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  1. #1

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    Default ISO: Information on SRS technology

    I was wondering if anyone has some in-depth information on the SDA technology Polk uses? I've been into DiY speaker building for a little over a year now and would love to try to replicate an SRS, mainly the SRS1.2TL. If I can't replicate it I'd at least like to learn about it.

    Any information is greatly appreciated! Thanks!
    Last edited by Mazeroth; 04-28-2005 at 09:37 AM.

  2. #2
    Old Polk
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    DarqueKnight's SDA Compendium is a great source of compiled information. The reprint of Matt Polk's "Designed-In Stereo", from 6/84 'Audio' and found in the Compendium, has about everything you'd ever want to know about the SDA technology.
    Last edited by BlueMDPicker; 04-28-2005 at 09:21 AM.
    Be-Bop-A-Lula, Baby What I Say

  3. #3

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    Compendiums are out of stock at the moment.

    If you don't already have them, crossover schematics for the 1.2TL can be obtained from Polk customer service. The schematics have also been posted on the forum several times. Try doing a search on "1.2TL Schematic".

    I highly recommend the SDA technology article in the June 1984 issue of Audio magazine. You should be able to find it at a local library. Another source for the article is Roger Russell Reprints.

  4. #4
    Old Polk
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    BTW Mazeroth -- if you decide to build a replica, keep us posted. It sounds like a fun, and challanging, project. I'd still love to see Polk themselves issue an anniversary limited edition kit(s). But, I suppose the lack of readily available matching drivers and PRs dashes any hope of that.
    Be-Bop-A-Lula, Baby What I Say

  5. #5

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    Main HT
    Magnepan 1.6QR fronts, POlk R15 surrounds, Pioneer SC-25, Parasound Halo A23, Oppo BDP-105, Panasonic TC-P60ZT60, Sony PS3, Apple TV

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  6. #6

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    Just got to reading the replies. I'll have to check into these sources. Thanks!

    One question for you: If this technology is so great, why doesn't anyone use it anymore (that I'm aware of)?

  7. #7
    Old Polk
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    Hey! Some of us use it every day! :D

    But, I realize you mean why doesn't Polk, or another speaker builder, still use it? That's been cussed and discussed pretty thoroughly. To summarize, in part:

    1. Enclosure size requirements.

    2. The rise of HT demand in the marketplace vs 2-channel.

    3. Price point -- Polk has taken a step back from high-end, high cost designs. No slam intended.

    4. The SDA effect was not universally acclaimed by "audiophiles."

    5. Patent rights, possibly.

    6. Demand -- ties into 1 through 5.
    Be-Bop-A-Lula, Baby What I Say

  8. #8

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    A comment by Stereophile ages ago referred to SDA as a "gimmick"....and the sheep love Stereophile.

    I agree with 1-4. However the patent had nothing to do with it directly, as that was settled out of court with Carver, to the satisfaction of both parties....prior to the eventual end of the product line.
    Last edited by dorokusai; 04-29-2005 at 10:12 AM.

  9. #9
    Old Polk
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    Audiophiles in quotes for emphasis.

    By patent rights, I meant to infer that another builder might possibly be reluctant to pay royalties to incorporate the SDA design in the enclosure. I was unaware of the Polk v. Carver legal issue (which must have related to off-board similarity?)
    Be-Bop-A-Lula, Baby What I Say

  10. #10

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    Ok, I get where you are coming from in respect to a potential patent issue.

    Yes.

  11. #11
    Old School
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    ... and doro loves his sheep...

    Mike,
    Bob C. did pay Polk HQ a visit years ago to discuss their infringement of his patent(s). He left convinced (at least to the point that he did not have a viable case) their passive approach did not infringe on his active, SH approach.

    Maze,
    There's a whole 'nother thread on why no mo' SDA. Glad to see you have some intentions of playing with building an SDA. I've been looking at my Mon 12's and even 10's and thinking, "Hummmm, SD-mAybe's???"
    More later,
    Tour...
    Vox Copuli
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    "It's easy to get lost in price vs performance vs ego vs illusion." - doro
    "There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
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    Rebuilding Maggie 2-ch & Amazing 2-ch... Building 2-ch "wall"... Figuring out the HT

  12. #12

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    The patent issue should be moot since patent rights are given for only 17 years and it has been 23 years since SDA was introduced in the audio marketplace.

    Back in early 2001, I was interested in fabricating a pair of 1.2TL's from scratch. Here is the reply I received from Polk Customer Service:
    ---------------------------------------------------------------------------------
    Subject: RE: Recreating Classic Polk Sound
    Date: Thu, 1 Feb 2001 12:58:06 -0500

    Hello,
    I'm afraid we may be a little limited on the help you're looking for. We no longer have any of the crossovers or bass radiators, we have two of the grilles remaining. There is no problem with the tweeter and drivers, those can be bought from our parts department. also, I'm afraid we no longer have any of the plans/blueprints for the enclosure. If we wanted to build the cabinet again, ourselves, we would have to start with a blank sheet of paper. Sorry.

    Probably, trying to find a second hand speaker in good condition is fareasier, I would imagine, than trying to build one from the ground up.
    Best regards, Ken,
    Polk Customer Service
    ------------------------------------------------------------------------------------

    In December of 2001 I found a mint condition pair of SDA SRS 1.2TL's in mint condition. They had been sitting in a closet in Dallas for seven years before the owner decided to put them on eBay.
    Last edited by DarqueKnight; 04-29-2005 at 06:42 PM.

  13. #13

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    Originally posted by Tour2ma
    ... and doro loves his sheep...
    I'm not quite sure I like the sound of that.:D

  14. #14
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    Very old and very baaaaaaad joke...

    raife,
    Are the inductors the big stumbling block?
    More later,
    Tour...
    Vox Copuli
    Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb

    "It's easy to get lost in price vs performance vs ego vs illusion." - doro
    "There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
    "Death doesn't come with a Uhaul." - Dennis Gardner

    Rebuilding Maggie 2-ch & Amazing 2-ch... Building 2-ch "wall"... Figuring out the HT

  15. #15

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    I'm getting some inductors wound by North Creek for my CRS's. It's not a stumbling block IMO, just a choice whether you wish to bother doing it as it obviously adds to the cost.

    The physical measurements aren't that far off for my application, larger gauge, less loss, easy value.

  16. #16

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    None of the electrical components are/would be a problem. I see reproducing the cabinet design as the biggest stumbling block.

  17. #17
    Old School
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    Gotcha...

    Ever consider SDA-ing a pair of Monitor 10's?
    More later,
    Tour...
    Vox Copuli
    Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb

    "It's easy to get lost in price vs performance vs ego vs illusion." - doro
    "There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
    "Death doesn't come with a Uhaul." - Dennis Gardner

    Rebuilding Maggie 2-ch & Amazing 2-ch... Building 2-ch "wall"... Figuring out the HT

  18. #18

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    No. I hate messing around with the insides of my "real" SDA's. The thought of a monitor conversion project scares me.

  19. #19

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    Ah, come on Raife, take one for the team.:p
    '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 turd by the clean end."

  20. #20
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    Mr. "SDA X-over Upgrade" is scared of messin' with a lil' ol' pair of mon 10's?

    Sheeeeet, the tough parts done... Max has badges for them...
    More later,
    Tour...
    Vox Copuli
    Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb

    "It's easy to get lost in price vs performance vs ego vs illusion." - doro
    "There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
    "Death doesn't come with a Uhaul." - Dennis Gardner

    Rebuilding Maggie 2-ch & Amazing 2-ch... Building 2-ch "wall"... Figuring out the HT

  21. #21

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    Originally posted by Tour2ma
    Max has badges for them...
    LOL.....ya know I like them better than the Polk ones. Think I'll buy MM's and sell mine to bdaley.
    '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 turd by the clean end."

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