LPB-1 with Big Muff sounds quiet

[ironman180]

Hi everyone!

So I built the Big Muff using Musikding's kit (American version). Decided to add a 3 way switch for tone caps and LPB-1 with it in the same enclosure. The Muff portion works awesomely but there is a problem with LPB-1. When I turn it on it doesn't boost the volume, it just changes the character of the sound and actually makes the pedal sound a bit quieter even when the trimmer is turned all the way up. There is no hissing, buzzing or popping sounds anywhere.
The only thing I changed in the Muff portion of the pedal is that I used all linear pots because those were the ones I had on hand. LPB-1 parts are the same as in layout but I believe that doesn't matter here.
And also, I believe that this dual effect wiring would enable you to use both effects independently from each other. When I turn on just the LPB-1 there's no sound, at all.

I'm also posting images of the pedal's wiring, Muff schematic and BOM, dual effect wiring from tagboardeffects which I used, my illustration of the wiring for this specific pedal and LPB-1 layout with trimmer.

I hope someone can help me.
Thank you all!

[Steben]

Hi.

Not sure if I read it correctly, but did you specify whether the boost is before or after the Muff?

[ironman180]

I believe that it is before according to the wiring I made... But maybe I'm wrong..

[antonis]

Just to make things clear..

LPB-1 doesn't work properly by itself..
Big MUff does..
What about both effects engaged..??

[ironman180]

Just to make things clear..

LPB-1 doesn't work properly by itself..
Big MUff does..
What about both effects engaged..??

Yup, LPB-1 doesn't work on its own, Muff does. When both effects are engaged LPB changes the sound of Big Muff and makes it a bit quieter.

[antonis]

In such a case, let's "isolate" the issue and put the blame on LPB-1..

Could you take some DC voltage measurements on 2N5088 Collector, Base and Emitter..??

In case of voltages are OK (Collector around 4.5V, Base around 800mV and Emitter around 150mV) post some pics of veroboard build (both items and soldering sides) 'cause there is a possibility of IN or OUT cap discontinuity..

P.S.
Does the sound level alter with trimmer setting..??

edit: For your convenience..
(DMM's Black probe on GND (0V) - Red probe on respective rows..)

[ironman180]

In such a case, let's "isolate" the issue and put the blame on LPB-1..

Could you take some DC voltage measurements on 2N5088 Collector, Base and Emitter..??

In case of voltages are OK (Collector around 4.5V, Base around 800mV and Emitter around 150mV) post some pics of veroboard build (both items and soldering sides) 'cause there is a possibility of IN or OUT cap discontinuity..

P.S.
Does the sound level alter with trimmer setting..??

I'm currently at work so I'll post it in a few hours and yes the sound level alters with trimmer settings.

[antonis]

OK.. Just edited above post with layout expected voltages..

P.S.
I presume the only one layout cut didn't slip your mind..!!

[ironman180]

OK.. Just edited above post with layout expected voltages..

P.S.
I presume the only one layout cut didn't slip your mind..!!

Luckily the cut is there, it didn't slip my mind. 
Thanks for voltages!

[Steben]

Just to make things clear..

LPB-1 doesn't work properly by itself..
Big MUff does..
What about both effects engaged..??

Yup, LPB-1 doesn't work on its own, Muff does. When both effects are engaged LPB changes the sound of Big Muff and makes it a bit quieter.

Well, that's a bit strange if the LPB is in front of the Muff... 
When misbiased or something an LPB after a Muff could behave like this if the Muff's stronger signal "awakes" the LPB....
But ... never mind now.... on to the voltages! 

[ironman180]

OK.. Just edited above post with layout expected voltages..

P.S.
I presume the only one layout cut didn't slip your mind..!!

Collector - 4.72V
Base - 746mV
Emitter - 170mV

Now on to removing the glue and sponge I used to stick the board to the enclosure so that I can post pics...   

[ironman180]

Here are images of lpb-1

[antonis]

Voltages are fine..!!

I'd desolder the trimmer and wire output cup (100nF between Collector and trimmer) directly to Output..
(or better, short trimmer's upper lug to out - but firstly measure outer lugs resistance..)

[ironman180]

Voltages are fine..!!

I'd desolder the trimmer and wire output cup (100nF between Collector and trimmer) directly to Output..
(or better, short trimmer's upper lug to out - but firstly measure outer lugs resistance..)

I will try that but I also wondered would a bigger value trimmer help? I have some 500Ks laying around.

[antonis]

I also wondered would a bigger value trimmer help?

In brief: No..!!

(we could make an analysis of Volume/Output pot value in conjuction with present stage output impedance and next stage input impedance as well as with present stage gain but I don't think your issue is located here..)

[ironman180]

I also wondered would a bigger value trimmer help?

In brief: No..!!

(we could make an analysis of Volume/Output pot value in conjuction with present stage output impedance and next stage input impedance as well as with present stage gain but I don't think your issue is located here..)

Okay then! I'll try and follow advice you gave me in your last reply. Will post what happened! 

[ironman180]

Voltages are fine..!!

I'd desolder the trimmer and wire output cup (100nF between Collector and trimmer) directly to Output..
(or better, short trimmer's upper lug to out - but firstly measure outer lugs resistance..)

So I shorted trimmer's upper lug to output and it's still the same. Is it possible that my wiring is wrong, because I soldered lpb-1's 9v to Muff PCB lower 9V pad which connects to the other 9V pad on the upper part of PCB which goes to DC jack?
I posted wiring layout in the first post.

[antonis]

As far as I can see, both +9V pads on Der Muff PCB are directly connected, so no potential issue there..



P.S.
Did you measure trimmer's resistance, across outer lugs..??

[ironman180]

As far as I can see, both +9V pads on Der Muff PCB are directly connected, so no potential issue there..



P.S.
Did you measure trimmer's resistance, across outer lugs..??

Trimmer's resistance across outer lugs is 111.8 ohm, I believe we found the issue. I also checked my order and I added 100k to the cart but I believe they sent me the wrong one, btw the marking on it is 100, does that mean that it is 100R?

[antonis]

Trimmer's resistance across outer lugs is 111.8 ohm..

Say no more..!!

the marking on it is 100, does that mean that it is 100R?

Definitely..!!