Thursday, May 28, 2009

Speakers - Polk SDA 1A

I never owned this pair of Polks, but I had a chance to listen to them and snap a couple of photos with my phone. These employ what Polk calls SDA - Stereo Dimensional Array, and the idea is that both speakers work together to produce a very wide sound stage, thus adding another "dimension" to the music without a need for special, additional components, media, or modifications. The speakers are to be cabled together for the SDA to work, and the guy who was trying to sell these didn't have the cable for them.

At first examination, I noticed how light weight and shallow the cabinets were. These are two immediate warning signs for me. They reminded me of many of the lower-end polk and Infinity speakers from the late 1980s. Combine those two warning signs with the lack of that special cable to tie them together, the $350 price tag, and you can see why I decided to pass.

These retailed for $1,390 in about 1985 - a very hefty price for a light pair of speakers. I've read a few reviews on the SDA aspect of them, and they were all quite positive. For my money though, speakers need to stand on their own without special configurations, cables, or external equalizers (like BOSE 901's).

How did they sound? Somewhat thin across the mids and highs, and lacking in the low-end. They sounded a lot like my RTi 12A Polks I bought a year ago. Lots of small drivers still don't push enough air to get decent bass - especially in such a shallow, flimsy cabinet. Believe me - I'm a pushover when it comes to speakers. It doesn't take much for me to be impressed with most that I listen to, but these Polks left this reviewer cold.

Have any different opinions, better photos, or stories about your Polk SDA-1A speakers? Please leave a comment or send me an email.

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  1. Back around 1985 i listened to a pair of the Sds Srs two, it was thier top of the line at the time, something like over five feet tall, impressive, but i was interested in the Klipshhorns. The Klipsch blew them away, I bought em then, just under 5 grand. I don't have them anymore as I downsized the living arrangements but they are still in the family, went through two brothers and the one brother still has em. easy twenty five years now, and they still perform.
    i never did like the Infinity speakers, back around 1980 i bought a set of Jbl L 150 and my buddy bought a set of Infinity s found that emit tweeter harsh on my ears, maybe now that i am 50 they would sound better due to deteriating hearing especially the high frequencies. lol.

  2. You must have the interconnect cable to get the full sound from the polk SDA series. As far as comparing to Bose 901's, you are comparing apples to oranges. 901's are not designed for accurate sound production. They are designed to appeal to the average listener. The Polks also have to be driven with a quality amp or clipping damage will certainly take a toll on their abilities. I put my 901's in the kids room.

  3. I own a pair of SDA-1Bs. I replaced a tweeter (from Polk) around 2005 or so.
    (The 1B is electronically identical to the 1A -- the difference being vinyl-covered cabinetry rather than genuine wood. I paid $1250 for them, new, in 1987.
    The audio power spec on them is 98db at a 1W SPL (Sound pressure level). This is the industry standard for rating efficiency. You'll have to buy "horn" speakers to find better efficiency than these.

    They'll handle up to 500W/ch. I power them with a Hafler amp that puts out 250W into 8ohms -- which is around 380 or so into (these) 4 ohms. If I put the volume knob on the preamp at higher than 1 o'clock I can't stay in the same room.

    The audio curve is essentially flat from 10Hz (you can only feel that, you can't hear it) to 22KHz.

    These specs were virtually unsurpassed by anything, in 1987, and I doubt that you'll find better specs today.

    Several comments:

    First -- without the interconnect cable, you're losing the main feature. One of the tweeters and two of the mid-range are powered by the electronics in the OTHER cabinet -- hence the interconnect cable. The signal from L->R and R->L is inverted -- creating an audio cancellation to each ear -- significantly expanding the "sound stage" to more than the speakers' native 8 feet or so. Without the cable, you're only running half the speaker system. I also don't know what the reduced loading does to the magnetics in the speakers' internal electronics. You do them a disservice trying to run them without the cable -- and ESPECIALLY trying to evaluate them without it.

    I'm not sure you understand the "mechanics" of audio. Polk certainly did.

    You complain about "flimsy". Yes -- for a cabinet that size, they're relatively light. If you open it up, there's no "bass speaker". The cabinet is designed as a resonator -- which picks up the bass that's provided from the mid-range speakers, and MECHANICALLY amplifies it (via the design and construction of the cabinet). That is WHY there's so much "empty space" in the lower portion of the cabinets.

    These speakers cost me $1250 in 1987. The equivalent, adjusted for inflation, of around $2640 in 2016 dollars.

    In short -- when I purchased these I read the specs on EVERY available speaker in the high-end class (i.e., above around $500/pr). The specs on these were by far the best -- with the exception of the efficiency of Klipsch horn speakers -- but they didn't have the fidelity across the dynamic range.

    I annoyed the proprietors of at least eight or ten stores -- listening to the offerings from not only the JBLs of the world, but high-end producers whose names you've never heard, and I can't remember.

    These were by far the best...

    Sorry to so totally disagree with you.

    1. I agree with Bob Dvorak and the previous Anonymous. If you have the interconnecting cable, an audiophile type amp, and follow the placement geometry for the SDAs and listener - you will be amazed. The bass will help your heart beat, and when you hear different instruments behind you, you'll understand what Polk accomplished with this system - a sonic hologram. I bought my SDA 1As when they first came out. The specs were impressive (best of the high-end floor speakers I researched) and the sound quality is superlative.



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