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thedug

Well-known member
Joined
Jun 13, 2004
Messages
235
I am intrested in adding a eq bypass & a direct outs to my PM1000

I heard that somebody was doing this and even changign eq points.

Are there instructions or a thread somewhere?

Thanks!

d./
 
The EQ is polarity inverting. I think we beat it to death on the last forum, the eventual conclusion as I remember it was that since there is only (from memory) a single transistor in the EQ stage, and that it wasn't necessarily exactly unity gain, so bypassing it would result in: 1) a level change 2) a polarity reversal.

With this in mind, it looks like a completely pointless endeavour. The aditional circuitry you'd have to add in order to "flip the phase" again would have to be either an inverting op-amp -which would change the nature of the beast from an all-discrete console, or ... well.... basically the same single transistor affair that you want to bypass...

Keith
 
Thanks!

Would it be possible to have a switch that "zeroed" the eq?

The knobs don't have detents.
It might be cool to have a switch that basically disables the eq, but it isn't true bypass cuz you still need to the inverting.

What about the direct out and the eq points?

d./
 
Hey dug, welcome to the lab! Did you ever build that power supply? I still have not, but I'm just curious how it worked out.

There is a page out there that describes how to edit the EQ points. I can't recall where it is off the top of my head. If you do a search for PM-1000 or PM1000 (can't remember which) you'll find some a few threads out there. Within one of them, is the link to the website that shows you how to do it. It's pretty cool, and it's specific to the PM1000.

I still haven't been able to figure out how to add an eq bypass, or a direct out before the EQ.

Have you added any direct outs yet? I've still been putting that one off too while I've been building my SSL comp. If so, how did it go? Did you use transformers? I'm thinking of doing my first four channels with the B out transformers. If you did it, can you let me know how?? :green: :guinness:
 
There is a page out there that describes how to edit the EQ points. I can't recall where it is off the top of my head.

http://www.krashjones.com/pm1000/

elco
 
I've built up the power supply but for different stuff.

I need to read that other page about the eq links. Looks cool.
Has anybody tried this?

As far as the eq, I think a bypass that isn't a "true bypass" might work. I.e. Just lifting the grounds on all the pots. I.E. 3PST. Or even 4PST if you wanted to disable the hifreq. rolloff at the same time?

For direct out, you couldn't go pre eq, cuz the eq has the inverting stage, so you need it. You could put it after the eq. I plan on putting my direct outs right before the feed to the echo send. But I don't think I'll put direct outs on the console, but prolly on my extra modules.
 
[quote author="elco"]....

http://www.krashjones.com/pm1000/

elco[/quote]

Does anybody know this guy? Or how to contact him. His site says he is in Austin. I'd like to try and meet him.

d./
 
As far as the "untrue" bypass switch idea, I read something that said it was a pain to do, because you have to tie everything to ground but on cap. Apparently L1 is the hardest, cuz it has to be desoldered from the boad.

I thought another solution might be a 3PDT switch.
That basically switches between the pot and 2 resisters.
Where the 2 resister are selected to "recreate" the same as the pot being exactly set to 6 oclock.

This would require a switch per band.

Any thoughts? Is there away to "zero" out the entire eq that doesn't require lots of rework?
 
All that is needed is to open circuit the wiper connections on each cut/boast pot in the EQ as the Yamaha pots already have centre ground tabs on them. You could use a SPDT on each band to switch them individually or a 3PDT to switch them all at once. If you get a pop switching the mid and high bands in add a 1Meg resistor across the switch contacts.

Joe :)
 
I actually really like the idea of putting a small switch on each band. That would be pretty sweet. :thumb:
 
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