Quisitive

Gil - Very good thoughts indeed! Wish I had made them myself. You're quite right about choosing material, tools and technique based on skill level, as well. I once saw a guy carve an absolutely beautiful Chippenale cabinet leg using a hand axe, a couple of rusty old chisels, a claw hammer, and a throw-away paring knife that had been re-ground. Knocked it out in about 25 minutes. Saw another guy in a seminar with a couple thousand dollars worth of specialty tools who was trying to follow the instructor's directions. You guessed it. He ended up with a pile of expensive kindling, many wasted hours, and a heck of a lot of frustration. Here's the funny thing. You couldn't even talk to the secon guy. Oh well. But you know, at the end of the day, what's important about this hobby of ours is whether or not we get any personal satisfaction out of what we try. Getting there is where I think the fun is. Chris

Gil - Very good thoughts indeed! Wish I had made them myself. You're quite right about choosing material based on skill level, as well. I once saw a guy carve an absolutely beautiful Chippenale cabinet leg using a hand axe, a couple of rusty old chisels, a claw hammer, and a throw-away paring knife that had been re-ground. Knocked it out in about25 minutes. Saw another guy in a seminar with a couple thousand dollars worth of specialty tools who was trying to follow the instructor's directions. You guessed it. He ended up with a pile of expensive kindling, many wasted hours, and a heck of a lot of frustration. Here's the funny thing. You couldn't even talk to the secon guy. Oh well. But you know, at the end of the day, what's important about this hobby of ours is whether or not we get any personal satisfaction out of what we try. Gettint there is where I think the fun is. Chris

Even though I rarely get involved in contentious subjects in on-line forums (especially this one!!), I really must concur with filmboydoug. I've been working wood - in all forms and for many different purposes - for over forty years now, so I can speak from the perspective of some practical experience. The trick to all this is to understand what you're trying to accomplish, and then use the most appropriate material - and more importantly - the most appropriate construction technique. Furthermore, I haven't seen any mention of the relative amount of flexing for different material choices. Density (e.g., MDF, and I have used *miles* of the stuff) doesn't solve everything, nor does void-free plywood. The density that MDF provides won't do you much good once you exceed a certain dimension. After that, it starts flexing like any other sheet good because it has no lateral strength. Plywood, on the other had, uses veneers laid down in alternating direction - plus glue - to achieve less flex. As an example, let's look at the Chinese 11-ply sheet goods availabe at your local home center. Yes, it has ply overlaps and some voids, but more importantly, its density is no greater than common 7-ply with birch faces. If you want greater density, go with 13-ply Baltic or Russian birch, which is much denser, and flexes less. The reason it flexes less is due to the fact that it uses birch plies throughout, so it has more density, whereas domestic birch uses interior plies of fir. In addition, the moisture-resistant glue between each ply gives more strength and less flex. Now. That said, all of these can be used in speaker construction with effective and incredible results if you understand the physicals, mechanics, and construction techniques that they each may require. For example, on the back of large horns such as Karlson or University S-9s, you can use open-face torsion box construction techniques that increase the rigidity of large surfaces *incredibly*. If you're not familiar with this technique, do a Google search. I have yet to see this construction concept applied in any threads in the speaker forums. Most contributors just go for straight sheet goods and argue about the relative merits of each instead of talking about mechanical engineering approaches to the problem. Alright, so I know this may be a bit of a rant, but I truly enjoy - and value - the exchange of knowledge that forums such as these provide and it pains me greatly to see someone shut down simply by trying to prove positional authority by asking one of the members "how many of these have *you* done?" That doesn't prove anything. One member may have put together many systems that were just awful, even though they followed a cookbook example to every last detail. Not only that, they may not have understood *why* they were doing it, other than it was conventional wisdom. Someone else may have produced a superlative example exactly once by thinking everything through and carefully applying some innovative construction techniques. Others may be new to the hobby, have lots of enthusiasm and lots of questions, and are simply looking for some guidance and a better understanding of *why* things work. Forums like this aren't about egos. They're about sharing knowledge. So come on, let's have a little charity, OK? Because here's one thing I've learned over the years - no matter how smart you may think you are, or how accomplished you may be, you will undoubtedly come across someone who is far your superior, usually when you least expect it and when it will be most personally embarassing. Chris

Armando - Got your earlier email and glad the picture of the HF-206 works for you. These are some truly amazing designs! You are incredibly creative. I hadn't really considered going the low-boy route before now -- if it will fit. As far as the dimensions of my room, I have exactly 10.5 feet along the wall I need to use. If the Classics protrude 24", I'm limited to 7.5' of wall space due to the bi-fold door on the left and my monster printer on the right. So if the Classic is 40" wide each, that makes 80", leaving only 10". Hmmm. So I could consider the idea of using the tops (sides, whatever) of the speaker to hold components, but all of my current and future gear is tube. So I'm a bit concerned about vibration. Also for CD-transports and the occasional vinyl playing. So this may not work. If I only had 12' to use, I think it would. Oy yes, your last picture made me think of the University TMS-2 tri-mensional, which had horns on either side a single CW15 as a bass driver in the center. This was back in the days when consoles were all the rage. Maybe I should consider you University Belle design. That's really been capturing my imagination since you posted your drawing. Show's great promise, even though I still want to build a pair of Classics. Could be I need to go with something like the University Belle today, and a few years down the road when the kid is off to college, building something a little larger when I have more room. Just thinking out loud. Armando, keep those thoughts and drawings coming. You're a great talent and resource. Chris

While ajsons is busy drawing his plans, I thought I would introduce the topic of material for the enclosure. I believe early Klipsch products were built using domestic 7-ply birch plywood. I notice that the new La Scalas have 1" MDF walls, I suppose the sides but maybe the back as well, while keeping the internal walls at 3/4" plywood. In talking to different people across the forums, the consensus seems to be 13-ply baltic birch. It's certainly the densest of the available plywoods, but today's samples invariably have "cats eye" patches on both sides, so it's quite difficult to find a nice face. Another factor is it comes in (roughly) 5'x5' sheets instead of 4'x8'. I've used some 11-ply, 3/4" "birch" plywood that's made in China. Early samples from Home Depot rivaled some of the best 7-ply, cabinet-grade domestic birch I've seen. Lately though, all the samples I've seen are made from "mystery" wood, warped all over the place and not very usable in general. A couple of days ago I was able to visit a local hardwood and plywood distributor that has a small retail operation for hobbyists. The selection they had available was astounding. It wasn't on display, either. It was only when I brought up my impending project that I got an impromptu tour of the warehouse. Unbelievable. You would have never known what all was available. They had about 300 sheets of the 5x5 Baltic birch. Dead flat and good structure, but the faces weren't very pretty and they had plugs on both sides. So unless you're going to use paint as a finish, or veneer, it wasn't too appealing. Especially with the potentially low yield of 5x5 sheets depending on the eventual dimensions of the enclosure. As we were walking around, he pointed out some other interesting stacks, including 4'x8', 11-ply goods from China. There was the usual birch, but he also had flat cut, book-matched beech. Talk about nice! He also had oak, alder and Honduras mahogany. This was definitely *not* the stuff you would find in the big boxes. their main clientele are cabinet shops and custom contractors. They ship out three 18 wheelers of goods every day. So long story short, here are the prices I found here in Texas: Big Box, bad 4'x8' 11-ply "birch" $32.00 Distributor-sourced, "good" 4'x8' 11-ply "birch" $34.00 Distributor-sourced, 5'x5' 13-ply Baltic birch $35.00 Distributor-sourced, 4'x8' 11-ply Oak, Beech, Mahogany $54 - 60.00 So if you do the math, the local, big box stuff runs about $1.00 per foot, The good stuff will cost just a bit more, but it will be less convenient for you to get it. Good grade Baltic birch will cost you about $1.50 a foot, and the really nice face wood, which is 11-ply, will set you back as much as $2.00 per foot. If you go to 7-ply you can get even more choices, but then you need to worry about voids in the laminations and a lot of times, the interior plys will be "hadrwood", but generic, so the density may not be that great. There's a reason so many speakers are made of MDF these days. It has high machinability, especially if you use CNC machinery, it's available in all kinds of thicknesses, it's engineered to be flat, and it also has incredible density. The density leads to damping. Some people think the damping sounds "dead". I think it depends on the design of the enclosure and the matching of drivers. It's also a wonderful surface to veneer, but it sure is heavy! Especially if you're a one-man shop! We never got around to the "sound" of the enclosue, which I 'm sure can be a lively debate based on similar threads I've seen before. What would be more interesting is taking a look a density as it relates to damping and structural flex. Sometimes those aspects don't seem to get brought up, at least on other forums. Since this is more of a horn-oriented forum, this may be a subject that's beat to death. Since the search function doesn't seem to go back very far, it's hard for me to tell. I haven't even thought about cutting schedules yet. We'll leave that for later, at which time we'll have a better idea as to how many sheets will be required. Hope these little rambling thoughts have been of some help. Chris

Armando - I stumbled across these "corrected" drawings for the Classic on loudspeakerguru's site at this URL: http://www.geocities.com/loudspeakerguru/CorrectedUniversityClassic.gif: You may have already found it yourself, but I thought I would post it for general reference. I'm much more interested in your resulting designs!

Almost missed this one with another shot of the T-30, this time compared to the drivers that University marketed for PA applications. Notice that the T-30 and Cobreflex do dual duty for HiFi and PA. I think you're right about the Cobreflex. It's compact, utilitarian styling made it "look" like it was made for PA duty and causing audiophiles to dismiss it.

While I'm at it, here's a page of speakers, including the wonderful and rare 315C: Later versions of the 315C had a HF-206 horn without the grill.

Here's anothe page from the same catalog, featuring the Classic and Dean:

Here's another page from hifilit.com showing the Classic, Dean and C15W. These are from the 1957 catalog, probably before the H600 was introduced.

ajsons - Here's some specs on University horns from hifilit.com: The T-30 specifications are right underneath the Cobreflex.

Here's a .pdf of the CobreflexIII, which is still made by Electrovoice, although I believe it may now be made of fiberglas instead of cast aluminum. It appears they now promote the Cobreflex for PA use. Chris Cobreflex Spec Sheet - Electrovoice.pdf

ajsons - Thanks for starting the new thread. That appears to be a T-30 driver on an H600 mid horn. If there's an adjustable, black plastic phase plug in the mouth, then it's an H600. They also made a similar horn, the 4409, which I've never seen. I'm not sure if I have a picture on file. If not, I can shoot one. Chris

Oh, not a problem at all. I'm soaking up as much of this stuff as I can. Our posts most have passed each other. I definitely like the direction the conversation is heading, especially with your innovative design. If there was a way to shrink the depth, even at the cost of a little height, I would be all over it due to my dimensional constraints. I'd still like to use my set of University drivers, but if push came to shove I could always eBay them and get what's best. You guys are really something else, you know it? Chris

Dana, I 'm still woking on the cad drawings for the Classic with the added reflectors, just like we talked about. I think I'll start a new thread on driver specs, construction details, and mods. I'll post the cad drawings for the reflector mods there. Armando D-Man - Thanks for the input regarding the throat reflector of the Dean. I had been wondering if a similar implementation on the rectangular Classic would be of value, but I'm far out of my depth on the theory of bass horns. ajsons - If you want to start a Classic builder's thread I would be an active participant and contribute what little knowledge I have to the common good. I am a fairly decent amateur cabinet maker. Perhaps that would help. I am also interested in WAF, but more for myself. That extends to wondering how you might be able to construct 30"x40" speaker grilles that can handle being repetitively installed and removed, yet still be fairly acoustically transparent. I don't think the orginal designs would work. they look awfully bulky and have those cross-basrs, but they may not have that much influence on large bass horns and stand-alone mid- and high- horns that are suspended in the bass mouth. Again, an area I have no experience in. Another thought is the "shelf" created by one side of the doghouse at the bottom when the Classic is in the vertical position. Strictly for appearance sake, what would happen acoustically if it were enclosed? The last thought I had was if the Classics were going to be redrawn, are they currently optimized. I may have missed something, but D-Man's comments lead me to believe he thinks they're fine the way they are. Also, as Q-Man suggested, you can start with the drivers originally specified and then go from there. I suspect my 50'ish ears will probably be happy with the originals. Chris