A friend just gave me (gratis) a pair of SDA1's :-)

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Threshold400A
Threshold400A Posts: 2
in Vintage Speakers
Newbie here. A friend (original owner) just gave me (gratis) a pair of SDA1's :-) They have the vertical tweeters. They are oiled walnut tops and bottoms and black cloth on the front and sides. I have not yet hooked them up to my Threshold 400A so want to ask about the so-called 'frozen' magnet issue. How can I determine whether these units suffer from any 'frozen' magnet issues. I do not want to try to drive the speakers if any of the magnets are damaged and if doing so will damage the woofers or systems. Also, if I need to purchase any new woofer drivers what is the contact point at Polk (Tel #?) Thanks !
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  • Tony M
    Tony M Posts: 11,015
    edited January 2018 Answer ✓
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    Push on your mid-woofer cones gently and see if they push in and come back.

    If they do that, you're good till you glue them down later.

    Do you have the connecting cable ?

    Your Threshold Amp. . I don't know if it's common ground or not. Others will chime in to let you know about that issue.
    Most people just listen to music and watch movies. I EXPERIENCE them.
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  • Threshold400A
    Threshold400A Posts: 2
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    Thanks, Tony. I do have the blade/pin cable
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  • Tony M
    Tony M Posts: 11,015
    edited January 2018
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    Maybe it's discussed deep down in this link. I got tired of looking at a lot of reviews and comments after a while. Don't hook that amp up until you get the common ground issue answered.

    https://forum.audiogon.com/discussions/review-threshold-400a-amplifier
    Most people just listen to music and watch movies. I EXPERIENCE them.
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  • TNTsTunes
    TNTsTunes Posts: 751
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    Tony M wrote: »
    Maybe it's discussed deep down in this link. I got tired of looking at a lot of reviews and comments after a while. Don't hook that amp up until you get the common ground issue answered.

    https://forum.audiogon.com/discussions/review-threshold-400a-amplifier

    If the drivers are good/not frozen and the amps common ground issue hasn't been answered don't hook up the interconnect/SDA cable. You can safely use a non-common ground amplifier as long as that cable isn't connected. The speakers will just lack the SDA effect.
    "Make a man a fire and he'll be warm for a day. Light
    a man on fire and he'll be warm for the rest of his life."

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  • MrBuhl
    MrBuhl Posts: 2,419
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    Nice friend!! Congrats!
    VA HT HK AVR20II, Sony S9000ES CD/DVD/SACD, Polk Audio RC80i / Polk Audio CSi3, 60" Panasonic Plasma, Nordost / Signal Cable A2 / Wireworld / Pangea / Magic Power
    VA 2 Channel Focal Electra 926 speakers, Pass Labs X150.5 Amp, Eastern Electric MiniMax Preamp (Tutay mods), Eastern Electric Minimax CDP (Scott Nixon mods), Music Hall mmf 5.1 Turntable, Parks Audio Budgie Phono Pre , Audioengine B1 streamer, MIT S3 IC's / MIT Shotgun S3 Speaker Cables / PS Audio power cables
    Noggin Schiit Valhalla, Pangea, Phillips Fidelio X1, Polk UF8000

    Polk SDA1c modded
    Polk CRS+ 4.1TL modded (need veneer)
    Polk SDA2BTL (fully modded)
    A/L 1000VA Dreadnought Canare 4s11 SDA cable
    SACD Marantz DV8300
    Sony S9000ES CD/DVD/SACD
    Yamaha YP-D6
    Soundcraftsmen PCR800
    Audible Illusions L1 Preamp
    Vincent MFA based Cocci Tube Preamp
    Pho-700 Phono Pre
    Signal Cable Silver Resolution IC's






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  • agfrost
    agfrost Posts: 2,421
    edited January 2018
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    Of interest:
    http://www.diyaudio.com/forums/solid-state/284607-threshold-400a-bias-issue.html

    Of more interest (see post 10): Nelson Pass himself says the 400A *is* a common ground amp:
    http://www.diyaudio.com/forums/pass-labs/285958-threshold-400a-bias-issue-yes.html
    Jay
    SDA 2BTL * Musical Fidelity A5cr amp * Oppo BDP-93 * Modded Adcom GDA-600 DAC * Rythmik F8 (x2)
    Micro Seiki DQ-50 * Hagerman Cornet 2 Phono * A hodgepodge of cabling * Belkin PF60
    Preamp rotation: Krell KSL (SCompRacer recapped) * Manley Shrimp * PS Audio 5.0
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  • Tony M
    Tony M Posts: 11,015
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    @agfrost, Great Links! That was some great reading on a Threshold 400a amp and some insight by the man, NELSON PASS, himself.

    Common Ground amp, for sure.
    Most people just listen to music and watch movies. I EXPERIENCE them.
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