PRR-176 Vari-Mu REV 2 - *Group Buy 7/13!*

I would like to do another 176 with Carnhill output
which model should I use?
Thanks

???

http://www.audiomaintenance.com/acatalog/CA-18-VTB2281_extended_info.html

This one.

Thanks!!!

Hey Abechap, I was just wondering...

When will you do another batch of PCBs for this compressor?
Anytime soon? 

Hi all,
I got a second pcb and I'm interested in trying to add switchable thresholds for this one.
Before I waste money on parts, could anyone advise me if either a 3PDT switching between two pre-set trimmers would make sense? Or prehaps even a 3 pole Lorlin rotary switch with three or four different trimmers? Would anyone know if shorting vs non-shorting would matter in this sort of application (eg is there a potential for monitor-destroying pops or other switching noises)?
Thanks in advance.

ethervalve said:

Hi all,
I got a second pcb and I'm interested in trying to add switchable thresholds for this one.
Before I waste money on parts, could anyone advise me if either a 3PDT switching between two pre-set trimmers would make sense? Or prehaps even a 3 pole Lorlin rotary switch with three or four different trimmers? Would anyone know if shorting vs non-shorting would matter in this sort of application (eg is there a potential for monitor-destroying pops or other switching noises)?
Thanks in advance.

Click to expand...

Cool idea...you could even just make it a pot and have a genuine threshold knob. If you do use a switch, and their are pops, it won't be a big deal, it will just peg the gain reduction circuit which will be the opposite of a pop to the outputs...Just mess with the gain resistors around the sidechain amp, or replace the trim pot with a pot/switch

Hey thanks for the info Abe. hmmm if it were repeatable, pegging the gain reduction could even be a handy hack for starting a mix with the compressor slightly in recovery...

I might try the pot idea on one of the two units. I'd like to do the switches for one in order to have a more optimal fixed threshold for either line/tape return level or the much lower insert level on my mixer.

Hi all,


I'm yet another newbie - just ordered all the parts for Gyraf's PQ1549 and looking forward to putting that together. And as my next project I'd like to take up this - gotta plan ahead! So Abe, add my name to the list of people hoping for another run of PCB's!


Thanks for all the work and shared information here, this is a goldmine.

Does anyone do a 2RU front panel or case for this project?

Hi All!

After a long night of reading previous posts on rev1 and rev2, testing, soldering, desoldering, replacing everything possible on the PSU board, I'm still at the same point :

==> +/- 18V are ok.
==> + 1.5V is ok.
==> HT is 140V unloaded, It seems to be too high, isn't it ?
==> Heaters power : NO SHOW  . In fact I have 1.32V output, loaded and unloaded. The Lm350 is cold as Ice.
I replaced all regulators 3 times, diodes the same and resistors too.

I saw that some the same kind of weird issue, but nobody explain what they did to sort it!

Any help is welcome.

Best.

Chris.

At the input of the Lm350 I have 30V!

Direct output of the Lm350 I have 8.43V and the trimmer can only decrease it, this voltage is the max I can have.
At heater 2 only 1 and something Volts.

Best.

Chris.

Hi Chris,
Very interesting...your HV is OK because it needs to be loaded in order to have the correct voltage. Also I don't know whats going on with your Heaters, but your just going to have to work through it, the fact that the LM350 is cold is a big clue, it means for whatever reason it is not working, I would check voltages, your parts are probably OK the problem lies elsewhere on the power board. Its something simple, correct trim pot and resistor?

Hi Abe!

Thanks for the HELP!

I've found it! It was the Molex pin that does not contact the cable from deported LM350!

Sometimes it's right under your nose and you are blind!!!

Thanks again!

Best regards.

Chris.

Hi all,
I finally gathered all the parts for my second prr-176 (using a Rev 1 board) and before I start I was wondering if anyone had any opinion on the best use of the transformers I have on hand.
My already built rev2 currently has Edcor 10k:10k for input and interstage. I've since acquired four Lundahl LL1540s.
I was initially going to have one of them all-Edcor and the other all-Lundahl, but I just wanted to check if anyone has an opinion on where the higher quality Lundahls might be used to their best potential (input vs interstage).

ethervalve said:

Hi all,
I finally gathered all the parts for my second prr-176 (using a Rev 1 board) and before I start I was wondering if anyone had any opinion on the best use of the transformers I have on hand.
My already built rev2 currently has Edcor 10k:10k for input and interstage. I've since acquired four Lundahl LL1540s.
I was initially going to have one of them all-Edcor and the other all-Lundahl, but I just wanted to check if anyone has an opinion on where the higher quality Lundahls might be used to their best potential (input vs interstage).

Click to expand...

Interstage. There have been reports of the compressor picking up more hum/noise there.

Hi All!

Almost finished mine, with a lot of options onto.

Just one thing is going weird.

I've put Threshold on a switch (made with vischay/resistors). It's a nice option too, kind of compression switch.

On channel 2 when switch is fully CW, I have more compression, normal. On channel 1 it's totally over compressed and distorted (Nuke fonction).

I tried all: swapped the tubes, swapped all the IC's, swapped the switch socket. All is going well on Channel 2 but never on Channel 1.

Thing intersting is that I have almost 14VDC across the release tant cap on Channel 1 and Normal voltage across tant cap in Channel 2 when last position is engaged.

Any ideas, expsriences, help with this kind of problem.

Best regards.

Chris.

One more thing!

Do you know where could I find a Matched Pair of 6bc8?

I've tested a lot and actually I have a Zenith on one channel and a Sylvania on the other!

I have 1.5 db of gain reduction difference on high threshold settings. I cannot adjust it tightly because it's all detended and 1 set of switch for both Channels (Mastering Style).

Maybe if I put a trimmer before the threshold switch on both Channel, I could tight them?

Best regards.

Chris.

Hi Chris,
Have you adjusted the threshold trimmer for both channels?

Also I'm sure you've taken note of this, but I'll say it anyway, how the 2 connectors are wired aren't the same for both channels due to the way the stereo link has to work. So I would assume your problem is how it is wired up, somewhere...

baadc0de said:

Interstage. There have been reports of the compressor picking up more hum/noise there.

Click to expand...

Hey thanks for the advice, I decided to go all-Lundahl for the rev 1. My rev 2 is very quiet with the Edcors.