PYE Compressor/Limiter Thread *boards shipping* BOM up!

Rev 3 Boards

Thanks guys.

http://www.acsoundstudio.com/diy/Pye/rev314/REV314_BOM1.pdf
http://www.acsoundstudio.com/diy/Pye/rev314/rev314_pcbPNG.png

So boards are almost done and on their way to me, then I can ship them out! Thanks for everyone who participated, wouldn't of happened with you! Got a few extra so they are still available through the white market thread or store. Bring on the compression!!

Great project Abe. I must question the removing of the gain stage.  I would seriously consider leaving it in, even if it seems excessive. I'm sure in many studio situations the output gets padded down, just like older tube limiters like the BA6, etc do. I'd rather pad it, than not have enough drive for the next thing down the line.

The noise gate, otoh I could definitely do without.

Mark

Hi Mark,
The Gain stage in question is before the compressor. It was originally operated by a switch and I assume it was to make the unit able to interface with mic level.
-Abe

abechap024 said:

The whole circuit is fairly simple and I have no doubt it should work without too much trouble. The only thing that might be a little iffy is the Hartley type oscillator, as it centers around a transformer that I haven't been able to get specs on. But only one way to find the right one, in my mind and that's to dive in and test out a couple.

Click to expand...

I take it you're experienced at designing pcb's which have RF on them ?

I made an experimental PWM gain cell using a PWM control chip a few years back, which worked, but was quite sensitive.  It's not so easy getting stuff stable at RF.  

The transformer that you haven't got the specs for is a critical part of the circuit & probably not an off the shelf part.  It may have to be made to order.  

You could perhaps consider using a PWM chip, it contains the oscillator & you just feed it a control signal to change the pulse width.  You can program the oscillator frequency with a cap or 2.  The only issue may be that the response isn't the same as the Pye.

That said i would love to find a use for the 2 original Pye GR meters that I have sitting on the shelf  

[edit]

years in retrospect it seems I was really mean, don't know why. I'm sorry about that. The work you do is of great quality with all the prototype iterations visible here.

Kingston said:

how is that dbx 160vu clone project working right now? should you perhaps concentrate on getting one project working at a time? or are you just looking for help troubleshooting prototypes?

I'm just saying drawing PCB's with "iffy Hartley type oscillator that centers around a transformer that you haven't been able to get specs on" is shooting from the hip in complete darkness.

Click to expand...

Yes, I've been waiting for a while while the dBX 160 gets rolling. But In my spare time I've been working on this. I am now fairly confident that the DBX is going and just waiting on the boards to get here. So I'm starting on this project now. I originally was going to breadboard the whole thing, but then realized it would be easier to order a few prototype PCBs and experiment with those and other people raised interest in also wanting a couple, so this is merely a thread to see if other people would like some. I'm definitely not trying to say this is a completed Idea, but it needs to start somewhere, and personally would rather have something hands on to design around than an abstract Idea, or design.
   
    Also I could wait around forever trying to convince someone to open up their PYE comp and get some more information on the oscillator transformer, or I could just try it out myself. I realize many people on the forum would much rather not take such a leap, and I understand that. Many others on the other hand might get some enjoyment out of finding one that works and sharing with the rest. I somehow don't think it will be as hard as some might imagine it to be.  If no one else wants to also order a PCB I will be perfectly fine with that.

Rob Flinn said:

abechap024 said:

The whole circuit is fairly simple and I have no doubt it should work without too much trouble. The only thing that might be a little iffy is the Hartley type oscillator, as it centers around a transformer that I haven't been able to get specs on. But only one way to find the right one, in my mind and that's to dive in and test out a couple.

Click to expand...

I take it you're experienced at designing pcb's which have RF on them ?

I made an experimental PWM gain cell using a PWM control chip a few years back, which worked, but was quite sensitive.  It's not so easy getting stuff stable at RF. 

The transformer that you haven't got the specs for is a critical part of the circuit & probably not an off the shelf part.  It may have to be made to order. 

You could perhaps consider using a PWM chip, it contains the oscillator & you just feed it a control signal to change the pulse width.  You can program the oscillator frequency with a cap or 2.  The only issue may be that the response isn't the same as the Pye.

That said i would love to find a use for the 2 original Pye GR meters that I have sitting on the shelf 

Click to expand...

Ah Yes Rob,
I remember our conversation. I've thought about using a PWM chip and realize that I want an original to compare it to. That way I'm not shooting totally in the dark when designing a new oscillator.

Someone with RF experience will be needed to design the transformer. I'm not sure measuring a transformer from a real Pye will be much help.  I suspect you would need to do a CJ hack job on it to know how to recreate it.  I was talking with some very experienced old boy television engineers about the transformer, & they advised me to find an old school radio design engineer. 

denied.

dont try, then you cant design/make it wrong.
two projects at one time is not allowed or you may be banned.

just kidding,
I don't see what the problem is here. if I decided a year from now to design the same thing from ground up, I'm sure I would be very grateful for your efforts and documentation here.
even if it just meant me avoiding any hurdles you came up against and posted about in the thread.

good luck

Haha! Thanks, Yes at least we can start posting together ideas and anything we find. I'm going to post up what information I have. And maybe a whole redesign of the oscillator is in order. I secretly would love to redesign the whole side-chain.....stand by..

doubt I'll be much help but I say go for it, what to lose except time?

I know someone with an original pair - I may be able to open them up to get some basic info, voltages etc. I doubt the owner would be ok with taking a hacksaw to that transformer though!  ;D

[edit]

years in retrospect it seems I was really mean, don't know why. I'm sorry about that. The work you do is of great quality with all the prototype iterations visible here.

You have here a perfect opportunity to learn and design something completely new, and what do you choose? to clone something you haven't ever even heard?
What the heck is wrong with you people!

Click to expand...

I've never had the opportunity to hear a Neve preamp, a tube preamp, a 1176 compressor, etc. etc. but I started building these projects a year ago and not only have I learned an incredible amount about electronics and recording equipment, but I've started to learn what 'great' means for recording equipment - not just with my ears but interacting with other musicians. I believe one of the best ways to learn is to study what's been done before. Due to the high cost of recording equipment most people can't study an original example. But with the schematics & this forum, a person can learn a lot by jumping in with both feet.
Saying someone shouldn't try something, for this reason or that reason, isn't constructive.
Trying to design a great piece of recording equipment without a substantial background in using, designing, and building IS

shooting from the hip in complete darkness

Click to expand...

It's the challenge of doing it, Kingston - it's in our American DNA.  We try to create and re-create the impossible.  ;D

Kingston said:

You have here a perfect opportunity to learn and design something completely new, and what do you choose? to clone something you haven't ever even heard?

What the heck is wrong with you people!

Click to expand...

HAHA! Of course I have complete faith that this sounds fantastic. Seems Like "you people" have lost faith in a lot more than just cloning audio equipment. In my mind the stuff I SHOULD be cloning is the stuff I've never heard before. Maybe I'm just crazy. I don't have an extra 10,000$ sitting around to buy one.  ;D ;D ;D

And now that I think about it, every project I have built I've never heard the originals. NEVER. 1176, SSL comps, API pre, MElcor pres , 990 opamps, Eq's, UPGrading equipment. If "you people" think you have to hear a piece of equipment before you can work on it, then nothing would ever get done, and no new designs would ever get made!

Kingston,



  actually, this really might be worth doing blind . . . . There is nothing like a Pye, if they get it right . . .



        MIne rule . . .


         

    Here is my take on the schematic. Note there is a separate PCB for all the switches, for the sake of a easier build. There will be 3 Lorin switches, one for ratio, one for decay and one for limit (on/off). I moved the limit option from the ratio selector so simple Lorin switches could be used. Otherwise we would have to used a 3 pole 5 position external switch along with all the wires.

   Also shown are the most adequate transistor replacements I could find. If someone knows of a sub that would work better please let me know. Especially with TR11 , the CHOPPER transistor.

   PCB Layout soon to follow...

-Abe

NEW Circuit Layout Rev 1
Pye Front Panel
Original schematic: page 1
Original schematic: page 2
Pye User Manual

Abe - Can I suggest giving your schematics a revision name, ideally in both the image and the file name. That way as things are improved or changed we all know we're on the same page?

Thanks for doing this - I hope it works out!

Good Point!
Done and done.

I meant actually changing the image file - so that when you are looking at it you can see that it's rev1 or rev2 or whatever...   ;D - All good.