Utah Loudspeakers

 

 

A recent remark by message board poster indicating that many speakers sold under the Trusonic label were actually made by Utah got me to digging for evidence in support of this claim. In the process, I not only found evidence to support this contention, but I also came up with a family tree of sorts for Utah and Trusonic speakers circa 1970-74.

 

Utah was primarily a raw driver manufacturer with a single plant located in Huntington Indiana. It flourished in the 1960s and 70s, as it undoubtedly made drivers for a large share of the one-piece console stereos that were proving increasingly popular by the mass market during the 60s and the 70s. In addition, I believe that they were a major supplier of drivers for many Allied house brand (Knight) speakers in the 1960s. In my 1970 Allied Radio catalog, they were selling complete Utah speaker systems as well as two and three-way single raw drivers right along those labeled as Knight. I suspect Utah also supplied Allied and later Radio Shack with raw replacement drivers for low-fi and mid-fi applications during the period as well as drivers for many Radio Shack systems.

 

What happened to Utah the company has never been entirely clear to me, but I think the plant closed some time in the ‘80s as the Asians increasingly became the source for inexpensive drivers. Another fairly large driver manufacturer, CTS of Paducah KY, I believe also shut its doors around the same time. Utah loved Alnico magnets and used them even in inexpensive replacement speakers, and perhaps the declining availability of cobalt was also a factor. Jensen was the only other major raw driver manufacturer and is still around today as a Recoton subsidiary, but I don’t believe they do much in the way of raw driver manufacturing any more.

 

Ever since I was a little child I was fascinated with the idea that a magnet attached to a piece of paper could produce sound. I’ve never had much interest in high-end, expensive speakers, but have always been especially fascinated with speakers that offered exceptional value for only a small amount of money–hence my love for EPI, Advent–and Utah.

 

So hi fi speaker building was sort of a sideline at the Utah factory in Indiana and the speaker systems  never really received any attention from the Hi Fi press. To further complicate matters there seemed to be little ordering to their numbering systems for the various models. However, by carefully studying several catalogs and directories I  have been able to sort some of this out.

 


As a starting point, lets begin with their basic model. This speaker was always in a 14 x 23 x 10 inch box, in oiled walnut veneer. The drivers were a 12 inch cloth roll woofer with an alnico magnet, a large 8 inch mid-range unit with a completely sealed metal back, and a simple 3 1/2 inch sealed back cone tweeter. This same basic speaker appeared in a number of lines–the MK-17 from their “Musicaire” series (very dark oiled walnut with a flat finish with a decorative molding around the front-- This is the one I own). It appears (at $99.95) in my 1974 Lafayette electronics catalog, but I bought a pair at half price at the Team Electronics store in about 1972. At the time I considered that to be quite a deal given the size of the speaker and drivers and the cabinet work. Interestingly, this same box and drivers show up in the Model WD-90 which was probably more widely sold. It listed for $89.95 in my 1974 Olson Electronics catalog, and lacks the decorative molding og the MK 17 and appears to have a bit lighter finish. My 1970 Allied Radio Catalog shows a similar A-90 model–same box dimensions and drivers listing for 89.95 each but they offered a two for one deal as well so this brought the speaker down to $45 each. Also the same basic speaker was the MP-1000, listed in my Olson Electronics catalog for $99.95. The box and drivers were the same but this speaker had the sculptured foam grille. All of there were the same basic speaker. Despite the size of the mid-range my guide indicates that the mid range unit was only used in a very narrow band from 2.5 to 5 KHz The frequency response was rated at 32-18000 Hz for this speaker, but the overall sonic balance untweaked was decidedly towards the lower end of the frequency spectrum. 

 

After that, things get more complex. There was an upgrade in the Musicaire line called the MK 18, which replaced the cone midrange with an oval 3 1/2 x 8 horn and the cone tweeter was replaced with a round horn. As I recall the list price on the MK 18 was about 119.95. I think the box size for this speaker was a 14 x 23 x 10.  This was still a sealed box. This speaker also appears in my Lafayette catalog as the A-130 with a slightly larger box size on 14 x 24 x 12 3/8, and the rated frequency response was 30-20,000 Hz and a price of $129.95. My 1970 Allied Radio catalog lists a special purchase of an A-100 for $59.95 that uses these same drivers but in the 14 x 23 x 10 inch box. The rated response is 28-19,500 Hz with crossover frequencies of 2200 Hz and 5 KHz. Allied also lists an A-520 with horn tweeter and mid range in a 14 x 25 x 13 ˝ inch box ($118.95) and an A-501 which a mongrel that uses the 8 inch cone mid-range but with the horn tweeter (14 x 24 x 10 inch box) for 99.95 each. 

 


Below the MK 17 was an MK 16, also  an Acoustic suspension  model but with a 10 inch woofer and a 6 inch cone mid range along with the 3 1/2 inch cone tweeter. The model A-70 was essentially the same speaker and is listed in my 1974 Lafayette catalog for 69.95. The crossover frequencies are listed as the same as for the MK-17, but the rated frequency response was 45-18,000 Hz with a box size of 12 x 22 x 8.

 

Then there were the units with the 8-inch woofers. Apparently, in the 60s there was a small Utah speaker that did have a following among audiophiles on a budget. This was called the AS-2 and featured an 8 inch woofer along with a 3 1/2 inch cone tweeter (2 for one at $49.95 in my 1970 Allied catalog 11 x 18 x 9). It was a sealed box. Minor tweaking lead to the AS-2a and by 1974, the AS-2ax. I think this speaker was essentially the same as the MK-15. Somewhere I have a small sales brochure for the Musicaire (MK)series but I have been unable to locate it. The AS2ax listed for 49.95 in my Olson electronics catalog, had a crossover frequency of 5 kHz . Box dimensions were 17 1/4 x 11 1/4 x 8 1/4. And rated response was 45-17,500 Hz. The Olson Electronics catalog description indicates that the woofer cloth roll suspension was “permanently viscous” to stop edge breakup and this non foam surround treatment undoubtedly extended to the other Utah woofers.

 

The above speakers were all sealed boxes, but Utah also made ducted port systems, especially larger units. There were two large ducted port units in the MP series, the MP 2000 and the MP 3000. The MP-2000 had a 12 inch woofer but a 5 inch mid-range and a 1 inch dome tweeter with a horn. Box size was 15 1/4 by 24 x 12. These are identical dimensions and drivers to the Trusonic JR 200M. Both had sculptured foam grills. In fact the Olson electronics catalog has a page of Utah speakers and the Trusonic unit is just mixed in among them! (At $149.95) A close relative was the Utah HS4-B with the same drivers but a box just slightly larger at 15 x 25 3/4 x 14 also $149.95. The JR-100M used the same drivers as the 200M but employed a 10 inch rather than the 12 inch woofer, and had the common Utah box size of 14 x 23 x 10, and listed for $119.95

 

The biggest and most expensive speaker in the Utah line was the MP-3000 with a 15 inch woofer, and blue sculptured foam grille. This had two of the dome tweeters from the MP-2000 and was in a box of 20 1/2 x 27 x 14.

 


Some years ago I decided that while my MK-17 units were excellent in the low and mid-range, the highs lacked a crispness that made the sound somewhat dull overall. So I experimented with a couple different replacement tweeters in an effort to rebalance the sound a bit. I figured that since the speakers were sealed a tweeter with about a 90 db sensitivity would be about right. I first experimented with a small Radio Shack (Audax?) dome unit, but the speakers really sounded as if they had the wrong tweeter. So I went out and got a small horn unit (perhaps this was even made by Utah for Radio Shack)  rated at about 100 db. Interestingly, this tweeter suddenly made the speakers sound as they should have–just right in volume. The Acoustic Suspension  woofers in the Utahs are quite efficient compared with the better known brands of the era, but don’t lack for bass even in comparison with my Large Advents. The overall balance still perhaps still favors the lower mid range a bit, but the horn tweeters really open up the sound. What I discovered this evening is that by accident, I may have converted these into the A-501 model in my 1970 Allied catalog!!!

 

I’m sure this is more than you ever wanted to know about Utah (and Trusonic) Speakers! I see raw non-Utah Trusonic drivers from the 60s going for big bucks on e-bay.—David L. Debertin