now I feel guilty for asking and not just doing.

But anyway, the C10 > R47 bypass in the PM1K was still getting filtering from the PM1K eq. I'm not sure why but it was. So, I went back to the neg. leg of C9, and that provides a clean eq bypass. However, the gain decreases a tiny bit, and there is also a phase reversal. Since I'm running line inputs into the PM1K, there's of course more than enough gain to make up for this loss, and the phase switch remedies the phase reversal problem.

As for the G Pultec filter board, as was to be expected, on the output you lose a lot of gain. I didn't realize how much it was, and I'd definitely find it to be unusable without a makeup amp.

I think the impedance after C9 is also way too high to properly drive the pultec filter. My next idea is to wire in some inserts right before the signal leaves the PM1K input channel on it's way to the busses. These would be super useful anyway, and (I think?) drive the Pultec filter quite a bit better.

So, this gets me thinking. If there was a cheap and good sounding IC amp option for the back end of the pultec filter, then I'd be down to the one problem of locating some relatively cheap, but good sounding inductors and I'd be on my way to say, at least an 8 channel insertable Pultec in conjunction with the PM1K.

If somebody had a schematic for an IC amp that wasn't too complicated, I could probably build it up fairly quickly.

 

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