DIYstompboxes.com

DIY Stompboxes => Building your own stompbox => Topic started by: tele_guitarist on May 14, 2004, 08:41:18 AM

Title: Using 2 prong adaptor on tube amp...question
Post by: tele_guitarist on May 14, 2004, 08:41:18 AM
Hello!
I have a question--I've been having all sorts of problems with a 2 amp setup, with the hum of using an a/b/y box. The hum goes away if I use a 2 prong adaptor on one of the amps.
If I keep doing this, and simply plug both the amps into a good surge protector and/or GFCI , would that keep me from potentially being shocked?

Thanks!!
Title: Using 2 prong adaptor on tube amp...question
Post by: Basonsubatomia on May 14, 2004, 02:01:37 PM
I wouldn't try it... from what I've read, if something goes wrong with your lifted-ground amp it could potentially put a lot of voltage on your strings.
Title: Using 2 prong adaptor on tube amp...question
Post by: will on May 14, 2004, 02:14:43 PM
Hi,

When I got my Peavey Mace it was missing the ground pin. In a jam session another guitarist used it and got shocked when he touched a microphone. With a polarity switch on the back of the amp you have a 50% chance of getting it correct with the other equipment. I put a proper grounded plug on it.

It's better to be safe than sorry.

Regards,
Will
Title: Using 2 prong adaptor on tube amp...question
Post by: danelectro on May 14, 2004, 02:31:48 PM
snipping the ground pin wont help the hum. The hum caused by A/B boxes is because each amp's outlet has a slight difference in "ground" this potential difference (voltage) cause a small current to flow and cause hum. Try plugging both amps into the same outlet so that they both use the same ground wire to true ground.

having the ground pin there can only help
Title: Using 2 prong adaptor on tube amp...question
Post by: tele_guitarist on May 14, 2004, 03:56:50 PM
Quote from: danelectrosnipping the ground pin wont help the hum. The hum caused by A/B boxes is because each amp's outlet has a slight difference in "ground" this potential difference (voltage) cause a small current to flow and cause hum. Try plugging both amps into the same outlet so that they both use the same ground wire to true ground.

having the ground pin there can only help

That's what someone else suggested too...problem is, they are already plugged into the same outlet! I've tried it with different cords and such--and its not that.. :?:
I'm ready to pull my hair out!!  :lol:
Title: Using 2 prong adaptor on tube amp...question
Post by: Lonestarjohnny on May 14, 2004, 09:22:00 PM
If you can reread Wills post, he told you staight what the problem is, if you don't have a polarity switch on the back of your amp to change the direction of whichway the electricity is flowing through your amp, chance's are you will always have a hum when plugging those 2 amps together, when you play 2 amps together they have to be wired in unison when it come's to getting a clean sound, I have 4 different player's I work for that play a 2 rig setup and none have this problem you are describeing, first we make sure the plug is wired correctly to the amp, that mean's the hot wire of the plug is feeding the transfomer on the same side as the other amp, and the nuetral is feeding the same side of the transformer as the other amp, then like the gentleman said, plug them into the same strip, you should not have a hum unless there are other problem's. if you done all this and you still have a hum, it's time to see a tech.
Hope this helps you,
JD