So I was at practice the other day and something really strange was happening. The buzz from my amp got significantly louder when I rolled the volume on my guitar off. I have a killswitch on my guitar cable too and it did the same thing when I pressed that.
I thought it was possibly my cable, but I've tried to recreate this at home and it isn't doing it.
I think I may potentially have a bad tube, but I'm also thinking it's the electrics at the rehearsal studios that might have caused it?

Anyone with a similar issue?

Equipment is:
Fender 2003 American Standard Strat
Vox AC15c1 (a newer model roughly 3 years old)

I have a pedal board between the two but I don't know if that would affect it. I set up at home with all the same stuff, same settings etc and it wasn't doing it.
Unplug the guitar input at the amp. Does the buzz go away? You may have a ground issue. Try keeping one pedal out of the chain one at a time. If that pedal can take a battery, try one. It can take a while of unplugging one thing and then the other until the sound goes. The grounding issue usually comes from the fact that the amp is plugged into a circuit that isn't the same ground as the one the pedals are in. It can also be a problem when the ground is questionable in a venue. If the same rig doesn't do it at home, you can bet, this is likely your issue.
GoldJim That's most likely it. When I was in the rehearsal room my amp was plugged into one socket and my pedal board was plugged into an extension cord in another socket on a different wall. I'll try them both in the same socket next time and see if that helps, and I'll try unplugging the cable from the amp too. I didn't really look around much at the time as I assumed it was my cable that was fucked and we were in the middle of a band practice so I didn't want to be messing with my gear.
Thanks for the reply.
Good luck. If the power is crap, you might consider renting a power conditioner. It's (usually) cheaper than blowing out your speaker. You can get one used for $50 http://www.guitarcenter.com/Used/Furman/M-8X2-Power-Conditioner-112855369.gc?cntry=us&source=4WWRWXGP&gclid=Cj0KEQiA56_FBRDYpqGa2p_e1MgBEiQAVEZ6-zZb7EInW6v3iAzZX-Az9FuC7ZG9w1b8WnQV_JCF2TgaAlox8P8HAQ&kwid=productads-adid^66736785762-device^c-plaid^135210426522-sku^112855369@ADL4GC-adType^PLA or new for about $80 http://www.musiciansfriend.com/accessories/furman-m-8x2-power-conditioner?cntry=us&source=3WWRWXGP&gclid=Cj0KEQiA56_FBRDYpqGa2p_e1MgBEiQAVEZ6-_MkqbvK00eaMdAgOqIwVkYGMbC94_8gqShnsw9FttIaAtXX8P8HAQ&kwid=productads-adid^156403583515-device^c-plaid^265910349751-sku^712515000000000@ADL4MF-adType^PLA. The front only shows one outlet, but there are 8 on the back.

edited to add: there are cheaper models, but I've always been a Furman user. When it's not powering my rig, I use it at home for my home theater.
Last edited by GoldJim at Feb 21, 2017,
GoldJim Right we were at the studio again this week and I made sure my pedal board was plugged into the same socket as my amp. Same issue. Unplugged the cable directly from the amp and the noise stopped. So I guess it's not the amp, but that still doesn't explain why I've had no issues with the exact same set up at home :/
Not all homes are built the same. If the place your practicing doesn't have a good or consistent ground in the wiring, that can explain it. Unfortunately, without an electrician and some work behind the drywall, you may never know. It's why when I gig, I use a Furman. I never know if the place has good power, and one brown out can eat thousands in gear.
GoldJim I think you are right about this. We used a different room today and when I had both my pedals and the amp in the same socket all was fine. As soon as I plugged the amp into a different socket to the pedals I got a load of noise.

Now to find a UK Power Conditioner!
Yeah, I checked Anderton's site, and it was pretty danged expensive! £495.00. Guitar Guitar didn't even have on listed! I found one for €115, but you would probably have to mail order. Should be able to get in that cost range.