PRR-176 REV 4 Build Thread ***Manual up!***1/16/14 - (chk 1st post)

[e.oelberg]

Well, I am pretty certain that the LM317/337 devices can not provide an output voltage higher than the input voltage, and the voltage regulator circuit looks pretty much like the data-sheet implementation.

This is why I was curious about the voltages being applied to the regulator.

Otherwise, I would double-check which points are being used to check voltages, and if the volt meter has good batteries  8)

Naturally, I can't question your observations but I would like to make sense of them 

well I'm also curious, if you disconnect mainboard and set 18 v trimmers to 5k, whats your voltage ?

btw, my psu is working fine, i have set it to plus minus 18 1.7 and 105 volt

give it a try 1

 

[ilfungo]

hi Guys,
Working on the build manual but thought I would quickly address the stereo link option. The way originally specified in the wiring picture is sub optimal. There will be 2 different stereo linking options to choose from. This being the 1st one. This keeps both att/release controls active and sums the information of both channels via the dc control voltage. The second option will be ala Rev 1 and Rev 2 which only the left channels control the att/release which makes it a breeze for stereo matching but they both have pros and cons. Will have more info as I do more testing. Here is the option 1:

Notice that the right channels 2 stereo link pads are always bridged.

Hi ABE
can you post the old (REV 1-2) stereo link mode?
In dual mono the unit is perfectly matched on all the range
max difference L-R is 0.2 db on 8 db of compression.
In stereo mode is 1 dB off and I will try old stereo link
Thanks!!!

 

[ding]

I'm not sure if this will work ok but here you go.
http://www.acsoundstudio.com/prr_176/PRR_176_WIRING_GUIDE_j.jpg

 

[abechap024]

hi Guys,
Working on the build manual but thought I would quickly address the stereo link option. The way originally specified in the wiring picture is sub optimal. There will be 2 different stereo linking options to choose from. This being the 1st one. This keeps both att/release controls active and sums the information of both channels via the dc control voltage. The second option will be ala Rev 1 and Rev 2 which only the left channels control the att/release which makes it a breeze for stereo matching but they both have pros and cons. Will have more info as I do more testing. Here is the option 1:

Notice that the right channels 2 stereo link pads are always bridged.

Hi ABE
can you post the old (REV 1-2) stereo link mode?
In dual mono the unit is perfectly matched on all the range
max difference L-R is 0.2 db on 8 db of compression.
In stereo mode is 1 dB off and I will try old stereo link
Thanks!!!

Its VERY close to that....but a little different. You basically want to disconnect the wire that feeds the att/release on the right channel and connect the 2 outputs of the diodes and the CV. I'll post a picture as soon as I get it looking all pretty (I have most the build manual done)

 

[ilfungo]

Just some files
Some are extreme settings


https://drive.google.com/folderview?id=0B_crccV9IvIHZEY4cEZRdXk2ejQ&usp=sharing

All files are at the same peak level

 

[prh]

well I'm also curious, if you disconnect mainboard and set 18 v trimmers to 5k, whats your voltage ?

btw, my psu is working fine, i have set it to plus minus 18 1.7 and 105 volt

give it a try 1

;D I haven't built mine yet! 

BTW, when checking the PSU, did you have some load on the output?

 

[e.oelberg]

could someone please measure the voltage at minimal position of the meter trimmer I have around 360mV...
my problem is, I can't zero my VU and compression ratio seems low, I have to krank input to max to get compression

what could this be ?


thanks, Nicholas

 

[mrdarwin]

could someone please measure the voltage at minimal position of the meter trimmer I have around 360mV...
my problem is, I can't zero my VU and compression ratio seems low, I have to krank input to max to get compression

what could this be ?


thanks, Nicholas

what pin of trimmer? cw or ccw ?
do you use 470r pads?

 

[e.oelberg]

yes I have 470R pad and it passes audio without insury, but for compression I have to krank till it almost distorts, than I get about 4 db compression according to the meters.
I can't zero the meter.
I measured 360mV at the meter pin (plus of the VU Meter)
timing cap seems to work. threshold and thump are set for pleasant and strongest compression. If I set it very fast it tends to motorboat

thanks for your help

 

[ilfungo]

Hi e.oelberg
Have you linked this point?

 

[ilfungo]

Hi e.oelberg
have you solved your problems?


"hi Guys,
Working on the build manual but thought I would quickly address the stereo link option. The way originally specified in the wiring picture is sub optimal. There will be 2 different stereo linking options to choose from. This being the 1st one. This keeps both att/release controls active and sums the information of both channels via the dc control voltage. The second option will be ala Rev 1 and Rev 2 which only the left channels control the att/release which makes it a breeze for stereo matching but they both have pros and cons. Will have more info as I do more testing. Here is the option 1:

Notice that the right channels 2 stereo link pads are always bridged."


Hi ABE
news?
Thanks

 

[ilfungo]

Some photos of my build
Very , very DIY !!!

 

[ilfungo]

 

[ding]

WOW!! Really F*cking awesome!!! I'd call it the devastator  That thing looks right out of a robot invaded future, yeah.  ;D

 

[berkleystudios]

That is definitely tough looking. Good job!

 

[mrdarwin]

oh yeah! usefull for atomic sound

 

[ilfungo]

Thanks to all!!!

I just want resolve 2 small problems
the stereo interconnections
the unit in dual mono is matched
in stereo is 1 db off and I don't understand why...
also  left meter is 1db off...
The sound is great!!!
Thanks Abe!!!


I've another 176 PCB and want try:
- use a pot instead of 10k resistor (sc hpf)
  I've tried and if don't if I'm not mistaken
we ca have a variable HPF


- I've seen that the pad is something like 20db
  if we leave out the resistor and insert one Poor Man's           
  Pultec ???
  (without make up gain stage = -20 db)
  Can work?



To share....
My unit
Lundhal 1540 input
Lundhal 1540 itersrage
Carnhill 2280 output ( I've tried Lundhal 1539 and dont feel well for me)
Whith Lundhal no hum!!!
All stepped with Shorting Lorlin
6 different timing caps on switch (from fast 0.47 / 0.82 / 1 / 2.2 / 3.3 / 4 uf)
Toroidal from Don Audio
Meter from Hairball
Thanks

 

[Esoterimix]

Curious on the wiring of output transformers.... Can someone post a pic or a diagram? please and thank you...

I think I've got it right, just want to make sure before I start soldering wires. also, was there ever a diagram or anything on correcting the tube PCB mix up?

Were they literally just done backwards? If so, I plan on just cutting the traces. Thanks in advance!

 

[abechap024]

Curious on the wiring of output transformers.... Can someone post a pic or a diagram? please and thank you...

I think I've got it right, just want to make sure before I start soldering wires. also, was there ever a diagram or anything on correcting the tube PCB mix up?

Were they literally just done backwards? If so, I plan on just cutting the traces. Thanks in advance!

Yes they were done in reverse...pin 9 goes to pin 1, pin 8 goes to pin 2. The replacement PCBs are finished from the fab house and on there way to me, should be a couple days before I can send them out.
Good point on the output transformers I'll add that to the build manual. You just connect the + and - primary of the output transformer to the TX output and then the secondaries to pin 2 and 3 of the XLR connector and pin 1 to chassis.

 

[abechap024]

Stereo linking info