[turkey]

I would try stripping it down to the simplest configuration you can (2 ch. speakers, amp, preamp, and source or something similar). If that cures it, start adding stuff one thing at a time until the problem returns.

If it doesn't cure it, at least you have less variables to explore further.

I would also do some "sanity checks" if you haven't found the problem after the first steps.

Can you borrow an inexpensive receiver from someone? See if that fixes the problem. Also I'd try some cheap RCA patch cords and speaker wire from Home Depot or wherever.

I don't really know anything about the Linn or Totem speakers, but I would doubt the problem is with them, assuming they're standard non-powered speakers with passive crossovers. I would doubt even more that the problem is with the Salk speakers.

[geezer]

You've said you switched things around and the problem remains. But how exactly did you do the switching?

If I had your problem I'd try the following program that involves simplifying the system to the bare minimum of complexity:

1. Simplify the system by disconnecting everything (including power cords and interconnects) except for the absolute minimum required to get sound. In the case of my system for example, I'd leave only my tuner, preamp, power amp, and one speaker (say the left one). If the problem is gone with this simple system, start adding pieces one-by-one until the problem recurs, then you've found the problem item.

2. If the problem persists in step one, the conclusion is that the problem is in one of the four circuits (or the interconnects) in the simplified system (and therefore not in any of the units that you took out). Then switch out one of the four units, for example the L speaker, and go to the R speaker. If the problem is gone, you know that the L speaker is the problem.

3. If step two hasn't fixed the problem, it's not the speakers. Then switch out the tuner for, say, a CDP (using analog output so as tp not need a DAC) and see what happens.

4. continue this process until you've found the problem or have switched out all four units.

If you find that once you have switched out, one-by-one each of the four units, along with cables, if the problem still persists, the conclusion is that the problem is not in ANY of your pieces of equipment, and you have to look elsewhere for the solution. That would suggest that there is something wrong in your electrical system, but since you get the same problem at your friend's house it's hard to credit. That would be a real mystery.

Maybe you've already done this kind of methodical testing with a minimalist system, but if not you should give it a try.

[EDIT]: I see that Turkey had the same thought, and posted while I was typing.

[dogorman]

I've gotten so many good suggestions since my last post that if I responded to all of them I'd crash the site for taking-up all the bandwidth, so lemmie bundle a little bit here:

Ears / psychology: Certainly possible (anything's possible, at this point), but the consistent time-lag, together with the rapid reset and the ability of non-audiophile friends to hear the problem -- and the improvement -- would seem to rule this (mostly) out. Only a very strong power-of-suggestion would lead several different friends to hear the same things, I think.

Components: I've had this problem or else something very similar (way too many technical symptoms to start comparing different problems with different configurations) for long enough now that it seems to have ruled-out the possibility of a bad component, though not entirely. The Arcam's power supply gets *extremely* hot when running, and other owners don't report this--but the problem can also be heard when using DVD player as front end and leaving the CDP off. The preamp sends a "bang" down the signal path when the power is interrupted (due to an external failure, e.g.), and other owners of this unit don't report the same problem -- but the preamp and power amp were checked at McCormack and given a clean bill; the tech even said that a bang from the MAP-1 when power is interrupted is "normal".

Electricity: How to check? Where to start? My own suspicions for some time now have been things like DC saturation, RF pollution, bad AC polarity, ground loops, etc., etc., but I could easily spend thousands of dollars on more boxes (can anyone say PS Audio?) and not make any real headway, especially since every single thing I've ever tried seems to be the thing that fixed it for the first twenty minutes. If there was someone in North- or Central Florida who was trained in diagnosing this kind of stuff (and had an appreciation for audiophile-grade tolerances), that seems like it would be a better approach, no?

IC's: Not likely, especially since one previous set were, indeed, Blue Jeans LC-1's.

Any further thoughts?

[Tone Depth]

I have a friend whom is an electrical engineer.  Once when he was visiting, we got into analyzing my telephone system wiring and electrical wiring, armed with just a digital multimeter.  It was very helpful in straightening things out. 

Consider asking around to find someone similarly talented.

[dogorman]

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?

[jules]

If the Arcam's power supply runs very hot can you check [preferably after turning off] to see exactly where the heat is coming from? A transformer should run fairly cool, as in "only warm to touch". If the transformer is running hot, it could be a DC prob. Capacitors can run moderately hot [touchable but not frying hot]. Anything attached to a heat sink will also get fairly hot but not searingly so.

The instant recovery after a 20 min. build up has to be a clue [and doesn't quite fit in with the above idea] but someone more expert than I might be to put 2 and 2 together on this one.

Some local help does sound like a good idea, particularly if you can find an audio person.

Jules

[dogorman]

The Arcam's power supply gets seriously, frighteningly, like, "Oh, did I just burn my fingers" hot, and always has. I've had the cover of the cd-player off, several times, to add or remove RF snake-oil, and each time I've done so I've noticed how ridiculously hot the power supply is, even after the player has been off for some time.

Also, 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.

[*Scotty*]

dogorman,Please describe where your equipment is located. Is it in a rack that is open on all sides or is it located in an enclosed media center with doors that are closed when your stereo is playing. Also where are your components that produce the most heat located in your stack.
Scotty

[konut]

Call your local electric utility. Describe your problem. Usually, as a courtesy, they will come out to trouble shoot their equipment, if for no other reason than to, rule out their equipment as the problem.

[jules]

The Arcam's power supply gets seriously, frighteningly, like, "Oh, did I just burn my fingers" hot, and always has. I've had the cover of the cd-player off, several times, to add or remove RF snake-oil, and each time I've done so I've noticed how ridiculously hot the power supply is, even after the player has been off for some time.

That sounds very wrong. I get the impression you aren't in the position to check components at the moment, but maybe you could give it a go when you get home. It might also be worth checking all the transformers in your system after 20 min. of running. If they all run hot, it supports the possibility that there's something wrong with your [house] power supply and the next step is to have it checked for correct voltage or DC junk.

Jules

[richidoo]

My money's on DC offset from your electrical service. Banging preamp, overheating transformer, mechanical hum audible from a McCormack amp, works fine on tech bench, and your friend has it too (is he on same local power grid?) This all points to DC offset. The DC could be charging a cap slowly, like input or output coupling cap which discharges when power is cut, or a big feedback decoupler on output stage of the pre. When the cap gets full there is no capacitance left to use so the sound changes. When you discharge the cap by shutting off, it starts working again.

Ask your utility company to send an engineer with an oscilloscope to check for DC offset at your meter. It is sometimes called "asymmetry." I would ask them to fix anything more than a couple mV of DC. Ask what is their quality of service guaranteed offset specification. They have to work with a tolerance, you should know what it is to be sure you have been adequately repaired. National electrical code should probably spell it out.

The linemen and engineers are superb professionals, and since their business is as close to a monopoly as you can get, they have to really walk the line with the state regulators. So they will want to get it fixed asap.

If it's a significant offset it could have a noticable effect on many different components in your system, which have come and gone through the system all misbehaving. Makes sense to me. It is a rare problem with modern electrical system and safeguards. But maybe just on your street. Maybe a high resistance or corroded connection from a step down transformer. They'll find it.

Geez after all that, I hope I'm right. I guess I really placed my bet, huh?    haha

Here's a simple DC blocking circuit you could DIY:
http://www.audiocircle.com/index.php?topic=58879.msg522719#msg522719
But it still needs to be fixed.

[lonewolfny42]

Slight detour for a second....

If there was no Audio Central, where would this member have posted his problem...

Good luck dogorman....hope you find the answer...

[jules]

If there was no Audio Central, where would this member have posted his problem...

The Lab or maybe "TROUBLE SHOOTING CIRCLE"  where any problem you like to think of can be answered by the combined wisdom of all of AC 

Jules

ps or "ASK DOROTHY" circle?

[dogorman]

I'm liking richidoo's suggestion of "DC offset" -- if for no other reason, it certainly passes the 'scientific method' aspect of all of this, in that there comes a point when few other explanations will stand up to what's already been tried and experienced.

Follow-up questions:

1) Does PS Audio make something like what I would need, if indeed the problem is DC? Noise harvesters? Hum busters? A juice bar? Or is this a better DIY fix? (I have a nextdoor neighbor who is finishing graduate school in electrical engineering and might be able to handle the DIY project.)

2) Does the close proximity between the left-hand speaker and the furnace suggest anything? There's about twenty-eight inches of airspace, followed by an inch and a half of c.1949 plaster wall, between the two, and I know the furnace has a really big magnet-and-coil inside its electric motor. Connection?

[dogorman]

...third follow-up question for richidoo and the room: Would DC offset also explain what I was describing in reply number 24?

[richidoo]

Uh-oh, now you're singling me out. I know this is gonna end badly when I'm proven wrong....

Good morning Dogorman!

Your neighbor might be able to help, but still call the electric company anyway. They want to know when you suspect something wrong with their product. They will be there same day.

PS Audio says their Humbuster removes DC. So does CIAudio XDC-2, he is an AC participant.   The DIY project might cost less, depends what you want from it and if you do it yourself. I'm sure the busy EE student wants to get paid.

IMO, no connection to the furnace.

IMO, yes the water in your ears could be caused by the DC offset since it changes with time and goes away when you allow caps to discharge. 

Remember that IF you do have DC on your line, every appliance in the house is suffering with it. A humbuster will only clean up one outlet.

It makes sense to me, but I could be wrong. Wouldn't be the first time.  Good luck

[dogorman]

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?

[dogorman]

Sorry, richidoo, some of that is stuff that you've said independently -- didn't mean to make it sound like these were fresh ideas from someone else, just that they were being collated in an "order of attack" style, by this other person....

[*Scotty*]

dogorman,If you have significant DC offset on your AC line this saturates your transformers instantly upon turn on it doesn't take twenty minutes for it happen. The reason for my earlier questions had to do with heat build up inside your components. If your stack has poor ventilation or even worse you have physically placed one component on top of another with no shelf
between them excess heat could cause some kind of audible problem and the time frame for the onset is reasonable. Some people have even located their rack over a heat register and caused a thermal problem.
Scotty

[*Scotty*]

My money's on DC offset from your electrical service. Banging preamp, overheating transformer, mechanical hum audible from a McCormack amp, works fine on tech bench, and your friend has it too (is he on same local power grid?) This all points to DC offset. The DC could be charging a cap slowly, like input or output coupling cap which discharges when power is cut, or a big feedback decoupler on output stage of the pre. When the cap gets full there is no capacitance left to use so the sound changes. When you discharge the cap by shutting off, it starts working again.

A word about AC power lines and DC offset. The DC offset will affect the power supply transformer primarily by causing it to heat up. A transformer will not pass DC therefore a DC offset present on the AC line will not charge input or output coupling capacitors associated with the device. Coupling capacitors are used to block DC and allow AC to pass. A standing DC voltage applied to a cap does not negatively impact it's ability to pass an AC waveform.
Scotty