Cinemag CMQEE-3446A Step Up Transformer Grounding Issues

[drewrf]

I built a little SUT for my Denon DL-103 (on an empire 398) to A/B it against stepping up purely with my Vista Audio Phono-2. I am getting a loud ground hum from it and I was wondering if anyone with experience with these could help point me in the right direction. I have attached photos of the unit and the two wiring diagrams I referenced.

The tonearm has a ground wire that is connected to the SUT (disconnecting it doesn't seem to help). I have also tried adding a jumper wire from the ground on my SUT to my phono preamp and that didn't help either.

Thanks for any and all help!

 

[manfred77]

Try connecting the ground wire to the ground side of the RCA plug directly. I've found this works occasionally. Or move the step up to a different location with longer RCA cables. I have also had an Empire, it was a 208. The ground hum issues came from the old tonearm cable, so try making a better connection with the tonearm cable. Have you tried the step up with a different turntable? I have 4 turntables connected via a Jensen JT-346AX step-up to a switch selector box, then that output connects to the Phono preamp. I always have a slight bit of hum, each turntable has a separate ground wire. Some are not needed and others are connected to the step up or to the ground side of an RCA plug on the switch box.

I would suspect the location of the step-up. Good luck.

Thomas

 

[RajkoM]

Something similar ... when I modified DAC output with LL1544A transformers, I had a hum. I solved this by connecting the core transformer to case to source ground.
Maybe (just maybe) you get the idea ...

 

[kevinkr]

Doesn't appear that the case is grounded.
In mine I generally connect the arm ground to case, and case to pre-amp chassis. The RCA jacks provide isolation between the case and the audio ground(s).

Try disconnecting your red binding post from the audio ground and connecting directly to the case.

I don't share the ground connections between left and right channels either.

 

[drewrf]

move the step up to a different location with longer RCA cables.
...

I would suspect the location of the step-up. Good luck.

Thomas

Ha! It was this simple. That did the trick. Now it is dead silent. It may have been picking up hum from a nearby transformer in my poweramp or interference from my Sonos Connect. Now to listen to a bunch a records to see if I like it!

The ground hum issues came from the old tonearm cable, so try making a better connection with the tonearm cable.

Thomas

First thing I did when I picked up this turntable was replace the RCA terminations. It seems to work and sound great. Would you recommend replacing the wires all the way from the headshell? I am usually of the mindset of if it ain't broke, don't fix it. But, hi-fi is a hobby to me and I love tweaking little things, hand building RCA cables, etc.