Ugh, everytime i plug in a high gain pedal to my power supply it has a whistle!

tehfunk · April 22, 2009, 07:10:51 PM

This has happened with an OCD build and now a TS808 build, and on two wah builds. They work silently with a battery, and pretty silently if i run it through this offboard power supply filter, with a capacitor etc., which i know i could just put inside every pedal and there probably wouldn't be an issue. BUT the problem is, why is it that in the pictures i see on this forum, very few people seem to have the R-C power filter in their pedals when they are probably using a switching power supply like me?? Am i getting the whistle (or whatever you call it) without the filtering because of wrong doings on my part, am i the only one dealing with this?? Here's what I've been thinking may be the cause... I send all grounds; output jack sleeve, dc jack sleeve, board ground, and 3pdt switch ground all to the input jack sleeve (so 4 wires attached to the input jack sleeve), i've been reading about grounding, but I'm not quite sure if this is totally wrong or totally right, as again, i see inconsistent wiring in the pictures thread, some people don't even ground the dc jack, for instance, i'm so confused!

So, is it my grounding technique? or what do you think it is? i don't think my audio signal from output and input wires are "crossing" a lot and the wire runs aren't abnormally long, so I don't think it's the other cause i read about, but correct me if i'm wrong. this is extremely frustrating, thank you for the help!

-Sam

R.G. · April 22, 2009, 07:55:22 PM

What power supply are you using?

Are you using the "ground the battery to the input jack ring terminal" trick?

tehfunk · April 23, 2009, 06:30:20 PM

Quote from: R.G. on April 22, 2009, 07:55:22 PM
What power supply are you using?

Are you using the "ground the battery to the input jack ring terminal" trick?

I am using a 1.7A 9.6 volt regulated 1spot style power supply that came with the PB1000 pedal board from Behringer.. it's almost surely switching.

Yes, I am using the "ground the battery to the input jack ring terminal trick on one of the gain pedals and both wahs. And, on the other gain pedal, I am not--I am using only a dc jack. If you can, beyond answering my current question, here's another: what is with all of the variation on what people ground, it seems some don't connect the output sleeve to anything (i mentioned this for the dc jack sleeve as well)? Thanks, you're just who I was hoping would answer the question, I read your other responses to similar questions but I was a bit confused.

aron · April 23, 2009, 06:58:09 PM

> it seems some don't connect the output sleeve to anything

They are probably grounding through the pedal chassis.

My friend's setup, has that whistling all the time. I can't figure it out either. It's always been there. Now that you have mentioned this, it's probably oscillating through the power supply - it must need more filtering. I will try this.

tehfunk · April 23, 2009, 08:04:20 PM

Quote from: aron on April 23, 2009, 06:58:09 PM
> it seems some don't connect the output sleeve to anything

They are probably grounding through the pedal chassis.

My friend's setup, has that whistling all the time. I can't figure it out either. It's always been there. Now that you have mentioned this, it's probably oscillating through the power supply - it must need more filtering. I will try this.

yep, filtering gets rid of it.. it's that simple. but it seems that not too many other people complain of it and i don't see filtering in their builds, so i am wondering if it is something i can fix by changing my building methods--grounding or something like it--to fix it. I only bring up grounding because in other threads about the topic i've read something that you should or shouldn't do with the ground wires but i don't get it.

R.G. · April 23, 2009, 08:23:28 PM

Quote from: tehfunk on April 23, 2009, 06:30:20 PM
I am using a 1.7A 9.6 volt regulated 1spot style power supply that came with the PB1000 pedal board from Behringer.. it's almost surely switching.

I believe you may have found the problem. The 1Spot (which is a registered trademark, btw) is the only one of those power supplies I know of that was specifically modified for powering pedals, and is 100% tested with a high gain distortion pedal at the end of the assembly line to find any flaws. It took several months of back-and-forth with the engineers for the manufacturer before we had a design that was quiet in a pedalboard setup, met RF emissions standards, and was reproduceable (they all come out the same).

It's possible that others have put in the time to put the quality in, but it is also very easy to call up a switching power supply vendor and say "hey, have me 10,000 of those little plug-in power supplies here next month. About 9V, a little over an amp should do it.".

It's funny. Bob showed off the 1Spot at a January NAMM trade show back when, it being the first of its kind. Godlyke was in the booth diagonally across from him, and they turned up with a "Power-All" at the next NAMM.

All switching power supplies are not the same.

aron · April 23, 2009, 08:29:34 PM

It must be filtering, however I mean filtering in some pedals. My friend has used the One Spot since I can remember (longer than me) and he still gets the oscillating. I'm going to specifically check this out on his setup.

R.G. · April 23, 2009, 08:41:31 PM

You're right, even the 1Spot won't stop a pedal that squeals on its own.

High gain, high impedance, and lots of wires running around with no good grounding scheme is almost a prescription for self-oscillation. It's a wonder we don't see it more.

High resistance in either power supply or ground leads to the power supply can cause this. Clean the plugs and jacks if he uses plug-in switching, and retighten everything that connects to the enclosure. Those are things that often get missed.

slideman82 · April 23, 2009, 10:10:15 PM

Have you tried with the ground input wiring when bypassed? There are some schems at GGG.

tehfunk · April 24, 2009, 06:22:32 PM

Quote from: R.G. on April 23, 2009, 08:41:31 PM
You're right, even the 1Spot won't stop a pedal that squeals on its own.

High gain, high impedance, and lots of wires running around with no good grounding scheme is almost a prescription for self-oscillation. It's a wonder we don't see it more.

High resistance in either power supply or ground leads to the power supply can cause this. Clean the plugs and jacks if he uses plug-in switching, and retighten everything that connects to the enclosure. Those are things that often get missed.

So i was playing around with the pedals again, without using the offboard power filter i have, and I found that the one without a battery (thus, no ring trick), did not squeal at all. And, then i opened up the tube screamer that was squealing and thought, "why did RG mention the ring trick?", so i put my hand on the battery connection and when i put it on the part that connects to the ring of the input jack, the squealing went away, so then i decided to put a battery in there, but still power the pedal using the wall wart and guess what, it had the same grounding effect (im guessing that's what it was) as my hand, and it was silent. Yes! So, i still have to check out the wahs, because i believe the wahs have a battery attached to them, so should be silent by this rule, but who knows. What i'm thinking this means is that it was not a problem with my building, since i believe the wahs are known to do this, but yeah, i hadn't heard enough about it from the high gain pedals to believe that everyone gets it.
2 questions:
RG, you never finished your thought about the "ring trick with the battery", why does this matter? what is happening here that led you to correctly believe it was causing the problem?

I am still getting a reasonable amount of hum, that when i touch the switch, or the metal enclosure goes away, so i guess i am grounding it fully when i do that. Can you help me figure out why there is this buzzy hum (it sounds like the kind from a single coil strat pick up), as in what am i doing wrong with my grounding? Should i be separating the ground of the dc jack sleeve from the effect ground, as right now ALL grounds end up meeting at the input sleeve. again, is this the best way to ground (all to sleeve) or should some be separated or not grounded at all to most effectively reduce the noise from the pedal?

I'll go check out the wahs. Thanks for the help!
-Sam

tehfunk · April 25, 2009, 11:58:10 PM

the wah still does it with the battery connected...

rogeryu_ph · April 26, 2009, 07:34:24 PM

Quote from: tehfunk on April 25, 2009, 11:58:10 PM
the wah still does it with the battery connected...

I'm using Tonepad star ground outboard wiring just as you described for my TS808/DrBoogey built, All tapped to the input sleeve (output sleeve/DC/ground board/3pdt switch) and i don't have problem with it. Only i don't used a battery or input jack ring trick and using transformer type PSU.
Hummmm two variables to check i'm not sure, first try test using transformer type PSU or then disconnect the input ring connection too, im using both mono for input/output. I'm interested on your case, and also waiting for RG comments on input ring trick. i'll be watching this thread.....

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Ugh, everytime i plug in a high gain pedal to my power supply it has a whistle!