Hum from power supplies

[Scotticus]

Hey peeps,

Ok, so the pimping of my Pedaltrain Mini is almost complete. Last issue to resolve is the hum I'm getting from a particular combination of pedals - the very combo I intend to use most of the time

Here's the setup:
Bass -> tuner (custom build by SFX, so the noise isn't coming from here)
Tuner -> Barber Electronics TonePress
Tonepress -> SFX X&M crossover, with a Tech 21 XXL in the high loop
X&M out to my head

Running as much of this as I can on batteries to test, the rig isn't particularly noisy, to the point where I've given up worrying about a gate for now... happy days.
Plug in power however, and things start getting pretty buzzy! Running different combos of the pedals, I can hear a wee bit of buzz coming from the X&M, which is amplified a bit with the XXL active of course, but it's not a dealbreaker. The TonePress is what sends it through the roof though to the point where it's noticeable on pretty much any setting even when I'm playing... unhappy days.

After narrowing it down to the TonePress pedal, I've insulated the battery terminals of all pedals with batteries, tested all leads involved (freshly built Lava Cable), and tried different power supply outlets, all with no change.

Power-wise, I'm running a Johnny Shredfreak PSU into a Gigrig Distributer. Both units are under the board, with the power wires running separate from the patch cable just in case that makes a difference (it appeased my inner neat-freak). I've tried different wall outlets, and even a slightly cheapo Stag regulated supply instead of the Johnny Shredfreak, none of which made any difference.

What to do? Any tips muchly appreciated!

Scott

[cheddatom]

When you have the TonePress on it's own, powered by your PSU, is it noisy?

Could you try a seperate PSU for each pedal to see if it's a problem with daisy chaining them?

[Scotticus]

[quote name='cheddatom' post='1218568' date='May 3 2011, 01:34 PM']When you have the TonePress on it's own, powered by your PSU, is it noisy?

Could you try a seperate PSU for each pedal to see if it's a problem with daisy chaining them?[/quote]
I don't have enough PSUs to try a separate one on every pedal, but I have just tried the TonePress running on a separate one... same result.

Here's the thing, after untaping all the wiring (neat freak strikes again) and moving where the power is mounted on the board, the TonePress seems to be really fussy about where power and leads are placed in relation to it. I can have it running pretty quietly, then move a power wire a few MM and everything gets either very hummy or squealy. There doesn't seem to be any logic to it yet though, it can get noisy even with the PSU and Distributor under the board at the other end and no obvious entanglement between patch leads and power leads.

Is there anything I can do to make the TonePress less sensitive, a way of insulating or something?

Scott

[BOD2]

Can the power supply put out enough current for all of those pedals ?

Add up the "mA" ratings on each of the pedals then compare that with the "mA" rating on the power supply. If the power supply figure is significantly higher then that should be ok.

Are all of your patch leads ok ? You could try swapping a few patch leads around to see if that makes any difference - if one had bad shielding than that might contribute to extra noise.

[Ghost_Bass]

Also try plugging your power supply in diferent sockets around your house. Could be as simple as a electric device ( like a refrigerator, PC, washing machine, etc.) is sharing the same take from the electric board (i realy don't know if i'm using the corect terms...) and is causing that humm.

A friend of mine had a similar issue but with a amp, i told him to do this and he found it was the hall's light bolb causing the humm!

[phil.i.stein]

also, if you've eliminated all of the other options regarding power supply, try testing out your leads and bass input. you never know...

[Scotticus]

Hi chaps,

Thanks for all the advice so far, here's what I've tested.

PSU power - yup, it can handle the combined draw of everything on the board with plenty of head room.

Sockets - tried several different places in my flat, as well as two different buildings. The sound changes slightly from place to place (only to be expected I guess), but never goes away entirely.

Patch leads - tried all sorts of combos, even got some other cables involved in case I built my Lava ones badly, no difference.

Bass - I put a fresh battery in it, don't know how to do much else other than plonk it though

After all that, it still seems like the TonePress is hypersensitive. Any other advice, or should I get hunting for a new compressor? Fwiw, I like the TonePress, would rather not change it if there's anything else to try first.

Cheers all

Scott

[cheddatom]

is the tone press noisy even with a battery? If so it sounds like a problem with the pedal to me.

[pantherairsoft]

Is the Tone Press powered from the 'first' output on the distributor (that being the one nearest the input), if not, try it as it makes a difference.

Also worth noting I had noise and issues running my diago powerstation into a gigrig distributor. Once I swapped it for the Gigrig generator it was fine. Try the shreadfreak with a daisy chain rather than the distributor and see if that eliminates the problem.

Shep

[Monckyman]

Blag another compressor and abuse it.
it`s not clear still whether it`s actually the Tone press itself or some residual earth hum that`s being squashed and amplified.
Another compressor will perhaps show whether that`s the case.
If it actually is the Tone press, maybe you can try extra copper shielding on the bottom plate or have a good look at where it`s getting it`s earth from.

[thinman]

Do you have access to an oscilloscope?

If so you could look at the output from your mains PSUs to confirm that they're absolutely smooth when under load.

I wonder if there could also be an earth loop being introduced by the PSU. Can you try a cable between your effects and amp that has the shielding disconnected at one end?

[JimBobTTD]

I had hum on my board. I hate to say it, but it was the Johnny Shredfreak power supply. I removed the buzz with the gate on my rack compressor.

[fxpedal.co.uk]

Do you get hum when you have all the pedals other than the Tone Press connected to the power supply with the Tone Press running on battery? If the answer is 'no', then a [url="http://www.effectpowersupplies.com/virtual-battery-110-p.asp"]GigRig Virtual Battery[/url] will solve the problem.

Otherwise it may point to the power supply. The safest option would be one of the brick style power supplies like the T-Rex Fuel Tanks, Carl Martin Pro Power, Modtone Power Plant etc. all of which are, I'm afraid, more expensive.