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? |
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 |
Class Audio amps of that vintage may already have a zobel network built in at the output connectors. I know my Classe Model 15 does. This may have caused an issue with the additional Goertz Zobel
About the Anthem Pre, are there any tubes inside of it? What type of potentiometer does it have, an Alps carbon plastic motorized pot by any chance? Classe Audio amps have a lowish input sensitivity and tend to amplify small noise issues upstream.
Glad switching to XLR got rid of the hum. I had a hunch it would. I also felt strongly that the Cary digital pre had an issue. I mean no disrespect, but I often question some of the "engineering" going on at Cary. |
If the Anthem has a stepped volume control, some 'clicking' between steps is likely normal. A stepped control will have a 'make before break' contact scenario, but even with the best materials its normal to get some clicking as you adjust the volume. It should be very slight... |
Now that might be possible. I had the leg of an external Alpha-Core RC network snap under pressure from a speaker binding post. |
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. |
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? |
If there were indeed appropriate zobels in place, I can't imagine why the Adcom and Classe' amps had trouble with the Alpha-Core Goertz speaker cables. |
|
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. |
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. |
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... |
I had terrible hum problems related to the CATV box. I ran a ground from the offending box to the ground termination on my Furutech ETP-80, which is grounded to the ground in my dedicated circuit, and, blissful silence was the result.
Good luck and enjoy,
Dan |
If this Classe has a balanced input and you are running single-ended, **make certain** that the unused pin (probably pin 3, assuming pin 2 is the same as the RCA, refer to the owner's manual for clarity on this point) of the XLR is grounded to pin 1! Else a buzz (humm) will result. |
I used to own a Classe CA-300 that when run single ended with certain pre-amps, a buzz was heard from the speaker. Ran balanced (XLR), and buzz never occured.
Also, make sure you don't have a source component hooked up that maybe connected to a RG coax TV cable. You'll get a hum for sure. |
Actually, it sounds like you've made some real progress . . . the volume-control-related noise and the high-pitched squeal are gone. Would it only be that in diagnosis of an electrical system, solving one part of the problem always solved all of it . . . Your measurements at the wall outlet are absolutely no cause for concern . . . I would say that the Cary exhibited a failure for reasons unrelated to anything external - it simply broke. 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. So here's where we need some clarification. You need to hook up the Classe power amp up to the speakers, and to power (WITHOUT a cheater plug), and leave the inputs (coming from the Anthem processor) disconnected - that is, no interconnects attached to the amp in any fashion. If you have any other wiring to the amp (like a 12v power-control trigger cable, etc.), then disconnect it. I'm assuming conventional passive speakers (none with any built-in powered subs, no electrostats with power supplies, etc.). I'm assuming that the the amplifier is not physically touching a metal equipment rack, or any other electrical devices, or the metal ends of any other interconnects or cables. The only possible paths for electrical conductivity, with regards to the power amp, must be: 1) the loudspeaker cables, and 2) the power connection. If all of the above conditions are met, and then the power amplifier is turned on, then there should be NO hum . . . if there is, then there is a problem with it. (Side note - some may say that it would be normal to still hear a bit of hum unless a shorting plug was installed on the amp input - and if this were an old tube amp with a high input impedance, that may be true. But for a modern SS amp like the Classe, you should hear NO hum.) If you don't, then add the preamp/processor, with NOTHING ELSE physically plugged into it. Plug it into the same duplex outlet or power strip as the amplifier (again, WITHOUT cheater plug) and check hum. Continue this with every single piece in your system, individually, and in isolation, until you find the exact point at which the hum appears. Oh and if the power amp does turn out to have a problem, the cause is still overwhelmingly likely to be a coincidince. All of the stuff you own was built by humans, and humans make mistakes. |
You should move; seems like your house is haunted! :) |
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. :-( |
Wow, the Anthem is so lifeless. :-(
But it does sound a LOT clearer. |
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! |
Your plan sounds good to me. |
Just a guess here, but I suspect it might be the Cary pre that's causing the problem. If you could find another pre, you might work towards confirming it or ruling it out. I'd think about sending the Cary back to the manufacturer for some testing. |
^^^ and it would eliminate RF as well |
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? |
0.2V into 8 ohms is 0.005 watts, FWIW And this is a TON of juice, for noise voltage. Similar to the amount of average audio power required to play speech at normal conversation levels, with an average bookshelf speaker. The AC reading was even higher, 0.45v. This is NOT normal and SHOULD NOT be there. Also, there's no place inside a home-theater preamp-processor to spray any aerosols . . . it's sure to be a solid-state electronic volume control. |
Either the preamp has a noisy (dirty) volume control (Radio Shack tuner cleaner could sort that out quickly enough) or you have DC on the volume control too.
The DC levels are not enough to trip the Classe protection circuit (I am assuming it has one). 0.2V into 8 ohms is 0.005 watts, FWIW. Given the gain of the power amp, the DC at the output of the Cary is low, about 0.2mV. Although I would not expect trouble on that account, OTOH I would not expect any DC at all, so it *could* point to a marginal coupling cap. |
My vote is that there's a problem with your preamp, and it's putting out some kind of inaudible energy that's giving your amplifier(s) fits. It could be DC, or ultrasonic AC (oscillation). There are all sorts of things inside it that could fail and cause this problem . . . a likely guess would be that an electrolytic bypass capacitor on the output of a 3-terminal voltage regulator has dried out, making it oscillate. This could then be very effectively coupled into all of the internal analog circuitry by the supply rails.
A multimeter doesn't really give you a very big window on what's going on, because depending on its internal rectifier, shunt, and sampling characteristics, ultrasonic AC could easily give a reading when the meter is set to DC. An oscilloscope would give you a better idea . . . but then again, who really cares? Your meter readings indicate to me that there's some sort of energy at the speaker that shouldn't be there. And it appears when you add the preamp. Have it serviced, and/or try another.
There may still be a slim chance that the amp-preamp interconnect is picking up a ton of RF and causing your problem (is it unshielded?) . . . but it's easy to check by swapping it with another cable, even a cheap one. Given that you're in the stix [sic], I think that this is unlikely, but it's easy to check.
Anyway, hope this helps. |
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.... |
Leoturetsky, did you try a different speaker cable? I doubt the cable is an issue (I've used them for years) but its best to eliminate as many variables as you can. |
There is one thing I can tell you for sure . . . when problems defy repeated attempts at diagnosis, there is a fundamental assumption being made that is untrue. In this case, it's definately possible that there is/was more than one completely unrelated problem . . . that is, whatever's plaguing the Classe isn't necessarily the same thing that was afflicting the Adcom.
Noise that changes when cables are moved around is very common indicator of RF interference. Unshielded interconnects are especially suceptable, which is why I feel that they're basically worthless. But it's unlikely that it's another piece of audio gear putting out enough RF into the air, with sufficient field stregnth to cause a problem with anything other than radio reception. More likely it's some kind of nearby transmitting device, or something like a preamp output-stage going into oscillation and dumping RF directly into the amplifier.
DC usually manifests itself as noise that occurs when swiches and controls are being operated, much less common as steady-state noise. It also frequently triggers protection circuitry at unanticipated times.
In your system, I couldn't figure out what preamplifier/processor you've been using other than the Cary . . . problems that are volume-control dependent (with no sources connected) point pretty strongly to this component. And it's also hard to imagine that the Krell wasn't just defective in its own right . . . there's that thing about "it wouldn't turn on" that's usually a bad sign, and usually unrelated to other stuff.
Anyway, keep us posted on your progress . . . I just think that there has to be an element of coincidence and bad luck here. |
Hi Leoturetsky,
I wish I could give you something more helpful, but they're not just in airplanes anymore.
http://www.motionbox.com/video/player/d39fd4b81c5a |
I must admit, I've never seen a bigger collection of lost audio nerds than on this post. Leoturetsky, don't f*** around with exotic experiments. Eliminate one thing at a time. Do have your preamp checked for DC first, then if ok take out the zobel's and try your system. Then take out the Goertz if necessary. I'm sure the problem lies within this range of eliminations. Do you have a dealer nearby? |
You wrote:
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.
**THIS IS NORMAL One should never power up a high-powr amp with no ground connection thru the ICs.
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.
*THIS IS NORMAL
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.
*ALSO NORMAL
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."
DITTO, NORMAL.Your hand "shields" the spurious signal.
NEVER test a high power amp with an open input (open-ended ICs are an open input plus a long antenna to pick-up noise).
My suggestion: buy a pair of inexpensive Radio Schack RCA connectors; short positive to negative on those RCAs by bending the metal parts.
Connect the shorted RCAs to the amplifier input and measure DC mV across the amp's speaker outputs. If the DMM reading is close to zero, the amp is fine.
To double check, measure AC V (lowest range on your DMM), it should be zero.
Power down the amp and move the shorted RCA's to the preamp input and measure DC mv across the preamp's outputs. Use an RCA output to make it simpler: the external contact is minus, the center pin is plus. Adjust the volume control up and down. If the meter shows an up and down DC reading, your preamp is defective (DC on the output). If the DMM reads zero no matter how you move the volume control, the preamp is fine DC-wise.
To double check, measure AC V (lowest range on your DMM), it should be zero or close to zero.
Now connect the source to your preamp (no music playing), turn on the source and preamp. Measure DC mv at preamp output again. If the meter shows a reading, DC or AC, your source is defective.
To be certain, measure ACV (lowest range) and DC mV at the source's output.
If your meter shows a few mV DC or AC, your source is defective.
I hope this helps |
The networks keep wide bandwidth amplifiers from oscillating. |
"The Alpha-Core Goertz speaker cables shouldn't cause problems with most amplifiers, but I strongly suggest the use of the Alpha-Core RC networks or similar zobel networks to be sure!"
Why? What are these networks supposed to do? |
The Alpha-Core Goertz speaker cables shouldn't cause problems with most amplifiers, but I strongly suggest the use of the Alpha-Core RC networks or similar zobel networks to be sure! |
"The interesting thing?: I am also using Goertz MI2 Veracity Cu speaker cables. The problems only happened after I started using these cables, which was a couple of months ago. Could the cables really cause these problems, or is it just a coincidence?"
I'd sure hate to find out for myself, but the cable sure is suspect now. If the cable is the cause, not only could the amp be damaged but the passives in the x-over can short out. |
I happened to come across this thread and found something interesting. I've also recently been having some problems with my equipment; two different sets of tube amps developed a problem which then had to be sent back for repair. One channel of one of the sets ended up having a bunch of burned capacitors, resistors, and a bias trim pot. I just received a brand new set of tube amps, and one of the amps has a problem right off the bat, although it would be hard for me to believe that something in my system caused that to happen immediately.
The interesting thing?: I am also using Goertz MI2 Veracity Cu speaker cables. The problems only happened after I started using these cables, which was a couple of months ago. Could the cables really cause these problems, or is it just a coincidence? |
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! |
OOOOPS, I typed "preamplifier" when I meant to type "amplifier". I was checking the amplifier, not the preamplifier. It was an amplifier/speaker issue I was working on.
My point was even if someone can't type, they can check DC witha multimeter. |
If you suspect the preamp has DC at its output, that is where you should measure for it. Some amplifiers have an input coupling cap and many don't so there is no guarantee that you will read DC at the output of the amp just because there is DC at the input.
In addition, many solid state amplifiers have a DC output protection circuit, which will prevent the amp from running if DC is present. So you may not be able to read DC at the output for that reason either. |
Joeylawn36111, You are correct. A tech just had me measure my preamplifier using a multimeter set at V-DC 200m with everything powered on but no music playing. I measured at the speaker binding posts. I believe that is SOP but hopefully someone else will verify that. |
If you have DC on your preamp output couldn't you measure it with a voltmeter? Seems to me the output of a preamp should measure 0VDC when measuring with a voltmeter at any volume level. If there is DC present, the output caps in the preamp are bad. |
Leoturetsky, in this we have narrowed it down substantially. I'll be surprised if it is the speaker cable, but I would not let that stop me from trying a different one.
If the cable has no effect, the simple fact is you have had a run of bad luck, or you have a lot of mice :) |
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? |
Leoturetsky, OK- I'm convinced that the RF is not from a radio station or the like. In your testing above, was the digital system plugged into the wall even though it was not connected to the amp?
I would indeed try a set of zip cord or similar speaker wires just so we can put the speaker cable thing to bed.
XLO is an example of unshielded wire; it doesn't surprise me in the least that you have hum problems with that! In fact, with the further description you have provided, it sounds more like a ground loop or bad grounding in general.
If you have a preamp/power amp: the preamp should be the system central ground. All other components (sources and amplifier) should 'float' that is, not be grounded. They should get their ground through the interconnect cable.
If you have an integrated amp, it should be properly grounded, and your sources should float.
I would avoid using power line conditioners until you have the ground thing sorted out. Sometimes they can create confusion when chasing things like this. |
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! |
Leoturetsky, checking the preamp's output is a job for a technician unless you yourself know how to input a test signal and read the output for distortion. I would put it on the list for later and go with Atmasphere's advice for the present. It sounds from recent posts as though RF needs to be eliminated as the problem first.
That said, two things occur to me. It would be interesting to hear from Krell about the condition of your old amp. And... I know Atmasphere (who should know if anyone would) is skeptical about the influence of your speaker cables. I too find it hard to imagine (putting myself in rather good company), but all the same I would try swapping in something different just for a check. Maybe even zip cord.
This is a fascinating problem. Thanks and keep posting! |
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? |
I bet the RF problem is the digital Cary Pre-amp:
From the owners manuel
All of the Main Room audio output connectors have 24-bit/192 kHz D/A converters operating in
dual differential mode for excellent sound quality and high dynamic range. In addition, the
Cinema 11 includes 7.1 channel XLR balanced audio outputs for your main listening room if you
are using a power amplifier with balanced input connections.
The Cinema 11 is designed to remain viable in a future of rapidly emerging digital technologies.
It has a rear panel RS-232 serial port connector provided for home automation serial control and
allows us to perform flash-memory software upgrades with this connection. We have added an
unusual looking 'system link' connector to support digital future expansion for high definition
audio codecs included with the new higher definition video disks now being sold. The system link
connector is available for future new surround modes like Dolby True HD and DTS-HD, making it
possible to more than quadruple the Cinema 11s tremendous processing power. This connector
is originally from the computer industry and features frequency bandwidth capabilities exceeding
2 gHz! We will make an adapter for video processing to access this connector and offer high
performance video switching and scaling to our users.
|
