[dogorman]

If you recognize the user-ID, then you know the problem I'm about to describe because I've been yapping about it in these forums, on and off, for *years*. I'm only in here to try again because everything I've done so far to try to fix it has resulted in just more credit-card bills.

The sound is perfect for the first twenty or thirty minutes -- always has been, and I always think I've fixed whatever's wrong -- and then, gradually, the sound becomes reedy and increasingly sibilant in the upper midrange and apparently "over-modulated" right around the midrange-tweeter crossover.

If I shut everything off and reconnect everything, the problem often goes away for another twenty or thirty minutes, but not always.

It can't be a problem with components or speakers because everything in the chain has been repeatedly replaced, and many configurations have been sent off for service and returned with clean bills of health.

I don't think it's RF pollution because I've encountered the problem at a friend's house, and fixed it doing the same thing, over there: reconnected everything and had great sound for... twenty minutes.

I don't think it's a cracked RCA input socket because the problem has spanned several configurations of equipment.

I don't think it's a bad interconnect because the problem has spanned several configurations of cabling.

I don't think I'm delusional because non-audiophile listeners have commented on both the unpleasantness of the sound before reconnection, and the improvement afterward.

At all events, something seems to be "building up" in the signal path, somewhere, and the act of severing all the connections seems to cause whatever that build-up is, to be dissipated.

Lately I've been trying to fix this by... well... *reading* -- about everything from PS-Audio Humbusters to Audience Adept Response power conditioners and back to the XDC power filters by Channel Islands Audio. Trouble is, I'm cleaned-out financially and I just really don't feel like spending any more money before knowing with a bit more certainty that more dollars spent will point me more definitively toward getting to the bottom of this. Are there professionals who can help to diagnose the problem, and who are then also knowledgeable enough about the industry to recommend the proper fix?

Current system configuration: (many, many others have been tried!)

McCormack MAP-1 and DNA-HT5, connected directly to dedicated AC circuit via Signal Cable power cords

Arcam FMJ-CD23 connected directly to nearby, undedicated AC circuit, via signal cable digital power cord

Sony BDP-S550 blu-ray player and Panasonic TX50 plasma TV, connected to APC H-15 power supply, which is in turn connected to the undedicated AC circuit via Harmony power cord

Salk Songtower QWT speakers, front L and R, Linn Trikan center channel, Totem Mite-T rear L and R.

signal cable interconnects, element cable cross-connected speaker cables.

Thanks again, everybody.

Dave O'Gorman
Gainesville, Florida

[ted_b]

Is all the equipment plugged into the same undedicated AC line (i.e different outlets but same circuit)?  If not, try that first before moving on.  Mixing different circuits could cause a build up of ground (loop hum, etc.) that could possibly be alleviated at a "reset" then build up again.  Just a thought.

Edit:  oops, sorry I see the McCormacks are in another line.  Do what you can to experiment on ONE ac line (dedicated or not).  Let's remove variables.

[dogorman]

Great suggestion, thanks! Would it make any difference if I told you that I used to have everything on the undedicated AC line, before having an electrician install the dedicated one? ...And still had the problem?

Follow-up question: Would it make any sense to connect the McCormack stuff to the line conditioner *instead* of the video stuff, and just hook the video stuff to the wall?

Second follow-up question: Can an hdmi cable be the cause of a ground loop? I don't have cable or satellite and I've heard that those types of cables can cause ground loops; what about hdmi?

[ted_b]

Anything is possible, but usually HDMi simply carries the problem (cable ground loop, etc) not produces it.  Can you run a simple setup (one source, one amp, one set of cables, etc) and then add to as the evaluation goes on?  That would make it easier to find the culprit(s).

I'd run the audio into the conditioner, but eevntually eevrything into the same line (dedicated would be nice).  but let's keep video out of it (simple system idea above) if possible, for now.

[dogorman]

Okay, so I'm hooking the preamp, power amp, and the CD player to the APC-H15, and then that to the dedicated line? And no video connections at all? I'll try that. (Not home right at the moment.)

Do ground loops "build up" like this? I've been reading about something called "DC saturation" and thought that it might be a more promising culprit, since the notion of "saturation" seemed to fit what I've been going through, at least philosophically.

 

[jules]

Would it be possible to take your whole system somewhere else to test it? [This covers pretty much everything related to both power supply or your room].

Most systems take about the amount of time you've mentioned to warm up, so is it possible that your room is [acoustically] to blame?

Jules

[dogorman]

Anything's possible when the power of suggestion is factored-in to the mix. It seems as though a friend of mine experienced the same trouble over at his place, and alleviated it via the same disconnect-and-reconnect protocol (albeit by accident). It also seems as though the disconnect-and-reconnect solution wouldn't consume enough time for the system to become... er... "un-warm"? But, truthfully, I just really don't know anymore. The room acoustics would *seem* to be ruled out by the fact that the sound can sometimes be completely fixed by disconnect-and-reconnect, but even that is something I wouldn't altogether swear by, at this point. Heck, I suppose it could even be garden-variety listener fatigue, though the fact that non-audiophile friends have heard the difference might rule-out that possibility, too. Any follow-up thoughts?

[dogorman]

One other thing that might be interesting: The CD player's power supply gets *really* hot -- almost burn your fingers hot, when touched with the cover off -- and the preamp makes an enormous bang when disconnected from AC mains, both of which have been denied by other owners of the same products, in their own rigs, and neither of which was confirmed on the service bench. Could these behaviors be only happening in my system, and could that fact point to a specific culprit, e.g. DC-saturation?

[jules]

It also seems as though the disconnect-and-reconnect solution wouldn't consume enough time for the system to become... er... "un-warm"?

Yes,  , that seems logical

and the preamp makes an enormous bang when disconnected from AC mains,

You mean the pre-amp itself makes a bang or you get a bang through the speakers if you turn the pre off. You should really turn the power amp off first, pre-amp next and CDP last. The reverse goes for turning the system on, otherwise you can damage the speakers [in some systems].

Jules

[*Scotty*]

dogorman,Do you turn on your system to listen to it or do you leave it on 24/7?
Also the manufacturer of your preamp can confirm whether or not your preamp has a turn off transient or not.
Scotty

[Wayner]

Sounds like your interconnects between the amp and preamp may have high capacitance and is putting your amp into full bore oscillation. Try a cheap pair of short interconnects between the 2 components and see if that doesn't fix the problem.

Wayner

[ted_b]

Sounds like your interconnects between the amp and preamp may have high capacitance and is putting your amp into full bore oscillation. Try a cheap pair of short interconnects between the 2 components and see if that doesn't fix the problem.

Wayner

Wayner,
 Good point.  Would a Zobel network be something to look at on the speakers, also?

[*Scotty*]

From the information on the Signal Cable website the worst case set of IC's has 28.5pf/ft.. I don't buy the oscillation hypothesis in this case.
dogorman,Another question,how loud is your listening level during the onset of the irritating sound out of the system?
Scotty

[Wayner]

How long are the cables? I use Bluejeans cables and they only have 12.2 pf/ft. Some amps may be touchy with the loading put on them. I think it's at least worthy of a try.

Wayner

[konut]

Total stab in the dark here. Have you had the power tested coming off power company's nearest transformer that supplies your house?  Could be DC leakage. Maybe causing your power supplies to heat up and go crazy.

[dogorman]

Hey, thanks everyone -- will respond in more detail approx 9:30pm eastern; I'm teaching a three-hour class and they're in their break right now. Don't forget about me! 

[jules]

All of the above are clearly good things to check out though perhaps there's another darker possibility. I'm not sure how old you are but it could be that the SS sound is just not the right thing for your ears? Maybe you could have a listen to something with a tube or two in it [sorry if I've got this wrong but you don't appear to have anything "tube" in your system at the moment].

Jules

[richidoo]

Interesting problem.  First thought, get a shrink, but you say others witness the phenomena with you, so they can testify to your so called sanity.. (you are self admitted audiophile so not totally sane)

To address the occurance of the same problem at your friend's house, either you both have electrical phenomena from the same utility service, or you are both nuts. Unless you are sharing a component when you listen there, it's likely not the same issue.

You say everything has been replaced, and this phenomenon occurs in all of it, since you started? When did you first experience the problem? Where, in the current house and room?  When you first noticed it, what had changed from previous? Did you have brain surgery, or get some bad whiplash, maybe bionic ears installed?

Do you get the sound from all of your sources?

Do you have a pet in your listening room? An african grey parrot, perchance? Does he like you? Does he know how to whistle?

It is tempting to investigate the components, but you know Salk, McCormack is really solid stuff, so you're not likely to have junk caps or bad grounds in there. And you've replaced it all anyway. I'm really curious about when it first started and what had changed then.

Check your outlets for proper wiring and good ground using an outlet tester.  Make sure the whole system is using only one local ground. This is what ted_b was getting at, I think. Use an outlet strip or a fancy power conditioner whatever you have to get all the system plugged into one shared ground bus which is close to the system. Eliminate multiple outlets which might be grounded together only at the service panel. If you can't plug it all into one strip, then just use the basics, which isn't a bad idea anyway. Use just the minimum components to play music. Like Amp, Preamp, CDP and nothing else. Disconnect all external cables like FM antenna, cable tv, whatever. Just a single plug into the wall, and everything else into the strip. That will eliminate ground loops within the system, considering the quality of your components which should not have their own ground loops within circuit. The problem with the idea that the grounding is the cause is that the bad sound comes on gradually, so it's not a ground loop hum.

If the outlet is not earthed, static could be building up in the system. Test that outlet with one of these:.. Test the whole house while you;re at it. The important thing to test the ground is pressing the short button to verify that the circuit breaker at the panel trips. Without a connected ground, the breaker will not trip.  

Alternatively, you could plug the temporary power strip powering your system into a different outlet/circuit, use an extension cord if you need to. It doesn't matter for the test as long as the cord can handle the amps' turn on current without popping the breaker.  If all outlets still behave the same then ground is not the problem.

Do you have a CRT in your system, or in the house? They can get noisy after running a while. Tubes, high voltage coils, etc. Does the sound change at a specific time after turn on, or is it variable? If variable, what varies it, loudness of the system, turn off, turn on. You shouldn't be unplugging interconnects or speaker wires while the system is running. That's how you blow things up.

How about DC offset on your line? That could make your CDP's transformer get as hot as you describe, and would make other power transformers hum and get warm. I have been told that DC offset can only be tested with an oscilloscope. I learned that in The Lab, so it must be true. I have stuck my MM set to DC into an outlet and saw nothing, but that doesn't mean anything because I may have no offset. If you have a friend with a scope, or can rent one, you would enjoy seeing the quality of electricity you are paying so dearly for each month. If there is DC offset, you can cure it with a blocker like CIA Audio makes, or a power conditioner that blocks it, or make a DIY blocker, search AC for post about "dc blocker" by Gordy.

Look inside your components (unplugged)  for bad electrolytic caps. They will bulge at the top of the metal can, or show signs of fluid leakage.

Consider carefully whether all of the components have really been replaced, or whether there is still a CDP, or power strip, or some voodoo gadget that you still use like a ELF filter, or static spraygun, or cable risers, lucky haircomb, or something else. If you think of something within the simplified system that might have a connection, try to eliminate that.

Could there be a mechanical resonance somewhere in the room, like a glass crystal vase or tiny little silver bowl that gets to ringing with just the right note at the right volume. Smash it or cover with black tape, or dip it in that red plastic tool handle goo. haha

Similar to the parrot, consider your wife. Is she capable of cruel and unusual punishment, or pranks? If my wife was a (she just came up behind me put her arms around me and said, "You're not writing about me are you?" - oops busted) Like I was saying, If my wife were an audiophile as particular and nutso as me, I would most certainly mess with her mind by injecting some kind of noise into her system with a hair dryer or something.

That's all I can think of. Try the simplified system, and the outlet tester. I hope you find a solution fast before someone calls the funny farm on you.
Rich

(haha my reply's longer than your question!!)

[jules]

Great post Rich  . I particularly like the refs. to parrots, tiny silver bowls and [priceless?] crystalware. Tape and plastic goo rate with Chairguy's plastic putty as ghastly but wondrous solutions to different problems.

The unique thing about this problem seems to be the 20min lag factor and maybe that rules out some of the suggestions above [not parrots of course, they always learn a song carefully before joining in].

Jules

[orthobiz]

I would contact Bill Gaw at enjoythemusic.com.

I read a few of his monthly columns a few years back and he went wild with AC, transformers, batteries, etc. He had demons in his system, too, maybe he can fix yours.

Paul