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Why can't the SDA circuit be isolated in pre-fourth generation models?

From all I've read, it is not possible to modify pre-fourth
generation SDA speakers to isolate the SDA circuit to use with
non-common ground amps. Does anyone know why?

All I've found by searching the forums is someone who tried, but
said they reverted the mod because it didn't sound as good.

Is it because Matthew Polk is the Antonio Stradivari of SDA and
only he knows how? :P

Or is it something as simple as the crossover board doesn't allow
for the SDA circuit to be isolated? If so, would it be possible
to isolate it if the crossover was rebuilt with point to point
wiring?

Or is it even simpler, in that no one besides the above poster
has tried?

I read a common answer that it is easier to buy used 4th or 5th
generation models than to try and modify the older ones and you
get the improvements that come with them. Unfortunately, where I
live, I haven't found any for sale within a reasonable driving
distance over the past year.

What I'm interested in is modifying my SDA 1As to use with my
fully balanced amplifier. I don't need them to work with or
without an isolation transformer. Modifying them to only work
with an isolation transformer (aka dreadnaught/dreadnought) is
perfectly fine.

Upgrading to a common ground amplifier is also not an option for
me. I paid $4k for the amp 10 years ago. Upgrading to something
comparible would cost more than I've seen any SDA speakers sell
for, excluding the L800s, and I really like the amp! Granted, it
would be easier to find a good common ground amp, than it is to
find a pair of 4th or 5th generation SDAs.

As you can tell, I don't know anything about modifying
crossovers, but I am curious as to why It can't be done...

Best Answer

Answers

  • hauxonhauxon Posts: 141
    edited February 17
    What amp is it you have?
    SRS 1.2 TL | SDA 2B Studio TL | NAD M51 preamp/dac | Cambridge Audio Azur 851W | Chromecast Audio | RoPieee Roon Raspberry Pi endpoint
  • AstropetAstropet Posts: 24

    Ayre V-5XE

    Here is what the manual says:

    The Ayre V-5xe drives the loudspeakers with balanced outputs.
    Since none of the output terminals are grounded, connecting any of them to ground may result in damage to the amplifier. Do not connect the loudspeaker outputs to any speaker switch-box,
    accessory, or test equipment that has a common ground connection.

  • F1nutF1nut Posts: 43,972
    It would require a complete reconfiguration of the SDA circuit with completely different components, which is what Polk did with the later models.
    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

  • You might be able to separate the channels by utilizing 2 transformers and provide a signal plus a ground to each one. Not sure if it would work, others may know.
    Yamaha RXA1030, Yamaha CD, Bluesound node 2i, Tidal
    Polk SDA2btl highly modded
    Polk SDA 1C
    Polk CS350 LS x2
    Polk m5jr
    Kimber 8TC
    Sony 55" Bravia
    Wish list SVS sub

  • AstropetAstropet Posts: 24
    I called my dealer and they said that Ayre recommends disconnecting the negative leads and attaching them to a screw on the chassis to create a common ground. I tried this and got sound with the interconnect disconnected, but when I connected the interconnect, the SDA drivers are still silent.
  • SchurkeySchurkey Posts: 1,933
    Astropet wrote: »
    I called my dealer and they said that Ayre recommends disconnecting the negative leads and attaching them to a screw on the chassis to create a common ground. I tried this and got sound with the interconnect disconnected, but when I connected the interconnect, the SDA drivers are still silent.
    WHICH "negative leads"?

    Do you mean attaching the negative speaker cables to the chassis instead of the negative terminals on the amp? You'd be throwing away half the power the amp is rated for.

    .
    .
    For the good of the Free World, DEMAND COMPENSATION FROM CHINA for their release of an engineered virus from their Wuhan laboratory. Two trillion to start with, increasing as needed from there.
  • AstropetAstropet Posts: 24
    WHICH "negative leads"?

    Do you mean attaching the negative speaker cables to the chassis instead of the negative terminals on the amp? You'd be throwing away half the power the amp is rated for.

    Yes, exactly. My first impression was that it didn’t sound as good. This was likely due to the loss of power

    Do you know why the SDA still doesn’t work? Connecting and disconnecting the interconnect made no difference.
  • SchurkeySchurkey Posts: 1,933
    Sounds to me like a problem with the speakers, rather than a problem with the amplifier.

    Try the "usual suspects"; frozen SDA drivers, disconnected wiring inside the cabinet, loose SDA sockets that the SDA cable plugs into on both cabinets, etc.

    Also, make sure you've got a stereo source. (assure the mono button on the preamp isn't engaged.)
    .
    .
    For the good of the Free World, DEMAND COMPENSATION FROM CHINA for their release of an engineered virus from their Wuhan laboratory. Two trillion to start with, increasing as needed from there.
  • AstropetAstropet Posts: 24
    I did have frozen drivers, but @lawdogg fixed them for me.

    I tried them with a Phase Linear Model 200 amp and the SDA drivers work. The amp does not have enough current to drive the speakers though…

    It seems my options are to get a new amp or to get a pair of the L800 speakers. The manual indicates that common ground is no longer a requirement… The problem is there are no dealers here for me to listen to them…




    Thanks for your help. I really appreciate it…

  • SchurkeySchurkey Posts: 1,933
    I
    Astropet wrote: »
    I tried them with a Phase Linear Model 200 amp and the SDA drivers work. The amp does not have enough current to drive the speakers though…
    I guess I was very wrong about the problem being in the speakers rather than in the amplifier.
    .
    .
    For the good of the Free World, DEMAND COMPENSATION FROM CHINA for their release of an engineered virus from their Wuhan laboratory. Two trillion to start with, increasing as needed from there.
  • KennethSwaugerKennethSwauger Moderator Posts: 6,927
    The person at Ayre may have misunderstood what the speakers and the amplifier are requiring. The speakers, with the SDA interconnect connected, connect the left and right negatives together. They don't need to have their negative terminals attached to the amplifier's chassis, they already are connected. What has to happen is the amplifier has to be designed so that when the negative output terminals are connected together the amplifier isn't shorted out. The later series of SDA speakers created the necessary common ground connection via the amplifier rather that via the SDA cable. If the amplifier wasn't common ground compatible then all that happened was there was no SDA sound and nothing was damaged. Previously a miss-match caused potential damage to the amplifier (which would happen in your case). This later scheme allowed an AC-coupled isolation transformer to be used which allowed the SDA signal to be produced but didn't short the amplifier.
    "They thought we were too loud, but shoot, I had four army blankets folded over my amp, and the volume level was on 2. I'm used to playin' on 10!" S.R.V.
  • AstropetAstropet Posts: 24
    Just to clarify, the discussion I had was with my dealer. When I explained the situation, he said that they have an issue connecting a certain subwoofer to the amplifier and when they contacted Ayre, the recommendation was to connect the negative leads of the speaker cables to the chassis. He said they had good results with that… So, in no way did Ayre recommend this for the SDA speakers. This is all on me… Anyway, I didn’t blow anything up and everything still works so no biggie…

    I think I’m at the point now where a new amp is really my only option… Every time I listen to the speakers, I am amazed at how they sound without the interconnect. They are all stock. I have the new tweeters, but haven’t installed them yet. Nothing is upgraded and they sound fantastic! I really don’t need another pair of speakers. I just need these ones to work. ☺️

    I bought them used in 1988 and haven’t listen to them since 1997. I left them at my parents place when I move to another city. It wasn’t until now that I had a place where I could play them without getting evicted. 😉



    The problem is I like this amp as much as I like the speakers...


  • KennethSwaugerKennethSwauger Moderator Posts: 6,927
    Unfortunately with the SDA interconnect engaged the two are incompatible.
    "They thought we were too loud, but shoot, I had four army blankets folded over my amp, and the volume level was on 2. I'm used to playin' on 10!" S.R.V.
  • SchurkeySchurkey Posts: 1,933
    Astropet wrote: »
    The problem is I like this amp as much as I like the speakers...
    The obvious answer is to use that amp with other speakers in a different system in another room. Get a common-ground amp to use with the Polks.

    Twice the music.
    .
    .
    For the good of the Free World, DEMAND COMPENSATION FROM CHINA for their release of an engineered virus from their Wuhan laboratory. Two trillion to start with, increasing as needed from there.
  • AstropetAstropet Posts: 24
    Heheheh, that’s an even bigger problem

    I found a really good deal on a slightly used Parasound JC5. I’m going to pull the trigger on that…
  • pitdogg2pitdogg2 Posts: 15,945
    Or buy some 4th or 5th generation Polk SDA speakers and get rid of the blade/blade speakers.
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