TRL Dude or Joule 150 MKII for Major Pre Upgrade

This is *starting* to sound like the preamp is off the hook. Did you make sure a jumper is there between pin 1 and 3 of the XLRs? If that is missing it may not matter what the source is.

A balanced amplifier has 2 inputs: inverting and non-inverting. When you are using the RCA input you are usually using the non-inverting input, which is often the same as pin 2 of the XLR. If you don't install the jumper the unused input can pick up noise.

Granny, can you explain what you meant by "my CD player is grounded to the chassis by the power cord middle pin"? Did you use the multi-meter to measure the chassis and the power cord middle pin and then concluded that?

On the CD player, can you measure the ground of the RCA connector and the power cord middle pin, if you have not done that already? By the "ground" of the RCA connector, I refer to the outside surface area of the RCA connector.

On the power amp, can you also measure the ground of the RCA connector and the power cord middle pin?

Atmasphere, I think it is a system issue. The whole thing worked well previously with the electrostatic speakers. If the only change is the speaker, the only possible cause is the change of grounding.

It is possible that the power supply ground of the speaker is somehow also connected to the speaker terminals. That could cause some amplifiers to be ground-looped. A continuity test between the ground pin of the AC cord and the speaker terminals would sort that out pretty quick.

Atmasphere, my understanding is that Granny is now using a pair of passive speakers. There should not be power supply for it....

Correct, passive speaker. I ha!ve been working with Vett93 and he has stepped me through all kinds of tests. Thank you for being so patient with me! Through it all I still have the same buzz out of both speakers. The buzz is not present under three conditions we have tested.

1) the Atlas amp turned on and connected to the speakers with nothing else hooked to the amp

2) the Atlas amp hooked to an ic feeding into an RCA socket with the two leads connected and shorted

3) as above with a 1kohm resistor between the RCA ground and center pin.

The buzz is present with any other condition. Here is a recap of what causes a buzz through the speakers.

-Three different single ended preamps turned on or off hooked to the amp. They each caused the same buzz wether they were on or off with or without a source hooked up .

- hooked direct to two different cd players the buzz was the same - no preamp

- cheater plug on amp, then preamp, all xlr inputs on the amp shorted between pin 1 and 3 with purchased xlr connectors having pin 1 and 3 shorted

Vett93 can better explain all the RCA, iec, pin, chassis etc measurements we made concluding all was wired correctly with the amp's input.

Stumped is an understatement. I wonder if a conditioner of passive or active nature is needed to cure other issues?

Through all of this testing all 4 xlr inputs were shorted between pin 1 and 3.