Pedalboard whistle/whine drops when passive volume pedal removed

[Guitarist]

For some reason, there exists a faint high frequency noise amongst my pedals. It very hard to trace but was thus greatly reduced. The gear-steeped 50k volume pot went from 80% to zero. So when the signal went through the pot's resistance that whine somehow appears. It's placed after a number of dust boxes (two having buffers). How in the world does this happen? I have a isolating-toroid PS.

Similarly, my Carvin tube rack amp have 250K pots and they add general noise too. I just crank them and all's good. The pedalboard stereo outs go straight to those pots so maybe there's not enough current or Z mismatch but I think it acts the same even with a BBE rack inserted.

[Paleo Pete]

Dust boxes?? Term I'm not familiar with.

First thing to check is cables. Do you have any cables that are actually speaker cables instead of guitar cables? Any have bad grounds or connections? Any wired backwards?

The more pedals of any kind you add to your signal chain, the greater the opportunity for noise. So I would try it with only the volume pedal, nothing else, and see what happens. Add one distortion pedal, the most likely noise maker, see how that works, then remove the volume pedal and compare. One thing at a time is my best guess, and how about the electrical wiring in the house, or does this happen everywhere you plug it in?

What about the guitar itself, is it shielded? That can make a difference, especially with high frequency type noises not related to the common lower frequency ground issues common to guitar ground problems. Things like neon or flourescent lights and stray radio signals can be reduced by good shielding inside the pickup cavity. A computer with an older type CRT monitor can cause hellacious noise in a guitar system. First time I tried recording the newer flat screen monitors didn't exist, we had to start the recording program then turn the monitor off, turn it back on after the track was done or we had serious buzzing going on. An older TV in the room might do the same thing.

Bring it down to one item then add one at a time and see where it appears. I've been using a passive volume pedal for 30 years and never have I seen the volume pedal itself cause noise. Mine is a Schaller Fusschweller, same gear driven unit with a pot inside. I've used the same one for 25 years. I have to spray in a little contact cleaner every year or so to cut down the scratchy noise a dirty pot causes, but I can put it in and out of the system and it makes no difference in noise level I can hear. Every distortion pedal and overdrive I've ever used has caused buzz and hiss, I never turn mine on until we start playing and the overall noise level of the band masks the buzz from the pedal. I've never found a way to completely eliminate pedal noise. A true bypass box would help, but with all 5 pedals plugged in and turned off my rig is quiet enough I don't have to worry about it, all it does is lose a little treble, which I can compensate for by adding a little at the tone knobs.

I'm also wondering how many pedals and what is the order they are in? Sometimes putting the wrong one in front of the others can cause noise problems. Not often, but possible...

First thing is check all patch cables. Everything must have solid solder joints and be the same polarity. One wired backwards can be a big problem. Don't depend on commercially made patch cables to always be exactly right...then add one thing at a time, starting with nothing but guitar, make sure you have no old style CRT monitor or TV in the room, if you're using an extension cord for pedal power, check polarity, try it in another room or another building, turn off any flourescent or neon lights, get away from anything that might cause electrical or electromagnetic noise.

[Guitarist]

Thanks for the tech-wisdom. I have suspicions about a digital delay pedal. There are fluorescence lights in our shop but I off them to test. It may be some "dirt box" buffer circuitry is olde too...

`your sig. we've deer galore here too!

[pdf64]

How about if the pedals are powered from their own battery, or from power supplies whose 0V have galvanic isolation from each other?

[Richard]

I'm perplexed by the volume pedal causing the noise. Does changing the volume effect the noise? Is it possible that the input is connected to the wiper instead of the output? I'm imagining a high pitched hum like if your guitar is near a motor.

[Paleo Pete]

Richard - That might be a good call. I know little about he electronics of it, but I know my volume pedals, one gear driven pot and one Morley light operated, never caused any increase in noise, but bad cables, reverse wiring, lights, monitors, and distortion boxes always have. Never even thought about it being connected to the wrong terminal.

[Richard]

I believe if you switch the cables that will connect the output to the wiper if it is currently wired incorrectly. I wouldn't think that it would make a difference if the volume is fully up.