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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
almarg's avatar
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almarg
9,670 posts
 
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"?

Set the multimeter to read ac volts, on a scale that is greater than 120V, such as the scale that many multimeters have that reads 0 to 300VAC. Then for each outlet measure the voltage between hot and neutral, hot and safety ground, and safety ground and neutral.

How to orient a two-prong plug, if any, I explained in my earlier post. I'm referring to the fact that if the two prongs are not polarized (i.e., one is not wider than the other), they can be plugged in with two possible orientations.

If an ac neutral run is open, it should become apparent by performing the multimeter measurements described immediately above (i.e., you will not see any voltage between hot and neutral).

If you don't have a multimeter, or other ac voltmeter, or you don't feel comfortable doing these things, try my other suggestions first and if they don't lead anywhere perhaps you know someone nearby who has experience making electrical measurements.

One more possibility occurs to me: Somehow either a large dc offset or an ultrasonic oscillation may be being sent into the speakers (both would be inaudible), causing speaker driver or crossover elements to heat up excessively, producing the audible symptoms after the 20 minute period. Not sure what might cause that, given that you've apparently tried multiple amplifiers, and I'm not sure how a dc offset would affect the midrange-tweeter part of the spectrum, but I thought I'd mention these possibilities in case they trigger some further thoughts.

Regards,
-- Al
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?
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grannyring
6,436 posts
 
I think it is your sensitive hearing and fatigue. I feel very stromgly this is your issue. Only one way to fix this for good in my humble opinion. Here it is. Change your speaker to one that is less forward and better matched for your hearing. A speaker that won't offend with a very wide range of gear and wire.

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.

I, like you, have owned many systems and the Bolero is made for folks like you with sensitive hearing. Crazy thing is this speaker is still detailed and very transparent. Not front row, but rather more set back in the audience. Smooth and easy to listen to highs. You are drawn into the music and not shouted at.

Just my two cents from a distance. I may be wrong, but it sure seems you need a different audio experience.

I am sure there are other speakers for you, but this Bolero is one I know about. I have not heard another quite like it. Calling the Bolero warm does not go far enough. It it a radical departure from most of today's hyper detailed, front row perspective speakers.

Bill
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islandmandan
1,260 posts
 
Is the Arcam the only source unit you have? Maybe you have a turntable, tuner, or some such you could try, to see if the Arcam may be the culprit?

Good luck,
Dan
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.
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