Help troubleshooting McCormack separates?

Try moving the speaker to different position in the room. If it persist, try a different speaker. Ruptured cone or panel have been know to resonate at a certain frequency and produce the characteristics you mentioned. Sometimes it can be a loose wire hitting the cone.

You didn't mention which amp you are having trouble with but it is very unlikely to be an electronic problem. If the problem persist, the best bet would be to bring it to a service technician.

Well I've got a problem than I'm relatively confident can't be explained by speakers or room-response, most notably because it's intermittent.

I've had this persistent difficulty in the behavior of my gear for some time, now, and it's bad enough that non-audiophiles can hear it. I haven't been using the test-tones for long enough to say any of the following things about them, specifically, but with regular source material the problem has been...

a) unpleasant enough that my girlfriend can tell the difference
b) sometimes absent after powering-down and re-connecting everything
c) global to different source components
d) global to a different house, a friend's speakers and wall outlet
e) neither more or less likely during the day or night
f) not invokable by any known means if not already present by itself

At someone else's suggestion I just tried to run the test tone with two different pairs of speakers, and couldn't get any of the pathologies described in my OP to happen, with the original pair on which I'd been hearing all the problems yesterday.

A member of another forum also thinks that electronic explanations are unlikely, so I certainly don't mean to come across as having rejected that advice -- I just don't know how to reconcile what's been happening with any other "class" of possible explanations.

is it buzzing or humming? it is unclear from both of your posts what exactly the problem is.

You may have something as simple as a ground loop. have you tried cheater plugs or ground loop isolator? do you have a cable tv near your system or on the same circuit?
what are your components? all of them including the non-McCormack gear. What have you attempted to fix the problem?
Provide more detail. your description is not really clear.

Okay, I'll take that as a green light to leave a long post about all of this. :-)

I just won't do it right now because I'm going to bed. Audphile1, check back in about a day or so?

Okay. Sorry this is so long.

The problem I'm having is a very dry, reedy, over-emphasized upper midrange, on particular pieces it's discer0nible as trace amounts of electrical-sounding interference -- not unlike the audio equivalent of those little traces of snow you'd see on the TV when dad was in the next room running the electric carving knife.

When it happens, I can *sometimes* fix it by powering-down and disconnecting everything and the powering up again.

As a late-breaking update, when my problem is occurring, I can feel what I had always thought was a faint vibration on the front aprons of both the amp and preamp. Recently I discovered that when the problem isn't occurring, I couldn't feel the "vibration."

I hadn't thought much about this aspect, one way or the other, until last night -- when I realized that I could still feel it after powering everything down. I'm thinking this suggests that it's not a vibration at all, but a very, very faint electrical discharge, leaving the front apron of the two pieces and traveling down my hand into ground.

In answer to your other questions, there is a big-*ss plasma TV in the rig, but it isn't connected to any subscription service of any kind, cable or satellite; it's just for movies. The rest of the rig consists of:

An Arcam FMJ-CD23 cd-player
An Oppo DV-980H, discrete analog six-channel DVD player
A McCormack MAP-1 multichannel preamp
A McCormack DNA-HT5 multichannel amp
A Hsu Research VTF-1 powered subwoofer

Power cables are by Element Cable (CD player and Preamp), and Harmonic Technologies (Amplifier).

Interconnects are by Blue Jeans Cable (between preamp and amp) and Element Cable (between CD-player and preamp).

Speaker cables are cross-connected twisted pair, by Element Cable.

Speakers used have included Linn Ninkas, Audio Physic Spark IIII's, Totem Mite-T's, and Linn Katans.

RF treatments include self-adhesive copper sheathing inside the CD-player, an Eancom plug-in filter, power wraps on the power cable for the CD-player and sometimes on the interconnects between the CD-player and the preamp, snap-on ferrites the stock power cords for the DVD player and the subwoofer, and short plugs on the unused input sockets of the McCormack.

The power in the house pre-dates the three-pin technology and, despite the fact that the outlets have a third pin, that third pin isn't actually connected to anything.

I'd thought that a dedicated and properly-grounded AC line would fix everything, but I recently took the whole rig to a friend's relatively new house on the quiet side of town, far from most common sources of RF, and everything sounded just as terrible as it so often does -- and in the same ways -- as in my house with my antiquated wiring.

I might also point out that I've had problems that aren't exactly the same but aren't completely different, with earlier solutions for amplification, too. Three years ago when my Parasound separates started acting fritzy, they exhibited the same pattern of acting up intermittently, and I could sometimes -- but not always -- make them behave normally. In that case, one channel would get cloudy with background hiss, then cut out altogether, and if I walked behind the rig and wiggled the interconnects, the sound would come booming back in and stay that way for a day or two afterward.

Then I got a Naim Nait5i which would overmodulate the low midrange intermittently, and whose input selector would freeze whenever I detected the midrange problem.

Then I got an Arcam integrated that couldn't make decent sound under any circumstances in my own house, but sounded fine at my friend's place.

And now this.

On several occasions I've had various pieces of gear serviced, and always they come back un-modified because, "we couldn't make anything go wrong, here."

Really, if all of this doesn't add up to one, obvious solution pretty quick, I'm gonna fire-sale all of this crap and replace it with two Aiwa bookshelf systems with external inputs for the signals coming from the Oppo, and just be done with it all forever. This stuff was *horrifically* expensive, was supposed to make me happy, and now I'm completely unable to listen to it, and the laughing-stock of my friends to boot.

this has to be really frustrating for you.
you did a good job describing what's going, but I haven't heard of different pieces coming down with the same syndrome. Also what's puzzling is when you bring the stuff to your friend's house, it does the same thing. Wow. That is amazing. There is either a problem with the power supply section of your amplifier and/or preamp, or power in your area fluctuates so much....but that is unlikely. Have you tried power regenerators? Does your friend have a power regenerator? I used to own different McCormack amps and never had the problem you're describing.

Have you noticed a relation between time of day and when this is happenning? Have you ever had this problem late at night? Or is it more common during the day and, say, before 9 in the evening? Man, I really can not imagine what can be the cause of your problems! You know what, try not to use your system during the day at all for few days. Use it only at night, as late as possible. See if the problem occurs. I would also recommend you try a power regenerator. PS Audio makes one. They have 30 days trial. The entire damage to you will be in shipping cost. I would try that and connect all your components, including the big S plasma TV to it. By the way, have you noticed anything funny with the TV picture? See if you can spot anything weird with the TV when the stuff is happenning to your audio.
Whatever it is, it is messed up.
Good luck man.

Good luck, indeed! We're still shooting in the dark here, but I would like to suggest that you look into an improved Earth ground arrangement for your AC system. Just a thought, but worth pursuing. (Yes, I recall that the problem showed up over at a friend's house, but even so...) Here are some related links:

http://www.tnt-audio.com/clinica/ground_force_zero_e.html

http://en.wikipedia.org/wiki/Ground_(electricity)

Installing a good Earth ground and having an electrician check out your home AC wiring may be one of the best investments you can make in improved performance, and may not cost very much.

Best regards,

Steve McCormack

Thanks, everybody. Sorry I lost my center there for a moment.

There's no discernible pattern between daytime and evening, and there's no performance problem with the TV.

The friend doesn't have a power regenerator so that's an idea.

The electrician and I are playing phone-tag (mostly he's "it" but that's another story), but as I was saying in a different forum, the grounded, dedicated AC line seems a good idea whether it solves any of this or not.