Power conditioner

[spinynorman]

At our last gig there was a noticeable hum on everything including my amp and the PA. I suspected the venue's LED ceiling lights but couldn't prove it. So I was thinking of adding a power conditioner to the rig, but another rack mounted unit would mean another rack case, or a bigger one, and I don't really want either.

So, would a mains conditioner as sold by Maplin for home cinema/hi fi do the job as well as a Furman etc power conditioner in a rack?

[url="http://www.maplin.co.uk/module.aspx?moduleno=46830"]Maplin Mains Conditioner strip[/url]

[url="http://www.beststuff.co.uk/tacima_sc5723.htm"]Tacima Mains Conditioner Adaptor[/url]

[BOD2]

I don't know that these would solve "humming" problems. The mains supply in the UK is actually relativley "clean" and doesn't usually add any noise to equipment - not that you would notice in a gig environment anyway.

Plus, a more common source of humming is ground loops and airborne interference picked up by guitars and these devices would do nothing to prevent this.

I'm sure there was a thread ages ago (or it may have been on the old site) and the concensus was that these devices would not solve many noise problems in the UK.

Hopefully someone else might come along and back this up (or refute it) and add some clarification...

[obbm]

[quote name='BOD2' post='329467' date='Nov 14 2008, 11:06 PM']I don't know that these would solve "humming" problems. The mains supply in the UK is actually relativley "clean" and doesn't usually add any noise to equipment - not that you would notice in a gig environment anyway.

Plus, a more common source of humming is ground loops and airborne interference picked up by guitars and these devices would do nothing to prevent this.

I'm sure there was a thread ages ago (or it may have been on the old site) and the concensus was that these devices would not solve many noise problems in the UK.

Hopefully someone else might come along and back this up (or refute it) and add some clarification...[/quote]

+1. Don't need one in the UK. I doubt very much that the problem is mains originated.

[spinynorman]

We were all plugged into one socket, so I thought ground loop unlikely and some kind of interference the most likely suspect. Are you saying no kind of power/mains conditioner would help that?

I tried swapping leads and basses, it seemed to help for a bit, then the hum came back. My pedal tuner, when in standby, was cycling through notes at random. The landlord, of course, said no one else had ever had a problem. This was all in setup, once we got into the gig I forgot about it.

Sounds like something I shouldn't worry about?

Edited November 14, 2008 by spinynorman

[BOD2]

If the interference isn't mains-borne then there's no mains conditioner that would help.

A ground loop can still occur if everything is plugged into a single socket - it's possible to get ground loops on signal cables. A ground loop is just effectively a loop of wire that acts as an antenna a picks up noise in the environment.

It's probably more likely that there was something "noisy" in the room that was generating airborne interference and being picked up by everything else. It could be something in your equipment or it could be something at the gig - dimmer switches are a favourite suspect.

There's no easy answer to this, although if it never happens again then it does point clearly to the venue.

[rmorris]

[quote name='BOD2' post='329490' date='Nov 14 2008, 11:47 PM']If the interference isn't mains-borne then there's no mains conditioner that would help.

A ground loop can still occur if everything is plugged into a single socket - it's possible to get ground loops on signal cables. A ground loop is just effectively a loop of wire that acts as an antenna a picks up noise in the environment.

It's probably more likely that there was something "noisy" in the room that was generating airborne interference and being picked up by everything else. It could be something in your equipment or it could be something at the gig - dimmer switches are a favourite suspect.

There's no easy answer to this, although if it never happens again then it does point clearly to the venue.[/quote]

+1

The term "Ground Loop" is often used as a catch-all for different electrical wiring issues which have similar end results.
With unbalanced connections any system beyond the most simple setup is likely to have a 'ground loop' of some description as the 'Ground / 0V / Screen' connections are performing more than one function ie they are both a signal connection and a screen.
It may or may not have a significant effect depending on the electrical environment in terms of interference / earthing.

If it's a constant low frequency hum then almost certainly a ground loop issue assuming all connections are sound.
Is the hum still there if basses/guitars are unplugged ? - to take noise being picked up by the pickups out of the equation.

yeah - dimmer switches are bad news and the interference noise changes with the setting !
'energy saving' ccfl bulbs and fluorescent strip lights can be a problem also.

If you have chance to diagnosis it again the usual approach would be to plug one thing in at a time until a problem appears and work out what is happening then.
It's useful to have some isolating transformers or di boxes to break suspected ground loops.

[Happy Jack]

And some times it's just the electrical pixies.

Rehearsal yesterday, my power sequence:
RCD (as recommended elsewhere on BC) --> 4-way gang --> (1) Amp head + (2) Power supply for stomp box.

Everything works fine until the moment I stomp ... and my entire output turns into an enormous HUMMMMMM.

Drummer's an electrician. He spends a few minutes plugging & unplugging, and ends up with:
4-way gang --> (1) RCD --> Amp head + (2) RCD --> Stomp box.

Problem solved. And the two RCD's isn't a typo, I have two of 'em.

Then he says: "Now let's put everything back the way it was." I say "Why?" He says "Because".

So we put everything back the way it was originally.

You can see this coming, can't you?

It worked perfectly.

And people ask me why I don't like messing about with wiring ...

[BOD2]

Ah... damn those electrical pixies !!

Something also worth trying if possible is to move any small power supplies around to ses if that reduces the noise. This isn't easy if they are plug-in wall wart types, but I have found from personal experience that some power supplies will induce noise in adjacent cables when they come in close proximity to them. Moving the power supply (or the cable if you can identify it) reduces the noise.

If you can keep your cables aways from these power supplies as much as possible then that might help but on a small stage it's not always possible.

Could it be that when you reconnected everything you had moved the power supply or the cables around it ?

[Happy Jack]

[quote name='BOD2' post='335884' date='Nov 24 2008, 10:16 PM']Ah... damn those electrical pixies !!

Something also worth trying if possible is to move any small power supplies around to ses if that reduces the noise. This isn't easy if they are plug-in wall wart types, but I have found from personal experience that some power supplies will induce noise in adjacent cables when they come in close proximity to them. Moving the power supply (or the cable if you can identify it) reduces the noise.

If you can keep your cables aways from these power supplies as much as possible then that might help but on a small stage it's not always possible.

Could it be that when you reconnected everything you had moved the power supply or the cables around it ?[/quote]

Yes, everything had been moved several times, and various cables had been kicked all over the place.

By the time we'd finished, both the amp head and the stomp box were coming off the 4-way again, but almost certainly in different sockets to where they'd started.

Your analysis makes perfect sense to me (at least it doesn't involve electricity dripping out of unused sockets, which is my normal start-point) but damfino whether or not it'll happen again.

One thing I did do was to go straight out and buy some PP9's ... in the process discovering that no one calls them "PP9's" any more. [i]I think he means a 9-volt battery, you know, one of those funny square ones. Go on, ask him.[/i] I really am getting too old for this sh1t.

[rmorris]

[quote name='BOD2' post='335884' date='Nov 24 2008, 10:16 PM']Ah... damn those electrical pixies !!

Something also worth trying if possible is to move any small power supplies around to ses if that reduces the noise. This isn't easy if they are plug-in wall wart types, but I have found from personal experience that some power supplies will induce noise in adjacent cables when they come in close proximity to them. Moving the power supply (or the cable if you can identify it) reduces the noise.

If you can keep your cables aways from these power supplies as much as possible then that might help but on a small stage it's not always possible.

Could it be that when you reconnected everything you had moved the power supply or the cables around it ?[/quote]

yeah - power supplies / transformers radiate lowish frequency 'noise' which cable screening can do little about.
Unbalanced and/or high impedance cables are most susceptible to it but it falls off steeply ( square law ? - any physicists want to comment on H-field characteristics ? ) with distance so psu / cable placement and orientation can have a major effect.

btw I think the batteries are 'PP3'

[EssentialTension]

[quote name='Happy Jack' post='335899' date='Nov 24 2008, 10:33 PM']One thing I did do was to go straight out and buy some PP9's ... in the process discovering that no one calls them "PP9's" any more. [i]I think he means a 9-volt battery, you know, one of those funny square ones. Go on, ask him.[/i] I really am getting too old for this sh1t.

[/quote]

They still call them PP9s in my local newsagent but then the bloke in there is even older than me.

[tauzero]

[quote name='EssentialTension' post='338881' date='Nov 27 2008, 08:09 PM']They still call them PP9s in my local newsagent but then the bloke in there is even older than me.[/quote]
A PP9 is a completely different kettle of red herrings to a PP3, it's a big battery with similar terminals to a PP3 but much further apart. ISTR my mum's old transistor radio used one. One of these, in fact: