Roadster ground loop

[iceman]

I'm running an rg16 connected to my roadster, mark v and triaxis. Not surprisingly I have a ground loop. If I lift the ground on the roadster the hum is gone. I'm looking at picking up an isolation transformer (tripplite) that can handle the wattage of the roadster (costs about ~$190). I've seen the ebtech humX (costs about $60). So the humX is tempting but I don't trust it and I'm not sure how it works, and if it is safe and effective for a high wattage tube amp. I don't want to be cheap, but I also don't want to spend if it isn't really needed. Anybody have good knowledge/experience with this? Also I don't really want to break the ground on my instrument cables to solve it for fear of allowing noise into the system..

 

[shytfayse]

I run a digitech floor pedal in live applications and have used the Ebtech HE-2 with great success. I run two amps in stereo, so, I only use one of the two channels on the HE-2 to break the ground loop at only one of my amps. The HE-2 gets installed at my amp with a short cable going into the input.

Since you have three amps, you would use both channels on the HE-2 to break the ground loop on two of your amps.

The remaining amp that does not have the HE-2 connected in series with it will provide the signal ground to your RG16, pedals and guitar. All you are really doing is breaking the superfluous two extra signal ground connections that you dont need as well as getting rid of the hum and shortwave radio receiver you have made.

This product uses a 1:1 transformer. There must be some loss or signal degradation there in theory, but, my ears don't detect it!

On the Hum X, I was a little leary on what is inside the magic box that does whatever to my electrical ground so I veered away from that. I dunno - they may work just fine. I would not get crazy on the high voltage line side of your amps with high dollar isolation transfomers and the such when the problem is created on the lower voltage, safer to work with, and cheaper signal level side.

Hope you get it worked out.

- Pat.

 

[iceman]

So I picked up an ebtech HE8 but wasn't thrilled with the results. It broke the ground loop but it dropped the signal level and seemed to roll of some high end frequencies. Per their documentation they actually don't recommend the HE series for instrument level unless there isn't another choice. I returned the HE8 and picked up the humx. The ground loop seemed to move since now it is on another cable. I think I'll send the humx back as well.

Anybody know of prducts for the low voltage side of things built specifically for guitar? Maybe a DI box?

 

[domct203]

Lifting the ground on one end of an instrument cable will not allow noise into the cable - the other end is still connected to ground and will provide the necessary shielding. It is also alot safer to break signal ground than messing with the earth ground.

Pro's have been doing it like that for years.

Dom

 

[iceman]

Thanks dom. It is something specifically with the triaxis when on the ld2 circuit. I removed and separated all the gear and directly connected the triaxis to one of the other amp's return. It only ocurrs on the ld2 modes. Lifting the triaxis ground and or the other amp didn't help, nor did the lifted cables. I googled around and found that some triaxis users have had the same issue, while others didn't or didn't notice it. I'll go bug the guys in the rack gear section.