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back to ask again long sorry

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
dog_or_man

Showing 16 responses by dog_or_man

dog_or_man OP
68 posts
 
"could you describe the exact configuration that was being used when you tried the equipment at your friend's house and heard similar symptoms? That may help to rule some things out with greater certainty"

Yes, and thanks for all the helpful suggestions! At the friend's house we had the Arcam FMJ-CD23, McCormack MAP-1, and McCormack DNA-HT5, connected to a single un-dedicated AC line with no video or other sources, and the speakers and speaker cables were my friend's. Disconnecting and reconnecting was carried out because we wanted to try different interconnects -- which seemed to fix everything (just as this sort of thing always does), until I got back home with the new cables and listened in my own place for another twenty minutes.
dog_or_man OP
68 posts
 
Hey, thanks to those who've already logged-in with a thought; please don't take my silence as disinterest or lack of appreciation -- I'm teaching a three-hour class and they have their break right now. Will respond in more detail approx. 9:30 eastern.
dog_or_man OP
68 posts
 
Sns: Do you mean to suggest that I should connect the preamp, poweramp, and cdp to the same line conditioner and thence to a single outlet on the dedicated line?

Almarg: How do I "use a multimeter to check if one of the AC runs is miswired"? And how do I "orient" a two-prong plug? How do I diagnose, and what do I do about, an "open AC neutral run"?

Ghosthouse: The problem was "fixed" when we did a quick break-and-reconnect at the friend's house, and did not recur until I was back home, but it seemed unlikely to me that it would have happened at the friend's house in the first place, if the problem was in my home. Thoughts? Could the whole thing be attributable to the fact that my central AC and furnace air-handler are located about 28" away from the left speaker, on the other side of a thin plaster wall?

Uru975: Can I give specific instructions to an aftermarket tech, that will reduce the likelihood of a "false negative"? The Arcam CDP, in particular, gets *really* hot after it's been running for awhile, and other owners have said that theirs don't.

Mrderrick: Listener fatigue is certainly possible -- anything's possible -- but would that fatigue "reset" after such a short interval of time needed to break and reestablish the ic connections? Sometimes the problem has been "fixed" in as little as two minutes.

Cyclonicman: How do I "check the quality of electricity being delivered to the community, voltage fluctuations, etc." and what do I do when the results turn out to be bad? I've been thinking this could be it: We have a municipal power company here in Gainesville, Florida, and they... well... s*ck, frankly.
dog_or_man OP
68 posts
 

Just had a long conversation with a forum member from A-Asylum and he suggests (1) verifying that the house wiring has a good ground, (2) checking to be sure that the un-dedicated line has a safety ground and, if not, tying it to the safety ground on the dedicated line, and (3) checking the AC power for the presence of DC offset. These issues would seem to be of the sort that would explain why problems could be robust to different configurations of equipment, why the problems could get worse after extended use, and why they could seem to be solved after temporary disconnection.

Also, the power transformer on the amp makes an audible hum through the front apron, as well as sending a hum down the speaker wire to the speakers, and the transformer inside the cd-player gets extremely warm after extended listening -- both of which would seem to suggest, in his opinion, the presence of unacceptably high DC-offset.

Thoughts?
dog_or_man OP
68 posts
 
I should tell everybody one more thing.

Sorry this is coming out in dribs and drabs, but I have a hunch that this might be an important detail: I started shoveling money at my stereo in the first place because an old configuration of gear and speakers developed this *bizarre* characteristic that several different techies were unable to recreate on their own benches: After extended listening, the left channel would develop a "whooshy" kind of noise, almost like the sound your ear makes when it has water in it, and would attenuate in volume, eventually to zero.

If I went to the back of the stack and wiggled the left-channel IC between the pre- and power amps, I'd hear a series of loud pops in that channel, and then everything would work just fine again, for awhile. As I say, it was for this reason that I started swapping-out gear in the first place, but what the ancient problem and the current one seem to have in common is a tendency for "build-up" to be dissipated by mechanical processes at the back of the stack.

Does this shed any new light?
dog_or_man OP
68 posts
 
Worth a try, though a hum problem might also be related. The amp makes an audible hum, both in the speakers and physically -- through the front apron -- but not so much so as to be obviously indicative of a performance problem.

Also, I'm not sure but I think the hum in the speakers has an added, click-click-click component when the larger problem is occurring, and not when it isn't -- but I could be imagining that part.

I'd love to hear the Silverlines, but I'm hesitant to continue swapping-out boxes before ruling-out for certain if the problem is electrical in nature.
dog_or_man OP
68 posts
 
Yes -- I've even tried using the bluray player as my front-end for listening to redbook CD's, and the same things happen. One commenter in another forum suggested "excessive DC offset on your local grid," and another suggested "static buildup in your capacitors." Do the folks in here think either of those could be the problem and, if so, what would be the remedies?
dog_or_man OP
68 posts
 
Al's last point is a good one and begs more backstory: I've been eating components *and* speakers during all of this, at a rate that doesn't otherwise make sense. The whole trouble started most of three years ago with some Parasound gear that would develop a "whooshing" sound in one channel, almost like when one of your ears is full of water, that could be dissipated by wiggling the IC between the pre- and power amp.

Is that the exact-same problem I'm having now? No, of course not -- but the person from AA with whom I spoke on the phone suggested that, if the mains had an insufficient earth ground, and/or significant DC offset, these problems would compromise the components' ability to deal with the cr*p that was being handed to them from elsewhere in the signal path, like RF or digital noise, and could even lead to damage.

I've eaten a left-channel tweeter in one expensive pair of speakers, a left-channel midrange in another (using different amplification), and sent three different amp/preamp combos away for service, with varying conclusions coming back from the manufacturers. As often as not, even noticeably audible problems with the electronics have not been repeatable on the bench -- which would further suggest something having to do with power, no?
dog_or_man OP
68 posts
 
"Above moderate."
dog_or_man OP
68 posts
 
These are great action-items to checklist my way down. I'll try to get my electrician friend to come over and look into the earth ground and the DC-offset first, and then maybe take things from there in the direction of an isolation transformer. ...Yes?
dog_or_man OP
68 posts
 
I agree: the trouble seems partly due to contagious failure whose root-cause has never been identified. I always write too much on these things and my OP was *way* out of hand, but at this moment the most relevant points seem to be:

1) Similar problem years ago with Parasound stuff, couldn't be verified on three separate benches

2) Similar problem regardless of assorted gear-swaps in the meantime

3) Audible transformer hum in usually stone-silent McCormack amp, both through the front apron and down the speaker wires, and

4) Breaking and re-establishing the interconnect connections seems to fix everything for a while.

...It would seem that we're pointing squarely in the direction of either inadequate grounding or excessive dc-offset or both, as root causes of other things that aren't otherwise scientifically explicable.

Anyone think that conclusion, in the wake of the four salient points listed, isn't justified, or importantly overlooks other possibilities that should be addressed first?
dog_or_man OP
68 posts
 
I've just finished uploading eight images to a thumbnail gallery on a hosting site called imageshack, and will post the link to the thumbnail gallery here. The thumbnails are arranged in two rows of four.

Top row (L to R) :

1) My rig, in its latent state in a rack with no rear panel and front doors open

2) Points of conduit entry to the attic above the breaker (note the small white-painted copper tube, emanating from the wall, just below the elbow of the water pipe visible at right (more about this, below)

3) Electrician-friend's temporary solution to dedicated AC-line. He had two outlet boxes of two outlets each on his truck, so he overlapped the plates a little (background). Undedicated AC line is in foreground. At the moment the CDP, Amp, and Preamp are connected to the dedicated line, and the power supply (which manages the TV and BDP) is connected to the undedicated line

4) Sample of the "controlled chaos" at the back of the stack, including painstaking attempts to ensure that power cords, IC's, and speaker cables only cross at right angles. (Power wraps have no noticeable effect on problem, f-y-i).

Bottom row, (L to R) :

5) Inside breaker-box, made by "Square-D," c.1949. The un-dedicated line serving the home entertainment rig is bottom-left, single breaker

6) Close-up of break in that thin copper tube that emanates from the wall in picture 2, near that elbowed water pipe. I cut this thing with my hedge trimmer shortly after moving in to the house, and it is affixed to an external water spigot in such a way as to suggest that it's a grounding mechanism for something

7) Close-up of the thin copper tube's connection to the spigot, directly below the break -- is this a picture of some sort of grounding mechanism? Should I perhaps have avoided grabbing both severed ends of the thin copper tube, to take this picture? (Nothing happened, by the way)

8) Close-up of the outside breaker panel -- dedicated line is top-right, and it's a split breaker because electrician-friend didn't have a joint breaker on his truck (plans to replace).
dog_or_man OP
68 posts
 
Okay, will try that experiment. Sounds like a good one.
dog_or_man OP
68 posts
 
The electrician didn't do anything comprehensive before. All he did was install the dedicated line. The main electrical system of the house has no safety ground whatsoever ("the third pin on these outlets is just for show, Dave") and nobody has ever checked for openings or DC offset, either one. I was just sitting here thinking that maybe the best thing for me to do is trade-down in the actual sound system, and use the freed-up money to attend to the electrical issue more comprehensively. Indeed it's probably kind of a wonder that something ghastly (not involving sound quality or fried-up left-channel tweeters) hasn't happened already.
dog_or_man OP
68 posts
 
The dedicated line has a safety ground.
dog_or_man OP
68 posts
 
Just a quick bump to this thread -- with some new info to report:

1) My electrician-friend thinks grounding issues will be easier to check than dc-offset, which suggests he doesn't have the equipment to check the latter at his disposal.

2) The breaking-IC connections and re-establishing them turns out to be a red herring: It's the *POWER* connections that have to be disconnected and reestablished, only.

3) The CD-player transformer doesn't just get extremely hot, it also has an audible hum which I'd never noticed before this most recent round of tests. So the amp and the CD-player are both humming from inside their respective chassis.

Follow-up thoughts are welcome and appreciated as always.
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