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

[Patrick from Davis]

Yes, Dan at Collective Cases, I feel a little stupid for not including that.  I feel bad for Abe, something happened, and it didn't sound like it was anything good.  That being said, I never heard what happened.  However, you can't accept money for these things and not send them, so hopefully you can get your money back.

 

[Spencerleehorton]

I've spoken to Dan and he has about 40 pcbs left.

http://collectivecases.com/?product_cat=pcb

 

[Ilya]

Great news!  Count me in for a pair (PCB only), thank you.

When you have a chance I'd be interested to hear more about your design (e.g. discrete oscillator details, input/output transformer requirements, maybe even a demo...)  Or I could just wait for you to actually release it, I guess

Well, there's nothing revolutionary there. Cinemags input/output and Edcor on the sidechain. Discrete oscillator details will be provided with the boards. There will be an option for 555 oscillator as well, but discrete is the preferred type. GR meter is also behaving differently with different oscillators.

I'll leave a note here when I have the boards in stock.

 

[orangechili]

Hi All,

I picked up this project that need some love recently. I got both channels passing audio and some slight compression with the threshold control cranked (about 4db of compression).In comp mode it has plenty of gain and is virtually noise free.  I read through this thread but didn't see these issues I'm having so maybe someone can help. Here's my issues in BOTH boards.

Both meters sit zero in comp mode and function with light compression in most rotary switch settings. As soon as I engage Limiter mode the hairball meter drops to around 16 and volume goes waaayy down. Also in the 1:1 ratio setting in comp mode  the meter goes down and slowly rises back to zero after a about a minute.

I have messed with the calibration settings noted here but have not set the chopper calibration yet. Wanted to get over this hurdle first.

Any ideas would be greatly appreciated!

 

[Ilya]

I have messed with the calibration settings noted here but have not set the chopper calibration yet. Wanted to get over this hurdle first.

Set all trimmers to the recommended preset values (refer to schematic) and start from there. You need to check the chopper, but this is not that critical for initial tests (if it's in the ballpark).
1:1 should work fine and pass the signal with no gain reduction. I can't speak about Abes particular PCBs, but people reported not connected trimmer pads on the PCBs. So check for those.

 

[orangechili]

Thanks for the reply! All the trimmers have been bridged to the middle bottom pad and I started with preset values. My main concern is the lack of compression and the limit mode dropping signal and moving down on the meter. It's almost as if its not fully connected. I have triple checked the header connection to the rotary switch board. Running out of ideas. I wonder if there's a component around the limit section that may have failed or isn't connected properly...

 

[Ilya]

Thanks for the reply! All the trimmers have been bridged to the middle bottom pad and I started with preset values. My main concern is the lack of compression and the limit mode dropping signal and moving down on the meter. It's almost as if its not fully connected.

To me it sounds like in limit mode your unit is going in high gain reduction for some reason. Don't bother with the lack of compression until you solve the limit problem. I'd start with the sidechain. Check R5 and R69 values. Also scope the output of the 555 oscillator (at D1 cathode).

What happens when you switch to 1:1 mode? What interstage transformer are you using?

 

[orangechili]

Thanks for the tips! I'll check that out

I haven't even fussed with the oscillator yet, just moved the trimpot on that around but noticed no difference in the limit behavior so put it back to where it was roughly

I'm using an Edcor wsm 600:10k for the side chain and output, cinemag on the input

 

[orangechili]

R5 and R69 verified correct values. I notice the 2 pole 6 position switch was placed wrong on the decay rotary switch. There was a bridge connecting the pole where it should have gone. I desoldered it and orientated it where the 'A' pole goes to the slot where there is a track on the circuit board and left the 2 empty poles blank ... After doing that I still have the same problem with limit mode but now the channel is thumping when it compresses and is much noisier. Yay...

Tried moving trimpots to no avail.

 

[Ilya]

Aren't all switches there 3-pole except decay? At least from the schematic it seems so...

 

[orangechili]

Yep they're all three pole except decay which is one pole. I just verified all rotary switch controls to themselves and headers with a continuity meter so the issue is not on the switchboard.

 

[orangechili]

I should mention when I switch to 1:1 ratio the meter behavior is the same as when I switch to limit mode even while in comp mode.

 

[Ilya]

I should mention when I switch to 1:1 ratio the meter behavior is the same as when I switch to limit mode even while in comp mode.

In 1:1 and Lim modes the only common thing is not connected emitter of TR18. Check that. Also measure voltages at the D5/D6 cathodes junction - which values do you get on different ratio settings and in Lim setting?

 

[marcn]

Check your transistors are correctly installed TR15-18, especially if you used 3906 on TR16 and 18.

 

[orangechili]

So I checked all the transistors(diode tested each leg) and they are all good. 2n3906 were used and orientated backwards along with the 2n4124 like the manual says to do. I reflowed all solder joints. Checked electrolytic capacitors for capacitance and all are good. Resistor values are spot on. I am at a loss for why I can't get limit mode to engage and the 1:1 ratio mode. It's like those connections are not present when switched in if that makes sense.

To boot I have to crank the threshold control all the way up to get 3-5db of compression in the other settings. Sidechain transformer is orientated correct via the manual instructions, I even flipped to see if any change and I got no compression that way..

Running out of ideas

 

[Ilya]

Running out of ideas

Have you measured the voltages I talked about?

 

[Spencerleehorton]

my pcbs have arrived!! time to get building!!!

 

[orangechili]

On the cathodes of the D5/D6 I get  -6 volts Not sure what the voltage is supposed to be here? All the main voltages everywhere else line up with the schematic(-12V and -15 to -22V)

 

[Ilya]

On the cathodes of the D5/D6 I get  -6 volts Not sure what the voltage is supposed to be here? All the main voltages everywhere else line up with the schematic(-12V and -15 to -22V)

You need to measure the voltages at different ratio settings, otherwise it's meaningless.

 

[marcn]

Gonna chime in with what I get approx on my PPH board (no x-former or 3640 installed ):
1:1 =0v
2:1 =-8.3v
3:1 =-8.1v
4:1 =-7.6v
Limit = -6.1v

Plugging in my 2nd switchboard varies those measurements by 10mV max.