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AR mst's

Guest dogmeninreno

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MST's are "mini" LSTs / LST-2s. They are considerable smaller that their big brothers. The MST has one 8" woofer and 3 tweeters (looks like AR-17 / AR-18 tweeter). The 8" woofer is in lower part of the center section with 2 tweeters above it. The MSTs were supposed to be sold in matched pairs. One side had the third tweeter in the left section, the other had the third tweeter in the right section.

Good picture of MSTs over in Classic Speaker Pages, “ADD/Truth in Listening Models” pages.


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The AR-MST/1 was introduced in March 1975 along with the AR-11 and 10Pi as the first models in the Advanced Development Division series of products.

The MST was an obvious attempt to replicate the unexpected success of the original LST (and to a lesser extent, the LST-2). It was styled like a smaller-scale LST, but did not have a front-panel autotransformer control. The driver complement was an 8" woofer (essentially the same as the AR-7’s woofer) and three of the 1 1/4" cone tweeters, again, essentially identical to the AR-6/7 units. Two of the tweeters were mounted on the front panel side-by-side, above the woofer. The third was mounted on a side panel. The other side panel was blank. The speakers were supplied in mirror-imaged pairs, and could either have the tweeter panels facing inwards for a tightly-focused stereo image, or facing out, to produce a more spacious, diffuse sound field. Suggested MSRP was $159.00 each.

The front panel tweeters crossed over from the woofer at 1600Hz; the side tweeter handled only the top two musical octaves, crossing over at 5000Hz. For those who aren’t aware of this, an octave is a doubling or halving of frequency. So 20-40Hz is a musical octave (as in doe-ray-me-fah-so-la-ti-doe. The "does" are an octave apart), 40-80, 80-160, 160-320, 320-640, 640-1280, and so on. By time you get to 5000Hz, there are only two audible octaves (5000-10,000 and 10,000-20,000) left in the "20—20,000Hz" audible spectrum. Therefore, that side tweeter was not doing all that much, but it did add a little off-axis sparkle and aided the far-field power response.

AR did have a problem with early MST’s, especially European versions, which had 4 tweeters (one on each side panel, two on the front). There are frequency response difficulties that occur with interference/comb-filtering/cancellation when you have drivers mounted side-by-side, especially when they cover the same frequency range. The early MST’s had quite a problem in this regard, and their response was actually LESS uniform and accurate than the AR-7, which was less than half the price! AR devoted quite a bit of engineering time and effort to manipulating the crossover in an attempt to correct this, and they succeeded to some degree. AR learned their lesson well, and in future models, starting with the AR-9, all their drivers were arrayed vertically (hence the name "Verticals"), which threw what interference patterns there were into the far less critical vertical plane, while allowing the drivers to radiate horizontally clear and unfettered.

But the bloom was clearly off the MST’s rose by time they fixed it, and the speaker quickly faded from the marketplace. It’s too bad, because a "correct" MST was a very good-sounding speaker, quite apt for a small to medium-sized room, and, in my eye, a very attractive alternative to the conventional small rectangular box.

Additionally, the MST/1 is the answer to an obscure AR trivia question: "What was the last AR speaker made that used the white linen grille cloth?"

Steve F.

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Guest OpusX


Thanks for the great history and the technical detail on the MSTs. never stopped to think back that indeed, they were the last pair of AR speakers that came with the white cloth grilles. As I have posted here before, I am an original owner of a pair of AR-MSTs. they were my first pair of AR speakers and I bought them back when I was stationed overseas in Germany in 1976. I agree about the sound in a small to midsize room. I was driving them with a Sanusi AU-11000 integrated amp in the one room of my BOQ suite that served as my living room and they always sounded great in there. The Sansui could handle two sets of speakers and every once in awhile I would turn on both the MSTs and my AR-11s at the same time after I got my 11s and that really sounded great although I probably committed some mortal stereo sin by playing them all at once, but the audiophile police never caught me and nobody got hurt so I guess I got away with it...*S*. I still have that pair and they are packed away back in the original box and packing material and from time to time I pull them out and hook them up and listen to them.

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  • 2 years later...
Guest czaha

Do you have any intrest in selling your MST's ?

I have 4 that I originally bought several years back and I am looking for 2 more so I can stack...




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