DEMO PedalPCB Decadence PCB511 Peavey Decade

This post contains an audio or video demo

scheffehcs

Well-known member
Here’s my Decadence.

I’m a fan of Queens of the Stone Age, so I felt compelled to build this one. Demo down below.

My takeaways - sounds great, kinda gnarly and fizzy at times, nails some of those blown out tones from early Queens albums. The EQ is powerful and can very wide range of sounds. I see this a great tool for recording.

The build - everything went smoothly. A lot of gain is bunched up high on the B10k drive pot. Might want to sub for… C10k I guess? I tried to show it in the demos. Volume doesn’t go much past unity - I believe @Robert suggested a resistor substitution to boost the volume in another thread, can’t seem to find it right now. I was able to use an enclosure I fucked up drilling from awhile back, so that’s nice.

Here are the pics.
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Here are the demos. First one is through the front of my JC-22, second one is through the effects loop, bypassing the JC preamp. Guitar is a Gibson LP with P90s.


 
You want to change R26 (using the DEFX schematic). It’s the feedback resistor for the gain recovery stage before the output.
 
Hey thanks, I went over to deadendfx and saw that too. Problem is, there is no R26 on the PPCB board 😅. I should have taken a pic on the board before I populated it, but I’m pretty sure the only other 33k on there was R3. I guess it could be a coincidence that R11 on both boards is 33k. R3 on deadendfx is 1k5. Also has a lot more components. Hmm now that I’m looking at it, all that extra stuff is part of their “coda bypass,” not familiar.

I’m done for the night, but I’ll be back at it tomorrow. Maybe @Robert might be able to chime in to shine some light on it.
 
This is the resistor. Increasing the value should have increased the output gain, not lowered it.

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Update. I followed up on what @benny_profane mentioned and took a closer look at the deadendfx schematic. It looks like the resistor that needs to get bumped to 150k is the one between pins 1 and 2 of the op amp, which would be R3 on the PPCB board. Far be it from me to question @Robert, but I couldn’t help but tinker and try it out.

So two pulled pads, a jumper, and a couple burnt caps later, I put in two sockets for the two 33k resistors. I can say pretty conclusively that R3 is the one we want to change to 150k to give this pedal a nice volume boost!

I’m gonna go ahead and mark this one SOLVED.

Oh wait, this wasn’t a troubleshooting thread 😂


I was wrong, see below
 
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Ok I second guessed myself, and a bit earlier I took another listen. When I tested the volume last night, I only did it with the gain toggle on low gain. On high gain, it seems like the volume still doesn’t get much higher than unity gain. Since I socketed both 33k spots (R3/R11), I’ll go back and give them a thorough test. Hopefully can do that tonight. Sorry for the confusion.
 
Haha! No drama - we all make mistakes and that's what this forum is for - to humiliate ourselves for the greater good. :)

Thanks so much for posting this. I will be building one of these as soon as it arrives for a friend who is also a huge QOTSA fan. I'll incorporate that mod for him. I already made an Ultimate Fuzz with a few mods for him. It's so cool being able to make these things!
 
I would also change that 22k resistor before the volume pot. Either jumper it or change it to something much lower.
 
Alright, so I swapped the resistors both ways and it turns out I was WRONG. Here’s my semi scientific test if you want to see me embarrass myself. I’ll never question you again @Robert 😅. Not sure what happened the first time I swapped them!

Apologies all around for anyone tuning in.

Hahaha, can't embarrass yourself more than I have this week:)
 
Hello, new member here, and my very first post.

Since there are no schematics or build docs available to me, can I verify with you that the value printed on the PCB for C2 is correct? 100pf in what looks like a big box capacitor outline?
 
The values are correct, although you might want to consider the alternate value for R11 mentioned above.

When possible I use larger footprints to accommodate different capacitor types.
 
Did you ever hear the tragedy of @MichaelW The Capacitor Master? I thought not. It’s not a story the builders would tell you..

(Like I can talk, at least Michael's capacitors fit on the board..)
Hey....they DO fit.......(with a little persuasion). Then I discovered the wonders of tantalum hahahaha
 
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