grindstone

Um...I understood there'd be no math here today... Well, the throat expansion pieces are actually compound-angled boards and I just model stuff that makes my head hurt like that and take what the nice computer says. Yes re the Univ drawings but I just swiped them probably from here somewhere (WMcD?). Thanks for the work, X. I was looking at this thing a couple years ago but using the other driver data. I also see I've made a transcription error so here's that. I'm so happy I found my image-posting-holdup on this new board (gotta allow ajax.googleapis.com scripts to run or you can't "up" anything).

Yeah sorry for the confusion. Not criticizing your work, X, just trying to say that I used different drawings when I was modeling the horn. "Wrong" in the sense that the previously-posted plans in this thread don't match this official-thing which I deem "correct" due to provenance Not a big deal in the cause to get Moray his 2-way wallhorn, just nit-picking. Edit to add the hard number to get for anyone playing-along at home.

Should have said that I'm not using either of the previously-posted models because both were wrong when I built it. Using Univ drawing that I probably found here in one of the other University threads.

Doghouse models 5043 in3, very roughly 4200 after a driver is removed so the 80 L seems closer than 100 L.

from an old SB Avg series Avg parall 60.25 60.25 Fs 6.11 1.525 Re 18.55 7.565 BL 0.195 0.295 Qes 3.4 5.3 Qms 0.245 0.245 Cms 250 250 Vas (L) 0.26 Lvc (mH) 0.17 0.17 Rm

Good point, as-always, that you make, Moray. Yeah, limited sample-size. I remember GM said they changed the Z of the things (and dcr) when amps became less-thermionic aka more-sand-ey. I don't know what moved/how-far/when during the course of manufacture with all that was happening during "the life of the part" but it amounted to a Q change. I forgot what Dennis posted, too, but I remember he weighed-in at-least once to say something about that, too. All I can do on any of that is type of bunch of characters of speculation. TS--yeah I have that somewhere but it'll take me (tax-week!) until after the weekend at-least to root-it-out of the backups. Well, that's short for posting but the truth is that I never "sub-classifed" stuff really well when I made backups. I know I have to look through a few "university_stuff_n_of_m" folders to get that. If you're a unix-person at-all, the many revs of tar, well, you'll know and smile with me K33 will get a guy 10Hz lower bottom at the cost of some-(?)-two-hundred-Hz lower "top" (Fhm). Moray -- I owe ya the moon and the stars for all you've given for all these years on all these boards -- PM me with anything you want and I'll get it done if it can be done. May your health be Perfect and may your days be Better!

Just a few more "cents worth" acking a lot of what's here. Decided to respond because maybe a few of us have posed Randyh's question. Disclaimer: Haven't seen let alone heard one ever. Spent a lot of time trying to answer the question, but some of "my stuff" has disappeared from Imageshack and another forum containing the rest is now offline. What I can say is that ("what Moray said"), with the C15W's that are supposed to be in there (series coils), the response sims "gawdawfulflat" from 60 to 800Hz. I bet I've tried simming 45 drivers if not 60 -- currently-available drivers -- nothing does that. Flat-flat with one deep & narrow notch. Second, most "horns" (read: as constituted to fit in somebody's house and Blend And do "bass" w/o EQ) have a lovely-efficient half-wave mode and a lesser quarter-wave amplitude (spl). Say that they're "compromised" or that their designers have made tradeoffs about response, mouth size, rolloff slopes, EQ-decisions, space, blah blah. Mr. Abe Cohen's S-8 Classics with his C15W's, _also_ have the same "gawdawfulflat" _efficiency_ over their passband. No lame quarterwave and strong halfwave (with extraordinarily lame aka belly between)--no--hornresp efficiency is flat-flat with one deep/narrow notch. That was a lesson for me--that it's possible to make a system of an overall-reduced efficiency and yet still be plenty-suitable to call "high-efficiency" (teens of percent, IIRC, but flat teens of percent). Third, Z sims "gawdawfulflat" -- I wanna say 8 +/- a couple/three ohms from say 20Hz to 7kHz (C15W series coils). The sum of _that_ is why I quit my own personal Univ S-8 Classic-quest--check-that--it won't die, I'll just give-up hunting C15W's and choose something one day. No, what Abe did with that driver in that horn made me feel like a schoolkid when I first saw the sims after all my flailing-about. It both knocked the wind out of me and raised the bar of what was possible and I'm in some sort of debt to him for that. Thanks Moray for updating some local links and for general Moray-type-instigating and enabling PS As I remember from my quest, a guy can do worse than sticking a 15B or K33 in one but neither seemed worth it. That was some (?) bunch of years ago, too, so maybe there exist some schmancy drivers now that didn't fill the bill then.

Very nice and thanks for sharing. I'm mostly PPSL-ignorant, but if you have the time & inclination, is this general concept of bass bin something you'd have considered for applications w/o EQ (and assumed-?) multiamping?

Some ESR meters require the caps to be drained to test in-circuit so maybe heads-up to check that and prevent hurting the meter. Maybe the ARC has means to do that built-in already--no clue.

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

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.

Took a hack at modeling some of this today. Whole shot with notches is around 97L if I didn't screw-up. Less the ski slopes the total is around 82L. 61L or so for only the backchamber. No driver volume subtracted from any of this, BTW.

Yup, completely agreed if I was a conductor and if that was my train. That's the point--out-of-order posting created an Imaginary Train. Lesson-learned: Always include quotes when responding. Light me up for saying 5W is enough here and for omitting gain--I'll stand by all that. The "tube watts" bit, nah. Not that I can't cook-up some juicy troll of my own...just need time for that. Thanks for taking the time and hope you are well. Wow! Yes, I'm new here, but yours is a completely grand spirit and I am humbled.

Good to see everyone having fun and nice to have learned a new button of a board. For my bit, I was responding to huge's 5w spec as being Plenty loud but Jeff beat me to posting. I actually took huge's bait, not Jeff's. The clipping behavior arguments were settled years ago, watts are watts, gain is gain, and, in home audio, there are no standards for the connections between them. Touche on me for not qualifying gain--fair-point. Actually, I don't mind being made sport of if it'll drag Maron out of the shadows. <PS: Boxx -- is it true you made 13,549 posts in 3+ years? That has to be some sort of record for an organic.>

Sounds right to me. Since I've had Corns & Georgians I listen louder than prior. Could be that I'm making myself deaf by listening louder, but I swear efficiency just really makes me want to turn the knobs up higher. It's like the horn thing where you don't notice how loud anything is until you try to talk to someone next to you. I mostly run a low-watt tube thing and I gotta say 4w is about all it'll do and it's more than I can take in here (unless I've been into the beer or something--then it's fine or a little light). Thinking I've really only been to "eleven" 4 times--one of those was to see what it did, one was to try to study what the amp did, and the other 2 were probably beer-induced. Room is smaller than many spaces (guessing 25x14x8) but half-throttle is probably atypically loud in here. I remember reading Sound Practices years ago and Joe wrote something like "power ain't nothin' but a number" somewhere. I get that, now.

Cold spell dashed progress for a while. Finally finished the bottoms and got the rails on and bunged-in some furniture glides. Somehow hit yet one more screw when assembling cleats so one last drill-fill-sand-paint short loop on that spot. After reinverting and rewiring, just sat and listened (still in the garage and within 5 feet of each other). Did a lot of listening this weekend. Soooo, utility cabs pretty close. Be nice to get some insect-barrier similar to what Greg does across the rear end, but not sure about the form just yet...do casters somewhere down the line...permanently mount the xo and controls. Beyond that, not sure what's next. Still (loosely) trying to figure out what to do with the dress cabs. A lot of thinking, actually, all dependent on how they sound longer-term. Been picking at making a model for the (848HF) compression driver to be able to sim the reentrant expo + conical low-midhorn but that's tough-going and I can't get my ripple to line-up with the ripple in the measurement. Not anxious to disassemble the driver to try to measure internal V's yet either. Still also thinking about what started all this--the woodhorn conduction and isolation of same, etc. That can go a lot of directions but space is tight under the dress-cab. Definitely more to come on that at a later date. If there's anyone out there still reading this stuff that has thoughts on the current compound (PA?) drivers vs. the old one that'd be good stuff for me to hear. They do a lot of things very well. So much so I've been forced to confront some personal biases about the compound PA drivers and some other things. A couple times they've made me start giggling like a little kid. Still learning the sound and struggling with putting words to it. A neighbor happened by during today's testing and he was really surprised and enthusiastic. (He asked what I spent so far and I said about 200 bucks for xo parts, repair/finishing supplies & hdwe and maybe 300 bucks for craft brews...) Still it's been a rewarding use of every spare minute since late August. For now, the plan is to maybe horse the utility cabs inside for the winter and go from there. Be nice to get another set of measurements done outside if weather permits. Need to complete basshorn exhaust frames with the cane and all that. Not sure when the work on the dress cabs starts (or what that objective even is).

Yeah that was sort of what I was thinking -- use it as an anti-hot seasoner if you already have them. I tried the MCAP+SA recipe and it was indeed better but I'm still playing. FWIW, some FT3 bypasses added nothing up high to the combo. I may not have a hundred hours worth of AC into them, though, yet, FWIW. Giving them some time is low-effort.

I've bumped into a few and I've wailed hard enough and long enough to wreck impact drivers. The greatest thing about impact drivers is for those screws that have rusted & morphed to become indistinguishable from their adjacent surfaces--you can literally beat a slot into them in cases where there's no room to saw. Drilling heads is great until you slip and then it's indistinguishable from vise-grips and pliers. For easy stuff, the little left-handed screw-out things work about 50/50: http://www.sears.com/craftsman-3-pc-screw-out-174-damaged-screw-remover/p-00952154000P I can see an argument to just drill everything and go with the high-performance wood fillers if there are many non-critical areas to do.

Lots of work, little to show--mainly, sanding, filling, and painting basshorn grille frames. Drilled-out the last few broken screws. Still one broken frame to repair. Would have been smarter & faster to rebuild the basshorn frames from scratch, but it seems the fir needs to stay where it belongs so the little holes, broken staples, and dings each need some time. Starting (barely) to rebuild bottoms. Chose and cut some red oak to replace fir feet. Got sidetracked watching football instead of finishing the feet. Sat and listened to them a lot this past week (instead of working on them like I should have been). Ran a lot of material through them to try to learn their secrets. Walked around, craned my neck, moved them around, twiddled the pads, flipped through a lot of material. I can never guess which recordings they'll do better or worse with, and that's new for me. The only thing I know for sure so far is that they do not suffer poor recordings well. If something is poorly made, they are (giant) microscopes. Probably safe to say that the T350's are some good parts, too. They do the alnico slinky-ness and they can startle as well. For that matter, the whole rig can do startling dynamics sometimes. They do space better than I'd have guessed based just on running mono for a while. Can't separate them enough to be fair in the garage yet so that's pretty-much the end of reportage on sound-stuff for now.

Well so what happened Tim? Inquiring minds and all... Trying Choruses makes sense on space grounds, but, FWIW, the Crites'd Cornwalls in this house, despite size, are very tough to unseat and let move on to the next steward. The way I see it, khorns aren't big if you're okay with Cornwalls, they're just a little taller. Key thing with the size is to listen at night with the lights off...

Maybe one thing glossed-over was the bit of XO's. First, well, they're potted so I had to un-pot and fish-out the L's. Not really recommended, but I was sort of gung-ho about trying it with the values that shipped and well there was only one way to know that. The L's measured really close to the specs. One thing I wondered was how the EV engineers could pack so many L's so close together and toss them all in a steel can and call it done Seemed strange for men of science to use air cores crammed together inside steel cans... I don't have my notes, but, after I got the first can empty, I played games with my LCR meter and two chokes at various positions inserted into the can. It may be that I ran insufficient current, but I was surprised at the effectively negligible difference in readings between the parts in or out of the can. Still and all, it's not like these corner horns are about minimal space so my hacked-up board has a bit more space and will still fit in the woodhorn sideways if they end-up in-use. The filter responses are a little weird, too, but I trust those guys to have arrived at something useful and again I wanted to hear that. I just used extra barrier strips to be able to roll caps and make some fun. I never bought full-audio-nuts boutique caps before so I splurged on this project to see if I can hear anything. So far, I can't tell much if any difference but it's not much of a test in the garage, either. And I can't get too bent on the filters until I can convince myself of having a decent measurement of that unmeasurable reentrant + front expo compound horn. I don't even know what makes sense to measure and that's going to take a while to think about.

Pretty big-hour weekend effort. Got the other one almost caught-up to the first--scrubbed, sanded, & painted utility cab, built XO, inverted woofer and rewired, got second one running. Spent the afternoon & evening wearing a dust mask pulling staples and completing neanderthal work on the basshorn grille frames and de-cane-ing those. Cleats were glued and screwed and the screws of course have been rusting for ages so every one was a caveman focusing exercise. Chisel, gnaw, repeat. Little clouds whatever was growing on them fly out with almost every smack. The theme of patience continues, but it's even easier to work while listening to two of them than to just one. The environment is more like monitors running both in a single-car garage, but it was some good fun and a nice reward. Mostly listened to jazz and a bit of blues today and used a few boards propped for corners. Bass will not be a problem and the presentation made it worth a great deal of drudgery. There are a lot worse days in life than a day in the garage messing with cab-stuff while listening to two of these things even if it was freezing cold. There is still work to do on the bottoms of both utility cabs, but I was antsy to get them running and see what was to be seen. Full-disclosure, I'm racing winter in my uninsulated and unheated garage, too.

Neanderthalled the second decorative cab off unit 2 today. This one is was different in that the tailboard was glued. Pretty sure the utility cab hasn't been out of that thing for the whole time. Fewer things lived in it and more things lived on it Someone pitched a label and a knob inside the basshorn--a nice surprise to find between bouts of wailing on an impact driver and drilling hardware. Sick of drilling fasteners, mildew, mold, rust--and really pretty stoked. Classic stuff...do maybe 25 screws in 10 minutes and then an hour or something for one. It's at those times it's really nice to have one upped and running so 30 minutes of barehanding a hacksaw blade sails right by The basshorn grille frames are fir--the sort of stuff that's been long-gone for a while, or at least something I certainly never see. Apology for lousy photos again. So here's the newly-exhumed utility job on the right next to the runner on the left. And the Magna Carta has nothing on that label for brittle.

Thanks for that and for the support. I'd seen some of the photos on another site but didn't know of the thread. They were really in comparatively quite good condition before the top-notch effort--I bet they're amazing. Glad to see the really rare stuff saved (and glad I'm not the only poor sot learning exactly how much work this stuff is). These particular units are about endurance in every act; removing staples alone is a growth opportunity. There looks to be a lot of useful information in that thread. I'm not even started on the shell and in-fact the other cab is untouched completely. I'm just happy at least half the drivers seem to mostly work at this point

First AC and attempts at measurement this past week. Made some faux corners with plywood and whatever else laying around. Impossible to measure in the city with everything happening. Much to do and temperatures are falling. If any khorn-people are still out-there on my monologue-thread: how much space do these things need to really work? My experiments say I just start to get bass right at about 8-10 feet? I don't know where to measure that stuff, for one, but I'm also (re)considering where they might land. (And yes, one day I promise to return to the topic of the mud and all that--thanks for the bandwidth).