Power Supply Hum

[stevew14]

Hey Everybody,

 

I haven't posted here often, if at all, but I have an effects question that may also be specific to the Mesa F-series amps. I hoped maybe someone here could help. I am running a few pedals in front of my F30, and several in the loop. I found that when I try to power the pedals in front of the amp and the ones in the loop with the same power supply, I get a very noticeable hum. If I use two different power supplies, all is well. I have tried a couple of different supplies,(one spot and gator) and had the same result with either. I have also stripped down to just one pedal before and one in the loop and the hum remains. I just can't seem to get the before amp and loop stuff to get along.

 

I am curious if anyone else has experienced this, or if maybe this is an F-series problem, or even more specifically my amp. I called and talked to someone at Mesa about it. He really couldn't explain it, and said I might just have to use the two seperate supplies. Not a huge deal, but it would be nice to simplify.

 

Any input would be appreciated.

 

Thanks

[andreas]

You have a ground loop issue - it is a fairly common problem when powering up-front and loop pedals from the same supply, so it is not specific for the F30. When you power both groups from the same supply, you add a very short ground connection between them (through the power cables) to the existing much longer ground path (through the signal cables). This can cause a difference in ground potential, which manifests itself as hum.

 

The best and easiest way to solve the problem is to simply give both groups their own separate supply.

 

/Andreas

[stevew14]

Thanks for the reply. I figured it was some kind of ground loop issue, but thought maybe there might be another way around it. I guess I'll just leave it the way it is.

Thanks again for the response.

[Mad Hatter]

I hate ground roops.

[willburford]

I've got an f-30 too and I don't have that problem.

That's all I can do to help. Great little amp!