DAMN!!! I woke up to a ground loop!!! How did that happen?

_scotty_ · « **Reply #20 on:** 2 Jan 2006, 02:15 am »

The motor is not your friend, obviously, but you might get lucky and and its noise may be on the other side of the transformer, you have a fifty-fifty chance of that being the case depending on how the dryer is wired.
Scotty

Zero · « **Reply #21 on:** 2 Jan 2006, 02:24 am »

I do not mean to hi-jack Marbles thread - but since I am running into an identical issue I feel I wont be intruding to much to post some questions.

I am running and Odyssey Khartago amp and the 50-60hz transformer buzz comes and goes. Often times it can be so loud that it can be heard in another room.

At first, I felt the buzz was only in association to a major appliance dumping noise into the line. A good example is when someone would use the micro-wave, there was an instant buzz from the amp. Valla!!! I thought!

Well, now she is buzzing often and typically after 8 pm. I've checked nearly every light on the line, fan, and other electronic devices. I am wondering if a power condition will be the easy fix.....

TomS · « **Reply #22 on:** 2 Jan 2006, 02:39 am »

Marbles- must be a Fort Wayne thing. I have an annoying hum problem too, but it is always there, constant amplitude, same 60hz or multiplier pitch, coming form the amps even with the pre turned off or muted. I have a sound applications filter (not isolationg xfmr) which is great for grundge, but not this sort of problem. The Reimers apparently excerbate it because they're so darn efficient. It's barely perceptable on the Merlins. I'm a little skeered to just start cheating the grounds to find it though. I'd like to try an iso transformer just to see. I'm too lazy to unbox the McCormack to swap it out to see if it's just the amp. Good luck - I know it's annoying.

markC · « **Reply #23 on:** 2 Jan 2006, 05:29 am »

Just to go to the basics here. have you tried wiggling the ic's to make sure that you don't have a bad contact or ic?

Marbles · « **Reply #24 on:** 2 Jan 2006, 02:05 pm »

Quote from: markC

Just to go to the basics here. have you tried wiggling the ic's to make sure that you don't have a bad contact or ic?

I'll do it, but it is on both channels so the odds are them going on and off at the same time are pretty small.

Thanks for the suggestion though.

ctviggen · « **Reply #25 on:** 2 Jan 2006, 02:42 pm »

OK, you guys have to get your terminology correct here. Noise from an electrical appliance that's injected onto the line is NOT a ground loop. A ground loop occurs when one electrical device is coupled to another using an electrical connection that is grounded at both of the devices. For instance, I have a ground loop between my SVS sub and my NHT X2 crossover. Humming occurs because the two "grounds" (i.e., centrally located points in a device where all grounds are connected) are at two different potentials, causing current to flow. See:

http://www.epanorama.net/documents/groundloop/

Personally, I'm of the opinion that if you have a device that you know is injection noise onto the line and causing humming, use one of these:

http://www.smarthome.com/1626.html

Fixing the source of the problem is easier than fixing it later.

Anyway, A6m-zero probably has a ground loop and not noise from electrical devices. Disconnect every input so that there's only the preamp and amp and no sources. Is there any hum? If not, it's a ground loop. If there is hum, it's injected power OR could be your speaker wires/ICs from the preamp to amp picking up noise. Have someone move these. Does the hum change? If so, it's coupling to the IC/Speaker wire.

_scotty_ · « **Reply #26 on:** 2 Jan 2006, 06:15 pm »

TomS, is this a hum loud enough to be heard from the listening postion or is it only hearable close to the loudspeakers woofer. The hum could be caused by a problem with the cable tv ground.
Scotty

TomS · « **Reply #27 on:** 3 Jan 2006, 12:34 am »

Yes I can hear at listening position. This is in the 2ch rig, no cable at all though. I think I'm going to get the cheaters out this week to nail this down once and for all.

_scotty_ · « **Reply #28 on:** 3 Jan 2006, 07:45 pm »

Tom, if all of your equipement has three prong plugs and is grounded try lifting all of the grounds but one,this would eliminate multiple grounding points and have the effect of star grounding your entire system.
You also could try lifting all grounds, this is the way my system is set up and I don't have any hum at all. The other thing to consider is that the with the Tetons in the system you have a lot of cone area to couple bass frequencies to the air with and with their efficiency you have automatically degraded your low frequency signal to noise ratio by 10dB. This, coupled with potential standing wave nodes and room gain below 150Hz could have added another 10db degradation from a standing wave at 120Hz or 60Hz at your listening position. Your low frequency signal to noise ratio may have been reduced by more than 15dB. Another question is what is the claimed signal to noise ratio on each piece of equipement? An A weighting curve is usually speced
when signal to noise ratios are measured and this assumes that we don't hear as well at low and high frequencies so the noise is still there but the curve makes the number look better. If you raise the level of low frequency noise enough then the curve no longer applies and you are well over the threshold of audibility.
Let us know how your efforts to solve this problem work out.
Scotty

TomS · « **Reply #29 on:** 3 Jan 2006, 09:15 pm »

Thanks for the suggestions and explanation. This will hopefully be weekend project. It also just occured to me that the Joules actually use a Variac as the power input, which is a form of isolation transformer as well. It's probably worth talking to Jud about, but they're headed for CES as we speak. I'll let you know what I find out.

TomS · « **Reply #30 on:** 4 Jan 2006, 03:15 am »

I replaced all the Cardas Golden Reference IC's and bi-wire speaker cables with Gregg Straley's Reality Cables tonight and it is almost totally gone (they already sound really good, by the way, even with no breakin time on them). One wouldn't think that going from totally shielded to totally unshielded IC's would do that. I suspect that it has more to do with the bi-wires which I just doubled up since these Reimers only permit single wiring. Perhaps the Joules don't like that for some reason.

warnerwh · « **Reply #31 on:** 4 Jan 2006, 03:19 am »

It could also be you had interconnects running near a power cord or rearranging your speaker cables etc. No way an unshielded interconnect will reject emi and rfi as well as a shielded one will.

brj · « **Reply #32 on:** 4 Jan 2006, 04:45 am »

Marbles, I know that you have been swapping ICs lately, so you might want to try plugging in another pair to see if you still get the "hum".

A bad solder joint to the ground pin in an IC may generate a buzz that sounds similar to the hum you describe, as I found out this past week. The buzz that I heard was in one channel of a new pair of ICs, and the buzz changed pitch and volume based on the status of other gear being powered up or passing a signal, and "jiggling" of the IC connection. Over the course of approximately 5 days, the buzz increased in volume until the (now identified) IC had to be removed from the system for fear of damage.

Just another idea for you to consider...