Annoying and strange buzz (sound clip provided)

[southsider]

Hey everyone, I recently moved my gear into a new building, and have been having issues with a strange buzz/hum with the guitar/bass amps. It sounds almost like the old tesla coils you'd see on TV shows. In addition, the ground hum appears to be louder than normal. I've tried everything: ground lifts, power conditioners, different cables/guitars, etc. I think the building wiring has a problem. Anyway, i've recorded the amps so you can hear what I'm talking about. Amps are AMPEG V4 and PEAVEY SESSION 500. The noise is exactly the same on both. (as well as ALL the other amps i've used there. marshalls, fenders, etc). It should be noted that plugging a guitar in with the volume knob all the way down will silence the amp, however, the buzz will come back as soon as the volume knob is turned up.

Sorry about the low recording level at the beginning. Here's the link to it.

http://soundcloud.com/rad_brad/

Let me know what you think.

[Nick Sevilla]

This sounds like transformer buzz on the mains line. Typical 60 cycle hum along with it's harmonics.

I don't think you used the correct isolation transformer.

you do mention having used "power conditioners"... do these happen to be the under 200 bucks Furman ones? Because they do not filter this type of hum at all.

You need a true isolation transformer to run your power mains from. These do not cost 100 bucks, but a lot more, since they actually place a transformer between all the power lines and the ground line, in order to completely isolate all wiring after the transformer, thus rendering any outside noise completely gone.

Is this hum ONLY happening with the amplifiers? Or do you also notice it with your monitor speakers and / or other equipment?

Does this hum happen absolutely all the time? Or does it die down after 5 pm or whenever your building neighbors go home for the evening? Is there a car shop, paint shop, or other heavy machinery shop within the same city block? They use heavy machinery which creates this nasty hum and that gets transmitted through all power lines to all neighbors within the same distribution transformer.

Cheers

[The Scum]

Are the building grounds 100% beyond reproach?

If the grounds don't give noise somewhere to go, it'll find it's way out on other conductors.

If the grounds are fundamentally bad, then an isolation transformer won't help.

The ol' Jensen noise hunting whitepaper is full of good, factual info and troubleshooting advice, and the student handout is similarly good:

http://www.jensen-transformers.com/apps_wp.html

[southsider]

Thanks for the responses. What you were saying makes total sense. We were thinking that the grounding was bad, in addition to some machinery causing the issue. The building is in an industrial section of the city, so I bet there's some machinery close by causing the strange sound. I don't notice this sound at all through the console/monitors or any other gear, just guitar and bass amps. Thanks for the link, I'll check it out.

[Snarl 12/8]

Have you tried different outlets? I.E. the same ones that the console and monitors are plugged into?

[Gregg Juke]

Cool resource, Scum!

GJ

[ashcat_lt]

I don't know guys. The fact that the noise gets silenced when the guitar is turned down leads me to believe that it's an EMI/RFI issue. The cable and/or guitar is picking up the some radiated buzz from somewhere. Turning the volume knob down shorts that out. Seems like power supply buzz would be affecting the amp directly - after the guitar - and the guitar's V pot should have no effect.

I could be mistaken, though.

[southsider]

I have some updates. I noticed that when I plug a guitar or bass into a DI and then into the console, the same weird noise appears. This made me think it could be RF interference. (at least part of the problem). Running a guitar amp off the same circuit as the console does not help, and this problem occurs from outlets all over the building.

Aside from the weird 4 pulse buzz sound, I must say that the guitar amp buzz is louder than what it should be. I was wondering if something like this may be worth a try.

http://www.ebay.com/itm/ONEAC-ON910A-ON ... 3a77ea4f13

Thanks again for all the responses.