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
20 or so years back was an electronic tech for a few years, Almarg's thoughts on a capacitor problem agree with mine. Moving pieces in and out till you find the one that seems to cause things after 20 or 30 minutes should reveal at least the unit.
I'll take a stab at this. You mention that you have moved different components and speakers in and out and still experience the same effect. Could it be that you have a tolerance to "fatigue" that wares off after about 20 - 30 min and then sets in? Sometimes I experience this when initially setting up a new set of speakers. At first they sound all right, but after listening for a while I can feel the fatigue setting in and know that I haven't got them positioned correctly yet.
Since you fixed everything and it even occurs at your friends house, maybe it's the quality of electricity being delivered to your community, voltage fluctuations, etc.
Heat. I had a Saturn Car that would just stop running after 20 minutes of city driving, but never on the freeway. As it turned out the fuel pump had a contact that started to arc when the engine got really hot.

20 minutes. Something in system gets to a certain temperature and then goes 'off'.

That's the best I can do for you. i don't want to talk about how many mechanics and dollars were involved with tracing this problem/
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.