software

I just purchaced a simple and cheap a/b box with 1 switch for switching between 2 amps. I am finding i am getting alot more noise and high end hum. I have one amp on overdrive and the other on clean. The overdriven one hums more. Is there any way to fix this i.e opening up the case and fiddling with the sheilding on the wires? also will a noise gate do the job?

Dills

ground loops, amps can have what called ground faults due to differences in their circuits and how the amps are grounded - causes lots of hum. The only amp switchers I've found of any use are the Tonebone model and the Voodoo labs switcher - their expensive though.

so even if you made ur own one wud it make a difference?


Originally Posted by Dillsso even if you made ur own one wud it make a difference?

No...... Unless you have a design to lift or isolate the grounds like the Tone Bone A/B box....... Years ago when guitar amps only had 2 prong power plugs and no 3rd ground safety plugs you used to be able to play thru 2 amps without the extra noise and a/b between them... Now all amps must be made with power cords that have the 3rd ground...

I used a 5150 head for my last band and it does not have a clean channel really... You can clean the sound up but it is not really a clean channel. So i tried to a/b between two amps and got fed up with the extra noise.... I ended up buying an Axess Head Switcher from and it works great but has some risk in using it. First off the HS2 works like 2 FX loops.... The imput and speakers out on each amp are fed into the HS2 and then you can switch between 2 Tube heads into a single speaker Cabnet. The down side is if the power cuts cut to the HS2 or if you hook it up wrong you could damage stuff.... And they can not be used with delay effects in the amps loops... The HS2 isolates one amp when using the other and stops the imput.... if you are using delay effects the notes the delay carries over to the un-used amp are still trying to send signal thru the amp..... it could damage your gear. But when set up right it is magic! no noise and tones are amazing. The HS2 runs off a Boss pedal adapter.....

I want to try the ToneBone a/b box oneday..... it seems so much more simple and safer.... But the HS2 works!

WhoFan

Yep, I got sick of stereo rig noise. That's why I ended up with a 3 channel amp. Solved everything! Before that, I even paid a lot for a Lehle Amp Switcher, which worked good, but even that had some noise. You just can't connect 2 amps, a pedalboard, and anything else without causing some ground gremlin. Drove me nuts!

So if you removed the ground plugs on both amps that you're using (safety aside of course) would that remove the hum?

I use a Tonebone switcher and it works really good. No hum, but the price is rather high.

Here's a simple A/B box that I designed awhile back that solves the quot;ground loopquot; problem. You just need a 3PDT footswitch.
Note: If you use a metal box, you must use ground isolating jacks.


Originally Posted by GuitarStvSo if you removed the ground plugs on both amps that you're using (safety aside of course) would that remove the hum?

Well first off it is never concidered safe to do so but you would only have to remove one ground plug from one amp and leave the other amp alone.... Hardware stores in the USA i think still sell Ground Lift plugs that turn a 3 prong plug power plug into a 2 prong UNGROUNDED plug. In theory if one amp in the system is grounded it may be safe... I am no expert on this matter and make no claim of that fact. But i have seen stereo rigs out on the road where one of these ground lift adapters from hardware stores were used... Here in Canada i don't think they sell those adapters anymore for safety reasons.

I myself would never use a rig where a ground has been taken off an amp..... but some people do it..... I concider safety first and tone second.... What good is tone when you could be dead....

WhoFan

Actually, I think that would only make matters worse anyway. If both amps are grounded, through a third prong, to a cold water pipe, you have a common point of reference. The different distances within the amps wiring would account for the difference in potential on the two input jacks.

If you remove one, (or both), ground lugs, you increase the likelyhood that those two plugs will be at a different potential. (No common ground reference.)

I'm speculating a bit here, because I don't mess with guitar amps much, but it always held true for studio amps.

I run stereo, and it is not only the ground loop noise... but the drag on the pickups, it sucks, it sucks your tone. I play in a trio so I use alot of EFX's... have been looking at the Radial stuff. But I don't need to A/B, I just need the noise to be gone and my tone to be back. You can run wet and dry, or you can bypass loop it. But what about in stereo? Larry Carlton uses a small stereo JBL PA on stage and mic's his dry Dumble amp, that's great if your only using rack EFX's. Any more ideas??? Thanks Dills for asking!

Hardware stores used to sell Ground Lift plugs but they removed them from most stores here in Canada now.. they are adapters that you plug a 3 plong power plug into it and it only has a 2 prong plug on the other end.. For stereo rigs they use one of these ground lift adapters on one amp and the other is used with the ground.. I hear there is still big name acts on the road with stereo rigs and one amp has the ground lifted to get rid of the noise.... It is said to be safe as long as one of the amps still has a ground...

To me it just does not sound safe and that's why i have never done it... I even added a modern 3 prong power cord to my 40 year old Fender Deluxe amp as i didn't like the idea of a 2 prong amp....

These new expensive noise free A/B boxes are sounding like the way to go.... I do love my HS 2 headswitcher but you can't use 2 amps at once with it....

WhoFan