The Adcom was plugged directly into the wall. The Krell was plugged into the wall for half its life. Can't see what a functioning line conditioner can do to an amp, either its getting non-shorted power of the right voltage or not, right? And I ran my own dedicated lines, three in fact, though I'm only using two currently.
Oregon, what in the power system could slowly fry an amp except for under/over voltage which would affect everything else in my house too? |
Tobias, what is this simple test of an outlet?
I just broke out my Fluke MM. The voltage at the wall is 123.0. The voltage at the power cord to the UO is 123.0. The voltage at the outlet end of the UO is 123.0. The voltage at the power cord to the amp is 123.0. Both UPSes in the computer room report 123.0.
What else is there to look at please? What principle of electricity in physics that isn't voltage can cause this anyway?
Newbee, if I swap in some lamp cord, how will I know the problem is gone? These amps aren't even supposed to be susceptible to oscillation from what I understood and the Zobels are there but I too seem to think this is where I should be looking. |
Ait, just plugged the polarity checker into the wall outlet and the UO outlet. Reports polarity correct. I've wired my entire house and numerous others and been through state inspections. We can call me an electrician. |
Newbee, thats the other way around. Goertz cable causes oscillation because the wires are so closely spaced together that they have very high capacitance. Still, this should be an issue with Zobels and these particular amps from what I know.
Maybe the Zobels came loose? Hmmm. |
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Reb1208, Gs5556, can you explain how DC from the pre affects the amp? Why would the amp care what signal it amplifies? I'm not arguing, just not understanding.
Gs5556, how does DC come from the wall socket? Or do you mean the UO?
Jsd52756, the lines from the wall to the outlet are Romex, no issues there. The PC on the Classe is a brand new PS Audio molded cord that has never been used anywhere else so I can't imagine it can be a problem. The PC to the UO is a Belden 83803 cord I made myself and I've used it without issue in multiple other places. Also, wouldn't the low amperage you describe be an audible problem? The Thiels would have VERY harsh treble without enough juice, no?
Justlisten, no kidding, huh? I don't even want to put more gear in my system and I have the money for an SACD player ready to go. :-(
Tobias, how do I check the preamp's output? I don't even have a guess here. And the AC is a sine wave... I have graphed it for kicks before. :-)
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Dave_b, we're you being helpful, insulting, humorous, or stupid? I totally missed anything useful in your entire post. |
Alright, I guess the Cary goes to the dealer. And I'll pull the Goertz temporarily as well.
Don't you guys think the Classe is already shot? Or will it recover because its own protection circuitry says nothing is wrong?
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Dave_b, how does a guy with MIT and Transparent cabling tell anyone not to add extra networks in front of their speakers? Is your Zobel better than mine? |
Atmasphere, I had done these tests with the Krell before it exploded and I did the same tests with the Classe just now with equivalent results.
The scenario:
1) Amp plugged into wall. I tried all three dedicated circuits.
2) Nothing is plugged in except the amp.
3) Speakers are connected to the amp with my Goertz cabling.
4) No connections between amp and other gear (which isn't on anyway).
5) Plug in one XLR or RCA cable to the amp.
My home:
1) In the boonies.
2) I used to have a satellite exception because I can't pick up local channels via an antennae without serious ghosting. The local FOX, ABC, and NBC affiliates were all at my house to confirm this (CBS gave in without a fight).
3) My cell phone only gets service on the top deck of the pool and then only on certain days.
4) There is a power transformer with a sodium vapor light about 700 feet down hill from me and it seems the electric company repairs things there every time the power goes out.
5) I have a power line on a right-of-way about 100 feet behind my listening room but its one power line running to the six houses behind me, not a distribution center with 75' towers.
6) I have never heard any crosstalk on anything and cannot see any towers around me from my house.
The result:
1) A quiet but high pitched squeal through the speaker when no ICs are connected. Its definitely abnormal and isn't there when the preamp is on.
2) Using XLO or MicroPurl ICs, ie not shielded, if you move, wiggle, or rub ANY part of the IC on ANYTHING, you get static and white noise in addition to the quiet, high pitched squeal.
3) Try an AudioQuest IC, ie shielded cable, the squeal is still there but rubbing the cable against the rack doesn't produce extra noise and there is no static.
4) Wrapping either RCA end with my hand, without touching the middle plug, eliminates all the noise, including the squeal, on the AQ and MP but only gets rid of the static with the XLO.
Interference kind of makes more sense to me too. Hadn't even occurred to me. And since I know something was already wrong with the Krell when I got it, that would explain why all three amps have the same symptoms but why one amp actually died.
AND it would make me feel better... or is that because I don't know enough about it? |
Tobias, if I has an oscilloscope I would test the pre. One of my customers has dozens of them but I don't know if he'd let me borrow one.
I would be most interested to hear from Krell now too. They've had the amp for three weeks and only promised to get started looking at it next week. Thats after I had to call one of the D'Agostino's themselves since no one else in their entire phone directory (!!!) would pick up the phone or answer email over almost two weeks time! |
Atmasphere, no other components were plugged in during my testing, digital or otherwise. Just the amp. So it can't be a ground loop, right?
I've had a ground loop before. It sounded like a loud hum/buzz. The noise I'm getting is a "wavy/wiggly" squeal like a hundred of mice talking at once. It doesn't sound like any crosstalk I've heard before though.
A bad ground, eh? Another member on this site asked if I would like him to check it out (he's a professional electrician) but I didn't want to bother him (particularly for free) if we couldn't get this narrowed down better. When you say "bad ground" you mean at the electrical box not the wall outlet, right? That wouldn't surprise me I guess since I did redo all of the wiring in this house for a reason, but, would I not have some kind of effect from a bad ground in other appliances of my house? Shouldn't air conditioner compressors go bad quickly?
I can add cheater plugs but if the problem exists with one component the answer has to be elsewhere, right? |
I will check for DC at the preamp on Sunday. How does one measure an XLR output? Both pins, one at a time, to ground?
Atmasphere, I'm confused as to what your final opinion is on whats wrong?
Thank you everyone! |
I plugged everything into the one PS Audio Quintet (not UO). Every 3-prong cord got a cheater plug except the preamp (Cary Cinema 11). I have not taken out the Goertz cable because I want to make as few changes as possible at one time.
Using shorting plugs on the RCAs of the Classe amp, 1.5mV AC, 0V DC, at the right speaker output of the amp.
For the next test, before I measured I noticed the volume control on the Cary was ridiculously staticy particularly as it increased the volume.
Using shorting plugs on RCA Input 7 of the Cary, and Micro Purls to the RCAs of the Classe amp, 0.45V AC fluctuating, 0.2V DC fluctuating, at the right speaker output of the amp.
Thats 0.2 volts, not millivolts. By fluctuating I mean it was never constant but those were the high numbers. When the preamp RCAs were disconnected from the amp, the number slowly dropped to zero and held steady.
So...
1) Is this really the problem?
2) Why does the amp care about DC at the input and how does DC break it?
3) Shouldn't the Classe be shutting itself down if I turn it on while moving the volume control back and forth?
This is why I switched from ECE to CS.... |
So I think my next step is a new equipment purchase. I'm thinking I will buy a consumer grade 5-disc changer with variable output that I can hook right to the Classe. And I can use it outside in zone two later.
Without touching anything else, hook it to the amp, and see what it sounds like. If there is no problem, its not the Goertz speaker cable, the dedicated lines, or the line conditioner.
Good plan? |
^^^ and it would eliminate RF as well |
More updates:
I swapped speaker cables, eliminated all line conditioners, changed ICs, nothing changed.
Then I hooked up an Anthem AVM 20 processor in place of the Cary. Volume control problems, popping, high pitched buzz problems solved. Generally I would say the problem is resolved.
BUT, I still have a buzz at the speakers when everything is on. Is not a ground loop because everything has a cheater plug but the Anthem. And its present even when only the amp is hooked to the speakers and the wall.
Also, I have -0.48VDC at the wall outlets. I have turned everything in the house off at the circuit breaker and still measure -0.48VDC at the outlets (the only one left on with nothing on it). I get -0.80VDC at each phase of the incoming power with the main power off.
SO... is the DC at the wall outlet a cause for concern? Is this my buzz? Did it ruin the Cary? Should I be looking into power isolation?
Thanks! |
Wow, the Anthem is so lifeless. :-(
But it does sound a LOT clearer. |
I take it all back. After an extended listening session, the Classe and Anthem were humming. But there was no volume control problem at least. I will try new speaker cables tomorrow for an extended listening session.
Why did it take an hour or so for the problem to materialize? Very confused. :-( |
I am at this very moment conducting a listening session with new XLRs and new speaker cable. The XLRs did eliminate the buzz. I forgot about that, I'm pretty new to balanced.
The volume control on the Anthem could be heard in the speakers this time....
If the new speaker cables don't change anything, I'm plugging everything into the wall. If that doesn't work, everything in the chain has been replaced but the speakers. I have two new in box SCS4s so I guess they would come after that.
Grrrr... |
So the amp never hummed after five hours of listening and watching last night.
I can still hear the volume control of the Anthem through the speakers (at the loud end of the spectrum only).
Right now I am turning up the volume very high and we'll see how that goes for an hour. |
Still no problems. I listened very loud, which normally induced the humming, nothing happened.
So I guess the current answers are:
1) the Classe and the Adcom didn't like the Goertz cabling.
2) the Krell was bad from the start.
3) there are no power or line conditioner issues.
Up for further testing is whether their is a problem with either the Anthem, the Cary, or both.
Does that sound reasonable to this point?
Thanks again for everyone's help. |
Nothing wrong with the Zobels on the Goertz. They are securely attached. The Classe just didn't like them and I don't think the Adcom did either.
Switched between the Anthem and Cary for a bit. The Cary is definitely broken in some way. I don't know why the Anthem volume control clicks through the speakers but it appears to be the only glitch in my entire system at this point.
So wow, I got bent over twice this year on Agon. Once on the Krell, once on the Cary. Don't know how I could have been any more careful, on the Cary in particular.
Anyone know anything about why a volume control would click in the speakers? |
Hahahaha. Unsound, I wrote that about the Zobels at the same time you did. I was not responding to you.
Maybe the Zobels are loose inside the heat shrink?
I've had two or three other people tell me that older Classe's are not compatible with Goertz speaker cables in the last two weeks. |
Atmasphere, thanks thats good to know. I wondered that about an old Rotel I had too.
The problem with the Classe was definitely the Goertz cables. It has not done a single strange thing in three days now and it has been on the whole time. So, lets vote:
a) broken Zobel
b) just incompatible
c) something else |
Reb1208, my recent experience with their new VP of Marketing was a real eye opener into the workings of Cary. I am never purchasing another product of theirs again: new, used, or otherwise. This piece being broken, I don't know whether to pile it on Cary or to blame the Agon seller though.
I do not think the AVM 20 is a tubed HT Processor.
Why would a double-Zobel cause issue? |
