# JHS Double Barrel clone sounds like dying fuzz at times



## Sasan

I just finished a JHS Double Barrel clone yesterday and it sounds great. It’s desinged by effectslayouts.com

One thing I’ve noticed though: the TS side sometimes sounds like a fuzz with a dying battery or gated fuzz. When I disengage the TS side and turn it in again, it sounds normal.  
Here’s the schematics: http://effectslayouts.com/wp-content/uploads/2020/02/Break-Action_build-doc.pdf

Does anybody know where to look at?

thanks


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## Barry

Maybe a funky capacitor somewhere? Have probed the circuit at all?


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## Sasan

Barry said:


> Maybe a funky capacitor somewhere? Have probed the circuit at all?


Thanks for your reply. 
no, I haven’t. Actually, I wouldn’t know how to properly do it...
I just checked the ICs, they seem to have good values at 4.44-4.58V. The Emitters of the transistors show 3.53 (Q1) and 0.36 (Q2). 

Could it be the R3 at 10M is a reason? The normal TS/Moonshine schematics show 1M resistors...


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## Barry

I think you'd have other voltage issues if it were that resistor, can you post pictures of both sides of the board?


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## Sasan

Only this side for the moment. Will try to unscrew everything and make pics of the other side tomorrow


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## Sasan

Barry said:


> I think you'd have other voltage issues if it were that resistor, can you post pictures of both sides of the board?


Hi Barry,
here’s the other side:


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## Sasan

I wrote the guy at effectslayouts who only responded:
„I have not run into that with my build. Maybe adjust R4, which is biasing the gain/clipping stage.“

do you think this could be a Solution?

further, I measured the following values on the TL074:
Pin 3: 4.01V
Pin 5: 1.07V
Pin 10: 1.07V
Pin 12: 4.40V

BTW, do you think R7 needs a decoupling cap? Would it help to change R7 with a 100nF cap?(that’s a suggestion a Buddy came up with)


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## zgrav

the starved fuzz sound seems like it is getting low voltage, but since it is intermittent I don't think it is your bias.  the comment about the funky capacitor seems likely.    try measuring the voltage on the transistors when the effect sounds OK, and also when you are getting the gated fuzz sound to see if there is a difference.


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## Sasan

zgrav said:


> the starved fuzz sound seems like it is getting low voltage, but since it is intermittent I don't think it is your bias.  the comment about the funky capacitor seems likely.    try measuring the voltage on the transistors when the effect sounds OK, and also when you are getting the gated fuzz sound to see if there is a difference.


I just checked. When I don’t play at all or play slow and calm, the emitter of Q1 shows ~3.33 V. The fast and louder I play, the sound gets fuzzy and the value Q1 if Q1 decreases to under 2V, lowest was 1.76V and really fuzzy sound...when I don’t pick anymore, the value slowly increases to 3.33V (peak) and sounds relatively normal again... :/


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## zgrav

That means you are getting a voltage drop that causes the gating at the transistor.  Now the question is what causes the voltage drop.  What power supply are you using?  Check the power where it goes into your pcb from the jack --- measure it like you did at the transistor to see whether the incoming power is dropping when the effect is not working correctly.  If your power where it comes into the board stays at the same level, start checking other places on the board to see if you can isolate the part where this power drop happens.


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## Sasan

zgrav said:


> That means you are getting a voltage drop that causes the gating at the transistor.  Now the question is what causes the voltage drop.  What power supply are you using?  Check the power where it goes into your pcb from the jack --- measure it like you did at the transistor to see whether the incoming power is dropping when the effect is not working correctly.  If your power where it comes into the board stays at the same level, start checking other places on the board to see if you can isolate the part where this power drop happens.


Tried several power supplies (Cioks DC7 and DC10 and Strymon Plug). All with the same results.
How do I do that to get reliable results? Would you check only the TS side of the pcb? Or both sides? Check the voltages of all components?


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## giovanni

If the DC bias is changing it could be a power issue (9V oscillating down), but since you tried different supplies my money is on a biasing issue. Maybe you have an intermittent short somewhere or a cap that’s letting DC through. Check that your solder joins are not cold maybe? If the issue is on Q1 only I would check the components in its close proximity (biasing resistors and coupling caps).


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## zgrav

Use your schematic to see where the power goes for C1 and look for other spots where the voltage changes like it does at the transistor.

Did you swap out that transistor to try another one to see if you still have the same problem?

Make sure Q1 has a good fit in its socket.   ALso try swapping Q1 and Q2 to see if that makes a difference.


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## Sasan

giovanni said:


> If the DC bias is changing it could be a power issue (9V oscillating down), but since you tried different supplies my money is on a biasing issue. Maybe you have an intermittent short somewhere or a cap that’s letting DC through. Check that your solder joins are not cold maybe? If the issue is on Q1 only I would check the components in its close proximity (biasing resistors and coupling caps).


Sorry, I don’t have much of a clue...which ones would that be?


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## Sasan

zgrav said:


> Use your schematic to see where the power goes for C1 and look for other spots where the voltage changes like it does at the transistor.
> 
> Did you swap out that transistor to try another one to see if you still have the same problem?
> 
> Make sure Q1 has a good fit in its socket.   ALso try swapping Q1 and Q2 to see if that makes a difference.


Yeah, I tried several transistors. All with the same result. I swapped C1 now, but all caps show 0V on one side and 1.07V on the other. What I noticed: R1&2 show 0V on both sides.

Because basically all components on the TS side showed the same voltage decrease, i then started to measure the components after the 9V input (remember I have no clue!)



this is what I noticed:
R34 and R32: 4.04 & 8.5V
R35 and R33: 4.04 & 0.0
C27: 0.0 & 4.04
C26: 4.04 BUT voltage decreased when I played something!

Could this be the one?


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## giovanni

R1&2 are good. The resistors biasing Q1 are R12, R32 and R33. Can you measure the voltage at either end of R12? You could also try replacing C26: if the voltage is changing there maybe it’s leaking current? Just a guess but this is definitely close to where the problem lies.


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## giovanni

You could also try removing C26 and see if things change. If I read the schematic correctly it’s there just to filter power noise so the circuit would work without. You can put a replacement back in if removing it does the trick.


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## Sasan

giovanni said:


> R1&2 are good. The resistors biasing Q1 are R12, R32 and R33. Can you measure the voltage at either end of R12? You could also try replacing C26: if the voltage is changing there maybe it’s leaking current? Just a guess but this is definitely close to where the problem lies.


R12 shows 4.04 & 2.66 without playing; 2.39 &1.57 when playing 

will try replacing/removing C26


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## Sasan

Replaced C26 and it's still acting the same way.
Even before reaching C26, the voltage of R32/33 drop when I play...


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## giovanni

That’s really weird. Do you have cold joins at R32 and R33?


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## Sasan

I just finished a JHS Double Barrel clone yesterday and it sounds great. It’s desinged by effectslayouts.com

One thing I’ve noticed though: the TS side sometimes sounds like a fuzz with a dying battery or gated fuzz. When I disengage the TS side and turn it in again, it sounds normal.  
Here’s the schematics: http://effectslayouts.com/wp-content/uploads/2020/02/Break-Action_build-doc.pdf

Does anybody know where to look at?

thanks


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## giovanni

Just to be clear, the voltage you are measuring is DC not AC? Do you have a probe to test the audio path? Next thing I would do is test the audio before the transistor, i.e., before or after C9. If the pedal sounds normal there, it’s definitely that Q1 stage.


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## giovanni

Also what happens if you blend the clean tone 100%?


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## giovanni

One more measurement: what voltage do you see across C9?


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## Sasan

First of all: Thanks for the time you're taking to help me! I really appreciate it! Thanks!


giovanni said:


> That’s really weird. Do you have cold joins at R32 and R33?


I don't think so; I even changed them both...


giovanni said:


> Just to be clear, the voltage you are measuring is DC not AC? Do you have a probe to test the audio path? Next thing I would do is test the audio before the transistor, i.e., before or after C9. If the pedal sounds normal there, it’s definitely that Q1 stage.


You had me for a second....but I checked thrice, I'm 100% sure I measured DC. Unfortunately, I don't have a probe...


giovanni said:


> Also what happens if you blend the clean tone 100%?


Nothing changes....


giovanni said:


> One more measurement: what voltage do you see across C9?


8.34 & 5.99

Don't know what I've changed but it seems most of the values that have been 4.04V before are now around the 8.6V mark...
And there's basically no sound coming from the TS side at all....just fizzly noise....BB side works perfectly though!


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## zgrav

Sasan said:


> Replaced C26 and it's still acting the same way.
> Even before reaching C26, the voltage of R32/33 drop when I play...


what parts are you testing where you see the voltage drop?


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## Sasan

zgrav said:


> what parts are you testing where you see the voltage drop?


What do you mean?

by the way, would it help to decrease the values of R32/33/34/35 to 10k?


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## zgrav

Where are you touching the probe and measuring the voltage drops?  Which side of a specific part?  

I don't suggest changing any parts until you isolate the cause for your voltage drops.  Seems unlikely to be a short or a resistor.


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## Sasan

zgrav said:


> Where are you touching the probe and measuring the voltage drops?  Which side of a specific part?
> 
> I don't suggest changing any parts until you isolate the cause for your voltage drops.  Seems unlikely to be a short or a resistor.


Hmm, one of the probes is touching ground (from the DC jack) and the other one leg of the particular component...


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## giovanni

Ok so 8.6V means some of the components you replaced are now shorted 
If you have 100% clean but still experiencing the same issue that tells me that Q1 may not be the problem. But to verify it you really need a probe. You should be able to make one with two alligator clips. Connect one to the path you want to test and to your guitar cable tip, the other to ground (on the board and the cable).


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## giovanni

To clarify, the voltage at the node connecting R32 and R33 should be around 4V.


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## Sasan

giovanni said:


> Ok so 8.6V means some of the components you replaced are now shorted
> If you have 100% clean but still experiencing the same issue that tells me that Q1 may not be the problem. But to verify it you really need a probe. You should be able to make one with two alligator clips. Connect one to the path you want to test and to your guitar cable tip, the other to ground (on the board and the cable).


I just built myself a simple probe and checked some of the flow...
The sound is clear until I reach the TL074...not sure if it's supposed to be like this, but on pins 5 & 10 I hear the clean/clear sound, on the pins 6/7/8/9 it's already fuzzy...obviously, everything after these parts in the schematics sound like shit...


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## giovanni

Test pins 7, 8, 1, 14 of the TL074. 7, 8 should always have the clean sound; 1 should be the TS sound with full tone up; 8 is after the tone control. If it’s fuzzy at 7,8 it means we have a problem with the IC. Check the solder joints (can’t tell from the picture) and if you can, try replacing the IC. The IC is powered directly by the 9V so it shouldn’t be a power issue since the other side works fine.


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## Sasan

Could it be that IC2 got too much voltage due to the lately measured 8.6V? On the other hand, the sound was the same before the change...


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## giovanni

Updated my post above. The 8.6V reading wouldn’t affect the IC because that voltage divider is not part of the IC circuit. My guess is cold solder joints or a busted IC.


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## giovanni

And by the way, you should also address the R32/R33 divider where you measured 8.6V. It really should be ~4V at the node connecting them. That’s why you no longer hear any output.


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## Sasan

giovanni said:


> And by the way, you should also address the R32/R33 divider where you measured 8.6V. It really should be ~4V at the node connecting them. That’s why you no longer hear any output.


I replaced the diode and the two resistors, it now shows 4.2V again.



giovanni said:


> Updated my post above. The 8.6V reading wouldn’t affect the IC because that voltage divider is not part of the IC circuit. My guess is cold solder joints or a busted IC.


I replaced the IC and re-soldered EVERYTHING...don't know what helped, but it is working now!!!! At least the TS side! Thanks a lot, man.

Somehow I get a real loud beeping sound when I turn on the BB side now


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## giovanni

Awesome that the TS side works! Bummer about the BB side. In the debugging process, I believe you might have replaced some resistors used in the BB circuit? Like R34/R35? Maybe something got messed up there?


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## Sasan

giovanni said:


> Awesome that the TS side works! Bummer about the BB side. In the debugging process, I believe you might have replaced some resistors used in the BB circuit? Like R34/R35? Maybe something got messed up there?


Yeah, this thing is driving me nuts  Will try to check the BB section over the weekend, but I am pretty sure I haven't touched or replaced anything on the BB side...


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## Sasan

Ok, I really really thought it’s *only* my fault and disability to properly solder that this sounds as it sounds...but I have a second one built that behaves almost the same (It sounds great until you really start shredding, then the TS side starts to get fuzzy) and therefore i think that (besides my soldering capabilities) something in the schematics of this pcb is not thought out well...


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## Sasan

I've changed all the 100k resistors in the power section to 10k and R3 (10M) in the TS-side to 1M....not facing any problems atm


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## Sasan

I just finished a JHS Double Barrel clone yesterday and it sounds great. It’s desinged by effectslayouts.com

One thing I’ve noticed though: the TS side sometimes sounds like a fuzz with a dying battery or gated fuzz. When I disengage the TS side and turn it in again, it sounds normal.  
Here’s the schematics: http://effectslayouts.com/wp-content/uploads/2020/02/Break-Action_build-doc.pdf

Does anybody know where to look at?

thanks


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## Travis

Sasan said:


> View attachment 10516View attachment 10517View attachment 10519View attachment 10520
> Only this side for the moment. Will try to unscrew everything and make pics of the other side tomorrow


Where did you buy this pcb??


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## giovanni

Changing the resistors in the power section will increase the current drawn from the power by 10X, nothing more (I did some math and the power dissipation is still within the resistor tolerance so that’s fine), but it won’t affect how the circuit sounds. The value of R3 will affect how the two input stages on the TS side are biased but I would need to do the math to figure out how (haven’t done that in a while!). I thought you said the TS side was working no?


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## giovanni

Quick update: the PPCB schematic for the moonshine (the TS side of the double barrel) actually does use 1M for R3 so that’s probably a good change. The power section dividers all use 100K though.


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## Sasan

giovanni said:


> I thought you said the TS side was working no?


It was in the beginning....but faced the same problem after a while again.


giovanni said:


> Quick update: the PPCB schematic for the moonshine (the TS side of the double barrel) actually does use 1M for R3 so that’s probably a good change. The power section dividers all use 100K though.


OK, so the real change came from swapping R3? Is there any disadvantage of leaving the 10k inside in the power section?


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## giovanni

Using 10K will draw a lot more current which is not advisable. If using batteries they will drain faster, if using a power supply you will need a higher current draw which may make things less flexible for powering other pedals. It may also cause the pedal to heat up a bit more but I’m not sure how much.


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## Sasan

giovanni said:


> Using 10K will draw a lot more current which is not advisable. If using batteries they will drain faster, if using a power supply you will need a higher current draw which may make things less flexible for powering other pedals. It may also cause the pedal to heat up a bit more but I’m not sure how much.


Ok, thanks. I think I can live with this since both are connected to one power output of a Cioks DC7 that delivers 660mA on that output...if that’s the only drawback, I won’t change anything and run the risk of breaking something...


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