#1
Ok so I have 3 active pa speakers, (Seismic Audio PWS10's) I have them all on the same circuit at home, no buzz, I gigged them at a Home Depot Easter egg hunt ( OK OK you can stop laughing) outside ran everything off of 1 extension cord, no buzz. I gigged them last night at a local bar/club and got a buzz, I ran my Crate Telluride on the same circuit with no buzz (ground lift didn't change anything). Any ideas??? Thanks for your help.
#2
The power at the venue.

Pickup a power conditioner and run your rigs through that to help clean up noisy circuits.
Guitars:
Jackson Kelly KE3 - MIJ (Distortion/Jazz)
Jackson DKMGT Dinky (EMG 81/85)
ESP E-II Eclipse Custom (JB/'59)
ESP LTD EC-1001FR (EMG 81/60)
Fender MIM Strat

Amps:
Mesa/Boogie Dual Rectifier Roadster 212
Laney IronHeart IRT-Studio
Peavey Vypyr 30
Peavey ReValver Amp Sims
TOOOO many T.C. Electronic Pedals. . .
#3
Bar/Club venues often have disturbing mains power, and you're sometimes dealing with things like neon signs and ice machines on the same circuit that can produce buzzing and spikes. Worse mains power happens when you're dealing with flatbed rigs with diesel generators.

There are "power conditioners" and then there are power conditioners. Simple surge suppressors won't get the job done and most Furman-type rack setups can't bring brown-out level voltage up to minimums required to get reasonable sound out of your amps, etc. The degree to which you need to provide power conditioning depends on the power sources themselves and the ability of your existing gear's power supplies to filter variations.

I actually have a big old server-farm-size uninterruptible power supply (UPS) with a lead-acid near-car-battery from APC that goes along to some venues, and that feeds a Carvin AC-120 power conditioner (rack mount) that features a sequential power-up for my gear. That last avoids MY creating a power spike when I flip the switch to turn on my own gear.