Just bought SDA SRS's...have hookup question

autoconsortium
autoconsortium Posts: 64
edited October 2005 in Vintage Speakers
I just got a very mint pair of SDA SRS speakers. On the way I have Bryston 7b ST 800w monoblock amps. The manual says to hook these up only to amps with a common ground. Will it work with these amps...and, what do I look for when they arrive to hook these up properly?
Alex Cagann

Polk SDA SRS
Lexicon DC-1 preamp
(2) Lexicon 501 monoblock amps
Parasound CD Transport 1000
Parasound DAC1000
Nakamichi Dragon
Nakamichi RX505
Post edited by autoconsortium on
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  • hoosier21
    hoosier21 Posts: 4,413
    edited September 2005
    mono block amps are not common ground amps. Those SRS have a blade blade type interconnect, so the AI-1 adaptor won't work either.

    Your only chance will be contacting Bryston and ask if you can run a speaker wire from the neg terminal of one amp to the neg of the other amp, making the the two amps "common ground", good luck
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  • fredv
    fredv Posts: 923
    edited September 2005
    First, welcome to the forum.

    I suggest you to do a search on e.g "SDA common ground". There are a lot of discussions in this area. 2 possible solutions came to my mind:
    1. ** CHECK WITH BRYSTON FIRST", connect the -ve posts of the amps, and connect the case of the amp with a pair of cables. This is to create a common ground. Like I said up front, check with Bryston first because this is not a universal solution. It only works for some amps.
    2. Buy and make an AI cable to replace the "normal SDA" cable that came with the SDA SRS. Polk no longer sells it, so you will have to look at the used market and build one yourself). There are instructions of how to make one. Do a search at the Polk forums. Since you said SDA SRS, there is a chance that the AI cable still won't work. You need to look up the serial number to see you are the lucky one. There is a thread about that, too.

    Good luck,

    -fredv-
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  • autoconsortium
    autoconsortium Posts: 64
    edited September 2005
    I just looked at a photo of the back of the amps. They have a "ground lift" toggle switch. Will this solve my problem?

    Thanks for your info.
    Alex Cagann

    Polk SDA SRS
    Lexicon DC-1 preamp
    (2) Lexicon 501 monoblock amps
    Parasound CD Transport 1000
    Parasound DAC1000
    Nakamichi Dragon
    Nakamichi RX505
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  • autoconsortium
    autoconsortium Posts: 64
    edited September 2005
    Also, on each monoblock amp, there are four connections...two neg and two positives, and they have indication lines going around for either parallel or series operation on the single channel. Does this mean they will work?
    Alex Cagann

    Polk SDA SRS
    Lexicon DC-1 preamp
    (2) Lexicon 501 monoblock amps
    Parasound CD Transport 1000
    Parasound DAC1000
    Nakamichi Dragon
    Nakamichi RX505
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  • BobMcG
    BobMcG Posts: 1,585
    edited September 2005
    All SDA-SRS channels have to have a serial number of 5001 or greater in order to qualifiy for AI-1 use.

    If your speakers aren't compatable with AI-1 use: Bryston saying "yeah go ahead and connect the two amps together" COULD still leave you open to damaged equipment down the road. Just words of warning.
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  • BobMcG
    BobMcG Posts: 1,585
    edited September 2005
    autoconsortium wrote:
    I just looked at a photo of the back of the amps. They have a "ground lift" toggle switch. Will this solve my problem?

    Thanks for your info.

    No. Won't change a thing pertaining to the SRSs. Might help get rid of a ground hum problem if you have one though.
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  • autoconsortium
    autoconsortium Posts: 64
    edited September 2005
    On a search on this topic, the solution seems to be to connect the ground on each monoblock, and you are good to go. I will still contact Bryston to make sure it is fine with these amps.
    Alex Cagann

    Polk SDA SRS
    Lexicon DC-1 preamp
    (2) Lexicon 501 monoblock amps
    Parasound CD Transport 1000
    Parasound DAC1000
    Nakamichi Dragon
    Nakamichi RX505
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  • madmax
    madmax Posts: 12,434
    edited September 2005
    autoconsortium wrote:
    On a search on this topic, the solution seems to be to connect the ground on each monoblock, and you are good to go. I will still contact Bryston to make sure it is fine with these amps.

    Make sure you check. If those two grounds happen to be different potentials it will cost you. :)
    madmax
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  • autoconsortium
    autoconsortium Posts: 64
    edited September 2005
    It looks like you can run Bryston 7B's with the grounds strapped. Seems like I'm OK, I found someone who has a couple tied together and they work fabulous (need to make sure and use a large cable). Thanks for all your help. Glad I looked on this great forum before I hooked all this up...I would have never known about the common ground thing.
    Alex Cagann

    Polk SDA SRS
    Lexicon DC-1 preamp
    (2) Lexicon 501 monoblock amps
    Parasound CD Transport 1000
    Parasound DAC1000
    Nakamichi Dragon
    Nakamichi RX505
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  • thehaens@cox.net
    thehaens@cox.net Posts: 1,012
    edited September 2005
    You may want to connect the two chassis together as well. Not sure if the neg (-) terminal is common to the chassis or not.......tie them together as good as you can, and report back what you find when you hook em' up.

    scott
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  • BobMcG
    BobMcG Posts: 1,585
    edited September 2005
    Welcome to the Forums and let us know how you make out.
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  • danger boy
    danger boy Posts: 15,722
    edited September 2005
    good luck. this this your first pair of SDA's? be careful not to fry anything with those amps. it could be costly to repair.
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  • autoconsortium
    autoconsortium Posts: 64
    edited September 2005
    Yes, my first pair. I've wanted some since I was 16 years old and saw them at a friends parents' house.
    Alex Cagann

    Polk SDA SRS
    Lexicon DC-1 preamp
    (2) Lexicon 501 monoblock amps
    Parasound CD Transport 1000
    Parasound DAC1000
    Nakamichi Dragon
    Nakamichi RX505
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  • BlueMDPicker
    BlueMDPicker Posts: 7,569
    edited October 2005
    BobMcG wrote:
    All SDA-SRS channels have to have a serial number of 5001 or greater in order to qualifiy for AI-1 use.

    Bob,

    Is this the cabinet label serial number, or a serial number on the Xover boards?

    Mike
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  • BobMcG
    BobMcG Posts: 1,585
    edited October 2005
    Mike,

    To the best of my knowledge the serial number on the cabinet.

    Bob
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  • BlueMDPicker
    BlueMDPicker Posts: 7,569
    edited October 2005
    Bob,

    Thanks! Just some wishful thinking here -- mine are early SRSs with numbers of 3767 and 3768.

    Mike
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