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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
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almarg
9,670 posts
 
"Static buildup in capacitors" sounds to me like a non-technical person trying to be technical. Also, static is most severe when humidity is very low, which is the opposite of what you've got in Florida.

In principle there shouldn't be significant dc offset from your power grid, because if you live in a typical house your ac is coming from a transformer on a nearby pole, and transformers don't pass dc. I suppose improper grounding somewhere in the path nearby could result in an offset, but I would think the other possibilities that have been mentioned are more likely (including the ones I suggested about problems in your house wiring).

Regards,
-- Al
somec59
245 posts
 
I can understand your frustration, try speaker cables or interconnects that are not detailed and/or roll of high frequency response. Buy a mellow 1980s era Onkyo or Sansui integrated amp or receiver through your local Craigslist.org, ($75.00 +/-) and see what happens, you should be able to sell it again if you don't like it.
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?
acoustat6
357 posts
 
Grannyring said," I would very strongly suggest Silverline Bolero speakers. Not a trace of anything that could cause your ears discomfort. I have very good and sensitive hearing - especially in the upper mids and highs and this speaker is just perfect."

You got that right, check here,
http://www.soundstagemagazine.com/measurements/silverline_bolero/

Bob
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almarg
9,670 posts
 
I agree with the AA person. What he is saying is very similar to what I had suggested. When I said that I felt the likelihood of a dc offset situation was minimal I was unaware of the hot transformer and hum symptoms, although I still feel that a wiring problem is more likely to be the cause.

I think it would be best to have a qualified person check out your ac. He should be able to very easily tell if there are any miswired or open connections, along the lines of what I and the AA person suggested, and he should be able to easily measure dc offset with suitable instrumentation.

Regards,
-- Al
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