What to do: isolate or regenerate

doctorcilantro · « **Reply #20 on:** 16 Oct 2013, 07:27 am »

Now the buzz occurs through speakers greatly reduced, I can barely hear it when dishwasher is on. This is via analog input on DAC.

If I place my hand on the Decware transformer and touch DAC or AC regen. the buzz completely disappears.

In USB mode, with USB connected to PC but relay open, i.e. no sample rate lock for playback, that buzz is LOUD. So it would appear the grounding scheme is ok since when that relay closes the noise is shunted to ground?

Either way, I am still thinking of picking up either a new Richard Gray RGPC Pro 400 shipped overseas for 650 with no warranty but can be sent back for repair. The Gray would offer some surge protection as well IIRC which I need.

Or trying a Keces PT-112 shipped for $330 to my home.

doctorcilantro · « **Reply #21 on:** 27 Oct 2013, 04:47 pm »

So today I put a cheater plug on the Rachel SET amp, hooked it up to an AC regenerator, and turned on the dishwasher.

A loud buzz comes out of the speakers when dishwasher is running.

I measured 20V AC across chassis of DAC to + Rachel binding post, 30V AC across AC Regenerator chassis to + Rachel binding post, and 3v from chassis of Rachel to + Rachel binding post.

I wonder if neutral and ground are tied at dishwasher?

Also, the grounding scheme on this amp seems to be unique. It has a floating design so it can be bridged, and all (4) +/-speaker terminals and the - RCA short to the IEC ground and each other.

doctorcilantro · « **Reply #22 on:** 27 Oct 2013, 04:51 pm »

Quote from: Speedskater on 15 Oct 2013, 11:48 am

Tell us about the (7-9v) voltage readings?

There was 7-9v on both what I thought to be the Earth and Neutral wire. It should read 0v?

Quote

The neutral (connected to the center tap in the main panel) can and does carry an electrical charge, so the neutral bus bar should be grounded to the outside through the use of a grounding rod to bring Neutral to Earth Ground.

doctorcilantro · « **Reply #23 on:** 29 Oct 2013, 05:56 am »

We opened the panel, electrician and I, and I took pictures.

When I measured the wiring coming out of wall for dishwasher it found what seemed to be 2 hot wires and a ground. One of these hot wires goes to chassis. Dishwasher says 120V (of course I can find no info online about the model!):

Today, I put a cheater plug on the amp for testing only, hooked it up to an AC regenerator, and turned on the dishwasher.

A loud buzz comes out of the speakers when dishwasher is running.

At this time, I measured 20V AC across chassis of DAC to + Rachel binding post, 30V AC across AC Regenerator chassis to + Rachel binding post, and 3v from chassis of Rachel to + Rachel binding post. Trying to measure DC just kept rising.

Also , the noise filter just mentioned appears to only filter noise above 80kHz, and this buzz is very audible.

Folsom · « **Reply #24 on:** 29 Oct 2013, 09:42 pm »

It sounds to me like you have the problem I just had. Your sources need to referance to safety ground from circuit and are doing it through the signal cords.

You can connect the sources circuit ground to safety ground (earth) so that they will referance the proper potential that is the same as the amplifier. Perhaps it has this but isn't wired right? I dunno, I am not in front of it.

Either it's referanced through signal or through AC power.

The thought is to avoid needing this because of ground loop potentials, but it's unlikely the impedence through the AC could be higher.

Speedskater · « **Reply #25 on:** 30 Oct 2013, 12:13 am »

I'm not very good at puzzling things out from photos, but that looks like a very full 32 breaker box, you must have a large home. Anyway I see lots of White wires, it's easy to make mistakes when everything looks the same.

Folsom · « **Reply #26 on:** 30 Oct 2013, 12:32 am »

Your 20v and 30v measurements are potentials, not current.

Trust me, if the sound goes away by touching those things, my solution will work.

I doubt you have faulty house wiring.

Is your turntable/phono in any way connected to safety ground? That would mean it's potential is the same as amp, but DAC is picking up noise because it is doing this through the AC all the way back to your breaker box (where common and ground meet), and then through signal. It causes massive noise. In fact this has a lot to do with why balanced systems have low noise.

doctorcilantro · « **Reply #27 on:** 30 Oct 2013, 06:01 am »

Thanks for the ideas. I wonder if the Decware is more susceptible to this than other amps would be.

There is a floating ground system as I mentioned upthread. When just this amp is connected to the speakers, ground floated, the buzz comes through.

You said:

Quote

"You can connect the sources circuit ground to safety ground (earth)"

I think that is how the Decware amp is connected, but probably not the DAC.

I think I did get the buzz to go away when I touched the negative speaker terminal, and the AC regenerator (which it was not connected to). The AC regenerator connects to DAC, but DAC is not connected to amp for testing

I need to get the dishwasher checked. I have a huge air handler here and no issues with other appliances when they kick on.

doctorcilantro · « **Reply #28 on:** 30 Oct 2013, 10:49 am »

Couldn't take it any more

Folsom · « **Reply #29 on:** 30 Oct 2013, 12:57 pm »

Amps without a source plugged in tend to make noise unless they have a circuit that senses it and turns itself to standby. It's not real good for some either.

Having all the equipment plugged into one power unit might help some.

Is the amp and power unit for the DAC on the same wall receptical? That might lower noise floor too.

Essentially you'll have improved sound too if you can get them to "talk" right to eachother.

Todd Willhoit · « **Reply #30 on:** 30 Oct 2013, 01:13 pm »

Maybe it is the picture, but are one or two white (neutral) conductors connected breakers?

doctorcilantro · « **Reply #31 on:** 31 Oct 2013, 12:19 pm »

Quote from: Todd Willhoit on 30 Oct 2013, 01:13 pm

Maybe it is the picture, but are one or two white (neutral) conductors connected breakers?

Hi Todd,

Sorry, is there one spot in particular you are referring?

doctorcilantro · « **Reply #32 on:** 31 Oct 2013, 12:25 pm »

Quote from: Salis Audio on 30 Oct 2013, 12:57 pm

Amps without a source plugged in tend to make noise unless they have a circuit that senses it and turns itself to standby. It's not real good for some either.

Having all the equipment plugged into one power unit might help some.

Is the amp and power unit for the DAC on the same wall receptacle? That might lower noise floor too.

Essentially you'll have improved sound too if you can get them to "talk" right to each other.

Yes, all grounded into one powerstrip for time being.

The DAC I had would open a relay in a stop state - this would cause a "ground loop" - a loud buzz. But if you pressed play, a click with relay closing would eliminate the noise. You could listen in a quiet passage (some DACs mute on silence) and it was obvious the ground loop was gone.

My point is with high efficiency speakers this was really annoying even though could just press play, and then pause. Also, the buzz was still audible, but BARELY, it me think something was wrong with dishwasher.

With my new DAC I don't have this particular problem, but it is still barely audible on speaker when run which makes me wonder why my transformer is such my hotter lately and humming. I just don't think it's good for my equipment.

Big Red Machine · « **Reply #33 on:** 31 Oct 2013, 12:26 pm »

In your second photo down it looks like two, could be one due to the light, coming out of a breaker on the right side. It raises eyebrows on why white (typically neutral and not hot) wires and why possibly two of them, which is a no-no.

doctorcilantro · « **Reply #34 on:** 31 Oct 2013, 12:30 pm »

Yeah I wonder...could be that we had some hacks come in and wire 240v in kitchen. Probably a bad idea. But we didn't have a 110 microwave.

Probably need to get that checked out. Should have thought of that earlier.

Folsom · « **Reply #35 on:** 31 Oct 2013, 02:44 pm »

If your transformer is hot and buzzing then something is feeding it DC.

You can get a DC blocker for not too much.

Speedskater · « **Reply #36 on:** 31 Oct 2013, 06:37 pm »

Well a dishwasher or a cloths dryer is very capable of making DC on the AC power line. But it will go away when you unplug the appliance.

jtwrace · « **Reply #37 on:** 31 Oct 2013, 07:00 pm »

Quote from: Speedskater on 31 Oct 2013, 06:37 pm

Well a dishwasher or a cloths dryer is very capable of making DC on the AC power line. But it will go away when you unplug the appliance.

....or in some states in the USA just put the switch in the off position.

doctorcilantro · « **Reply #38 on:** 1 Nov 2013, 01:37 pm »

Breaker with 2 wires is a single 20A "Upstairs Lighting". There are no 15A circuits.

Of note, the breaker direct to right of my hifi room 20A, on same phase, is the "kitchen receptacle".

I'm bringing the electricians out to ask about the 220 mod in kitchen, and the 2 wires on breaker.
Dishwasher installer will come verify wiring installation.
I'm turning off every breaker in the house to see if the hum/DC is killed.

doctorcilantro · « **Reply #39 on:** 5 Nov 2013, 05:52 am »

Regarding 1. Electricians came I had them move a neutral wire from freezer? that had been moved off the neutral bar onto a breaker to create a 220 for microwave in kitchen.

I still have the freaking buzz, now without the dishwasher on. WTF

Previously, I was 100% it was not a ground loop as I could turn dishwasher on and off and terminate the buzz.