# Microphonic Pedal? Whut?



## Greg Ellis (Oct 1, 2007)

Troubleshooting some hiss in my electric rig and I've determined that one of my pedals is "microphonic".

If I unplug the input, and tap on the pedal casing, that tap gets amplified in the signal chain. Fairly loudly too.

This weirdness stops when I plug a guitar into it, but there's still a fair bit of hiss - that's what I'm trying to solve.

My first reaction is uh... whut?

Any ideas about what might cause this to happen?

I'm guessing it's a bad ground maybe?

The pedal is a Silver Pony.


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## Greg Ellis (Oct 1, 2007)

With nothing in the pedal input, I get a lot of buzz from just touching the enclosure, and I don't get that at all from any other pedal in the chain.

I thought I had it figured out when I noticed one of the lugs from the output jack might be touching the bottom plate of the enclosure. I insulated with electrical tape, but things didn't really get any better.

There's still something wrong.


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## CathodeRay (Jan 12, 2018)

You might try touching a bunch of different points in the circuit that are supposed to be ground, individually. 
If any of them does not result in the issue, you're one step closer. 
Possibly maybe could be a ground loop due to a failed solder joint.


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## Greg Ellis (Oct 1, 2007)

I switched out some cables and reset the power supply (Dunlop DC Brick) and the problem seems to have gone away, for now.

I'm not entirely convinced that this is AOK, but it will do for the moment.


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## mhammer (Nov 30, 2007)

1) Lotsa pedals make noise until you pluig something into them. It's generally higher-gain pedals that do so.

2) I'm not certain that what you are describing is what is generally equated to being "microphonic". Microphonic pickups, for instance, generate a teeny signal from looser winds moving around in response to being shaken by higher volume. Although we are more accustomed to disturbing the field around a pickup by wiggling nickel-laden string over them, moving the coil around a magnet is also one of the ways in which a coil surrounding a magnet can generate a signal.

But that isn't what your pedal is displaying.

3) It can be the case that components like ceramic caps, which have conductive surfaces packed in tight against insulation layers, can become microphonic. Obviously there is no coil in there, but intermittent contacts that vibrate in place can generate a sort of signal. However, this is unlikely to occur unless the cap is being shaken or otherwise vibrated.

I don't say any of this to scold or criticize. Rather, how one characterizes a problem - sometimes by the name we use - can send us off in the wrong direction, looking for a cure.

I was largely unaware of what a Silver Pony is, and see it is a BYOC Klon Centaur clone. A properly built Klon should not exhibit the behaviour you describe, no matter what you call it. Are you the builder of the pedal, or simply a purchaser?


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## chuck_zc (Dec 6, 2009)

I've had the same problems with a couple of high gain pedals. My Angry Charlie was consistently like it. Sounded the same as a microphone tube. You could actually tap the switch with a cable end and it would ring right through the chain. Can't remember what I did to fix it but I did sell my Charlie since


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## Greg Ellis (Oct 1, 2007)

mhammer said:


> A properly built Klon should not exhibit the behaviour you describe, no matter what you call it. Are you the builder of the pedal, or simply a purchaser?


I bought this pedal used, and I don't really know the history. 

It might have been sold fully built, or perhaps some prior owner did the assembly from the kit.

The "microphonic" thing was really just a notable oddity, to me. I've never seen a pedal make a signal from tapping on the enclosure. 

It seemed like it probably shouldn't do that.

The real problem I was chasing was excessive hiss, and that seems to have gone away after I swapped out the first cable in my chain - the one between my guitar and first pedal.

It SEEMS ok now, but I haven't spent a whole lot of time with it since the problem went away. It wouldn't surprise me to be back here in another day or two with continuing issues.


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## mhammer (Nov 30, 2007)

I'm glad the problem seems to have abated. Don't be shy about broaching it here again if it crops up again.

Noise issues can stem from the most banal and mundane sources, and be cured by the most mundane face-palm-inducing strategies as well.


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## epis (Feb 25, 2012)

Greg Ellis said:


> With nothing in the pedal input, I get a lot of buzz from just touching the enclosure, and I don't get that at all from any other pedal in the chain.
> 
> I thought I had it figured out when I noticed one of the lugs from the output jack might be touching the bottom plate of the enclosure. I insulated with electrical tape, but things didn't really get any better.
> 
> ...


I didn't believe until it happened to me. These crappy Chinese jacks can be microphonic ! Replace both with Switchcrafts . Input jack should be stereo with shorting contact to eliminate buzz when input isn't plugged.


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## mhammer (Nov 30, 2007)

I find the biggest source of problems on phone jacks is a poor rivet joint, where the ground connection is crimped against the rest of the jack chassis. It doesn't happen often, but when it does it's aggravating.


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## Greg Ellis (Oct 1, 2007)

This wonky pedal has been out of my signal chain for a long while, but I've come back to it now.

New symptom - powering the Silver Pony from an old Dunlop DC Brick with a few other pedals connected puts the power supply into some sort of panic mode - the bright blue LED on the DC Brick flashes a warning message.

Disconnecting the Silver Pony from the DC Brick makes the error code go away, and the Brick is doing just fine powering a Dunlop wah, Suhr Riot, Voodoo Sparkle Drive and Visual Sound H2O all at once.

If I understand the specs right, the DC Brick can supply up to 100mA on each of seven 9V outputs, and also has three 18V connections, not sure of the current available there.

I'm going to try powering the Stone Pony with a separate wall wart to see if that fixes things. I haven't tested whether the Brick can power the Silver Pony when there aren't any other pedals attached - that might be worth looking at.

I'm curious about what could be wrong with this pedal that would create a problem like this. You wouldn't expect a Klon Clone to pull more than 100mA, would you?


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## mhammer (Nov 30, 2007)

The original (so I'm assuming all attempts at cloning it as well) uses a charge-pump to convert +9V into higher voltages; generally multiples of +9v, minus what the diodes take away, such that "18V" turns into something like 16.8V, and 27V turns into 25V or so. Charge-pump chips vary in their current-delivery capacity. Another way they also vary is with respect to _frequency_ doubling. Huh? These chips produce a medium-frequency clock pulse. The pulses are summed/averaged, and that's what allows them to produce a voltage greater than what is input. Connecting pins 1 and 8 in _some_ of them will double the frequency of that internal clock pulse. This can be very helpful, and indeed necessary, when the circuit needs to have reasonably wide audio bandwidth, since the default clock frequency is well within the range of human hearing. Doubling it puts it at the limits of our hearing and well above what guitar speakers can reproduce, so that can take care of any audible clock whine.

I did have two ungooped Klons in my possession temporarily a dozen years back (the reason why I initially joined this forum), and a schematic, courtesy of Bill Finnegan, but I honestly forget what charge-pump chip he used, and whether pins 1 and 8 were bridged. I also don't know if it is the same one as the Stone Pony uses.

Use of a charge-pump doesn't make it a "digital" pedal, but anything with a higher-frequency clock can run the risk of heterodyning with anything else having a higher-frequency clock that shares the same power line. If you have a choice of wallwarts, consider using an old-school analog one, rather than a switching type (readily identifiable because they weigh next to nothing, relative to their current-delivery capacity).


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## CathodeRay (Jan 12, 2018)

Greg Ellis said:


> I haven't tested whether the Brick can power the Silver Pony when there aren't any other pedals attached - that might be worth looking at.


Yes - check it & let us know.


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## Greg Ellis (Oct 1, 2007)

Ok...

I ran the Pony on a 200mA "Ibanez" wallwart for a while yesterday and it was just fine on its own like that.

So tonight I decided to disconnect everything from the DC Brick and see if it could power the Silver Pony.

I forgot to disconnect the wah. It was good plan though.

As I connected the power lead to the Silver Pony, the DC BC Brick shut down, lights out. And then came back on.

And the Pony worked. And I connected the other pedals, one at a time, an H2O, a Sparkle Drive, a Riot at 18V and a Ditto looper. They all worked too.

I tried disconnecting AC and then reattaching, to see if this was all a joke.

And that worked too. It's fine.

I don't know what this means, or why it's better now.


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## Wardo (Feb 5, 2010)

I think I’d send that pony to the glue factory before it does some damage... lol


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## BMW-KTM (Apr 7, 2015)

Don't give up on the Klone idea because they're great sounding pedals but maybe give up on the home built copy idea, particularly if built by someone you don't don't know to be a quality builder.
Based on the description, it seems like a ground issue to me but the truth is there are dozens of things that it could be.
If you did not build it and/or you are not particularly tech savvy about pedals then I wonder if your time and money couldn't be better spent looking for a quality replacement Klone and just chalk that one up to experience and lessons learned.


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