Loud vs traditional (low volume) bluesbreaker

[ChrsGuit]

Hey folks... So, a long time ago I built a Musikding Bluesbreaker clone... I LOVE it... It has a great tonal Character and very loud... unlike bbs of old...

I recently put together a PedalPCB Bluebreaker pcb using the same values found in the Musikding kit... it sounds really good, BUT... it's also very quiet with a different tonal character...

My goal was to recreate a 1for1 clone of my Musikding build in the more tidy 125b enclosure...

So, I have my old My old Musikding kit cracked open and I found something interesting... The R1 resistor in my Musikding kit is dead... I'm getting .5 Ohms with a multimeter...I also have continuity on both sides of it, telling me it's effectively "open" and applying no resistance...

If R1 isn't applying any resistance (supposed to be 1meg), and thus the response is much louder and tonal Character is different...
Would this be the logical conclusion, and, in theory if I remove R1 from my Bluebreaker build, it would yield the same result?

 

[jwin615]

Plug cables in and see if it changes.
Pretty sure the schem is showing a switching jack which may (intentionally) create a ground loop with nothing plugged in, effectively connecting both side of R1 to ground. So. Yeah. No resistance.

 

[jesuscrisp]

If R1 had no resistance you'd get no signal at all as it would short your signal to ground.


Edit: when your pedal is in bypass, the input of the board is grounded, hence no resistance and continuity to ground. Click the footswitch, you'll measure 1M.

 

[jwin615]

To add, R1 sets input impedance. 1M to ground isn't going to make a huge difference in level aside from keeping ICa happy.
Not advisable to remove as then the impedance seen is solely reliant on whatever is plugged into the pedal

 

[jesuscrisp]

No, it's a pulldown resistor. It also influences impedance but the main function is to discharge the input cap to avoid switch popping.

 

[jwin615]

Split a signal and run into both pedals and probe through them simultaneously. Ground them together so you only move one probe.
Don't have to hit every point. Try just input and output of the opamps at first. Let's figure out where in the circuit you're seeing losses and go from there.
I'd turn both pedals knobs fully clockwise and be careful not to overdo the signal level if using a line level source.
If using a phone signal generator for instance, turn the phone volume to 15% or so.

 

[jwin615]

No, it's a pulldown resistor. It also influences impedance but the main function is to discharge the input cap to avoid switch popping.

That as well. Bigger point, not making any difference to level.

 

[ChrsGuit]

Plug cables in and see if it changes.
Pretty sure the schem is showing a switching jack which may (intentionally) create a ground loop with nothing plugged in, effectively connecting both side of R1 to ground. So. Yeah. No resistance.

Now that you mention it, I am using two different jack styles on these... I built the original when I had NO CLUE (well, some clue) what I was doing and it happened to turn out great... but now I'm trying to figure out exactly why it does so I can replicate it...

 

[ChrsGuit]

Split a signal and run into both pedals and probe through them simultaneously. Ground them together so you only move one probe.
Don't have to hit every point. Try just input and output of the opamps at first. Let's figure out where in the circuit you're seeing losses and go from there.
I'd turn both pedals knobs fully clockwise and be careful not to overdo the signal level if using a line level source.
If using a phone signal generator for instance, turn the phone volume to 15% or so.

Also, I wanted to preface the new version I made seems to be functioning correctly with a good volume sweep. So it isn't losing anything volume wise... the old Musikding kit is just VERY loud... I usually get above Unity at 9o'clock, which is very uncommon for a BB circuit... they usually struggle with volume...
I should note, all my pots are correct value as well, as I was initially thinking I'd slipped up and put a higher value in or something

 

[ChrsGuit]

If R1 had no resistance you'd get no signal at all as it would short your signal to ground.


Edit: when your pedal is in bypass, the input of the board is grounded, hence no resistance and continuity to ground. Click the footswitch, you'll measure 1M.

You are correct... now I have 1meg.

 

[ChrsGuit]

One glaring thing I noticed was the unorthodox way they had me wire the switch. I guess it doesn't really matter with a 3DPDT, but it's certainly different than the way PedalPCB is laid out... I doubt this could be anything to do with it

 

[ChrsGuit]

Also, my soldering was pretty substandard back then, however I spotted no bridges or any suspicious joints

 

[ThePanda]

Hey folks... So, a long time ago I built a Musikding Bluesbreaker clone... I LOVE it... It has a great tonal Character and very loud... unlike bbs of old...

I recently put together a PedalPCB Bluebreaker pcb using the same values found in the Musikding kit... it sounds really good, BUT... it's also very quiet with a different tonal character...

My goal was to recreate a 1for1 clone of my Musikding build in the more tidy 125b enclosure...

So, I have my old My old Musikding kit cracked open and I found something interesting... The R1 resistor in my Musikding kit is dead... I'm getting .5 Ohms with a multimeter...I also have continuity on both sides of it, telling me it's effectively "open" and applying no resistance...

If R1 isn't applying any resistance (supposed to be 1meg), and thus the response is much louder and tonal Character is different...
Would this be the logical conclusion, and, in theory if I remove R1 from my Bluebreaker build, it would yield the same result?

Did you switch the dmm to 2M Ohm and test R1?

 

[jwin615]

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?

 

[jwin615]

I'd still feed them identical signals and probe back and forth.
Hit the in and out pins of both ICs first then go from there. Also check the in and out of the board to rule out a switch issue.
There are a few different ways to wire the switch. No worries on the wiring.

 

[manfesto]

Hey folks... So, a long time ago I built a Musikding Bluesbreaker clone... I LOVE it... It has a great tonal Character and very loud... unlike bbs of old...

Which, as you’ve noted is *very* unusual for a BB circuit.

This makes me think that you may have some wrong values on your Musikding build (“wrong” as in they don’t match the schematic - but if it improved the sound and functionality to your ears, clearly not “wrong” as in “bad”).

Have you double checked all the values on your Musikding build? I’d check the gain-setting resistors around the op-amps maybe?

 

[ChrsGuit]

Which, as you’ve noted is *very* unusual for a BB circuit.

This makes me think that you may have some wrong values on your Musikding build (“wrong” as in they don’t match the schematic - but if it improved the sound and functionality to your ears, clearly not “wrong” as in “bad”).

Have you double checked all the values on your Musikding build? I’d check the gain-setting resistors around the op-amps maybe?

I have, and they are all correct values.

 

[cdwillis]

Using a 3.3k for R5 is going to result in a lot more gain in the second gain stage. Usually there's a 10k there, so max gain in stage two would be 470k/10k=47 and minimum gain would be 470k/110k=4.7. Compare that to 470k/3.3k= 142.42 and 470k/103.3= 4.56. I'd imagine your overall volume is going to be limited by the two sets of silicion diodes in stage two, but the percieved volume should be much louder just more compressed.

I bet that C5 is 220nf to compensate for the smaller value R5 so you don't lose low end, but I'm not sure if C5 and R5 are calculated like a regular high pass filter or not.

 

[ChrsGuit]

Yes

Did you switch the dmm to 2M Ohm and test R1?

I did, and it's good. I had it switched off

 

[jwin615]

.

low end, but I'm not sure if C5 and R5 are calculated like a regular high pass filter or not.

Since there no path to ground, I think C5 only bass blocking, but to what extent at this point in the circuit, especially with a 10n input cap, I doubt the values differential matters much aside from cleanup.