Loud vs traditional (low volume) bluesbreaker

[ChrsGuit]

Compared the two schematics.
The red are components no on the PPCB pcb. Green are different values, though you populated otherwise.
Now, the red bit may play into some tonal difference, at least in the low end.
Also, I missed the R7. Ignore that. But that C3 may be cutting come lows?
Have you tried flipping the tl072s around?
View attachment 58421

I forgot to mention that I actually went through the pedalpcb schematic and changed the appropriate values necessary to replicate the other circuit. in some cases they were labeled differently but I made notes to get them corrected

 

[jimilee]

That 3pdt wiring is interesting, indeed. If I’m looking at it right, it isn’t grounding the circuit on bypass, which would be the only real difference.

 

[cdwillis]

The input doesn't get grounded, but all that signal the first stage generates is being shunted to ground along with the input of the second stage. Maybe it was just convenient to run the wire from there. I really don't understand why you'd ground there instead of at the input plus it would save a couple parts.





I built a blues breaker on a breadboard a couple weeks ago and replaced the 100nf/220nf cap with a jumper and got no difference that I could notice in the sound of the circuit.

 

[manfesto]

I have, and they are all correct values.

I forgot to mention that I actually went through the pedalpcb schematic and changed the appropriate values necessary to replicate the other circuit. in some cases they were labeled differently but I made notes to get them corrected

Then assuming you didn’t make any errors, one of the parts in the Musikding build is either way out of spec or failing (in a way that you like). Two identical circuits should sound identical, so clearly they’re not identical in a way that you can tell visually.

So yeah, I’m with @jwin615 start probing your way through both circuits and see where they diverge, then figure out why. It’s either that or pull and measure each piece from the Musikding build and measure them.

 

[ChrsGuit]

Compared the two schematics.
The red are components not on the PPCB pcb. Green are different values, though you populated otherwise.
Now, the red bit may play into some tonal difference, at least in the low end.
Also, I missed the R7. Ignore that. But that C3 may be cutting come lows?
Have you tried flipping the tl072s around?
View attachment 58421

Are the red ones not the ones I circled in blue?

 

[ChrsGuit]

Then assuming you didn’t make any errors, one of the parts in the Musikding build is either way out of spec or failing (in a way that you like). Two identical circuits should sound identical, so clearly they’re not identical in a way that you can tell visually.

So yeah, I’m with @jwin615 start probing your way through both circuits and see where they diverge, then figure out why. It’s either that or pull and measure each piece from the Musikding build and measure them.

I'm fairly certain. The Pedal has sounded exactly the same since I built it quite some time ago... It really does sound good, but it certainly has always had tons of volume on tap. I'll have to try probing and see where it leads...
It's funny, but doing this, I kinda hoped I wouldn't inadvertently "fix" whatever is going on with it and lose that sound for good .
Tonally the pedals aren't that different, but it does seem the Musikding (aside from the volume), has a more smoother midrange bump. It does the traditional bb thing but it seems to have a bit broader frequency response. I wish there were an easy way to upload a video demo... I think most would agree the Musikding sounds better

 

[jwin615]

Are the red ones not the ones I circled in blue?

Admitted to the R6/R7 at post. Didn't have time to redo the pic.
Missed the C3 and even had my mind on the wrong rail. Apologies. Trying to get the kids bathed feed and beded while pasting schematics together.

At this point, my money is that a pair of resistors got swapped in the original build.

 

[manfesto]

Just noticed that in your original pic, looks like R6 is hooked to a switch? What’s going on there?

That’s a gain setting resistor for that op-amp stage and could definitely affect output volume.

 

[ChrsGuit]

Admitted to the R6/R7 at post. Didn't have time to redo the pic.
Missed the C3 and even had my mind on the wrong rail. Apologies. Trying to get the kids bathed feed and beded while pasting schematics together.

At this point, my money is that a pair of resistors got swapped in the original build.

I feel ya, we're trying to do the same with ours, so I've been sorta spot reading as I go!

 

[ChrsGuit]

Just noticed that in your original pic, looks like R6 is hooked to a switch? What’s going on there?

That’s a gain setting resistor for that op-amp stage and could definitely affect output volume.

I have two values, 220k and 470k... a mild gain boost... I replicated that on the new build as well

 

[ChrsGuit]

That 3pdt wiring is interesting, indeed. If I’m looking at it right, it isn’t grounding the circuit on bypass, which would be the only real difference.

Yeah, it's a really weird way to do it. Compared to most wiring schemes for switches that are sort of "standard"

 

[ChrsGuit]

Yeah, it's a really weird way to do it. Compared to most wiring schemes for switches that are sort of "standard"

This is why I hate troubleshooting...

I currently have a LGSM/TS that I built that the tone control has zero effect on. Tested all continuity, tested resistance on tone control and all components, voltage on the caps, etc... but the tone control does nothing... All my solder joints are good Pedal sounds great... but no tone control...

 

[manfesto]

This is why I hate troubleshooting...

I currently have a LGSM/TS that I built that the tone control has zero effect on. Tested all continuity, tested resistance on tone control and all components, voltage on the caps, etc... but the tone control does nothing... All my solder joints are good Pedal sounds great... but no tone control...

That’s where getting good at probing gets useful, you can find where in the circuit it’s behaving unexpectedly and you can work backward from there

 

[ChrsGuit]

That’s where getting good at probing gets useful, you can find where in the circuit it’s behaving unexpectedly and you can work backward from there

This is a good time to ask... So I've done audio probing before, but very... um... ghetto... I made a probe with a jack and cap wired to a precision screwdriver hooked up to a loop I recorded on my dl4...
Is there an inexpensive device I can purchase to do a better job without being so janky?

 

[jwin615]

This is a good time to ask... So I've done audio probing before, but very... um... ghetto... I made a probe with a jack and cap wired to a precision screwdriver hooked up to a loop I recorded on my dl4...
Is there an inexpensive device I can purchase to do a better job without being so janky?

Really just need a cap and preferably shielded wire.
I just use an old DMM lead with a cap heatshinked into the middle of it and heat shrink on 90% of the probe.
It also works out because I use banana jacks for testing/interfacing with a proto box I made from one of those $4 predrilled boxes from small bear.
Keep in mind the cap size(use large to prevent bass rolloff).
Janky works.
Bean has a good write up on constructing a semi-pro one
Making a Prototyping Rig - Madbean Pedals https://www.madbeanpedals.com/tutorials/downloads/Making_a_Prototyping_Rig.pdf

But whatever works.

 

[ChrsGuit]

Then assuming you didn’t make any errors, one of the parts in the Musikding build is either way out of spec or failing (in a way that you like). Two identical circuits should sound identical, so clearly they’re not identical in a way that you can tell visually.

So yeah, I’m with @jwin615 start probing your way through both circuits and see where they diverge, then figure out why. It’s either that or pull and measure each piece from the Musikding build and measure them.

I found the difference... When I built the original a long time ago, it was missing the volume pot... I had one lying around, and I just noticed I used a B100k instead of an A100k... so when I built one using the PedalPCB board I missed that and installed an A100k