PYE Compressor/Limiter Thread *boards shipping* BOM up!

does this look right?

Yes!
Though on Abe's board switch A (decay) has position 1 on 100ms and position 6 on 3200ms.
But that's just orientation. Either way it will work.

Why are you doing it by yourself? You don't have that board in your set?

i have to run wires so i can fit the lorlins in the 2U, its a bit pushed for space due to the big VU meters.
I do seem to be getting decay (release i'm thinking this is?) working now on both channels.
Limit switch and ratio dont seem to do anything yet?

limit switch does do something when ratio switch is set to 2nd position, but nothing on 1st position and 4th position.

looking at voltages on bottom part of circuit TR20 is looking good.
TR12 on its collector has 0v and on other channel -0.585v
TR13 has CH1 = E = 0v, B = 0v, C = -11.01v
CH2 = E = -0.052v, B = - 0.532v, C = -10.95

When limit is engaged, ratio should do nothing!
Either you compress - then you select the ratio - or you limit!

well this is starting to grind me down!!!!, as i seem to now have everything correctly connected but its not operating correctly?

i do understand how the unit operates as i use the plugin version, just very frustrating when i dont understand the circuit or really know where to look. Its been a busy week and i will have another look at this next week, as i have a bit of time away from it, when i come back hopefully i will find the problem.

Spencerleehorton said:

Anyone provide some working voltages for all transistors please?

Click to expand...

There's a voltage chart in pyebook on Abes site. But you'll have to do some cross-referencing because original designators are different

the site is down as far as i can tell, does anyone have that info please?

really need to fault find this build!!!

Is there a voltage guide available?

Anyone provide some working voltages for all transistors please?

Here's that page

ah, spot on dude, thank you.

right had another look today and error on wiring sidechain transformer!!! i'd connected pins wrong way round then put txf in mumetal can!!
controls now working as should and both channels seem to be working within very close range.

next step is getting meter working correctly!!!

any ideas please?

right i'm starting to get there now!!! meter now working, had it wrong way round.

distortion present with compression or limiting, ok when on 1:1 but this is bypass right?, so gonna wait for my frequency meter to turn up then i'm gonna try and set it up correctly.

I'm glad you're debugging this build, SLH - my boards just turned up (purchased from Collective Cases) so I will start my build soon, hopefully learning from all your mistakes and discoveries

yes, most of my mistakes so far are down to not taking enough time on everything!!
difficult when balancing work, family life!!!
i've just got to get rid of the distortion now, everything seems to function correctly apart form the compressed sound!!!

good luck mate!!!

Im getting saw tooth waveform at R41 / R43, distortion present in both channels, think im ment to get rectangle waveform?

I’ve taken some voltage readings with 1:2 ratio and slow release

TR20
E = -11.55
B = -12.65
C = -21.65

TR12
E = -11.41
B = -10.82
C = -1.718

TR13
E = -.143
B = - .649
C = -10.82

TR15
E = -.821
B = -.1.398
C = -11.55

TR16
E = -11.55
B = -1.890
C = -1.379

TR17
E = -8.30
B = -7.70
C = -1.850

TR18
E = -7.10
B = -1.371
C = -.756

any ideas?

is this voltage chart off the original schematic?

I think it would be good for everyone to have a full voltage chart as I'm really stuck on where this distortion is coming from!

I'm only getting distortion when it is compressing, clean signal otherwise?

And when I put sinewave through waveform looks clean with compression, when I put bass guitar through I get distortion, could this point to the input txf?

That voltage chart is from one of the original Pye manuals. I have a different one from another old Pye manual, but the callouts are similar.

Spencerleehorton said:

Im getting saw tooth waveform at R41 / R43, distortion present in both channels, think im ment to get rectangle waveform?

Click to expand...

The waveform depends on the compression and turns the transistor on and off. Your sawtooth is probably fine. You're getting distortion somewhere else. I suspect the first block before the output pot. Check R19, R20 and R23. Try adjusting R23 and see if it makes any difference.

Spencerleehorton said:

And when I put sinewave through waveform looks clean with compression, when I put bass guitar through I get distortion, could this point to the input txf?

Click to expand...

This could point to anything, really. It depends on the input level. This comp is very easy to overload. Both input and output stages. Especially if you're on 16V. You need proper measurement tools to read THD value, even 1% THD sinewave will look fine on the scope, you won't spot the difference with your eyes. So make measurements and tweak the resistors I wrote you earlier. This should make a difference in THD. You can measure THD in different places of the circuit and see which part adds more distortion, so you can zero on that particular spot.

Are you using a proper threshold switch or two separate pots?

Voltage chart is for 16V rail. If you feed your comp from 18V rail, voltages will be off. The sidechain voltages will remain valid though because it's regulated separately to -12V.

Threshold switch?

Have you built this pi 3141?

It sounds like your talking about something else, no mention of threshold switch on BOM or schematic?

I'm on -22.54v giving me -11.55v rail.

I had conflicting info, it's been said that I should run it at -22v and you seem to say if should be run at -16v?