vitopower

Re: PRR 176 vari-mu (check first post for docs)
« Reply #840 on: April 03, 2021, 01:01:03 PM »
I missed this, this is killer  8) thanks!
Can a similar ratio mod be applied to the prr r4?

  Hello dear friends, here's my PRR 176, it has 2 ratio modes, "compress" and "limit" :

http://sub-continental.com/partage/d%26d%20schematic.jpg

  We could use a that1246 instead of the 2:1 transformer, if you use a 1:1 transformer just change the gain of IC1 but use the unity gain compensation capacitor.
  I used a 600:600Ohm transformer before the grids, because it is driven by a low impedance source and the grids have a high impedance so a lot of transformers would work here.
  The anodes drive a LL1521, because they have a high impedance we need a good input transformer like LL1540 or any good quality line input transformer.
  If you use other transformers' ratios just change the gain of the according stages (IC1 IC2 IC3).

  The trimmer before IC2 is to ajust tube gain differences between left and right channel, you can trim to 1dB, if you need more just use a 20K trimmer with a  68K for instance.

  The deeser is not very usefull (to me), so I will modify it to get a 2nd HPF mode like 100Hz or I don't know yet..

  Well, it's an awesome compressor and thank you PRR and Abechap and everybody who provided great brain juice on the forum!

  Here are some pics of the finished unit :











saint gillis

Re: PRR 176 vari-mu (check first post for docs)
« Reply #841 on: April 07, 2021, 05:09:14 PM »
Do you have the complete schematic link for the prr r4?
What is R86?

vitopower

Re: PRR 176 vari-mu (check first post for docs)
« Reply #842 on: April 08, 2021, 06:15:24 AM »
nice! r86 is threshold adj
« Last Edit: April 08, 2021, 06:18:51 AM by vitopower »

vitopower

Re: PRR 176 vari-mu (check first post for docs)
« Reply #843 on: April 08, 2021, 06:25:24 AM »
attached

vitopower

Re: PRR 176 vari-mu (check first post for docs)
« Reply #844 on: April 08, 2021, 06:44:07 AM »
.


 

Related Topics

  Subject / Started by Replies Last post
2 Replies
3147 Views
Last post April 13, 2010, 11:45:20 PM
by EmRR
10 Replies
4400 Views
Last post March 27, 2011, 02:50:44 AM
by Brian Roth
16 Replies
6271 Views
Last post February 16, 2012, 12:22:16 PM
by G-Sun
276 Replies
73841 Views
Last post November 06, 2020, 03:55:13 AM
by evil grill