[wrxr7]

I recently built a Bugle.  While on battery power, it sounds excellent.

I then built the matching power supply, and now I have significant buzzing that I cannot get rid of.  The buzzing gets worse when I touch the positive input wires.  My preamp looks exactly like the one in this post:  http://www.audiokarma.org/forums/showpost.php?p=2179087&postcount=4. 

I have tried shielded and non-shielded wire for the inputs, as well as moving the power supply away from the preamp; neither helped.

Any suggestions as what to try next are greatly appreciated.

Thanks in advance!

[hagtech]

A buzz indicates an issue with the power supply rectifiers.  Such as a missing ground connection or ground loop (too many grounds).  Or perhaps the chassis is not grounded?  Or maybe it is and also connects to RCA input returns (they should not touch anything but BUGLE inputs.

jh

[wrxr7]

Thank you very much for your reply Jim.

Please bear with me as I try to explain and understand things.

The input RCAs are wired to the terminals on the board.  The grounds from the input RCAs (the outer part of the RCA jack) go to the circuit board's common (I think that is the correct term) ground.  This ground is shared with the grounding screw for the turntable.  Therefore, the turntable's ground is shared by the input RCAs grounds.  Is this correct?

Regarding grounding the chassis, I am using a plastic enclosure, so I am not sure where to ground the chassis to.  I know the ground for the Bugle board is not shared by the ground (negative side) of the power supply.  Does the Bugle's ground need to be connected to the Earth ground terminal on the IEC jack?

Regarding the problem of too many grounds.  The turntable, which has a two-prong plug, is grounded to the Bugle, which is not using the ground terminal of the IEC plug.  I believe this is called "floating" or "lifting" the ground.  Is this correct? 

The Bugle's outputs are connected to a headphone amp, which has a three-prong plug.  All of these components are plugged into the same power strip.  I have tried plugging this power strip into a different wall outlet that I know is grounded.  The buzzing does not change.

Thank you for taking the time to help.  I hope this additional information makes sense and helps.

wrxr7

[hagtech]

Does the Bugle's ground need to be connected to the Earth ground terminal on the IEC jack?

You might want to try it.  Normally, the return conductors from the output interconnects supply an Earth ground from the linestage. 

Buzz could also be from having a power supply too close to the phonostage and/or input phono wires.

jh