question regarding adcom amp

mlastarza
mlastarza Posts: 32
edited December 2007 in Electronics
Bought an adcom GFA 555 amp on audiogon about a month ago. Hooked it up to a Yamaha RXV 661 av receiver and my RTA 11t speakers. Everything seems to work fine except after I turn off the amp, after about 15 seconds a noise is emitted from the speakers (like an electronic burp for lack of a more technical description). I've never had a seperate amp before and don't know if this is typical or of concern?
MWL
Post edited by mlastarza on
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  • venomclan
    venomclan Posts: 2,467
    edited December 2007
    Some Adcom amps and others do emit that electronic blurp. My Adcom does it also. They are missing a component in them that most modern amps have, I do not remember what it is exactly (relay?), but do not concern yourself with it as it is normal for that amp.
    Venom
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  • tcrossma
    tcrossma Posts: 1,301
    edited December 2007
    I'm kind of new to the external amp world myself, so i'm not sure exactly what should be expected from different amps. The documentation for mine recommends that the receiver be turned off first, then the amp. That's the way i'm doing it and i've never heard a "thump". I'm sure someone else here has experience with that particular amp and can chime in.
    Speakers: Polk LSi15
    Pre: Adcom GFP-750 with HT Bypass
    Amp: Pass Labs X-150
    CD/DVD Player: Classe CDP-10
    Interconnects: MIT Shortgun S3 Pro XLR
    Speaker cables: MIT MH-750 bi-wire
    TT:Micro Seiki DD-35
    Cartridge:Denon DL-160
    Phono Pre:PS Audio GCPH
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  • nms
    nms Posts: 671
    edited December 2007
    I've read this is not a problem as long as it is not too loud. Judging by the time delay I'd guess you're hearing a capacitor discharging.

    Most amps do not do this because they have a solenoid that physically opens the circuit when you turn it off, so those noises do not reach the speakers. This is the thing Venom mentions that your amp is "missing" ;)
    My system

    "The world is an ever evolving clusterf*ck." --treitz3
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  • mlastarza
    mlastarza Posts: 32
    edited December 2007
    Thanks for the replies. The owners manual for the amp states to turn the amp off first and wait for the red display light to go out before turning off the receiver. How much of a risk is it if it's not done in that order?
    MWL
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  • venomclan
    venomclan Posts: 2,467
    edited December 2007
    The amp should be the first one off and the last one on. An amp will amplify any signal, or lack thereof through a speaker. If a receiver or preamp is turned off first, it can sometimes send a high pitched signal or other unwanted amplified signal to your speakers and potentially cause damage.

    Turning on a preamp or receiver first will allow you to make any adjustments needed volume wise or input wise before or right when an amp is powered on.
    Venom
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  • george daniel
    george daniel Posts: 12,096
    edited December 2007
    Adcoms,, particurlarly the 555's are notorius for the " thump"
    JC approves....he told me so. (F-1 nut)
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  • mlastarza
    mlastarza Posts: 32
    edited December 2007
    Thanks folks. I shall resume my happy listening without worry.
    MWL
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  • cfrizz
    cfrizz Posts: 13,415
    edited December 2007
    How do you like having your speakers driven by a separate amp?
    Marantz AV-7705 PrePro, Classé 5 channel 200wpc Amp, Oppo 103 BluRay, Rotel RCD-1072 CDP, Sony XBR-49X800E TV, Polk S60 Main Speakers, Polk ES30 Center Channel, Polk S15 Surround Speakers SVS SB12-NSD x2
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  • mlastarza
    mlastarza Posts: 32
    edited December 2007
    It sure sounds good. My son asked me "Does it sound BETTER?" I think it does but I look back on threads discussing cables and I wonder is my brain just hoping it sounds better? Between the amp and the new RD0-194 tweeters it seems I hear things I hadn't before versus my imagination? Redardless for a whopping $400 investment between the amp and the tweeters I'm pretty happy!
    MWL
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  • ruf993turbo
    ruf993turbo Posts: 39
    edited December 2007
    It is perfectly normal what's happening..
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