What'd I do wrong?

sandworms
sandworms Posts: 1,043
edited November 2010 in Electronics
So, I was doing some experimenting last night, comparing my current amp (xpa3) to a parasound hca 1000. I bridged the hca for the left channel and left my xpa on the right while listening to 2ch, well the parasound was humming loudly at low volume, which I have never had a hum with my xpa3. could there be an issue with the amp ( just got from flee bay ), or is this the way older amps pick up interference (ground loop). sorry for the beginner questions, but I still learning this hobby, slowly but surely
Samsung pn64f8500
Sonus faber venere 2.5
Sf venere center
Oppo 105d
Squeezebox touch
Parasound hca1500a
Apc power filter
Audioquest cables asst
Polk rtia3 SB
Polk fxia6 sl,sr
Dual hsu vtf3 mk3

Post edited by sandworms on
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Comments

  • tonyb
    tonyb Posts: 33,077
    edited November 2010
    In bridged mode, some may hum a bit more. Also some amps in bridged mode don't like anything under an 8 ohm load. Take it out of bridged mode and just use one channel if you want to compare the way your doing it.
    HT SYSTEM-
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  • reeltrouble1
    reeltrouble1 Posts: 9,312
    edited November 2010
    good advice tony, whenever you have a system problem, simplify, no bridging, bi-amping and so on, hook the parasound up regular and see if there is hum, make sure it is hum not hiss, if you have hum it can be a ground loop, it can be a bad connect or there can be something amiss in the signal path, but keep it simple to begin with. If it still hums both channels or just one??

    RT1
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  • cnoat
    cnoat Posts: 315
    edited November 2010
    +2 I run a 750a in bridged mode for my center.Not alot of hum but a noticeable "hiss" when you put your ear to it.
    Parasound Avc-1800
    Mains-Rti 12 -Parasound 1500a
    Center-Csi5-Parasound 1000a
    Rears-Rti 8-Parasound 750a
    Sub SVS Ultra Tv 12
    Diamondback and King Cobra IC's
    AQ T4 SC
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  • sandworms
    sandworms Posts: 1,043
    edited November 2010
    definetly a hum, so I will try it not bridged first, see how it sounds. I'm hoping it's not an internal issue, just a connection issue. Thank you for the help guys, love this place!
    Samsung pn64f8500
    Sonus faber venere 2.5
    Sf venere center
    Oppo 105d
    Squeezebox touch
    Parasound hca1500a
    Apc power filter
    Audioquest cables asst
    Polk rtia3 SB
    Polk fxia6 sl,sr
    Dual hsu vtf3 mk3

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  • TroyD
    TroyD Posts: 13,124
    edited November 2010
    I'm reminded of the old story:

    Patient: Hey, Doc, it hurts when I do *this*
    Doc: Well, don't do that.

    BDT
    I plan for the future. - F1Nut
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  • sandworms
    sandworms Posts: 1,043
    edited November 2010
    I took it out of bridged mode and 80% of the hum went away,I didn't try the other channel yet, however it still has what I consider to be unacceptable low volume hum. tomorrow I'll try the other channel and a cheater and see if it goes away. I'm running RTi10's so not a difficult load.
    Samsung pn64f8500
    Sonus faber venere 2.5
    Sf venere center
    Oppo 105d
    Squeezebox touch
    Parasound hca1500a
    Apc power filter
    Audioquest cables asst
    Polk rtia3 SB
    Polk fxia6 sl,sr
    Dual hsu vtf3 mk3

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