Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Effects => Topic started by: dwp on April 29, 2009, 10:11:44 pm

Title: hum with stereo chorus pedal, no idea.....
Post by: dwp on April 29, 2009, 10:11:44 pm

hey I'm new to pedals, I bought a boss CH-1 stereo chorus, I get full blown loud hum through both amps as soon as I plug the second amp in to the B output. Cannot affect the hum with the pedal knobs. Using all combo's of tube amps, blackface and tweeds, 6l6 builds. I get a bad pedal you think? or is this a normal problem? i'm not using anything other than guitar in, amp A, amp B out. Quick answer appreciated.
Thanks, dwp

Title: Re: hum with stereo chorus pedal, no idea.....
Post by: LooseChange on April 30, 2009, 05:01:09 am

Try each side of the stereo output separately... Any hum?  When both amps are connrcted... Hum?
I'm going to say you have a ground loop.

Title: Re: hum with stereo chorus pedal, no idea.....
Post by: Dynaflow on April 30, 2009, 11:05:48 am

 I'd say so too, lifting the ground on one of the amps might work.

Regards,

Dyna

Title: Re: hum with stereo chorus pedal, no idea.....
Post by: dwp on April 30, 2009, 08:56:58 pm

problem is/was, two different circuits, opposite phases, intensifys the 60 cycle hum. Plugged both amps in to the same wall outlet, hum gone. was able to return the chorus pedal as defective, which it was, it sucked. Got a delay pedal instead, way cool. tried the same thing with the delay, opposing circuits, hum....(not as bad as the chorus, but bad) both amps in same plug strip, no hum, dead quiet........

thanks for the replies.......

Title: Re: hum with stereo chorus pedal, no idea.....
Post by: jhadhar65 on May 03, 2009, 09:29:05 am

That's a new one on me - inverted phase from one wall socket to the next in the same building.  About the only way I can imagine this could happen would be if live and neutral were reverse wired on the other wall outlet you used.  I don't know enough about structural wiring to know if I'm right or not, but one of those little, cheap plug in circuit testers could tell you pretty quickly.  You (or a licensed electrician) could then fix your house.

(http://i92.photobucket.com/albums/l23/jhadhar65/Misc/CT120.gif)

If you do find out how this happened, I hope you post it again to this thread.

Title: Re: hum with stereo chorus pedal, no idea.....
Post by: birt on May 03, 2009, 10:58:01 am

i've encountered this on several occasions on festival stages. a quick fix was to use a Dutch schucko plug (it's the schucko 230V plug but without the ground pen. it has contact ground on the sides) and plugging it in with a Coca Cola bottle wrap wrapped around it. a simple way to lift ground without having to change anything structural to any amp or power cord :p