Is the Meridian 559 amp considered common-ground and thus safe for SDA SRS?

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Gofastr
Gofastr Posts: 19
in Vintage Speakers
Talked to one individual at Meridian US who discussed my question w/UK, but their answer that it's not straight-forward but yes, was a little fuzzy for me. Have another call out to Meridian's go to repair shop, but thought someone here might know.
Thx
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  • codycatalist
    codycatalist Posts: 2,662
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    I read it is a dual mono design, so while it can be I would not chance it unless you have a chance to measure the negative leads.
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  • hauxon
    hauxon Posts: 161
    edited December 2019
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    You can check yourself by using a simple multimeter. Set the meter to measure continuity, unplug your amp from the wall and stick the pins into the ground (black) binding posts on each side. If you hear a peep sound from the meter it is a common ground design. Amps may have common ground even if they have been advertised as dual mono.
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  • Emlyn
    Emlyn Posts: 4,367
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    Agree it’s always best to check an amp oneself for a common ground between the channels when it comes to SDA speakers. Lack of mention on the back of the amp or in the manual is not an indicator.
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  • Gofastr
    Gofastr Posts: 19
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    Thank you both. I've received a wealth of advice - similar to yours - on the thread (indicated below) to which I originally posted. FYI, note that merely having continuity is generally deemed insufficient; that have very low resistance, i.e. < 1 ohm; on some threads <0.5 ohm recommended, is important as well.

    I'm a noob to this forum and am impressed with the knowledge and responsiveness of members!

    https://forum.polkaudio.com/discussion/180029/what-adcom-amp-for-my-sda-srs-s#latest
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  • Gofastr
    Gofastr Posts: 19
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    Forum,
    I'm resurrecting this thread, as COVID delayed my AV room construction, thus my purchase of some SDA-SRS' was similarly delayed. Everything is back on track now, and I've got my sights set on a nice pair of 2.3s, so want to ensure I don't blow up either speakers or amp when I audition these at home.

    My Meridian 559 measures 20ohms between L/R negative terminals. Measuring between either L/R negative and the chassis gives 10ohm. So it's apparent that while both sides have a common ground at the chassis, there is a 10 ohm resistor between each side and the chassis.

    Does this mean I will need the Polk AI-1 Amp Interface (or Dreadnaught), or am I safe to run the 2.3s without it?
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  • F1nut
    F1nut Posts: 49,794
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    Your amp is not common ground.
    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."

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  • Gofastr
    Gofastr Posts: 19
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    A long overdue update. I jumpered the L/R negative terminals and the system sounds great and has been performing flawlessly for months.
    Cheers
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