SDA 2A Specs

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n8thesk8
n8thesk8 Posts: 13
edited August 2007 in Vintage Speakers
Hello everyone, I've been a lurker for a few months finding out info on the speakers that I've been collecting. Actually my first set of Polks were the RTI 6's. Then a set of monitor 10's and then another set of monitor 10's. Now I'm the proud owner of a pair of SDA 2A's. I found the specs for SDA 2's and the SDA 2B's but not for the SDA 2A's. Someone told me thry are 4 OHM and 500WPC. The problem is my Pioneer SX-1050 will not drive them after 1/3 volume. Now my Technics SU-8600 will drive them nicely all day long. Has anyone seen the same problem with a SX-1050 not able to drive SDA's? I'm happy to finally be a member of Polkaudio forums. Thank you for any info.
N8
When the music's over...turn out the light.
Post edited by n8thesk8 on
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  • avguytx
    avguytx Posts: 1,628
    edited August 2007
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    I thought I posted this on another forum site, too! Here are the spec's straight out of the Polk SDA Compendium. The 4-ohm load that these show the SX-1050 may be lower than it can actually handle. That happens with some of that series of Pioneer gear. They liked an 8-ohm load and some would work into a 4-ohm load but some speakers "act" differently than others. Have you set the bias, etc on your SX-1050?

    * Driver Compliment: Two 1" SL2000 silver coild dome tweeters. Three 6 1/2" tri-laminate polymer bass-midrange drivers. One 12" fluid coupled subwoofer (passive)
    * Size (inches): 39 1/2H X 16W X 12D
    * Weight per Cabinet: 65lbs
    * Frequency Response: 15 Hz to 26,000Hz
    * Recommended Amplification: 10-500 watts per channel
    * Crossover frequency: 50Hz and 2000Hz
    * Nimonal Impedance: 4-ohms
    * Maximum Output Level: 120dB
    * Efficiency: 92dB
    * Price: $500 each
    * Dates of Manufacture: 1985 to 1987

    I'm thinking the Compendium may have an error on the "driver complement" portion of it's specifications as the picture in the book shows the SDA 2A as having the 2) 6.5" mid/woofers and 1) SL2000 tweeter (similar to the CRS+) but the specs say 3 woofers and 2 tweeters. Hmmmm....:confused:

    Hope this helps....
    Richard? Who's your favorite Little Rascal? Alfalfa? Or is it........................Spanky?.................................Sinner.
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  • n8thesk8
    n8thesk8 Posts: 13
    edited August 2007
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    You did post this on another site. I’ve been searching all around to find answers so I don’t burn up my 1050. My SDA's only have one tweeter and two drivers. I have not set the bias on my 1050. Will setting the bias make a difference with 8 ohms also? I used my Pioneer SA-6800 amp to drive the SDA’s and it seemed to do a better job. It still cut out but at a much higher volume setting. I’m considering a 200 WPC amp for the 1050 to help drive the SDA’s. Is there a thread on how to adjust the bias? Thanks AVGUYTX for the info.
    When the music's over...turn out the light.
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  • avguytx
    avguytx Posts: 1,628
    edited August 2007
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    If I were you, I would set the bias and DC offset on the receiver and get it to specs or somewhere close to it. You might check in that forum and see if anyone has a page with the schematic that shows the adjustment instructions and their locations. Do you have a DMM? You HAVE to have one to check those adjustments. You might check with "Echowars" there because he is the "shiznit" on the older Pioneer, etc stuff or do a search.

    Actually, here is a link to that exact topic there and a scanned couple of pages of the schematic in question.

    Yes, it will make some difference in heat build up, sound quality, etc. You have to remember that with the age of the older equipment, they benefit from capacitor changes and checkouts to get them back to where they once were. Adjusting the basics is as least a good start. Plus, there is a "sticky" at the first of the forum called "DC Offset and you". There are a ton of pages on it but it's a good read (in sections).

    I'm assuming that the older receivers are common ground amps but I am not for certain. If the SX series is not, and you have the SDA cable hooked up, it could cause more damage to the receiver. You might think about a separate power amp someday for them like a Carver, Adcom, etc, etc.
    Richard? Who's your favorite Little Rascal? Alfalfa? Or is it........................Spanky?.................................Sinner.
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  • n8thesk8
    n8thesk8 Posts: 13
    edited August 2007
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    Thanks avguytx, I hooked the SDA's back to the 1050 and now I don't get the cut out until way past listening volume. I spoke to soon, it's back. I'll set the bias and check the DC offset. I'll post results later.
    When the music's over...turn out the light.
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  • DarqueKnight
    DarqueKnight Posts: 6,765
    edited August 2007
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    avguytx wrote: »
    I'm thinking the Compendium may have an error on the "driver complement" portion of it's specifications as the picture in the book shows the SDA 2A as having the 2) 6.5" mid/woofers and 1) SL2000 tweeter (similar to the CRS+) but the specs say 3 woofers and 2 tweeters.

    You are correct. Per the picture shown on page 17, the specs should have been stated the driver complement as two 6.5" mid/woofers and one SL2000 tweeter.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
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