Popping On True Bypass When It Shouldn't Be Happening

[guitarkill]

I've read all the articles on true bypass switch popping and how to *usually* fix it. But why on earth would you get a pop on a bypass switch on a delay pedal with nothing else on in chain? I can understand why it may happen on a high gain dist pedal but I don't get why it would happen on a delay pedal. 

Can anyone explain that?

[midwayfair]

I'm not sure what you read that led you to believe that it would only occur in a high-gain pedal, but popping is almost always caused by a a DC offset: When you turn the pedal on or off, the DC resistance on one side of either the input or output capacitor changes, resulting in a pop. Usually a resistor is used to bleed off any excess voltage that leaks through the cap to ground. There are almost no other causes.

[Elijah-Baley]

I got a pop with my IC buffer, but just after I power it for 1-2 minutes, then it become a little "tic".
Probably it could be solved, I don't have fix it yet.

If you need: http://www.diystompboxes.com/smfforum/index.php?topic=112304.msg1036264#msg1036264. About the pop.

[guitarkill]

I'm not sure what you read that led you to believe that it would only occur in a high-gain pedal, but popping is almost always caused by a a DC offset: When you turn the pedal on or off, the DC resistance on one side of either the input or output capacitor changes, resulting in a pop. Usually a resistor is used to bleed off any excess voltage that leaks through the cap to ground. There are almost no other causes.

I still get popping noise even with a 1M pull down resistor on the input.

[R.G.]

I got a pop with my IC buffer, but just after I power it for 1-2 minutes, then it become a little "tic".
Probably it could be solved, I don't have fix it yet.

When this happens, there is some capacitor that has to charge up to the normal operating voltage, and it takes a while to get there. Until it gets charged up to its normal operating voltage, there is a "dc" offset that is continuously decreasing. This happens sometimes when coupling capacitors are too big, or fed from too high an impedance source to charge them up. Something like a 10uF cap on the input of a FET or FET opamp. There are other situations, but this is one that's common.

[idy]

Try reducing the 1m to like 500k. Try another on the output if there isn't one already. If you do this, in between replacing the pulldown resistors, power it up and check for DC voltage at the input/output.
Leaky capacitors at in/out may be replaced.
Grounding the board when bypassed also helps. I do that and do away with input pull down.

[R.G.]

I still get popping noise even with a 1M pull down resistor on the input.

Pulldowns are a specific cure for leaking input or output caps. If there is some other issue, pulldowns do nothing.

This just means that it's something else. There are many possibilities. Not knowing what delay pedal it is, or what the schematic for it is, that's about all that can be guessed from the info so far.

By the way, true bypass is NOT pop-free. It's a cure for "tone sucking" pedals as were common in the late 1960s (!) and sometimes a dying battery, which is another problem we don't usually have today.

As Albert Einstein said, everything should be as simple as possible, but no simpler.

[Philippe]

Try another on the output if there isn't one already. If you do this, in between replacing the pulldown resistors, power it up and check for DC voltage at the input/output.
Leaky capacitors at in/out may be replaced.

and if you have an on/off LED indicator/circuit, check that too. AMZ has a 'fix' for popping LEDs.

[guitarkill]

Thanks everyone, that helps. 

[GiovannyS10]

Guitarkill, you solve your problem? I was something like that, i used pulldowns, and others things... Dont work  The problem was my pedals is mono, my cables is mono, but my amplifier was stereo. So i made a cable stereo/mono, and now me pedals work right without pop sound 

Good luck

[idy]

Also what kind of bypass switch? And these do make mechanical sounds too. Is it a commercial pedal? Homemade? Is the pop so loud you would never dare use it live or is it subtle? So loud you are afraid to use it at home?

+1 the LED/ capacitor+resistor thing. Also something you read if you read *all* the articles.

[idy]

Another thing I think of is:
if you have "nothing else on in the chain" but you still have other pedals that are bypassed, what if they are buffered bypass with leaky caps? Then another "true" bypass pedal will get a sudden pulse of DC when you switch it in.

[guitarkill]

Guitarkill, you solve your problem?

No, I have pop even if LED is disconnected. 

Also what kind of bypass switch? And these do make mechanical sounds too. Is it a commercial pedal? Homemade? Is the pop so loud you would never dare use it live or is it subtle? So loud you are afraid to use it at home?

Mechanical. DIY pedal, an FET emulation of a tube pedal. Pop is much too loud to be acceptable. 
Circuit input is grounded on bypass BTW.

[guitarkill]

I'm not sure what you read that led you to believe that it would only occur in a high-gain pedal, but popping is almost always caused by a a DC offset: When you turn the pedal on or off, the DC resistance on one side of either the input or output capacitor changes, resulting in a pop. Usually a resistor is used to bleed off any excess voltage that leaks through the cap to ground. There are almost no other causes.

I've only ever had this problem in high gain pedals and it was usually fixed by putting a 1M pull down resistor on the output, but that doesn't work this time and I have the pop even though the LED is disconnected.

The problem on the delay pedal is the same situation, and the first time I've experienced it in something that is NOT a high gain dist pedal. 

[idy]

Make sure you eliminate the easy by taking testing it alone, no other pedals, guitar-delay-amp. Worth trying a replacement switch? Check with a meter, any DC on input/output?

[guitarkill]

I just used a Mammoth Electronics clickless true bypass on it, problem solved. Although I need to figure out why that was happening for my own edification.

[GiovannyS10]

Although I need to figure out why that was happening for my own edification.

A friend had a similar problem, the problem was the out cap was delaying so much to discharge, he used a resistor to solve it, but the problem continue, same when the battery is unconnected, so he used a couple of 4m7 resistors on input and out.. But on the end, the problem was the 3PDT was cuting all signal when pressed, and when the signal returns made the pop sound. The resistors solved it. Maybe your problem is similar, maybe not. Glad you solve.

[guitarkill]

A friend had a similar problem, the problem was the out cap was delaying so much to discharge, he used a resistor to solve it, but the problem continue, same when the battery is unconnected, so he used a couple of 4m7 resistors on input and out.. But on the end, the problem was the 3PDT was cuting all signal when pressed, and when the signal returns made the pop sound. The resistors solved it. Maybe your problem is similar, maybe not. Glad you solve.

Interesting.

[Philippe]

I just used a Mammoth Electronics clickless true bypass on it, problem solved. Although I need to figure out why that was happening for my own edification.

cool...btw, was this Mammoth Electronics 3pdt switch 'smoother' in operation than a typical 'taiwanese blue' 3pdt?  if so, it might be attributable to internal switching & damping factors.

those imported 'blues' IMO have always seemed kind of crude & inconsistent...like summertime watermelons, one always runs the risk of getting a crappy one as they are being produced cheaply with minimal QA/inspection.

[guitarkill]

cool...btw, was this Mammoth Electronics 3pdt switch 'smoother' in operation than a typical 'taiwanese blue' 3pdt?  if so, it might be attributable to internal switching & damping factors.

those imported 'blues' IMO have always seemed kind of crude & inconsistent...like summertime watermelons, one always runs the risk of getting a crappy one as they are being produced cheaply with minimal QA/inspection.

They are completely different switches. The Mammoth one is a soft switching (I'm assuming bounce free) 2-pole momentary type and the 3PDT switch is a clunky mechanical affair. The switch time on the clickless bypass circuit is about 10mS, much faster than a mechanical 3PDT could ever switch.