Using Polk SDA-2s with a vintage 1976 Pioneer SX-1250 Receiver

70sMusicMan
70sMusicMan Posts: 7
in Vintage Speakers
Hi Everyone,

So glad to find this forum! After years of inactivity, I finally decided to repair a few sources and start using my stereo system again. And that means enjoying my SDA-2s! I had forgotten how good these speakers sound and I'm so glad that I have kept them all of these years. But, I recently acquired a vintage Pioneer SX-1250 receiver. And I've been reading in some forums that the amp in my receiver does not "play" well with SDA speakers. I'm not clear but something about the receiver's amp is not a "Common Ground Amplifier." Can someone please shed some light on this situation? I'm sure I'm not the only person out there using a vintage receiver with a pair of Polk Audio SDAs. If this is true how do I use this receiver with my beloved speakers?
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Comments

  • FestYboy
    FestYboy Posts: 3,861
    If you take a continuity reading between both ground posts of the receiver and DON'T have continuity, DO NOT use it with the SDAs with the IC cable attached. Depending on which model of SDA 2 you have, a dreadnaught MIGHT be a solution.
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  • pitdogg2
    pitdogg2 Posts: 25,440
    Most receivers are common ground. Depending on which "SDA2" you have could be why. SDA2a for example are 4 ohm and dip much lower. Most receivers do not do well trying to push a 3 ohm or lower load and that could be the problem.
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  • BMF35
    BMF35 Posts: 86
    I tried an SX-1280 for a week or so last year and it didn't do anything for me. My Marantz 2325 killed it in every way. No comparison.
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  • mhardy6647
    mhardy6647 Posts: 33,801
    edited July 2018
    BMF35 wrote: »
    I tried an SX-1280 for a week or so last year and it didn't do anything for me. My Marantz 2325 killed it in every way. No comparison.
    The 1280 (IMO and FWIW) is inferior to the 1250. You might well still prefer your Marantz to the 1250, but I suspect a 1250 in good tune will likely strike most folks as substantially better sounding than a 1280. Dunno about the tuner sections in the two, though, FWIW. I suspect the 1250 would better the 1280, but I have no recollection of ever listening to either.

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  • F1nut
    F1nut Posts: 50,543
    It appears to be dual mono, but it still could be common ground. As FestYboy suggested, you will have to test it.
    Pioneer developed the now legendary power section of the SX-1250 with completely independent power supplies, including separate power supply windings, rectifiers and smoothing capacitors for each channel, the components of which include a massive 22 pound toroidal core transformer
    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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  • pongshi
    pongshi Posts: 376
    I have a 1250 and modded SRS 2nd gen speakers which causes drops below 4 ohms pretty regularly. Definitely not good for an original 1250. The last thing you want to do is stress these older receivers on a consistent basis. I run my 1250 as a preamp and have a parasound amp which handles loads down to 2 ohms without breaking a sweat. I have the 2250 v2 which is a common ground amp and loves vintage polks. Just throwing this out as a consideration.
    Living Room
    Parasound Model 2250v2 amplifier
    Parasound P5 preamp
    Turntable 1 - Technics SL-1210Mk2 turntable with Shure V-15 Type III cartridge
    Turntable 2 - Dual 1229 turntable, Dual AS-12 45 RPM stacker, Shure V-15 Type III cartridge
    Schiit Mani Phono Preamp for Turntable 2
    Oppo UDP-205 CD/SACD USB and FLAC duties
    Technics RS-1500US reel to reel
    Polk SDA SRS (2nd Gen) fully modded
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  • BMF35
    BMF35 Posts: 86
    mhardy6647 wrote: »
    BMF35 wrote: »
    I tried an SX-1280 for a week or so last year and it didn't do anything for me. My Marantz 2325 killed it in every way. No comparison.
    The 1280 (IMO and FWIW) is inferior to the 1250. You might well still prefer your Marantz to the 1250, but I suspect a 1250 in good tune will likely strike most folks as substantially better sounding than a 1280. Dunno about the tuner sections in the two, though, FWIW. I suspect the 1250 would better the 1280, but I have no recollection of ever listening to either.

    As I greatly respect your experience, I appreciate your reply. I've been told in the past the 1250 and 1280 were pretty much the same other than a few cosmetic changes and the 1280 will bring a little more money. As I remember it was punchy and played loud but clearly didn't have the sound the Marantz had. The Marantz took it up a notch or two.
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  • mhardy6647
    mhardy6647 Posts: 33,801
    edited July 2018
    I think that the SX-1280 represents some value engineering of the SX-1250. The US (and, in fact world) economy was pretty unstable in those days, and things were changing fast for the Japanese in the late 1970s in terms of their ability to keep prices (price increases) in line with the American market's ability (willingness) to pay for things.

    Here's a raft of opinions from AK; you've probably seen this.
    http://audiokarma.org/forums/index.php?threads/pioneer-sx-1250-vs-sx-1280.452659/

    Disclaimer: I don't own a 1280 or a 1250. I do own a 1050, which is pretty nicely built (and nice looking) if mediocre sonically.

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