test for common ground amp

egp823
egp823 Posts: 74
edited July 2005 in 2 Channel Audio
is there a simple do it yourself test to check if an amp is common ground or not? tks
Post edited by egp823 on

Comments

  • disneyjoe7
    disneyjoe7 Posts: 11,435
    edited July 2005
    Is this a single body amp? If so most are common ground. What is your model number, so we could double check for you?

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  • dorokusai
    dorokusai Posts: 25,573
    edited July 2005
    If you have a VOM/Multimeter, sure....easy. Continuity is good, none is bad for SDA owners. If you don't own SDA's....who cares.

    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.
  • nadams
    nadams Posts: 5,877
    edited July 2005
    Take the cover off and trace the grounds back? That might not be a definitive test, but it'd give you a pretty good idea, pretty fast.
    Ludicrous gibs!
  • egp823
    egp823 Posts: 74
    edited July 2005
    steve
    Yamaha m-70 and 85 , adcom gfa 545II

    doro,
    how do i check using a VOM/multimeter? I have an SDA

    thanks
  • dorokusai
    dorokusai Posts: 25,573
    edited July 2005
    Originally posted by egp823
    steve
    Yamaha m-70 and 85 , adcom gfa 545II

    doro,
    how do i check using a VOM/multimeter? I have an SDA

    thanks

    NEG(BL) - NEG(BL) binding post....Continuity = OK....None = No-Go. I'm betting AOK.

    What SDA's?

    Nadams offers a good idea, but I personally don't like to infer what may be inside a component, unless I've actually seen it naked.

    There are sometimes changes within model lines that preclude any forward thinking.

    That being said, pop the top, take a picture, file it, VOM it....now you are an expert ;)
    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.
  • egp823
    egp823 Posts: 74
    edited July 2005
    pls forgive my ignorance but what setting should i use in the VOM? smallest no. is 200 and highest is 2000k . at the 200 setting i get reading of .5 and at 2000k its 0 . does this mean that my amp is common ground based on the reading at 200? thanks.
  • disneyjoe7
    disneyjoe7 Posts: 11,435
    edited July 2005
    Originally posted by egp823
    pls forgive my ignorance but what setting should i use in the VOM? smallest no. is 200 and highest is 2000k . at the 200 setting i get reading of .5 and at 2000k its 0 . does this mean that my amp is common ground based on the reading at 200? thanks.


    200 is the lowest resistor level that you can read, so anything under 200 ohm can be seen. So you can .5 ohm so you have common amp.

    Speakers
    Carver Amazing Fronts
    CS400i Center
    RT800i's Rears
    Sub Paradigm Servo 15

    Electronics
    Conrad Johnson PV-5 pre-amp
    Parasound Halo A23
    Pioneer 84TXSi AVR
    Pioneer 79Avi DVD
    Sony CX400 CD changer
    Panasonic 42-PX60U Plasma
    WMC Win7 32bit HD DVR


  • dorokusai
    dorokusai Posts: 25,573
    edited July 2005
    You should get a value either way, continuity is continuity. You're just checking to see if there is a electrical connection, not launching a rocket into space.
    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.
  • bikezappa
    bikezappa Posts: 2,463
    edited July 2005
    To use the ohm meter to check the resistance between the two black or negative speaker connections you should:

    Set the ohm meter to the lowest setting, in this case it's 200 ohms.

    Next touch the two wire leads together, this should be 0.0 resistance and the ohm meter should also read 0.0.

    In the old days the meter reading was adjustable with a potenometer to read 0.0 when the leads were touching.

    You need to do this step to determine the exact resistance of anything you are measuring. Shorting the leads will tell you if the meter is reading zero and correctly.

    You have a common ground amp.
  • egp823
    egp823 Posts: 74
    edited July 2005
    Thanks a lot for your replies. Am learning a lot from these forums and I know that I didn't make mistake when I purchased my CRS+ because of all your help and support.
  • PILAC
    PILAC Posts: 23
    I know this is an old post but just wanted to ask if anyone knew right away before I ask an eBay seller to pull out a multimeter they might not have, is the Sonance Sonamp 260 (mk 1) a common ground amp? And if so would bridging both of the channels affect anything? I have a pair of SDA’s so I do need it to be common ground.
  • F1nut
    F1nut Posts: 49,704
    In stereo mode it may or may not be common ground. When bridged it most definitely is not. Bridging raises the noise floor, cuts the ohms the amp is seeing in half and cuts the damping factor in half. Never a good idea, IMO.
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  • PILAC
    PILAC Posts: 23
    Ok thanks for the info.