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

Thanx ANdyP, that's what I thought, but the guy I got it from, told me it was the same principle as a PYE compressor the bastard!
That makes this project even more interesting to me
Of the topic but have you got any schematics or info on the cadac G255?

Hi,
Yea...this project is a tad adventurous I guess, but if a pye is going to be (re)born anywhere in cyber space I do believe this forum is the place for it

Point and case: one great forum member sent me a run down of pics of the oscillator circuit and an oscilloscope readings.

Thats a huge boost to this project I'll post the pictures asap. It looks like the transformer is a small toroid core with a few wire wraps around it. Really not as hard as I imagined making a transformer for this might be. Not saying it will be really easy, just that at least now we know what we are trying to recreate looks like.


Still a little fuzzy on exactly how it works, but we'll figure it out.

Pictures soon to come....















Much Thanks Rob!!

Hi Reanimator,


  you might try FunkyJunk, cos thats where I heard em . . .

About the cathode of D1 :
- What is the DC voltage ? I suppose it is +Vcc but it would be better to mesure it.
- What is the exact duty cycle ? Frequency seems to be around 310 kHz but I can't read the "time off" duration.

Any ideas about the variable cap ?

I wonder how this would sound if one brought the switching frequency into low mid frequencies?  :-X How about a FPGA to give some nice harmonics with DSP power? Its friday and listening to some The Flamin Lips

strangeandbouncy said:

Hi Reanimator,


  you might try FunkyJunk, cos thats where I heard em . . .

Click to expand...

please guys let us know if you need schematics and stuff. we don't have much about htese comps here at FUNKY but I will do my best to help.

Mattia.

Yes lots of questions too on my mind. I just ordered a bunch of toroidal cores approximating the size of the one pictured and also some magnet wire. I figure If I make a hundred of them I'm bound to get some results that can lead  us in the right direction. I:'m sure there is a much more scientific way to approach this but until I know how its the brute force method! I'm hoping maybe these prototype boards will lead to something worthwhile after all...

Why are you trying to clone the oscillator ????????

Niketouille said:

Why are you trying to clone the oscillator ????????

Click to expand...

Why not?
Its a very fundamental part of the compressor. It will be interesting....

Niketouille said:

Why are you trying to clone the oscillator ????????

Click to expand...

Because we don't know to what degree the oscillator contributes to the sound of the compressor? - perhaps it's inconsequential, or it might be completely intrinsic.

The waveshape, duty cycle etc could make quite a difference...?

I'm no expert though... hopefully in the long run it can be replaced with something simpler.

yes exactly.
Also if anyone is interested I put a link up on my site to pre order

Cheers!
Abe

"The waveshape, duty cycle etc could make quite a difference...?"

As you said we don't know but I guess it could. Depending on the chopper frequency (and spectrum) the audio spectrum before filtering will change. Perhaps the filtering cancel all those effects but I'm really not sure about that.
As I understand in a blocking oscillator all these parameters are dependant of the ...é"'(§è!ç.. transformers. That's why I think it is far easier and faster to reproduce the waveshape with another oscillator. Anyway if the cloned oscillator works it is... groovy.

duty cycle looks to be 20-30% but fewer sec/div on the ol' scope would be beneficial. that's quite a fall time!  not quite a classic square wave, is it  :-\

too bad we don't have an FFT plot, that would make life much easier.

Niketouille said:

...é"'(§è!ç.. transformers.

Click to expand...

Haha that about sums up my feelings on the transformer too!

;D

They are here!

hey abe

nice looking pcb's man!!!
i dont know if this will help but i was trawling through the internet the other day and i found a posting (cant remember what forum) about a pye comp that had a faulty inductor?? the person didnt know what it was for but he did posta picture and it looked like one of the carnhill inductors.
now i dont know if its the oscillator or something else but unfortuneatley i didnt download the photo of it and now i cant find the bloody site no more
would an inductor be used anywhere else except the oscillator?

This might be the one :
http://www.gearslutz.com/board/geekslutz-forum/380364-variable-inductor-pye-comp.html

btw, money sent for 1 x pcb

cheers bru...

Niketouille said:

This might be the one :
http://www.gearslutz.com/board/geekslutz-forum/380364-variable-inductor-pye-comp.html

Click to expand...

52.5mH, 80 series resistance, and a standard core with a tuning slug. That should be pretty easy to wind. Then it only needs to be tuned to the resonant frequency. I'm guessing it's a steep filter for the PWM signal.

That's not really the difficult part to source, it is used in the low pass filter that removes the chopper HF signal.

The difficult part is the RF transformer, which I think Abe is working on at the moment.

By the way good looking work Abe !