PRR 12AU7 Comp (Help)

Hi,

I started to build PRR 12AU7 Compressor.Board is almost done.But i need some info about transformer,output and power.

This is original circuit.There is no info about transformers.And there are only two transformer.In and Out.

http://i.hizliresim.com/LY3Rbz.jpg

And it's modded circuit by me

http://i.hizliresim.com/A03Qvv.png

What are transformers ratios for input and output? I think in and out 600:600.

And what about power transformer?

Thanks.

I think transformers should be like this...

Input Transformer -> 10K:10K or 600:600
Interstage Transformer -> 15K:600
Output Transformer -> 600:600 (After output section)

Right?

And i want to use ALPS stepped potntiometers for in & out.

I think you are right about the input and output transformers. I think the interstage can also be a 10K:10K because the 5532 is used in a non-inverting configuration and should therefroe have a relatively high input impedance.

Cheers

Ian

ruffrecords said:

I think you are right about the input and output transformers. I think the interstage can also be a 10K:10K because the 5532 is used in a non-inverting configuration and should therefroe have a relatively high input impedance.

Cheers

Ian

Click to expand...

Thank Ian.

I researched about this compressor and some people using 10K:600 for interstage transformer.By the way can you check my modded circuit.I did it to understanding.

And i will use your Tube Gain Make Up.I think it's possible.

About in & out controls,i will use 23 step switch to same control for two channels.

Modified circuit looks OK to me but PRR would be the best judge. Stepped pots will be OK.

By the way, what is V10??

Cheers

Ian

ruffrecords said:

Modified circuit looks OK to me but PRR would be the best judge. Stepped pots will be OK.

By the way, what is V10??

Cheers

Ian

Click to expand...

Yes,i hope PRR see this topic. 

There is info about V10 like this...

Power supply shows the 1.5V supply for the bias on the full wave rectifier.

if I remember correctly the first version didn't have an output transformer. input and interstage are 600:600 and they does not need to be top high quality. PRR said that they had little impact in the sound, so provably a pair of edcor are good enough.

I built my own 600:600 ohms for this project and after some test they work ok.

Read and reread PRR's original notes on the project, they are very complete.

12afael said:

if I remember correctly the first version didn't have an output transformer. input and interstage are 600:600 and they does not need to be top high quality. PRR said that they had little impact in the sound, so provably a pair of edcor are good enough.

I built my own 600:600 ohms for this project and after some test they work ok.

Click to expand...

Thanks.Yes,it has no output transformer but i will add instead of ic balancing.I decided to use 10K:10K for input but still i have no idea about interstage transformer."PRR 176" has 4:1 interstage transformer. ruffrecords said it can be 10K:10K.And you say 600:600. ???

ruairioflaherty said:

Read and reread PRR's original notes on the project, they are very complete.

Click to expand...

There are really good infos.

http://tr.scribd.com/doc/23468783/DIY-12AU7-compressor#scribd

http://web.archive.org/web/20110223205028/http://www.diyfactory.com/projects/diy12au7comp/diy12au7comp.htm

I'm reading it and everything is ok but i still need some info to understand.