On Jan 4, 10:04*am, Tim wrote:
On Jan 4, 10:00*am, I am Tosk wrote:





In article 197db70b-8619-4665-b3a4-63236cad6414
@k17g2000yqh.googlegroups.com, says...

Its a long shot, but I was hoping that Gene or others with good
electrical experience might help.

Well, some friends of mine have a pretty good local band, and they
play at various venues around a tri-county area. OK, so I went up
town
to hear them Sat. and one member and I got to talking on their break
and he asked me so i thought I'd try to get some ideas here.

One place they play is an older brick building with everything that
can plague an older brick building.

I'm sure the wiring is sub-standard and I dont' know if it has
fluorescent lights causing fits or not. But all the amps and PA have
a
"hummmmmm" that they can't get rid of. The guitarists amp hums the
worst. Not totally obnoxious, but really annoying.

It seems that today's equipment(for the most part) doesn't have any
provisions for a "reverse" switch on the amps, and with three-prong
plugs it's kind of hard to do the old "turn-the-plug-around" trick.

Even with a reverse switch, I've seen instances where when flipped the
hum only got louder.

The manager says all the bar/ kitchen equipment is in good order, ,
but that's left to be seen.

So my question is, does anyone here know of any type of device/ power
bar etc, that can help compensate for this type of a problem?
All these players have good late model quality equipment and this is
the only venue they have this problem.

it's a good gig for them but event the patrons come and ask them
"what's the hum?" They don't know, I don't know.

Any ideas?

Thanks!

Call Dick...- Hide quoted text -

- Show quoted text -

I posted over on his board and haven't gotten a reply yet.- Hide quoted text -

- Show quoted text -

Wow. I spoke too soon. Here's the reply I got when I checked his
board:


You may need to experiment at the venue and with the owner's help to
identify the source of the problem. Tell him that patrons are
complaining and you want to see if you can cure it.

I think it depends on the source of the hum or 60 hertz noise.
If it's RFI radiating from lighting fixtures like florensent lights or
other ballast type devices, you should be able to tell by simply
turning the lights off temporarily. Older equipment in the place could
also be introducing it either via RFI or on the AC line.
With the owner's permission and help, set up an amp with a guitar
plugged in, turn up the volume until the hum is very noticeable and
then, one by one, have someone turn off each circuit breaker in the
power distribution box. See if any of them dramatically reduces the
hum and then see what electrical device is powered from that breaker.
Older electrical appliances and equipment can actually introduce 60
hertz hum in the power lines, particularly if they draw high currents
when running.

http://www.federalpacific.com/litera...ormernoise.pdf

Another possible solution is to power the band's amps through one or
two devices called an "Electrostatically Shielded Isolation
Transformer". These transformers do not step the voltage up or down.
They are used to isolate the load side from the primary voltage
source. I'd check with a local electrician regarding the use of them.
They need to be sized appropriately for your equipment's current draw.

Another possible solution may be to use a power conditioning unit.
"Monster" and others build units that have both active and passive
filters in them. They are typically used in higher end home theater or
audio gear applications.

Here's some info on isolation transformers:
http://www.audioholics.com/tweaks/co...m-hum-and-buzz

and here's some info for those of us that like screwing around with
old, vintage guitar amps and have lived to talk about it:

http://www.instructables.com/id/Isol...d-guitar-amps/

RCE