Persistent humming in a dual pedal

[Kost1978]

Hi to everybody,
the question is:
could the building material of an enclosure be "guilty" in amplify the usual radio humming of a pedal?

And now the story:
I built a dual pedal (Rockett Pedals Animal + Zendrive) in an old Marshal dual footswitch enclosure, wich I think is made of iron (???).
Actually this is the ONLY pedal of my rig which hums like crazy, even if I have a well balanced multi power supply (which make my othe pedals dead silent) and even if I use the famous "huminator" (which solved my problem for another circuit, but not this one).
So, I'm thinking of drilling some holes in a new 1590BB enclosure, but I guessed to ask you your opinion first...

Will changing the enclosure have some effect on the humming?
Or is it just something wrong with the circuits?

Just to be clear, the hum is NOT always present, when I'm at home there's no noticeable hum. When I play live the hum is usually present, probably because of the not very stable power sources out there or because of the many electric devices connected to the same source (PA, lights, other amps...).

As usual, thanks a lot!

[Beaker]

Kost, you have just answered your own question.

If it does not hum at home, but hums when using it live, there is no problem with the pedal. All the hum problems are being caused by "dirty" power at the venue. It is not caused by your enclosure - you would be wasting your time re-housing it.

However shielded wiring, may possibly help - but no guarantees that it will.

You would be suprised how many venues - even "professional" ones have really bad, even dangerous issues with their grounding. Earth hum can be caused by strip lights, and electrical appliances as well as other sources.

I remember doing a gig in a bar once, and every time the beer bottle fridges kicked in, it sounded like a jackhammer coming out of the PA system!

My advice is to buy a plug in socket tester, and keep it in your box of leads. Always test every socket at a venue before you plug anything in to it. If it does not test ok, do not use it! Your life is potentially at risk.

Blown amp fuses, and electric shocks from touching microphones are unfortunately all too common.

[Kost1978]

Beaker, thanks for the info.

The strange thing about this pedal is it's the ONLY one always more or less humming (in live situations), but it's also the only one I built which is not housed in a "normal encolsure" (you know what I mean), that's why I was concerned about the box containing the circuits.

Maybe I need to open it up and rewire everything and/or check for any grounding issue... (???).
Anyway, thanks for listening!

[Neil mcNasty]

Venue Power is allways horrible!
For all the reasons you mention: P.A, Lights, Backline, Refridgerators, House-lights, Office stuff, and so on... Most of the time it all connects at the same spot: at the main inlet to the building.
Since there are no regulators involved after the main power inlet, it also means that all this stuff is connected together/is connected to the same power-source, no matter how many fuses/lines you divide it into.
It is not much more different than a one-spot power supply with a huge daisy-chain...

Finding the source of the problem in a place like that, is almost impossible, unless you unplugg eveything (except your gear), and start switching on every device in the building, one at the time.
At home this is easy.
At a venue located in a huge building in New Yourk, it is something else...
So that is clearly not an option!

After 20 years as a light-tech at concerts (we always get blamed for noise, never the sound-guys!)
I have found that in a case like this we need is a magic box of dirty tricks that contains various power-filtering tools, splitters, isolators, experience and so on...
But first I do a thurough walktrough in my mind of any potential differences between home and the venue... So that any of that stuff is cleared and out of the way.
I ask myself questions like:
Do I use two amps live, but not at home? If so: Did I remember to add a transformer isolated splitter in order to avoid ground loops?
Are the cables excactly the same cables as I use Home, or do I have two different sets?
Are the pedals ALL the same...?
And so on...

If all is good after my mental walktrough, I try lifting the ground it (allways last resort, specially when dealing with amps!).
If that solves it, you'll need something that can "lift" the ground without it getting dangerous.
You do not want to remove any ground connections completly from a device, even if it seems to "fix" the problem!
Trust me on this one!
I watched Moby's Bass-Tech almost die, during soundcheck, because of "lifting"...
He was left with 4 large burnmarks in his hand from the bass-strings, and one spot in his forehead (where the microphone got stuck, like glued to his forehead).

Here's a thingy that I recently came across that is safe, and I think it would solve this problem:
HUM X
I will aquire this one in the future, as it seems like a very good tool in many situations.
And I am also very curious about what I will find inside it...

I've been looking around to see if I could find any schematics/info about it, but I'm not shure if I found the right information...
But I did find something that looks like it might be similar... And it could be very simple!

Here's what I think it does:
It filters the ground wire (removes unwanted traces of voltage) by going trough two Diodes facing opposite directions of each-other... Preventing traces of both positive and negative voltages to pass via ground cable, leaving the ground signal clean.
Does this sound realistic? Am I on to something...?
Does a "ground connection" pass trough the diodes, but at the same time block the voltages, when arranged like this...?

Anyway, it seems like a clever little thing that filters the ground connection, without lifting the ground. Keeping you safe.

There is one more solution that will cost you a little bit more, but is No.1 on my priority-list, when performing live:
Hire an old guitar-tech with 30 years of touring-experience, that does not believe in snake-oil stuff like, Nut-Oil, Tone-Polish, NOS Mojo Components, and Tonewood bull, and he will fix it in less than 2 minutes!
I hire a experienced Guitar-Tech, before anything else. They are worth their weght in gold!
Speaking of crew:
Never ask the sound-guy what to do!
You'll never afford his solutions! (and it probably won't help!)

Good Luck!

Neil

[Beaker]

A metal enclosure is a metal enclosure. Makes no difference whether it is a Hammond type enclosure, a Marshall, Boss, EHX or anything else. Those Marshall footswitches are pressed steel.

If like you say, it is the only pedal that seems to be picking up noise, then yes, by all means open it up and see if you have any grounding problems. If not, then shielded input and output wire might work. I've not build the circuits you have in there, so don't know how noisy they are.

My rule of thumb is that if it is a fuzz or high gain overdrive or distortion, I will always use shielded wire (if possible) - just to be on the safe side.

But as Neil says, trying to solve all noise problems when playing live, can lead you down a very deep rabbit hole.

[Kost1978]

Thank you guys, now I know for sure I FIRST need to check the circuits before anything else...

@Neil: for sure the huge venues like the one you describe are not my problem (unfortunately...), but it was interesting anyway to read your post!

Thanks again!