Cake or PYE?

[abechap024]

Hi All...
Wondering if someone would be willing to answer some of my questions about this circuit. I don't want to be a question Hog, so I've been holding these questions back for quite sometime, looking for answers on my own. This forum speeds up the learning process a lot...

Any information on the transformers and Input attenuation would be great. I have some *ideas* about what to use, but assume I know nothing.

Also anything a person like me (knows just enough to get themselves into a world of trouble! ) might overlook.


really...really....really

http://www.acsoundstudio.com/DIY/Pye/PYE1.jpg
http://www.acsoundstudio.com/DIY/Pye/PYE2.jpg

Thank You.

 

[damnyankee]

Would those be Altec-Lansing transformers?  If they made a 22-series in the '70s, that would likely be them.

DY

 

[strangeandbouncy]

transformers made by Pye in house I believe.

 

[abechap024]

interesting. I wonder what the transformer in the Oscillator loop is?  
Just has to work around 200+khz I believe...

My Guesses:
T1 Input line step down (1:1, 2:1)
T2 Line Out Step up (1:1, 1:2)

T3 Oscillator feedback transformer (1:1, 1:3)(must pass 200khz - 250khz, also ratio? I'm totally guessing but probably want a step up since you want it to feedback)  
T4 transformer feeding side chain - (1:1) doesn't have to be high quality.

EDIT: If they were custom made, then the only sure way of knowing is if someone had an original PYE unit and was able to look under its hood and take a look,see.

Edit: Edit:It would be for a good cause...wouldn't it be nice to have a PCB for these?

 

[Wonderlandaudio]

At least output transformer and power supply transformer were made by Tessier Windings. The rest I can tell for sure. Attenuators were made by Painton.

 

[haima]

nice sharp schematic abechap! the only one i have seen up until now was borderline unreadable.

EDIT - actually... the "PYE2.jpg" file looks blurry from about half way down to me - perhaps it was uploaded/downloaded partially? how does it look to everyone else?

also - do you have the diagram for the attenuators?

it'd be great to clone these one day - they are very hard to find and expensive - but they sound great, of course (what "hard-to-find-&-expensive thing doesn't??! haha)

 

[damnyankee]

AC,

When you make the boards, put me down on your list for one pcb.

DY

 

[abbey road d enfer]

Part 2 of schemo is completely illegible for me...

 

[Kingston]

Yes, it would seem at some point the image was saved in the middle of download, leaving the last detailed layer unfinished (feature of PNG format).

 

[haima]

i have a friend who has a pair of pye compressors - not sure if it's the same model in these schems, they have a horizontal layout with the black meter on the left from memory. i MAY be able to convince him to let me open them up and take some measurements of the transformers. however it won't be any time soon - i'm very busy/overseas for the next few months...

 

[abechap024]

Hi,
The second picture must of got interrupted during upload. I'll reload it when I get a chance, the internet I'm currently using blocks FTP ports.? (don't ask why..)

A look and a couple pokes in an actual unit would be great...

Thanks,
AC

EDIT: Also forgot they are uploaded to the group mail account.

 

[abbey road d enfer]

OK, got the full schemo on the group account.
Since the rail voltage is 17V, and according to the claim of operating up to +24dBm, the output xfmr ratio must have been at least 1:2.2, actually probably 2.5-3.
I think a relatively common 1:2 would allow clean +20 dBu operation, which is generally enough in all practicality.
For the same reason, the input xfmr should be 2:1 ratio.
As to T4, one can only guess, but the ratio cannot be very high because the secondary has to drive the relatively low impedance presented by TR17 in common-base mode.
The oscillator is of the Hartley type, so the turn number between 3-4 is much lower than between 1-2.

 

[abechap024]

Awesome Thanks  Abbey. Gets us in the ball park at least

Also Updated the #2 Schematic

Cheers
AC