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AC regenerator through audio rack causing speaker buzz

75.60.99.68
Posted on July 18, 2009 at 09:22:14
Adriel
Audiophile

Posts: 627
Joined: October 13, 2001
 This appears to be a highly esoteric problem, yet it is true nonetheless.

I have a Monarchy AC power regenerator. It powers up fine on the carpet no buzz problems.

However, if I power it up while on the Adona audio rack, there is an audible electricity-like buzz through the speakers.
It is audible with your ear right up to the driver. Below are some graphics, photos, and an mp3 file for you to study.

Ambient system hiss, turn-on thump, and subsequent buzz riding on the wave

Turn-on buzz mp3 file


The facts are:

-Not an EMI issue. I can hold the AC Regenerator right on top of the amplifiers, buzz doesn't appear. ERS sheets do nothing for this buzz.

-Not a mechanical transformer noise. I cannot hear the transformers in the AC Regenerator with my ear next to them.
Also I tried Vibrapods under the AC Regenerator feet, but on top of the rack the buzz is still there.

-Not a power cable noise. I have nothing attached to the AC Regenerator at the moment, and moving its power cable around does nothing for buzz loudness.

-Racks are granite with mdf damping, and steel supports, and brass spikes. The subflooring is concrete. Speakers, subwoofer, all racks are on brass spikes.

-The AC Regenerator has toroidal transformer AC input, DC filtering, sine-wave frequency generator, and toroidal transformer AC output.

-Top shelf has tube preamp, middle shelf sacd/dacs/reclock/ground, bottom shelf ac regen

I originally suspected the AC Regenerator was dumping trash or DC into the electric wiring, but if that was the case it would be audible whether on the Adona rack or on the carpet.

Next, I suspected some type of ground loop contamination, but why doesn't it disappear if I use a cheater plug? And why does it disappear immediately if placed on carpet? I've already acquired the $600 Granite Audio Ground Zero and it won't solve this specific buzz.
Although it did silence some existing system noises and helped me narrow it down to the AC Regenerator.

Totally confused, because this appears to be totally esoteric.

The effect on vinyl recording, posted on October 31, 2009 at 14:25:34
Adriel
Audiophile

Posts: 627
Joined: October 13, 2001
 I had been recording vinyl to hi-rez digital, with the Monarchy Audio AC Regenerator in system. However, with the PurePower APS in system, the buzzing noise makes it onto the recording, such that archiving vinyl is no longer possible.

PurePower has some sort of noise filter that can plug into an unused APS outlet; I will see what effect that has.

Hello? Answering posters troubleshooting questions may yield valuable data points. n/t, posted on October 29, 2009 at 07:19:20
Ugly
Audiophile

Posts: 1420
Location: Des Moines, WA
Joined: August 22, 2006

The Tripath test, posted on October 26, 2009 at 16:52:37
Adriel
Audiophile

Posts: 627
Joined: October 13, 2001
 I hooked the left speaker up to a Charlize Tripath amplifier. The Charlize is totally off the ac grid, and powered with an Optima car battery. Its inputs left disconnected.

Then I turned on the PurePower APS.

Surprisingly, I could hear the sonic signature of the PurePower through the left speaker once again. I have linked the sound file in a previous post, but I will simply describe it as cicadas / crickets at night.

The only known paths of contamination in this instance would be airborne via the speaker wires, or the open RCA inputs.

The RCA jacks on this Charlize were Neutrik-type plastic connectors. Depending on how I oriented these RCA input wires, and which center connectors I touched, I could cause the cricket sound to stop.

The RCA caps I've ordered are the Isoclean with removable shorting pin. Therefore, I can short the preamp's inputs, and also cap the tape and main2 outputs without shorting them. They shipped today so I should know soon whether open RCA inputs are what is picking up airborne regenerator noise.

RE: AC regenerator through audio rack causing speaker buzz, posted on October 25, 2009 at 09:57:37
Adriel
Audiophile

Posts: 627
Joined: October 13, 2001
 The PurePower APS 700 arrived last Thursday. It has a buzz all of its own, that is even louder than the Monarchy Audio AC Regenerator. It is audible at listening position, while with the Monarchy Audio it is not.

Currently there are no multi-outlet adapters plugged in, as the PurePower APS has 8 outlets.

Download the mp3 sound file recording

Download the uncompressed wav version

This is the interesting thing: both AC regenerators affect products that are not plugged into it. I even dug out a dusty Jolida mosfet-hybrid amp to determine if it was an amp incompatability.
The Jolida was plugged directly into the wall and turned on. No buzz occured. Then, the PurePower APS was turned on. Buzz occured.

The good thing about the PurePower APS is that it has a battery backup operation. Therefore I can unplug it from the wall in order to test:

1. Left amplifier is ran straight to the wall outlet.
2. Preamp is ran straight to the wall outlet.
3. Left amp and preamp are powered on.
4. There is a soft pink noise, like tape hiss. Normal.
5. The PurePower APS is unplugged and powered on in battery-backup mode, turning on the source component.
6. Now there is a slight buzz signature coming through the speaker.
7. Now the PurePower APS is plugged into the wall, switching it out of battery-backup mode.
8. Now there is a strong buzz signature coming through the speaker.

Therefore, I suspect the sources of buzz contamination are twofold:

1. affecting the components in which are plugged into it, by making the components themselves buzzy.

2. dumping noise into the ac outlet, making all components on that ac circuit buzzy.

The quietest buzz occurs with all inputs disconnected except for the DAC. Still present, just quieter.

My last ditch effort will focus on the preamplifier. I will install those RCA input caps on unused inputs and outputs.

I totally forgot about this: I also have a Tripath amplifier. Being ran totally off the grid, I will use it to test my hypothesis sometime this week.

RE: AC regenerator through audio rack causing speaker buzz, posted on October 11, 2009 at 08:27:01
shermanr@prw.net
Audiophile

Posts: 497
Location: Sunny San Juan, PR
Joined: June 8, 2004
Contributor
  Since: June 24, 2009
 Have you tried to eliminate the multi-outlet adapter that I can see in the photo? Maybe that unit has some internals that are causing the buzz in your system? Or are the two power cords connected to this multi-outlet filter unit going somewhere else?

yes i have eliminated then......nt, posted on October 30, 2009 at 15:02:03
Adriel
Audiophile

Posts: 627
Joined: October 13, 2001
 .

RE: AC regenerator through audio rack causing speaker buzz, posted on October 8, 2009 at 11:44:29
Adriel
Audiophile

Posts: 627
Joined: October 13, 2001
 Ok I will try replacing all powercords when they arrive this friday.

However, I am not the only one on the planet who has speaker buzz. There are reports of other brands of ac regenerators, in a system with efficient speakers, and certain amplifiers, that will cause audible speaker buzz.

My best guess is, this ac regenerator puts out a magnetic signature that is somehow amplified by large steel racks and makes its way into the speakers. My new turntable reveals a tonearm/mm cartridge needs 1.5 feet distance to the ac regenerator or buzz occurs.

If I had a dedcated room, the ac regenerator could be located several feet away such that it causes no buzz. But I a forced to put all my equipment against the wall.

The lowest noise location I could find was placing the ac regenerator underneath one of the smaller steel amp racks.

RE: AC regenerator through audio rack causing speaker buzz, posted on October 12, 2009 at 11:05:27
shermanr@prw.net
Audiophile

Posts: 497
Location: Sunny San Juan, PR
Joined: June 8, 2004
Contributor
  Since: June 24, 2009
 I meant the white plastic multi-outlet unit with green LED's that you have connected to the duplex outlet on the wall.

Sometimes these multi-outlet units have internal spike supression circuits and noise filtering circuits that may interact with your AC power conditioner or the way the protective earth is handled.

Try plugging the two power cords that I see in your photo straight into the duplex outlet.

Maybe you already tried this and somehow I didn't see this from your response.

currently disconnected.....nt, posted on October 30, 2009 at 15:02:53
Adriel
Audiophile

Posts: 627
Joined: October 13, 2001
 .

RE: AC regenerator through audio rack causing speaker buzz, posted on October 10, 2009 at 09:37:41
Adriel
Audiophile

Posts: 627
Joined: October 13, 2001
 Okay, the triple-shielded powercables did nothing for this buzz. Therefore, I was forced to order another ac regenerator, this time from PurePower which unfortunately was several times the price of the Monarchy unit. The PurePower APS lacks the heavy transformers of the Monarchy unit, so I'm hoping for the best.

RE: AC regenerator through audio rack causing speaker buzz, posted on September 2, 2009 at 22:27:12
casouza
Audiophile

Posts: 485
Joined: March 18, 2008
 I would suspect that maze of wires near and apparently below the AC regenerator...they may be picking up 60 Hz from...a 60Hz power amplifier/regenerator!
ERS does not reduce EMI to zero, nothing does, except turning off the EMI source.

RE: So have you fixed it! (nt), posted on July 24, 2009 at 19:20:47
benie
Audiophile

Posts: 1050
Location: B.C. Canada
Joined: October 24, 2004
 nt

RE: AC regenerator through audio rack causing speaker buzz, posted on July 19, 2009 at 22:50:32
Ugly
Audiophile

Posts: 1420
Location: Des Moines, WA
Joined: August 22, 2006
 Try tying a wire from the safety ground to the chassis of the regenerator and see if that causes the same effect as putting it on the carpet.

RE: AC regenerator through audio rack causing speaker buzz, posted on October 30, 2009 at 15:06:02
Adriel
Audiophile

Posts: 627
Joined: October 13, 2001
 I have two regenerators now from different companies. I also have the $600 Ground Zero from Granite Audio. It has about eight or twelve ground chassis inputs, and their impedances to ground are adjustable. Tackling the ground issue does nothing, unfortunately.

RE: AC regenerator through audio rack causing speaker buzz, posted on July 19, 2009 at 04:30:36
benie
Audiophile

Posts: 1050
Location: B.C. Canada
Joined: October 24, 2004
 Your rack looks like a metal rack, maybe try a wire from the chassis of the AC Regenerator to a bolt or screw on the rack, maybe grounding it to the rack might help. Hey stranger things have happened.
You got nothing to lose, I know a guy you grounded his metal rack the tha water pipe and he swears he got a lower noise floor, all his componets were grounded to the rack as well.
Don't know what his system was like before, but it is very quiet.

RE: AC regenerator through audio rack causing speaker buzz, posted on November 3, 2009 at 20:47:46
hennfarm
Audiophile

Posts: 29
Location: Oregon
Joined: October 8, 2008
 maby on the middle shelf its too close to your sacd/dac

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