SDA2 A crossover refresh rebuild?

jacobmeyerammo
jacobmeyerammo Posts: 53
in Vintage Speakers
I have looked through the forum and see a ton of info on crossover rebuilds but none seem to be the 2A crossover. Has anyone done these? Does it pay? Are there driver upgrades worth doing?
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  • pitdogg2
    pitdogg2 Posts: 25,437
    I've done the XO upgrade. I used the big Axon caps for the 130uf cap and Sonicaps for the tweeter section. I also used @Toolfan66 rings for the drivers. There is no driver upgrades other than gluing the magnets and sound deadening sheet for the baskets.

    Yes it pays very well to do them but I warn you it's can be very pricey because of the caps.
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  • jacobmeyerammo
    jacobmeyerammo Posts: 53
    Can you explain or send a pic of sound deadening? Im unsure what you mean.
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  • jacobmeyerammo
    jacobmeyerammo Posts: 53
    I guess im asking i just use sticky sound dead on the outer basket?
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  • jacobmeyerammo
    jacobmeyerammo Posts: 53
    Ok. But do i cover the entire driver magnet and all then cut out the windows in the basket? Or do i only cover the stamped part of the basket? Im sorry ...im a noob and dont want to mess anything up.
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  • aprazer402
    aprazer402 Posts: 3,147
    Some have opted to skip the rebuild of the original 2A two-piece crossover and convert to a 2B-TL. I think Dave @westmassguy did this to his 2A's years ago. Either way an improvement will be heard. You may, depending on your budget, look for some other vintage SDA's of 4th or 5th gen. with pin-blade IC instead, as the cost to rehab. 2A's is not inexpensive. You could sell the 2A's and invest in 2B's, 1C's or CRS+ to start with. One of these may be all you'll ever desire. Later, if you're still hooked on vintage Polk's, move up to the SDA-SRS 1.2TL, 2.3TL, 3.1TL's as your space and budget allows.
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  • tonyp063
    tonyp063 Posts: 1,083
    @jacobmeyerammo

    This is what F1Nut is talking about.
    Do both sides

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    This is what a decent Dynamat job looks like. You can cut additional little strips & get the upper part of the basket if you wish.

    67713.jpg

    Not too fussy.
    And stop overthinking it.
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  • Gardenstater
    Gardenstater Posts: 4,459
    edited January 2020
    I must say one drawback of the Dynamat Extreme is they supply it in a tight roll and it's all wrinkled to sh**t. Perhaps the stuff @pitdogg2 used may be better. I have not tried it. The roll seems advantageous due to less waste but I don't like the wrinkles, which you can never get out and probably leaves some air spaces which is not perfect. If you don't have a little roller, a roll of electrical tape used as a squeege/roller and a putty knife will serve you well.

    Also, I would advise that if your passive radiators have any missing screws, like my 7Bs did, put them in! Polk only put 4 screws in my passives and it sounds so much better with 8, along with the dampening material.

    Another thing I am going to try is to feed as much clear penetrating epoxy into the edges of the particle board where it is cutout for the drivers. The higher the density of a material, the lower the resonant frequency. Should make the particle board denser and resonate lower. Will absorb about 3.8 g of epoxy per sq. in. if you just keep feeding and feeding it in.

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    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Onkyo A-8017 integrated
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
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  • F1nut
    F1nut Posts: 50,542
    A little Dynamat goes a long way.
    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

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  • westmassguy
    westmassguy Posts: 6,850
    jacobmeyerammo wrote: »
    I have looked through the forum and see a ton of info on crossover rebuilds but none seem to be the 2A crossover. Has anyone done these? Does it pay? Are there driver upgrades worth doing?
    My SDA-2A Journey:
    https://forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
    Home Theater/2 Channel:
    Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
    Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
    Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
    Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
    Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer

    dhsspeakerservice.com/
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