University 312 Coaxials - Yay Or Nay?

[Cornwalled]

Hey guys,

I found a pair of University 312 Diffaxle speakers for $125 and wanted to know what you guys thought. They're within driving range, so I could check them out before committing. They're together in one homemade cabinet that seems more appropriate for subwoofers than full rangers. So, I'd have to find appropriate cabs, which will probably increase cost. Unless someone here's got something knocking around they don't want that will work?

What do you guys think of these speakers and the prospective deal? What kind of sound can I expect from these, and what cabs would you recommend?

Thanks,

Jon

[grindstone]

Okay, I'll bite. I don't know your rig or preferences or habits, so this will be wordier.

The Q could be anywhere from say .5X to low 1.X's. It is very hard to find data on these types of "mechanical xo" coaxes simply because you have to put them in a test box to get a Vas (ie can't just sweep them with WT or whatever). My guess is that Fs will likely be 50's or so, but the original spec was lower I think.

Using them OB with LF support would be one "cheap cab" option. These are maybe 60-ish year old drivers and I may have some University cab design for them somewhere (unable to find just now). Most of the University plans I'm aware of from then used the then-popular "ducted" port reflex boxes. I forget why, but I think Cohen's books said the cabs could be slightly smaller with ducts than round ports for some reason or other. Most of those were on the order of 5 or 6 ft3 if memory serves. You might get by with half of that if yours end-up lower Q and if you don't push the design so hard for LF.

Remember, these things were pre-TS and many people just stuck 12's in boxes that had baffle holes for 12's or used graphs and tables from the manufacturer. If that's the spirit for your project, it might be fun to do the same. You could DIY an Aristocrat or a Karlson or something and attempt time-travel.

The sound will be..."lovely" in a single word (think of all the words not used). LF will be slightly challenged. HF may be a bit as well (think k77's or t35's--what you get depends on which ones you get). They do have a bit of rawness but also somehow seem to have good tone. They are not about "res", they are not microscopes. They do not pound your chest or flap your pant legs. They are not "flat" in the sense of things discussed in hifi for some decades (peak 1.X kHz, another maybe 3kHz, etc.).

They are from a time when dispersion was big and they spray HF well. This may or may not be objectionable to you depending on what you're used-to and what you expect of them. There is something to the soundfield that is different about them, but they do have more "air" than you would expect.

For example, if you are used to more waveguide-ey and less gain-ey HF, they do not match the MR and lower HF clarity of those which employ current well-regarded compression drivers. Still, if you are used to using "normal" expo horns the likes of which our generous sponsors purveyed, they can sound very open.

I'd treat the 25W limit as valid maybe 45 or 50 years ago and pretty heavily derate it--especially for OB use. If you run them OB, you will hear it and you will know where the limits occur.

They perform well at lower levels and don't need a bunch of juice to "come alive" like is the case with so many current pro drivers.

They are a reasonably easy load. Peak Z is maybe 30-some ohms and phase is better than you'd think.

Probably everyone will tell you to replace the very old caps. If you have an ESR meter, I'd check them and maybe run the originals a while if ESR is still low because their tone is partially due to those old cans. If you get them, you can play cap games.

The "brilliance" controls will likely be shot beyond cleaning and will need replacement, but you never know.

If your tastes tend toward electronica or metal, I'd pass them by w/o blinking. I would not put them in an MI cab and play through them. If you frequently enjoy orchestral pieces at near performance-hall levels, move-on. If you need the sorts of dynamics and headroom that many on this board seem to require (welders for amps into 4-way horns), ditto. Sparser-spectrum stuff in modest spaces, well now you have a ballgame.

Within those limits (power/room size/level & programming preferences), they will make music sound like music. Longer-term, all bets are off (people just hear so differently).

You know the arguments--drivers currently produced are "better" in many ways and there is much objective data to accompany the assertions, etc. Personally, I passed over all this stuff for years and years. The whole diffaxial line, in-fact, seemed a little nuts (I mean, what do all those little holes radiate off their edges anyway and _mechanical_ XO's--are they kidding me?)

I look at any of these deals as transactions in hearing education, but then again I'm a speaker junkie and I'll listen to anything and everything for a while just to hear it.

Interested to hear what you decide.

[Deang]

What a great post.

[Guest David H]

What a great post.

I agree, it certainly addresses the open ended question without skepticism or preference.

Nicely done.

Dave

[grindstone]

Thanks, you guys--appreciated coming from such heavyweights as yourselves.

Looked and my memory has failed--I have zero cab designs for 312's.

For whatever reason, I'm unable to post images on the new board, so the best I can do is give a steer to a cab for a sister product (6201's) from the period that measure quite close to 312's. Alternatively, I'll say that time has made them appear similar despite whatever differences they may have shipped-with.

http://www.hifilit.com/hifilit/University/1952-B-4.jpg

[blimfark]

What a small world. I am looking at the same pair of University/Altec drivers. I have a pair of Klipsch designed E/V Aristocrat speakers with the right EV/Wolverine metal horns and crossovers which needs woofers. I have forgotten the name of the '60s vintage woofers that were in there, but they fell victim to dampness when our home at the beach flooded in hurrican Sandy. I replaced the woofers with a nice pair of JBL D131 that I picked up but the result was just too fat bottomed for my taste. It is powered by a Fisher KX-200 integrated amp and sounded really sweet before the dampness did them in. They just didn't sound the same with the JBLs. During the google search I saw the picture of the cabinet that the speakers are in and it led me to this site. Trying to make the deal this weekend.