SDA 2a Upgrades

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Hello all!

First post here, although I've been observing from afar for quite sometime!

I recently inherited a pair of SDA 2a's from my father. In addition to being sentimental, they are great sounding speakers. I grew up on them, and always loved the sound.

Recently, I feel as though they have been missing frequency content. All of the drivers are moving air, including the passive woofer. But it feels like there might be some content missing in the 120 to 500 range- yikes!

My dad bought them in 86', and I do not believe they have ever been serviced. They have the original SL2000 dome tweeters, and identical MW 6510 driver pairs on each channel.

I've done some lurking on how to upgrade/restore theses guys, and think I have a pretty good grasp on the next steps, but I was wondering if anyone could provide some updated info. Most of those other posts are from pre-2010, and many of the shared crossover schematics are missing.

I think what I'd like to do is upgrade the tweeters to the RDO-194's, assuming those are still available. Recap the crossovers, after sourcing the components. I also saw talk of using dynamat behind the passive radiator, and would be interested in trying this as well.

I'd love any thoughts/suggestions on this project. I come from a concert audio background, but passive speaker modification is a whole new world for me. Eager to learn and get these things up to stuff. Also happy to provide serials and pictures, if that would be of any help!

Comments

  • pitdogg2
    pitdogg2 Posts: 24,927
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    I can save you some time, I have a set of SDA2a crossovers already recapped with Sonicaps and Axon poly caps and Mills resistors. they would be plug and play. All you would need to do is buy the RD-0194-1 tweeters.
  • turtleman559
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    pitdogg2 wrote: »
    I can save you some time, I have a set of SDA2a crossovers already recapped with Sonicaps and Axon poly caps and Mills resistors. they would be plug and play. All you would need to do is buy the RD-0194-1 tweeters.

    Hey Pittdogg, Thanks for the reply! I feel as though I recall seeing your name on those older forums. I appreciate the offer on the built crossovers, but I must admit that I'm pretty set on doing it myself. Especially given the sentimental value of the speakers, it's something I really want to dig into and learn from. As I said, I'm pretty new to this, and it seems like a fun project!

    I would be very interested to pick your brain about which components you used specifically, and where you got them. I've seen mention of the Sonicaps, Axons, and Mills- I plan to look into them next, now that I've found a crossover schematic.

    That said, if all goes south, I will certainly reach out about your crossovers. As much as I want to build these, I also want to hear them eventually!
  • bcwsrt
    bcwsrt Posts: 1,757
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    Well, now. That’s what ya call a “no-brainer,” right there.

    Brian

    One-owner Polk Audio RTA 15TL speakers refreshed w/ Sonicap, Vishay/Mills and Cardas components by "pitdogg2," "xschop" billet tweeter plates and BH5 | Stereo REL Acoustics T/5x subwoofers w/ Bassline Blue cables | Rogue Audio Cronus Magnum III integrated tube amp | Technics SL-1210G turntable w/ Ortofon 2M Black LVB 250 MM cart | Sony CDP-508ESD CD player (as a transport) | LampizatOr Baltic 4 tube DAC | Nordost & DH Labs cables/interconnects | APC H15 Power Conditioner | GIK Acoustics room treatments | Degritter RCM
  • dromunds
    dromunds Posts: 10,004
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    If it were me, I’d look into PitDogg’s offer. There are two crossovers on each 2A speaker and it can be an expensive proposition to price all those caps and resistors. If someone has already done the work I would at least be discussing it with him. He’s a good dude. Rebuilt crossover offers don’t come up that often, especially for 2A’s
  • turtleman559
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    dromunds wrote: »
    If it were me, I’d look into PitDogg’s offer. There are two crossovers on each 2A speaker and it can be an expensive proposition to price all those caps and resistors. If someone has already done the work I would at least be discussing it with him. He’s a good dude. Rebuilt crossover offers don’t come up that often, especially for 2A’s

    I just spent the last couple hours tracing the wiring diagram and specing out the parts, and I suspect you might be right.... As I said, a novice at work here!
  • pitdogg2
    pitdogg2 Posts: 24,927
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  • invalid
    invalid Posts: 1,325
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    You can use the RD0198 tweeters if you add a 5.8 ohm resistor. @westmassguy has a thread somewhere on this site on how to accomplish it, I did it to my 2a's but can't remember where to place the 5.8 ohm resistor.
  • F1nut
    F1nut Posts: 50,086
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    invalid wrote: »
    You can use the RD0198 tweeters if you add a 5.8 ohm resistor. @westmassguy has a thread somewhere on this site on how to accomplish it, I did it to my 2a's but can't remember where to place the 5.8 ohm resistor.

    It's a 5.8uF capacitor not a resistor.
    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

  • xschop
    xschop Posts: 4,837
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    Resistor, capacitor, inductor... It's like Ohm's law here at the CCP. Just crank up the Kraco dial 'till you get that 500wpc fix.
    Don't take experimental gene therapies from known eugenicists.
  • invalid
    invalid Posts: 1,325
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    F1nut wrote: »
    invalid wrote: »
    You can use the RD0198 tweeters if you add a 5.8 ohm resistor. @westmassguy has a thread somewhere on this site on how to accomplish it, I did it to my 2a's but can't remember where to place the 5.8 ohm resistor.

    It's a 5.8uF capacitor not a resistor.

    Dooo, I knew that, been working in the rain in Florida the last few days, not really with it currently.
  • F1nut
    F1nut Posts: 50,086
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    invalid wrote: »
    F1nut wrote: »
    invalid wrote: »
    You can use the RD0198 tweeters if you add a 5.8 ohm resistor. @westmassguy has a thread somewhere on this site on how to accomplish it, I did it to my 2a's but can't remember where to place the 5.8 ohm resistor.

    It's a 5.8uF capacitor not a resistor.

    Dooo, I knew that, been working in the rain in Florida the last few days, not really with it currently.

    So, you have wet brain. You're excused B)
    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

  • invalid
    invalid Posts: 1,325
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    So, you have wet brain. You're excused B) [/quote]

    I came down to Florida from Michigan to do a roof and take a weeks vacation after, now I'll only get 5 days of vacation because it's been raining about 50% of the time.
  • F1nut
    F1nut Posts: 50,086
    edited January 16
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    invalid wrote: »
    I came down to Florida from Michigan to do a roof and take a weeks vacation after, now I'll only get 5 days of vacation because it's been raining about 50% of the time.

    At least it's not snow.
    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