D-MAN

I've always liked A7's. They have a smooth mid-and-upper bass that is hard to beat. There are several thing going for the design. First, all of the drivers can be aligned in the same plane giving great phase and polar response. Second, the low end isn't too bad, either. They are quite efficient, too. This is when the "right" drivers are used. Most tend to stay with the original Altec components. However, it is a nice platform to play around with, too. Bear in mind that the original 416/516 drivers (did I get that right Altec dudes?) are rated at 75 watts max! Many, many A7's/825's have been used literally for DECADES in theaters and live bands for PA's so that is probably NOT a big limitation that you are likely to run into in home use! All in all, I'd say: if you have the space (they are pretty big), then by all means, if you get a good deal, go for it. DM

I haven't heard any of them but I suspect that they are likely too small and too limited in bandwidth for my needs. I'm going to play around with some cheap-and-dirty horn baffle extensions to see if I can approach the 90 deg. terminus of a true Tractrix flare on my horns. DM

My understanding is that the Tractrix flare is not particularily good at high frequencies due to the extremely short wavelengths employed, i.e., too short to make an effective difference between conical flare rate and tractrix, for instance. For example, make a tractrix flare tweeter horn that is less than 1" in overall path length, see what I mean? Not possible. Extremely short horns like that are all basically conical in expansion and effect. Bruce Edgar also reported the Tractrix to be bad at low frequencies below 100Hz. It seems to be relegated to the midrange frequencies, and I can attest to the fact that it is quite effective there. DM

3 of 4, these pics make them look alot worse than they actually are in real life, and even so, behind a grill cloth, who is going to care?

Another.

Here's some picks of Ricky's horns in action...

There are probably hundreds or even thousands of variables in the way. Whether the transients and small signal information actually get to the recorded medium or not is a concern of course, cause if it ain't there, you ain't gonna hear it no matter how good your system is. The recording of spacial reflections is not something that a lot of engineers are concerned with. The sense of depth and imaging is actually an artifact of how we perceive sound, and the chances are that the spacial references of the reproduced sound technically has little or nothing to do with the spacial dimensions of the actual space the recording was made in. Add to that some reverb is going to be artificial, and may have nothing to do with defining actual spacial information at all. We've all heard the reverb on some instrument or singer, but not on the drums, etc. How do our ears interpret that in the context of a soundstage? Not well, at least, not convincingly. Then there is the room and the speakers that you listen in with its own absorption and reflection characteristics. Given that your (and our) rooms are subject to their own coefficients based on their respective dimensions, contents, and layout, it's a miracle that anything sounds good, isn't it? Add to that the various elements that effect the signal, electronics and wiring, networks and speakers, and that is virtually unaccountable. I suppose that in the off chance that the recorded reverberation information (if there and ACCURATE) happens to fall within the limits of the particular room variable coefficients and speaker propagation characteristics within that area, certain recordings could reproduce the spacial information in some believable or convincing sense without the room variables altering it too drastically. Providing the math all lines up, which is not very likely. However, there would always be a window or threshold where the math lines up ENOUGH, even only in a certain portion or section of a recording... However, you CAN artificially enhance the subjective effect of imaging by reducing the reflections from the walls by moving the speakers away from the walls, closer together and out in front of you, like we have all seen and experienced with the small footprint direct-radiating tower-style speakers so in vogue. Unfortunately, these speakers are going to compress the available dynamics in doing so. They tend to give you the "Orchestra on a Table Top" sort of soundstage. Small, compressed, but still a very stable soundstage. Compressed tends to say it all, doesn't it? I think that we can easily agree that fixed-angle (45 deg) corner horns are not ever going to create a fabulous soundstage for a couple of important reasons, even if you are perfectly aligned with each speaker on a 45 degree axis from the listening position. There are still many, many variables in the way. DM

Rick, again, thank you. I took some pics of the setup in place. I hacked up the 2" mounting board that you had attached. It now has 2 big holes for mounting 2 of the 4-bolts on a 2" driver (the 6 you had are not used). It also mounts kitty-corner in order to clear the driver mounting bolts. I took some pics of the setup in place and you'll see what I mean, but I'll have to remember to download them. I re-glued one of the side pieces as one came off and set a couple of screws from the side that should be permanent to help hold them (the drivers weigh 20lbs each!). The mounting board with the driver in place is then attached with 4 angled screws from the front of the "side flange pieces", 2 per side. Worked great. Let me know who gets them next. JC, I like BMS, so try the midrange-only 2" version - I guarantee you will like what you hear, especially in the Tractrix. Also, the output is rated at 113db, so that is also going to be in keeping with the potential of a Jubilee bass bin. Another reason I like the BMS is that they are rated to 300Hz @ 150watts! That alone ought to sell you on them! Dana

Dual 12's each would have a smaller throat area requirement, and that means less width is required for the throat channels (especially if bifurcated at the throat). Depending on the drivers employed the Vb could also be smaller (the K33E needs about 3 cu. ft.) as small as 2 cu ft. Overall path length and mouth size would remain the same (the path length could lengthen, even), especially the mouth size which is basically fixed by flare rate and radiation angle. It remains interesting, though, that PWK concluded in 1976 in the LB patent that the horn pathlength could be as short as 1/12 wavelength. For 40Hz, that is roughly about 32 inches. This is predicated on having a fully-annulled back chamber on a front-loaded horn, in Plach's words, "a conjugate match". 720 sq. in for a 55Hz horn is rather small for a 1/4 and is not intended for 1/2 space placement, but is indicative that it was designed as 1/8th placement (a corner). The distance from the reflective walls minimum is .5 of a wavelength (on-axis from corner), which means that the higher frequencies (60Hz) on up would not benefit from reflections if the mouth channel terminus (walls) are over 18" from the walls, etc. You can have up to a 20% variance in SPL at those frequencies for an on-axis corner placement in the corner. Off-axis placements would be calculated as .75 wavelength, because one side is closer to a reflective wall than the other, of course. Wavelength is calculated as 1125 (ft per sec) / frequency. The mouth-to-reflective-surface distance determines the upper crossover frequency point limit, as you can see. DM

Rick (3dzapper) was extremely kind to send a pair of wooden Tractrix horns to me that he built. They were built to Bruce Edgar's specs from the Tractrix midhorn article which was intended for a cone midrange driver, if I remember correctly. I had to do some hardware shopping to get my 4 bolt BMS 4590 compression drivers to mount, but I finally did. The BMS drivers are coax, so that means that the tweeter is also going to propagate through the midrange horn along witht the midrange. Since very few midrange horns with a low flare rate can pass high frequencies (most attenuate above 15K), it was a question whether the Edgar Tractrix could do it also. The Tractrix DOES do something quite delicious in the lower mids - the only way I can describe it is the strange-yet-wonderful "damping" that a fine piece of tube gear can do in the mids. That was the sound. However, it attenuated the highs. I would have to guess somewhere around 9 or 10K. There could be a couple of reasons for this... one being that the throat was square, not circular. The driver throat is circular, and high frequencies are quite unforgiving of discrepancies in the throat area. Remember that the horn was intended for a cone driver. The other reason would have to do with the Tractrix flare rate - there are no tweeters that use a tractrix flare that I know of. Evidently there is a reason for that - who knew! The P-Audio horns that I'm using are very close in mouth size with the Edgar Tractrix horns, they are virtually the same area and proportion. The P-Audio horns are shorter in path length, though. They also have a "squeeze" of the throat (to extend the horizontal dispersion characteristic) which the Tractrix does not. The Tractrix had a wider midrange dispersion characteristic than the P-Audio but tended to beam on the upper end and THEN attenuated the highs. The P-Audio's that I use are 90x40. I don't know what the Tractrix is, but it is definitely much wider than that. Now, granted, the Tractrix wasn't intended to be anything other than a midrange horn, and I was using it in a coax configuration - but what the heck - it needed to be tried anyway. So it really isn't very suprizing that it doesn't work very well with a coax. I thought it would work well enough to make it worth trying, but I was wrong on that account. If I could get horns that do what the Tractrix does on the lower mids AND retain the high frequency capability of the P-Audio horn for using a coax, I could take over the horn world! My opinion is that as a MIDRANGE-ONLY horn (as it was intended), the Tractix is going to be very hard to beat. The tendancy is to beam, so keep the upper frequency limit fairly low, 5 or 6K would be a good guess. It has a deliciousness to the low-end (I crossover at 600 Hz) that frankly, I haven't experienced before. It is palpably delicious! That's the right and only word for it, too. You have to hear it to know what I'm talking about. I think it has something to do with "damping" (whatever that is), but it has a "tube-like" quality to it (in the best sense of the word "tube"). I'm using quality SS gear, too. I think that it has something to do with the trailing edge of the waveform - it just starts and is full-bodied and ends naturally - but there is something else there, too. I think it has to do with the way the sound ENDS. It's trailing edge is the difference lies, I think. It has a bit of a "suction" to it, if that makes any sense at all. It stops in a manner that can only be described as full "black space" - no overhang, no ringing, and not truly dead air either - more like an extremely large volume of space would respond, the quiver is there. It's more like a natural decay response in a really BIG space with no residuals or reverberation. Silver - it sounds a bit like silver cabling! So for coaxial use, don't use them - however, for a "straight" midrange, going to be very hard to beat. DM

For the switching faces, you can just squint, too. You don't have to actually move backwards. It worked great. DM

Probably a bit larger, i.e., 15 cu ft. I estimate the outside dimensions as 30w x 24 d x 39 h. Probably could be paired down a bit, but 10 cu ft is pretty small, depends on the Fc your going for. Could go smaller for dual 12" drivers vs. the single K33E, of course. DM

I am unaware of any info concerning a PWK 1/4 space horn, I am just proposing this as a possibility based on some assumptions. As a guess, given his historical propensity for using what he had in stock, I would guess the venerable K33E would be in order, as well as the crossovers, etc. virtually the same as the Khorn albeit with a more-likely 50Hz overall Fc. I would also guess that the height and appearance would be very close to the Khorn, preferably the style "B". At least that's what I'd want to see! DM

Here is what I figure PWK would come up with for a 1/4 space design. I've included all of the PWK "trademarks"... in keeping with the traditions of the Khorn. Bifurcated at the throat, single driver, symmetrical folding, bifurcated at the rear, you know, everything that points to a PWK design... DM

I agree with John, I don't think it could be done in the same footprint & overall size, simply due to lower Fc requiring a longer and larger horn mouth size. Dual drivers would also make it larger by necessity. The LB was smaller but had essentially the same response (albeit with other additional requirements). Even a double-stacked LB setup would be taller (although the footprint would be smaller than the LS), but no lower in response. Nope, not likely, at least not with a smooth (or acceptable) response. DM

It increases diaphragm "damping" due to its viscosity. It could therefore tend to smooth out some response peaks. It also transfers heat much better than air, allowing for increased power handling characteristics. The magnetic inclusions tend to keep it in the gap. Selenium midrange compression drivers use it, I know for a fact. DM

The only EV product that was subject to patent licensing was the Patrician, being a scaled up version of the Khorn bass bin. Since EV was supplying Klipsch with drivers, they had a business relationship to start with. Believe it or not, PWK did NOT own the corner, as some here evidently tend to think, and that kind of thinking was exactly what EV intended to exploit. EV sought a license agreement with Klipsch so they could further cash in on the Klipsch name, as "if it goes in a corner, it must be Klipsch", without actually attributing the design to PWK. The other EV products (Aristocrat, Centurian, etc.) which all were corner speakers, were not subject to any Klipsch patent rights, although they were "advertised" that way. I imagine that PWK would have made a sweetheart deal to reduce his costs as EV was a supplier, and he didn't actually have to do anything. Win-win. See the other famous corner horns available at the time that were NOT subject to PWK patents - the Jensen Laboratory Standard (aka the "Corner Imperial"), the L.E.E. Catenoid, and the JBL Hartsfield. DM

A7/825's truly kick tail. If they weren't so big, I'd have a pair. I traded my "Elephant Horns" temporarily to a buddy for a pair of A7's when I was a kid. The A7's were VERY impressive, even then. They just were TOO BIG. We used them for our PA cabs when I was in a band way back when. DM

Hey Mike - something is beaming in front of that setup! I finally get to put a face to the voice! Dana

Basically anything that Steven Seagal starred and directed is totally HORRIBLE. One another note, remember this one (you're lucky if you haven't seen it): "The Lion of the Desert"? DM

That all depends on where you want to crossover, what the drivers mass rolloff is, and just how much reflectors can get you... all rather up in the air. The K33E has a low roll off, and since PWK wanted to use the same components that he had in stock, the LS/Belle were not optimized for any extension of the upper frequency corner. What the stock versions use are untreaded folds and a "somewhat" radius-style splitting wedge that is more structural reinforcement than an effective 45 degree channel splitter. Since reflectors are of little use below 300Hz, the rather short horn length and limited folds allowed for the typical 400Hz crossover point to be used. Some have reported that the LS in stock configuration can be crossed over safely at 600hz, some even go as high as 800Hz, but take that with a grain of salt. I would venture a guess that WITH the use of proper corner reflectors and a full-channel splitting wedge that would be entirely possible, but again, that depends on the driver employed. DM

Yes, my backup plan is to cover up the port if I have to. I'd just like to avoid that before hand, i.e., if I knew better ahead of time, that would be one thing, but it feels like taking a blind risk. The problem is, the design works fine without it. It's just that the capability to port it is there and that is a powerful alure. To find out what a port can do below cutoff... tantilizing... Bob Crites has the perfect woofer for it, too. All these things make it possible. The front-horn won't be anulled (of course) and should fall off about like a Klipschorn. The available Vb is 4.8 cu. feet., which I don't need if its front-loaded only (I can annull it in that case). I plan on making the things as convertable (or reversable, that is) as possible. DM

That's an interesting point - I've got another design that is prime for a port and has enough Vb to resonate at 30Hz (with the right driver, of course), and that's well below the -3db down point below the front-horn 40Hz Fc. Since I haven't seen it done, except for the DJK modded La Scala's (and EQing was specifically mentioned), I'm a little afraid of actually chopping a hole in the thing to find out why I shouldn't have done it. However, what about the Altec A7? That is a front-loaded horn with a reflex port, and it seems to work quite well without EQ? DM

There is something to think about whether you WANT to notify all in hearing distance that you have noise-making stuff in your house worth stealing. Don't like to broadcast that fact, even though my neighborhood is quite safe. For PO'ing the neighbors, I'd recommend BAGPIPES. They tend to PO just about everyone. I think that's why they were invented in the first place. DM

I've seen some designs but they tend to be for the smaller (Lowther) cones. Here's one.