University Sound CTR
A diecast aluminum box that weighs less than two pounds and solves a problem most installers didn't know they had.
University marketed its speaker line on rugged construction and long-term reliability, promising a five-year warranty across its products (Audio, August 1965, p.33).
Overview
The CTR is not a driver, a horn, or anything that makes a sound on its own. It is a transformer housing — a two-piece diecast aluminum enclosure that University Sound specified for outdoor and industrial installations where a 70-volt line transformer needed to live somewhere weatherproof. At 0.6 kg (1.3 lb) net and 9.7 cm long by 10.7 cm wide by 12.5 cm tall, it is a small, dense casting finished in corrosion-resistant gray acrylic paint, and its whole reason for existing is the pair of gland nut cable entrances that University's own literature describes as affording "complete and assured weather protection."
That phrase is doing real work. A transformer housing is only as good as its cable entries, and the CTR's gland nuts are the feature University led with. The manual notes that the gland nuts can be removed entirely to open up larger-diameter passages, and that if the incoming cable is too thin to fill the nut's opening, the installer is instructed to wrap the cable with rubber tape first. That is the kind of instruction that tells you the designers had actually been on a roof.
The CTR accepts transformers up to 6.04 cm × 7.32 cm × 7.32 cm (2.35 in. × 2.88 in. × 2.88 in.), and University names the 5015 and 5030 as the intended companions — though the manual is careful to say "or any other transformer" within those dimensions. Mounting centers can run up to 7.0 cm (2.7 in.), handled either by direct mounting to bosses in the head casting when the transformer is at the maximum spacing, or via the supplied slotted adapter strap for anything narrower. That adapter covers mounting centers from 3.8 cm (1.5 in.) up to 7.0 cm (2.7 in.), so the CTR is less a single-product accessory than a bracket for a range of transformers.
What makes the CTR more interesting than a plain box is its mounting flexibility. The head casting carries a heavy cast angle bracket, and University furnishes a V-notched clamp that attaches to it with two screws and nuts. That clamp lets the CTR grab one of the uprights of a horn's "U" mounting bracket — the position you want when you're adjusting the impedance tap on a driver — or, thanks to the V-shaped center, clamp to a pipe or pole up to roughly two inches in diameter, with longer screws extending that range further. Six holes on top of the head casting accept the mounting bases of University paging speakers in a choice of orientations, since a speaker base only needs three. The angle bracket, used without the clamp, lets the whole assembly bolt to a wall or other flat surface. In other words, the same casting serves as a transformer housing on a horn, a paging-speaker mount, a pipe-mount junction, and a wall-mount terminal box.
That last role is worth calling out because University explicitly designed for it. The manual states the CTR "also makes an excellent junction box for terminating and tying speaker transmission lines," and describes using it without a transformer at all in complicated long-line installations. The two gland nut entrances — one for the signal line into the transformer primary, one for the cable from the secondary out to the loudspeaker — become, in junction-box service, simply two weatherproof cable entries into a cast aluminum chamber. The instruction to solder connections with resin-core solder only, "to prevent losses due to high resistance and corrosion," is a reminder that this is a piece of gear meant to be installed once and left alone for years.
Construction details are consistent throughout: two-piece diecast aluminum, gun-metal baked acrylic finish per the architects' specification text (the general specifications section describes the same finish as corrosion-resistant gray acrylic paint), threaded cable entrance and exit with weatherproof gland nut assemblies, and a shipping weight of 0.8 kg (1.8 lb) — about half a pound more than the net, which tells you the packaging was modest. University backed the CTR with a one-year limited warranty against defects in workmanship and materials, excluding finish and appearance items, and the manual carries the company's Burbank-area service contact (phone 818/362-9516).
Collectors should understand what they're looking at. The CTR is an installation accessory, not a hi-fi component, and it turns up in the wild attached to horns, paging speakers, and long-disconnected 70-volt lines rather than in original boxes. The pieces that matter are the gland nut assemblies and the slotted adapter strap — lose either and the housing's usefulness drops sharply, since replacements are not something University is going to ship today. The casting itself is nearly indestructible; the finish and the hardware are what age. For anyone restoring a University horn installation or assembling a period-correct paging system, the CTR is the correct period answer to a question about weatherproofing, and it does that job with more thought than the category usually got.
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