GT PRO and Mesa Maverick - Channel switching NOISE!

[NoisyPete]

Hi everyone,
I've posted this in connections, but I said I'd fire it in here too incase it catches someone's eye....

I just got my new GT PRO and tried to get it to switch channels on my Maverick 2x12 with the Amp CTL1/CTL2 jacks. To my absolute HORROR, connecting the GT PRO CTL outs to the footswitch input causes a really bad hum on the clean channel. Hitting the front panel switch changes channel alright, but the noise is ridiculous. Using my FCB1010's switch outs I don't have this problem. Any ideas? Help - I just spent 700 euro on this thing and having the facility to switch amps is one of the main reasons I got it....
Cheers,
Pete.

[Evilution]

Hi pete !

Well you will have to forgive me ,but buying a 700 euro unit that can do so much more to just switch channels on the amp when you already have the facility to do so with the fcb1010 just sounds unreal to me.

The problem is most likely due to a ground loop,its generally created because you have 2 or more units connected to each other but having separate powerunits and separate cords to the mains.

One thing to start with is to make sure they are connected to the same outlet another thing to try is to turn the mains connector on one of the units 180 degres.

If that dont work you have to try to isolate the grounds in the units from each other if they are connected to each other through the cord between the units.

What kind of cord are you using ?

[NoisyPete]

Ah! I didn't just buy it for that; I've been a Boss fan for a long, long time - I had been using a GX-700 for almost a decade now and it saw lots of (ab)use. It's been around Europe with me, gotten a fair few knocks, the front input jack is broken, the power supply is an external transformer that is very noisy, so I figured it was time to move on.
I do a lot of MIDI control stuff, both from the 1010 and from Ableton Live, sending CC streams to things like pitch/mix/delay time to get unusual effects; I'm also looking to use the main and sub outs to drive my maverick and F-30 seperately (although I've read that the sub outs are a bit flaky on this forum somewhere?)
Anyway, I came across lots of info that you had posted on the forum, I'm off to do some soldering now, see if I can't solve this problem with a stereo to mono wiring suggestion you have up here.
I'll let you know how I get on.

Thanks for the help, it's' in valuable!
P.

[Evilution]

No problem Pete i hope you will sort it out,if you still have problems just give me a shout.

I have never actually used this function on the GT myself ,i used to use it on my FCB when i was using my Boss VF-1 before i got the GT ,now i use the GT as my only source and my Marshall head as a power amp through the effect return.

[talius]

There is a ground lift switch on the rear panel of the GT-Pro.
Try to change the position of this switch while the GT-Pro is OFF.
The switch ON the GT-Pro and see what happens.
I hope it’ll help you solving the problem.

talius

[Evilution]

There is a ground lift switch on the rear panel of the GT-Pro.
Try to change the position of this switch while the GT-Pro is OFF.
The switch ON the GT-Pro and see what happens.
I hope it’ll help you solving the problem.

talius

This only disconnects the ground pin on the Sub XLR outs so i highly doubt it will help but nothing bad are likely to happen switching it to on.

[NoisyPete]

Man, what a crazy week. I soldered up all manner of cable: shielded, unshielded, balanced and unbalanced, black, green, you name it, I tried it. I even borrowed my mate's Furman power conditioner, and while it solved the nasty buzz (note to musicians coming to Ireland: watch out for nasty buzzes in some small clubs!) I'm still getting bleed from the lead channel into the rhythm channel. I had called the guys at the guitar shop letting em know I might have to return the unit, but I said I'd wait until I got the F-30 to see if the problem was present there too.
And guess what? It's not. It comes with a 5-pin style channel/reverb/contour switch, detachable from both the amp and the footswitch [thanks mesa], so I dismembered one of my midi leads and figured out what loops trigger the channel, reverb, and contour. So now it's all sweet, the GT PRO can call up Ch2, Ch2, Ch2+contour, and by some miracle the Behringer FCB1010 can switch the Maverick without any nasty noises. Routing audio through main or sub to either amp now gives me 5 sweet channels of joy!
So that still leaves weird things going on with the Maverick, but at least I can get programming now for the festivals etc. :-)

Thanks to everyone here who offered help and advice, good luck to you all!!!!
P.
http://www.petemeighan.com
http://www.davecouse.com

[Evilution]

Nice that you got something working at last Pete !

Good luck with everything now !.