EQD Warden Compressor questions

[snk]

Hello,
I have built the EQD Warden compressor yesterday (It is a full featured Vactrol compressor).
I have built it on veroboard using this layout.
Some schematics and PCB can be found here and there :
http://effectslayouts.blogspot.com/2020/04/eqd-warden.html
https://www.pedalpcb.com/product/delegate/
https://pcbguitarmania.com/product/tone-guard-device/

1 - All the compressor part works fine, but it seems that something is wrong with the tone pot : from the user manual, it is supposed to be a tilt eq :

Counterclockwise is treble cut, clockwise is treble boost. The tone is nearly flat around 11 o'Clock

.
On my build, only the "bass" portion seems to work : I have a quite dark tone, and turning the TONE knob colockwise doesn't increase the highs, but it acts as a "fade out" pot : when fully clockwise, there is no more sound heard.

I have isolated the eq section of the schematic, but i am not sure how to find from it which parts might be the culprit? I mean : the TONE is neither a Lowpass, nor a bandpass, nor a hipass, right? So, it must be a tilt/baxandall eq?




2- Also, I would like to add a gain reduction indicator led. Where should i wire it (without affecting tone or compression behaviour) ?

Thank you in advance for any help

[Mark Hammer]

When the wiper is rotated towards lug #1, that connects C15 to ground, such that C15/R13 form a lowpass filter rolling off just above 720hz.  When the wiper is rotated back towards lug #3, then C15 is connected directly to C16, and C15 and the 100k of the Tone pot, form a sort of highpass filter.  If R14 wasn't there, then C15/Tone would roll off lows beginning around 72hz.  But R14 provides a bypass of C15, yielding full bandwidth.

I guess the question to ask is how the circuit behaves at different "Level" pot settings, since what it does for gain depends on the input resistance to that op-amp stage as well as the feedback resistance.

[PRR]

> ask is how the circuit behaves at different "Level" pot settings

Don't care. IC1.2 pin 6 is a Virtual Earth, "zero ohms" (<100r).

So full-up, the VE is driven with 67k for lows and 20k for highs, good 10db top-boost. Full-down, all over 800Hz is sloped-down and then fed through 57k to VE.

> fully clockwise, there is no more sound heard.

Well, then it is not wired as drawn.

32 cuts seems like a lot.

[snk]

Thank you for your help, Mark & PRR.

It sounds indeed like a wiring error (or a trace cut issue), as the pot acts like a fader... unless it fades up to silence while it shouldn't.
The layout was reported as verified, and with "big" veroboard layouts like that i tend go carefully, but sometimes careful is not enough I will check again if i didn't make a mistake, and also see what happens if i change the tone pot wiring.
I am not even sure that i need a tone pot on a compressor... but i wouldn't want a compressor working as it shouldn't
Today, i finished some enclosures for some older projects, so my desk is less messy and tomorrow i will be able to focus better on that Warden tone issue.


By the way, is there any easy way to have a gain reduction led indicator (without messing with the sound obviously)?

[snk]

I re-looked at my wiring, and it seems done according to the layout. Do we agree that Level pot Lug 3 is not connected?
I also made pictures of my build (sometimes watching them full screen helps finding traces, cuts and small errors), but everything seems fine.

I was staring at the schematic, and trying to "map" it to the veroboard. I noticed a slight difference :
- on the schematic, R16 comes first after the opamp  pin7, and then C17 follows, before going to the output.
- On the layout, it seems that C17 comes first, before R16 : does it make a difference?



(For what it's worth, I'm also posting the zoomed pictures of the layout)

[snk]

Well, then it is not wired as drawn.
32 cuts seems like a lot.

Out of curiosity (and because sometimes my eyes fool me when staring at a small verobaord with many cuts), i took the layout picture, applied a symmetry to it and overlayed it on top of my build's picture : the cuts of the layout match my build, so it doesn't seem a cut issue (i know this is not a proof or a very scientific method, but it confirms what i could see at least).
Tomorrow, I'll investigate further.

[snk]

Can you believe it?
It was just a crappy pot 
I tried with another one, and it works fine now!

If i don't have any 100KB pot, would you recommend a 50KB, or a 250KB?

[snk]

Hello,
Would anyone know if it is possible to add a gain reduction indicator led to the circuit?
Thank you

[PRR]

Would anyone know if it is possible there is a complete schematic available?

[snk]

Would anyone know if it is possible there is a complete schematic available?

Yes, page 3 on this PDF (link also available in first post) : https://www.pedalpcb.com/docs/Delegate.pdf
And page 5 of this PDF : https://pcbguitarmania.com/wp-content/uploads/2020/02/Tone-Guard-Device.pdf

I hope it is ok to post the picture here too :