Carver Amp Problem ?

Marty913
Marty913 Posts: 760
edited August 2011 in Electronics
I know this is a very general question with probably a LOT of possible answers but I thought it worth throwing out there for possible ?which way to proceed? advice.

I happened to notice a ?hum? in my system yesterday ? audible in all 5 speakers. My receiver/processor (NAD T747) was turned off (standby actually), my Carver AV705 amp was on as is normally the case. The only troubleshooting I?ve done so far is to unplug my SDA 1Cs from the amp & connect them directly to the NAD and the hum disappears.

Obviously that points me to the Carver but since it affects all channels and the AV705 has 5 individual amp cards it would seem the problem would have to be at a ?common point? (capacitors, transformer?). Not sure if a bad amp card could cause problems in all speakers but I?m no engineer (locomotive or otherwise:rolleyes:). The Carver is 12 years old which doesn't seem that old.

The only other things I can think of beside the Carver might be some sort of ground loop / filtering problem however it does not affect the NAD. Is that possible? Both are plugged into the same power source.

Sorry for not giving you much to go on. I?ll continue to swap stuff around a little today. Unfortunately I don?t currently have another common ground amp lying around. Am I looking at an amp rebuild on the Carver? Sure hate the thought of packing that thing up and shipping it off.

Marty
Sony 60'' SXRD 1080p
Amp = Carver AV-705THX 5-Channel
Processor = NAD T747
Panasonic BD35 Blu-Ray
Main = SDA-1C Studio with RD0s, spikes, XO rebuild, rings, I/C upgrade
Center=Polk CS10, Surround = Athena Dipoles, Sub= Boston 12HO
Music/Video Streaming = Netgear NEO550
TT = Audio Technica
Post edited by Marty913 on
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Comments

  • jjwm27
    jjwm27 Posts: 123
    edited August 2011
    check your ICs i had that problem with my av806 and it turned out to be a bad. cheap. cable. drove me nuts for quite awhile. good luck.
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  • dekuda
    dekuda Posts: 756
    edited August 2011
    First, Bob Carver highly recommends to plug his amps directly into the wall outlet.Ground loopproblems can affect evrything on the same circuit. Then, if you have hum use a 3 prong to two prong cheater plug in the AC wall socket.This is the easiest. You may have a ground loop problem that is usually caused by cable boxes. I had the problem just with my amp,not my AVR, and used a cheater plug for the amp and now it is dead quiet. No problem just using chassis ground. Probably why newer amps have a ground lift switch built in.
    HT System
    Parasound Halo A51 Amp, Marantz AV 8003 Pre, Arcam FMJ CD36 cd player, Marantz 7007 BD/SACD player,Acoustic Zen Matrix IC's, Analysis Plus Crystal Copper Oval IC's, Acoustic Zen Satori speaker cables, B&W 703's Fronts, Center Martin Logan Motif hybrid, Surrounds DefTech BPX, 2 X DefTech Supercube Reference Subs, DSpeaker Antimode 8033 EQ.
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  • TNRabbit
    TNRabbit Posts: 2,168
    edited August 2011
    Cable is THE WORST offender for grounding issues. Disconnect the cable & see if that cures your problem. If so, cheap solution is to use the TOSLINK connector for audio.
    TNRabbit
    NO Polk Audio Equipment :eek:
    Sunfire TG-IV
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    Carver AL-III Speakers
    Klipsch RT-12d Subwoofer
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  • Systems
    Systems Posts: 14,873
    edited August 2011
    dekuda wrote: »
    First, Bob Carver highly recommends to plug his amps directly into the wall outlet.Ground loopproblems can affect evrything on the same circuit. Then, if you have hum use a 3 prong to two prong cheater plug in the AC wall socket.This is the easiest. You may have a ground loop problem that is usually caused by cable boxes. I had the problem just with my amp,not my AVR, and used a cheater plug for the amp and now it is dead quiet. No problem just using chassis ground. Probably why newer amps have a ground lift switch built in.
    ...=1...also ..maybe power supply?..had a Carver...sold it..but the guy who bought it from me, about 1 year later had a hum coming from it..when it was in standby...the repair shop replace the power supply in it..but your hum is when it is up and running ..so i would go with what dekuda said first..again [email]+1@dekuda..great[/email] advice!
    Testing
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  • Marty913
    Marty913 Posts: 760
    edited August 2011
    Thanks everyone. I eliminated the IC's because the hum is in all 5 channels thing plus the fact that the processor (NAD) is turned off. The sat/cable box is off as are all other connected components but I will disconnect them just in case something is passing through. No hum with the Carver out of the loop so doubt that's it.

    I did move the power directly to the wall (actually even another circuit altogether) but the hum remains. The Carver power supply mentioned by ctank may be the culprit, or some other common component in the amp.

    It still sounds great but just knowing the hum is there drives me crazy. Looks like I might be hitting the Flea Market or shipping it out to CarverAudioRepair or Rita's. Oh well, this stuff does happen with the older stuff.
    Sony 60'' SXRD 1080p
    Amp = Carver AV-705THX 5-Channel
    Processor = NAD T747
    Panasonic BD35 Blu-Ray
    Main = SDA-1C Studio with RD0s, spikes, XO rebuild, rings, I/C upgrade
    Center=Polk CS10, Surround = Athena Dipoles, Sub= Boston 12HO
    Music/Video Streaming = Netgear NEO550
    TT = Audio Technica
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  • tonyb
    tonyb Posts: 33,068
    edited August 2011
    First go buy a 2 buck cheater plug and put it on the carver,and plug into the wall. Sounds more like a ground loop problem than an actual repair being needed.
    HT SYSTEM-
    Sony 850c 4k
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    SVS SB-2000
    Polk Sig. 20's
    Polk FX500 surrounds

    Cables-
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  • EndersShadow
    EndersShadow Posts: 17,692
    edited August 2011
    If you do think about selling let me know.... 2 Carver 705x's hmmmmmmmmm
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
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  • Marty913
    Marty913 Posts: 760
    edited August 2011
    tonyb wrote: »
    First go buy a 2 buck cheater plug and put it on the carver,and plug into the wall. Sounds more like a ground loop problem than an actual repair being needed.

    Thanks Tony, tried it with no luck.
    Sony 60'' SXRD 1080p
    Amp = Carver AV-705THX 5-Channel
    Processor = NAD T747
    Panasonic BD35 Blu-Ray
    Main = SDA-1C Studio with RD0s, spikes, XO rebuild, rings, I/C upgrade
    Center=Polk CS10, Surround = Athena Dipoles, Sub= Boston 12HO
    Music/Video Streaming = Netgear NEO550
    TT = Audio Technica
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