Used (But just bought) Adcom GFA-5500 BUZZZZZ!

motobman
motobman Posts: 32
edited February 2010 in 2 Channel Audio
Just bought a used, very clean, good condition Adcom GFA-5500 from ebay and they have 100% feedback. NOT sure what to do.

Hooked up the Adcom 2-Channel amp to my right speaker and it is buzzing like no tomorrow. I hooked up the right channel with a new speaker wire, (Bi-wire) then used my single wire and hooked it to the bottom posts to my RTI A9 right speaker. Still same thing. Brand new single RCA cable from my Yamaha RX-V1900 pre-out front to the amp. Not sure what to do. Guess I can try the left channel but need to move a bunch of furniture and route the wires all over the place.

What do you guys/gals recommend? Is there an easy way to test the amp?



Thank you so much for your help,


-Brett
Post edited by motobman on
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Comments

  • F1nut
    F1nut Posts: 50,842
    edited February 2010
    Is there an easy way to test the amp?

    You just did.

    Either return it, if you can or take it to a repair shop.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • comfortablycurt
    comfortablycurt Posts: 6,745
    edited February 2010
    F1nut wrote: »
    You just did.

    Either return it, if you can or take it to a repair shop.

    That says it all.
    The nirvana inducer-
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    PolkAudio LSi9's/PolkAudio SDA 2A's/PolkAudio Monitor 7A's
    Audioquest Speaker Cables and IC's
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  • leroyjr1
    leroyjr1 Posts: 8,785
    edited February 2010
    How loud is the buzz? Does it increase with the volume? Once the music start can you hear the buzz?
    Try hooking the amp up to the speakers but don't connect the IC cables to the amp and see if it still buzzes.
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  • billbillw
    billbillw Posts: 6,904
    edited February 2010
    Could be a ground loop between your other gear and the amp. Try testing it without the input RCAs connected. Just an amp with no signal. If the buzz is gone, then its a ground loop. Search on the internet for ways to get rid of that problem.
    For rig details, see my profile. Nothing here anymore...
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  • dorokusai
    dorokusai Posts: 25,577
    edited February 2010
    You have to find out if its channel specific, so move what you gotta move or just get rid of it.
    CTC BBQ Amplifier, Sonic Frontiers Line3 Pre-Amplifier and Wadia 581 SACD player. Speakers? Always changing but for now, Mission Argonauts I picked up for $50 bucks, mint.
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  • motobman
    motobman Posts: 32
    edited February 2010
    Ok, first of all, thank you guys for your responses..... :)
    Here is what I did tonight.
    1) Plugged in the Adcom GFA-5500 to the wall
    2) unplugged my speaker cables going into my right Polk RTI-A9 speaker
    3) plugged in a new speaker wire from the Adcom to the right speaker
    4) Keep in mind, at this point there is Nothing plugged into the RCA jack
    5) Turned on the Adcom, and no buzz
    6) But, the second I touched, or plugged in, the single RCA to the Amp, BUZZZZZZ!!! and loud (the noise you know it is not supposed to make)

    SO, does that mean there is something wrong with the amp, or, the new single RCA cables?? I never got close to the Yamaha Receiver, so we know its not the pre-outs from the receiver....

    Thanks again and please let me know what you think,


    -Brett
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  • esowden
    esowden Posts: 55
    edited February 2010
    Sounds like EMI to me. I experienced a similar issue with one of my Parasounds. Bought some better shielded interconnects and the problem went away.
    Den
    Parasound 2100
    Parasound 2125
    Denon DCM-390
    LG BD390V
    Martin Logan Preface(x2)
    Denon AH-D2000

    Bedroom
    Adcom GTP-350
    Parasound HCA-800II
    Panasonic DVD-S54
    Denon AH-2000
    Polk S4(x4)

    ಠ_ಠ
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  • motobman
    motobman Posts: 32
    edited February 2010
    I don't get it, I have brand new Audioquest King Cobra (single) RCA interconnects, and never got to even plug them into the receiver. It started buzzing through the right speaker as soon as I plugged the RCA into the right channel of the AMP. Doesn't make sense. . .
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  • billbillw
    billbillw Posts: 6,904
    edited February 2010
    Noise when you touch the inputs is totally normal. Remember, your body is full of electrical signals and acts like a ground.

    The test for the amp is BOTH speakers hooked to the Adcom amp. No RCA inputs. Plugged in to separate outlet. Powered on. If it is silent. The amp is working as it should. If the amp is noise free in this arrangement, your problem is ground loop.

    Ground loop is common when hooking a receiver to a power amp. Mixing grounded and ungrounded power plugs can cause this, as well as having ungrounded antenna connections on the receiver. It can come from anywhere. I had problems once coming from my satellite dish, through my DVR, to my receiver, to the amp. Just isolate everything and test each connection.
    For rig details, see my profile. Nothing here anymore...
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  • motobman
    motobman Posts: 32
    edited February 2010
    I forgot to tell you that the Adcom GFA-5500 I have is ony a two prong outlet. Does that matter?
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  • zarrdoss
    zarrdoss Posts: 2,562
    edited February 2010
    One of the solder joints could have gotten a fracture in shipping, or the seller was hiding the fact, If you got insurance when you bought it, file a claim. Just my 2 cents
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  • billbillw
    billbillw Posts: 6,904
    edited February 2010
    motobman wrote: »
    I forgot to tell you that the Adcom GFA-5500 I have is ony a two prong outlet. Does that matter?

    Yes, especially if you are hooking it to gear that is grounded. (3-prong). Just test it like I said. No noise- Amp fine. Noise- amp has problems.
    For rig details, see my profile. Nothing here anymore...
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  • BottomFeeder
    BottomFeeder Posts: 1,684
    edited February 2010
    Hey! I had the SAME AMP & THE SAME PROBLEM! I wish I could send you to the thread on here but maybe if you search for it, you'll find it.

    Anyway, what FIXED the problem for me is simply using a full strand of speaker wire to connect the speaker posts on the back of the amp. Wrap the wire around one post & do the same to the other. Then connect your speaker wire just as you normally would. This solved the problem for me.

    Hope it does the same for you.
    "Wish I didn't know now what I didn't know then." Bob Seger
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  • MillerLiteScott
    MillerLiteScott Posts: 2,561
    edited February 2010
    If your AVR/receiver has a three prong plug and the adcom has a two prong plug get a cheater plug for the AVR/receiver to see if it is a ground loop issue.

    Also, I would connect everything as it should be before turning on the amp etc. Any open ended connections, RCA or speaker wire could cause noise or damage.

    Scott
    I like speakers that are bigger than a small refrigerator but smaller than a big refrigerator:D
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  • nooshinjohn
    nooshinjohn Posts: 25,484
    edited February 2010
    I would open the amp up and retouch the soldered connections for all of the inputs and try again.
    The Gear... Carver "Statement" Mono-blocks, Mcintosh C2300 Arcam AVR20, Oppo UDP-203 4K Blu-ray player, Sony XBR70x850B 4k, Polk Audio Legend L800 with height modules, L400 Center Channel Polk audio AB800 "in-wall" surrounds. Marantz MM7025 stereo amp. Simaudio Moon 680d DSD

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  • billbillw
    billbillw Posts: 6,904
    edited February 2010
    nooshinjohn wrote: »
    I would open the amp up and retouch the soldered connections for all of the inputs and try again.

    Dude, 99% chance he has a simple ground loop. Why you telling him to break out the soldering iron? He hasn't done a proper troubleshooting yet. Until he isolates the amp as the problem, that's an absurd suggestion.
    For rig details, see my profile. Nothing here anymore...
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  • motobman
    motobman Posts: 32
    edited February 2010
    Hi Guys,
    Found it.
    I first plugged the Adcom amp into a $50 surge surpressor/battery backup, then plugged in my "Left" speaker with the bi-wire cable. No RCA at this point. No buzzing. THen plugged in a new RCA. No Buzz. Then plugged in the new single RCA... No buzz. Then did the same on my right speaker but it "popped" as soon as I would turn on the amp. Never even got to the point of trying it with an RCA and had a hunch. The RCA output on the amp was just a tad loose, and could spin just a hair. SO, I took off the top and there it was- a broken ground wire coming off of the rca out to somewhere close to the speaker outs. The problem is it is tremendously short and I presently trying to extend the ground cable... Not much room to work with at all.

    Hoping this fixes it and I can finally plug it in and actually test it. I do not have a solder iron, but will try to rig it..OR try the neighbors.

    Thanks guys and will update you again!!!
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  • F1nut
    F1nut Posts: 50,842
    edited February 2010
    Solder iron.....$20.00 at Rat Shack.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • motobman
    motobman Posts: 32
    edited February 2010
    Yah, my neighbor is going to bring one home. Super Stoked. Thanks for all of your help.

    -Moto
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