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Understanding Utah (and Allied/Knight) speakers

Posted by DavidLD (A) on December 14, 2003 at 06:28:36

It sometimes seems that the Utah and Allied/Knight loudspeakers from the mid-60s into the early 70s were an alphabet soup of numbers and sizes, but in fact all of them are closely related to each other.
Basically there were 3 woofers with only slight variations, 8-inch, 10-inch and 12 inch. There were also a few large floor-standers with 15 inch woofers. All featured Alnico magnets and cloth-roll suspensions.

The one cone tweeter was a fairly large closed-back 3 1/2 incher pretty much the same wherever it was used.

The "small" Utah went by the name AS 2, or with slight changes later as AS 2A and AS 2AX. With cabinet variations this was also sold as the MK-14(in the so-called "Musicaire" series) It used the 8 inch woofer and the 3 1/2 inch cone tweeter in a sealed box 17 1/4 x 11 1/4 x 8 1/4. I've never actually heard these but I am led to believe that the big cone tweeter actually worked to build an overall better balanced speaker than when it was used in the larger-woofer designs. These had a list price of $49.95 to 69.95 but often sold for half that in system deals. My 70 Allied catalog lists two AS-2's for 50.95. All the cabinets were real walnut veneer, and quite beautiful. in my view these models are a sleeper collectible--quite efficient ans suitable for a small tube amp.

There is confusion on the woofer size of some of the 3-ways. My Allied catalog and my Stereo Review directory disagree on the woofer size in the A-70, with Allied claiming it was 8 inches and Stereo review saying 10 inches. I think it was 10-inch and my Allied catalog was wrong. I believe the MK-15 used the 3 1/2 inch cone tweeter from the 2AX, and combined that with a 5-inch sealed back cone and a 10- inch woofer. The A-70 was a 3-way with a box size of 19 x 11 3/4 x 8 1/2 and a list of 69.95. These all would have listed between $59.95 and 89.95. The 10-inch 3-way versions are rare, in part because you could get the 12-inch models for about the same price on the street. There was an MK-16 that used the 10-inch woofer as I recall, perhaps with horn mid and tweets.

The basic 12-inch model was sealed, and used the 12-inch cloth-roll Alnico woofer, along with the 3 1/2 cone inch tweeter. The feature is the giant 8-inch mid. The woofer crossover is quite high and the big sealed back mid only operates between 2500 and 5000Hz The box size on the sealed version was 14 x 23 x 10. This same basic speaker had many different cabinet and grille cloth variations but are otherwise identical. Numbers you see on this design are WD-90 (89.95) MK-17 (99.95) and MP-1000 (foam grille, 99.96). My '70 Allied catalog lists the Utah A-90 with these specs at 90.95 the pair. Interestingly there was also an A-80 listed that had a 5-inch mid,(probably the same mid as used in the 10 inch version) but Allied wanted 79.95 each for those so you can see why the A-90 model was popular. I got my MK-17's on a two for one sale at Team Electronics in 1971 for 99.95 the pair. A variation on this theme was the ported version--bigger box, the same drivers. The best known is the HSI-C. 15 x 25 x 14 When you see the HS prefix you know its ported. Allied sold this speaker as the Knight 2330 (later with A or AK suffix (59.95 Kit, 79.95 assembled).

Then there were the versions that used horns. These usually had circular horn tweeters and an oval horn mid, but the same woofer and box dimensions. In the versions above that had the cone tweets and mids, the bass (which was very good) tended to overwhelm the highs. Utah must have realized that too, as they sold a variety of models that replaced the cones with horns. The sealed versions were The MK-18 sold for $119.95 list . They also sold the A-100 (at a bargain 59.95 in my Allied catalog). The Allied Knight house brand version of this speaker was 2370K (129.95 assembled 14 x 25 x 13) that used some fairly fancy horns and a larger than normal woofer magnet. or a version that used less expensive horns ($99.95 assembled 14 x 25 x 13 1/2) and a smaller magnet woofer. The ported-horn version was the Utah HS4-B ($149.95 list) 15 x 25 3/4 x 14.

Finally, there were the big 15-inch versions topped by the MP-3000 (20 1/2 x 27 x 14, $199.95). The Allied/Knight version was the 2385 (149.95)

All of these speakers are "sleeper collectibles" The ones that use the cone mids and tweets show up periodically on Ebay--the horn versions are rarer. Compared with the popular Acoustic Suspension two-ways of the day, the Utah models are far more efficient, and really have clean mids. They are ideally paired with a low-wattage solid state or tube amp/receiver. On any of the 12 inch 3-ways low bass is actually very very good. The rap on the big woofer models is that the ones with the cone tweets tend to sound somewhat dull and bass heavy. Swapping out the cone tweet for a horn similar to the ones used in the upgraded models greatly improves the highs but the overall balance as well. My current recommendation is to try Parts Express 270-050, a Pioneer tweeter horn very similar to what Utah would have made. It should be a drop in replacement from inside. In fact you would be converting a Utah WD-90 to an A-501 which used the combination of the 8-inch cone mid with a horn tweet.

David

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