|
OTL Asylum OTL, Output Transformerless Amplifier User Group. |
|
|
|
OTL Asylum OTL, Output Transformerless Amplifier User Group. |
|
In Reply to: Hum problem solved posted by JFP on February 19, 2006 at 15:54:56:
It seems strange that only one of the amps has a hum.
Check the ground for the new circuit. Is it hooked up to the same place in the fuse panel as the ground for the old 15 A circuit? Is it on the same side of the power as the 15 A circiut?
Adjusting bias in the amp does nothing but set the operating parameters for the output tubes and could damage them if you haven't reset the bias correctly.
Changing the "short" does nothing but change the amp from non ? inverting to inverting ? unless you shorted the input , which you seem to have done thus eliminating the hum but also the music. You did put the "short" back the way it was?
Do these amps have three conductor AC plugs? If so try a ground lifter plug , an adapter with the ground wire on a pigtail from the plug. Does using this eliminate the hum?
Are you sure that all of the cables are ok? Try changing them one at a time or testing them with an ohmmeter. One of the cables may have an open ground.
Do you have a TV or cable box hooked to your system? Try disconnecting the cable from the box , does this eliminate the hum?
If it does , go out and buy two 300 ohm to 75 ohm baluns and hook the 300 ohm leads from each one together and hook the cable to the 75 ohm connections of the baluns. This opens the ground path from the system ground and the cable ground , which may be different.
Hope some of this helps
Ed
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- It ain't the tubes ! You have a ground loop with the new circuit - eds65gto 11:53:34 02/20/06 (0)
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2024, Audio Asylum, all rights reserved ]
