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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 3 responses by sns

sns
3,719 posts
 
One guess. You say sound is perfect for first twenty minutes or thirty minutes. Hard to maintain perfection, only downhill from there. Have you thought you may be setting yourself up for disappointment, any little anomolie is eventually exposed.

If others hear this same problem, perhaps they've been pre-conditioned in the same manner. Have someone you haven't mentioned this problem to come in and hear your system.

Beyond that, I've never heard of this problem in many years in this hobby, most believe their systems sound better with warm up. I don't believe there is any kind of system build up that can lead to such a thing.

You may be on to something with the power conditioning, this should improve sound over long term listening sessions, your CDP is the component that will most benefit from clean power. Try plugging your digital into the amp dedicated circuit, this alone should improve things a bit.
sns
3,719 posts
 
All the power related stuff sounds reasonable. I don't get the breaking and re-establishing IC thing, this has nothing to do with power issues.

I don't recall if this has already been mentioned, but it sounds like you may have an over-voltage situation as well, this causes hum in my isolation transformer. Other than the hum, I haven't had any other issues.

Proper grounding of dedicated circuits is absolutely critical as well. As I previously mentioned, you should get all equipment off the non-dedicated lines, all kinds of crap rides in on shared grounds and mains. Digital will benefit most from clean AC, all your video equipment should be on seperate lines from audio equipment.

You should have 3 dedicated lines, one for amp, most likely straight into wall, another for CDP and preamp, a third for video components. You'll never get to the bottem of anything until you do this.

Next, get a quality power conditioner for digital and preamp, maybe amp. At this point you'll be able to make a correct diagnosis as to possible issues with the sonic palatte of audio components.
sns
3,719 posts
 
The electrical work shouldn't cost that much money, trading down will defeat your whole purpose. My first inclination remains over- voltage on your AC is causing at least some of your problems.

You are part of the way there already with the one dedicated line (if this is wired up comprehensively). You do need to properly ground this line, measure for dc offset, voltage and check for all the things Al mentioned, the measurements and check out should cost very little. Only after determining whether these are issues should you proceed further.

You could also borrow a power conditioner from the lending library at the Cable Company, shipping is the only up front cost. This should tell you something about the quality of your power.

I don't know about your knowledge base or handy-man skills, but DIY saves tons of money. I did all my own wiring after gaining requisite knowledge. Eventually, you will find every single inch of your power delivery system is critical. Everything from power in to your house to delivery into IECs on equipment is subject to improvement. One of the biggest payoffs in audio.
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