Amp/fx noise

hotpickups

Had a rehearsal this week and noticed that my kit was making a terrible noise I.e. hum and hiss. Really noticeable when I had vibe and the like on. 

I was a bit concerned and took my kit round to a mates house a few days later and it was as quite as a mouse. All I can think is the rehearsal studio I go to must have the worse wiring installed which is causing severe ground loops. Worrying really cos they are set up as a recording studio too .

ecc83

You cannot have an earth loop unless two pieces of equipment have a mains earth and are then connected together by an audio cable that ties both signal earths together.

If that is the case did you reproduce that setup at mates?

My worry would be more that the rehearsal room does not have a mains earth at all!

Dave.

ICBM

It's not necessarily ground loops, it's more likely just to be an electrically noisy environment - a ground loop doesn't cause hiss.

Did turning the guitar down stop it?

hotpickups

Absolutely no noise at my mates house with the same set up. Turning volume down helped 

ICBM

It's noise being picked up by the guitar if turning the guitar volume down stops it.

This is probably obvious, but did you have the amp turned up as loud at your mate's house?

ecc83

ICBM said:

This is probably obvious, but did you have the amp turned up as loud at your mate's house?

That is the kicker. Often people don't run at home nearly so loud as at gigs or practice.

Many a time people use an 5, 15, even 20W amp at home and are staggered at its loudness but when they get into a decent sized room and with a bit of competition from a drummer the amp seems to shrink in available welly!  This is most evident with solid state amps because they have a well defined overload point past which they sound horrible.

Another variant on the scene is the perhaps seasoned gigger who gets into home recording and is staggered at how noisy his beloved (insert amp/guitar) combination is!

Dave.

hotpickups

Same volume as I didn't touch any knobs since the rehearsal. Just turned up st my mates plugged in and it was immediatly quieter . In fact my mate said I'm not to carry on at that volume in fear of upsetting his neighbours lol

it was a smaller room we usually have about the size of your average house double bedroom - it was very cosy

ICBM

Must be something - maybe a lot of things - causing noise at the studio, then. Fluorescent lights, computer power supplies, large industrial transformers and switchgear nearby, that sort of thing.

hotpickups

ICBM said:

Must be something - maybe a lot of things - causing noise at the studio, then. Fluorescent lights, computer power supplies, large industrial transformers and switchgear nearby, that sort of thing.

I thought that might be the case. Just concerned that isn't good if anyone wanted to record there. Not that I ever would personally

professorben

Secret Al Qaeda base next door? 
I heard from a guy down the market they are working on an EMP weapon to disable automatic doors at supermarkets.......

steamabacus

My mates had a small studio under a (working) railway arch in south London. Guitars used to pick up an intense pulsing interference from the tracks above (sounded like you were about to be beamed up by UFOs).

The only way to record guitars was to orient yourself in a particular direction and then don't move!

I suggested a personal Fariday cage for recording guitarists might help but I don't think they ever tried that. It was a pretty small studio so there wasn't a lot of space in the live room - maybe something like the 'pods' from Spinal Tap but made out of wire mesh would have fitted? I'm not sure being shut in a tiny cage would have been conducive to a relaxed performance though but you could always leave your guitarist locked in there to stop them trying to turn themselves up during mixing.

Sassafras

Couldn't you just line the surfaces with tin foil?
Or is that a stupid idea that couldn't possibly work?

professorben

Sassafras said:

Couldn't you just line the surfaces with tin foil?
Or is that a stupid idea that couldn't possibly work?

Only if you don't set the Gas too high. 

steamabacus

Sassafras said:

Couldn't you just line the surfaces with tin foil?
Or is that a stupid idea that couldn't possibly work?

Well, if that tin foil was connected to earth and it there were no gaps in it (for things like ... er ... doors) then it might work - that is precisely what a Farady cage is. Chicken wire or something is a better bet for robustness. How small the gaps between the conductor can be is a physics thing defined by the wavelength of the  offending interference (I think?).

It's exactly the same principle as screening a guitar, just on a larger scale.

I once read a great interview with Chris Rea where he was talking about his endless battle between single coil pickups (which he finds necessary for his tone) and rf interference at venues. He said the only place he ever played a gig where he didn't have noise issues to a greater or lesser degree was when he did some event in the Kremlin. Apparently, the whole place is a giant Faraday cage to stop foreign spies eavesdropping.

Mind you, he was talking about a time before the most of the planet was saturated with wifi.