Are pedals supposed to leak DC voltage?

[thared33]

I was under the impression that just about every pedal had some caps to prevent DC leakage. I just tested all of my pedals and all of them are leaking some DC voltage on input and output. Is that normal?

 

[mcnabbanov]

odd. probably shouldn't be but that might explain various noise issues between pedals. though i imagine it is probably normal if every pedal is doing it, unless it is the same voltage just being carried through each patch cable and circuit. what happens when you bypass the effect (true bypass) or unplug the dc from it

 

[thared33]

All of my pedals do it so I'm guessing it's supposed to. I actually don't have any noise issues, I tested my pedals just because.

There's always a DC reading no matter what, but the number changes when I turn the pedals on and off. I read somewhere that pedals always leak a bit of DC but I'm not sure that's accurate.

 

[DRS]

Why is it an issue?

 

[MikeMcK]

How did you test?

 

[thared33]

I plugged a patch cable into the input and output and checked the tip/sleeve.

 

[chance0]

Voltage or current leak? If there are caps, I assume it's to block current. Well, maybe someone has more info.

 

[SKWIRE #1]

Why is it an issue?

For one, thats the main source of alot of 3pdt footswitch 'pops'.
I'd like to hear the answer on this topic, if thats normal and how much V+ is too much.

 

[thared33]

I read that pedals passing too much DC either on input or output can cause pops. I don't have trouble with it, but I decided to test just in case. There's some passing but I'm not sure if that's normal, and if so, 'how much' is normal.

I believe your amps aren't supposed to pass DC on input under like, ANY circumstances, but pedals do for some reason or another.

 

[fahrner]

What meter are you using and what DC setting are you on?

 

[SKWIRE #1]

bumping for... I dont know, maybe an answer?

 

[juansolo]

Some do, and as mentioned, it's not great and can be a cause of stomp popping. We've just had this in fact with a PS-1A clone we did. We modified it to run true bypass and it had DC on the output as standard so popped. Just required a cap and resistor on the output to stop that.

 

[stinkfoot]

Some DC voltage present at the input/output is to be expected, but we're talking millivolts. If it gets too much, it can cause switch pops in pedals with mechanical switches.

 

[amp_surgeon]

Most pedals have a series cap to block DC following by a resistor to ground. Unless the cap is leaky it shouldn't be passing any DC. However, that doesn't mean you won't measure something with a DC voltmeter. Many pedals generate a small amount of noise even with no input signal, and that noise will pass through the output cap and be dropped as an AC voltage across the resistor. Sometimes they pick up noise from the environment, like fluorescent lights. You can often measure the average of this voltage with a DC voltmeter, especially if you have a sensitive meter.

I wouldn't suspect there was a problem unless I was measuring a stable non-fluctuating value over 100mV or so. Also, if the pedal doesn't pop when you switch it on or off then you probably don't have any problems, and there's not much point in looking for one.

 

[shoepedals]

How much DC are we talking, here? Like milivolts? Because you could possibly read some of the actual signal from your pickups as DC if you're on the DC setting of your multimeter.

It's really not normal for the pedal to be outputting DC in most cases.

I would try each pedal individually with nothing plugged into the input to see if you cna isolate the issue, but really the next pedal (if it's engaged) should block any DC to the input with its cap.

 

[oxtone]

I think I had a DC voltage problem on my pedalboard some months back. I was noticing more noise, and my TC Delays (Nova & Flashback) were making big POP! noises when I stepped on the switches. Then, suddenly, my Bogner Ecstasy Blue "blew up" right in the middle of a song, and I heard this huge BUZZ in my In Ear monitors. I turned off the Blue, and the BUZZ went away.

Long story, short: Bogner replaced all the circuitry in my Blue, and that solved the problem. The Blue works fine now. I think something in the Blue went bad that was causing the DC problem, like a Cap.

 

[bluesoul]

Quote by Frank Zappa "shut up and play your guitar". Why would you want to test each pedal just because? If you have a noise problem, I understand.
But the answer to the question is ...yes, always a little leakage. Some times it is a problem.
Mostly it is not an issue...but now that you know, try not to let it bug you. And please take this tongue and cheek!

 

[fahrner]

What meter are you using and what DC setting are you on?

Funny thing is, the OP went MIA after 1/30 and this thread continues on.