D-MAN

I'm still wondering about why one would want to pursue the technology of the 1930's compared to what can be done with today's drivers? I really think that crossing over lower is a mistake, after all, they ALL did it in the old days, and everyone (PWK especially) eventually went the other way when technology advanced enough to crossover higher effectively! So now that it can be done, there are those who specifically WANT to go "back" to the old days? Hmmmmm.... The main point I am saying is that it's been done (to death) and NONE of the speakers that did it are alive today! And the reason(s) for that is.... DM

The benefits of an all-cone setup tend to be in the coherent soundstage and rock-steady imaging. This effect comes part and parcel with dynamic compression (and higher IM distortion). The horns tend to be very clear with low distortion and increased dynamics, as dynamic compression is not a problem with horns. The so-called "soundstage and imaging" tends to suffer a bit (comparitively speaking) with horns due to the expanded coverage angles and less of a tendency to "beam". TYpically, the main drawback to horns (besides their size) is a difference in pathway lengths between horns and non-horn speaker types, which tends to give the horn designs a "lag" on the bass, in particular, as well as different point-sources compared to other designs which MIGHT be linearly aligned for phase. Some people think that this gives the direct-radiators an edge in imaging, but myself, I regard the inherent dynamic compression unacceptable. They are all trade offs, it depends on what aspect you want to enhance, and what aspects you want to "ignore". Of course, some designs are worse than others... The general effect of the best of the direct-radiator class (IMO) is that they can give a very enticing rendition of a soundstage, but that is unfortunately rather small in scope, such as the "orchestra on a table-top" that we have heard about. That's great, I suppose if you live in an apartment, or otherwise don't listen very loud at all, i.e., you don't ever "rock out". I know it sounds like I'm bad-mouthing all direct-radiators, and I suppose I am, as an owner of a large pair of KEF's (which certainly can "rock out" as needed), I know whereof I speak... If you want to hear what the best-of-class sounds like, the KEF's are as good as any of the "tall-and-skinny" breed at their respective price range. They certainly have their advantages, as well as their drawbacks. I have come to prefer the soundstage that horns produce BIG, WIDE, and FULL-SIZE. The soundstage of the T&S (tall and skinny) class is only as wide as the separation between the two speakers. It has depth for days, is entirely stable, but that is still relatively small in overall width and not-so-much "life-size". They are smooth, precise, have lots of "air" and black-space, etc. All of the things that we read about speakers should have, etc. How about the things they don't have - dynamic range (compared to horns, exclusively speaking). Yes, they DO have dynamics, just not like horns do. They lack the ability to sweep you along with dynamic changes, particularily part of orchestral work that I have become accustomed to listening to horns. They also create a smaller soundstage width (I suppose you could call this true "compression" although it is really not, but only appears that way when compared to corner horns in particular which produce a soundstage as wide as the room dimensions. That is what I would state is the main differences between the two. The KEF's in particular have always been fairly efficient, I used tubes on them. Another important point to make I think is that my friends all tend to remember the KEF's as being the ones that "floored" them when I lived in an apartment years ago, even though they can hear the corner horns in my house today. The difference in presentation is the room, which is too acoustically horrible to contemplate. However, I gave up ever getting the KEF's to sound remotely OK in it - the horns do a much better job given the circumstances. There has never come a time where I was ever even remotely convinced that the performer was actually standing between the speakers of the direct radiators, well maybe ONCE with Linda Rondstat (?) and orchestra. However, I have felt exactly that with the horns on MOST recordings. Aside from their size, the horns (mine are corner horns) fit rather unobtrusively in the corners, where the direct radiators needed to be well out into the room. Electrostats are even worse as they broadcast on both sides, so therefore, I have ZERO interest in them as I am unwilling to live around them in the middle of the room, regardless of the sound quality that they produce. Nice but actually I think my horns are close-enough in sound quality to compete DIRECTLY, as well as being much more convienient to live with. Their size is only a problem if you have to move them! I actually don't feel that I am sacrificing any floor space for the horns, what else would I put in the corners? Furniture? A chair? The corners are a virtual waste of space anyway. Dana

Correcto-mundo! You are getting DC bleed-through from the power supply - the ps caps are definitely the culprits. DM

Go, JC, Go! I would glue the T-nut in so it won't break loose from the wood when overly tightened. This is just a precautionary measure, though. Dana

Yes, I actually went towards the punchy-side of things myself. I am just of the frame of mind that 12 inchers just don't have the low end muscle that a good 15 has for low end. BTW my horns are 35Hz Fc and crossover at 600Hz quite easily from a single 15. That is an appreciable bandwidth regardless. I wouldn't want to cross them over any lower than 500Hz, because like the Jubilee, it would dispense with the capabilities of the design. jc, here's the University Dean plans... Dana

I'm a bit confused, the Jubilee is intended specifically to crossover HIGHER, not lower. If you are intent on crossing over lower (i.e., below 300Hz), a corner horn is probably NOT your best bet, especially the Jubilee which some have reported lacks low end grunt anyway. The Klipschorn bass bin would work fine with a reduced bandwidth. The Jub would be a waste of potential, IMO. I would look at an Edgarhorn bass horn/sub combo in that case, or something along those lines, some sort of straight horn setup (Edgar's got a 100Hz straight mid-bass horn, etc). The University Classic should also be on your list, it was intended to crossover at 300Hz or below. The University Dean is a corner version. Or the venerable Khorn. But not the Jubilee. DM

I got it, finally. Olson stated in "Acoustic Engineering" that for wavelengths SHORTER than the diameter of the horn mouth tend to follow the dispersion characteristics of the horn flare, not the mouth. The larger wavelengths follow the mouth dispersion characteristics. So the Jubilee horn is designed for wide coverage even at high frequencies, which would normally close into a "beam" determined by the flare angle of the horn sides (not the mouth). So that explains the wide conical expansion flare. Ok, makes sense now, I couldn't see why Klipsch would want such a monstrous (i.e., ZERO-WAF) horn on the Jubilee. DM

Originally, that's exactly why I bought them (All KEF 5-channel). However, now that I have corner horns, I prefer the horns on the mains. That leaves me with a pair of "orphaned" KEF's. Not a thing is wrong with them, they image like crazy, and have good bass (dual 10" in each cab) but I like the horns much better. They have a small footprint, but like I said, they are 48 inches tall. They weigh about 90-something lbs each. If I remember correctly, they are rated at 200 watts ea. They want to be out in the room a bit, too - they won't work well placed in a corner, like with all of the "tall-and-skinny" ilk. Next to a big screen TV, now you're talking. I forgot to add that if you like the "British" sound, that delicious and thick midrange that British speakers tend to have, then these are your pups! Did I mention that they image like crazy, probably the best I've ever heard - the tweeter is a coax on the top driver and the height is just right. Those are two standout features. Bass isn't lacking, either. DM

I blame myself. DM

Ah, the "foreshortened horn" problem. If the path length of the horn is too short, it will produce a "peaky" frequency response. Famously illustrated by Olson in his seminal work "Acoustic Engineering". However, Olson left out one very important consideration, he did not show the results of a foreshortened horn WITH a reactance-annulled driver. He simply changed the mouth sizes, which automatically shortened the horns, too. Salmon, Plach, Klipsch, Edgar all agree that the horn can safely be "foreshortened" IF one also pays attention to the back chamber sizing with regard to frequency. The detrimental response from a foreshortened horn can be alleviated somewhat by fully reactance-annulling the back chamber. The drawback is that the roll off below the horn Fc will be exagerated, and may not be effectively EQ'd. A fully-reactance annulled driver is less susceptable to variations in acoustic resistance (from a fore-shortened horn) than a non-fully annulled one. Another consideration is that PWK stated in the Gillum patent that a horn mouth could be as small as 1/12th of a wavelength (with a reactance-annulled driver). That also means that a horn pathlength is also reduced by the same ratio (as determined by the flare rate), and consider the result the minimum horn path length that you can safely use. DM

Sam, I have a pair of KEF model 4's in rosewood I'd be happy to sell you! They are in "as new" condition. They are 4 ft tall. Dana

Dean, are you complaining that 104 db sensitivity isn't enough? LOL (I know you like it LOUD, but SHEESH!) Lower efficiency increases bandwidth and "flattens" out the response to a degree, it also raises distortion. We are speaking of the woofer/horn combination specifically. The corner placement and horn-loading adds approximately +9 db to the output of the driver. Also, the output of the bass horn is dependent on the efficiency of the driver put in it. If you put in a 100db driver, you should reasonably expect 109db output, etc. I know the tweeter is restricted to below 105db, and therefore, so is the woofer/horn combination, because you can't attenuate the woofer effectively. The T/S specs of the K33E don't make sense in the Khorn UNTIL you figure for reduced efficiency, that is, operating it under pressure, and then more than usual. Then the light goes on! For instance, the K33E Vas is over 13 cubic feet. The Khorn back chamber is under 3 cu. ft. In simplistic terms, the horn throat cavity opening is reduced to attempt to "equalize" the pressure on the front of the cone with the back, so the excursion is fairly equal in both directions. This raises the Fs of the driver (a lower starting point is a good thing) and in a perfect world, you want the Fs to equal the Fc of the horn (reactance annulled), but in the case of the Khorn, it is not technically a match anyway. A match would cause a steep fall off below the horns Fc, which PWK purposefully avoided, the benefit is that the LF response can be EQ'd effectively due to the more gradual fall off employed. I've operated the K33E in a horn using the wider opening (78 sq. in), and I didn't like it at all. The driver in question really needs to be used with a high degree of resistance in order to flatten out its response. This started to give me a clue as to what was happening with the K33E in the Khorn. DM

Bob Crites woofer is the way to go, in leiu of a stock K33E. It has two things going for it, one being a low Qts (lower than a K33E) which indicates that the magnet has good control over the cone which you want in a horn driver, and the low Fs, allowing it to be used sucessfully in an undersized back chamber like the Khorn (the Fs raises when in the horn). It will also use the 3" wide slot (since 1962) just FINE, as the slot size was reduced to increase the upper frequency corner (K33). It also reduces the efficiency down to a reasonable match to the mid/tweets. Slot size should be widened for most other drivers, but it depends on their specs. DM

You can add another lower flare rate which will lower the overall Fc, very much like placing it backwards in a corner. However, it's square shape makes this difficult to be as efficient as a horn actually designed to do it. Lot's of horns out there use this approach, especially in the PA and single-driver world. How good they are, I'll leave up to you. Here's a Danley subwoofer for instance... DM

All, I relaced the DFH fuse attachment that I had posted previously. Forgot that editing a post deletes the previous attachment. Now its back. Dana

Hey, Bob! I've designed a dual 15" corner horn specifically for your drivers! That's 4 drivers just for my prototype pair! Shouldn't you want to NOT piss me off?! Dana

The term comes from the old days when most tube amps were current-limited in that the plate current is restricted to tube limits, or it would smoke the tube or worse. Therefore a tube is a high voltage, low current device. The power rating (Ohm's law) is Power (in watts)=current x voltage, or P=ie. Transistors are technically not current-limited, being low voltage, high current switching devices. Even thought the output wattage may be exactly the same for both amp types, the ratio of current-to-voltage to arrive at the same exact power output is entirely different. DM

Shawn, if you have fuses, try it for yourself. You've got Khorns, right? {edit} Shawn, if I remember correctly, you're running an active crossover, so nevermind. Al, I suspected as much, I could sense the mischievous delight in your emails! Dana

Shawn, I don't know what to make of that, the speaker/network is a reactive load and is constantly changing its overall impedance. Add to that the vagaries of the autoformer, and who knows? I once demoed a stock ES with the fuse in place and then jubped around the fuse with a piece of short 12 ga. speaker wire for a friend who used to sell speakers for a living. He agreed with me - took about 1 second for him to make up his mind. The difference is in "clarity" and how the soundstage is "presented". One is preferred over the other, that's for sure. I use the term "clarity" in a manner which describes a degree of openness and precision compared to a constrained or congested presentation. This experiment convinced me to permanently jumper around the fuse holder with good copper speaker wire. But I don't want to solder on something I just paid $900 bucks for! The next pair of ES xovers I ordered, I specifically had Al leave out the fuse completely. As far as gaining some form of driver protection, as I said earlier, I've owned more expensive speakers, and none of them had fuses. Here's a quote from PWK concerning fuses: DM

Shawn, I'm using a Mac MC300. Al, just rattling your cage a bit! BTW, my custom ALK-ES's without fuses (OMG!) are doing JUST FINE! Dana

Well, I don't think the Jubilee bass-midrange crossover point has a great deal to do with the size of the monster horn on top, at least I don't see it. A super-wide conical high frequency horn, broadcasting into a larger 90 deg. conical horn (e.g., the corner), it would seem to be more of a diffraction-reducing effort, IMO. Yes, I agree that it is associated with producing a continuous wavefront, but that it doesn't seem to have anything to do with where it crosses over with the bass horn. DM

If anyone thinks they need a fuse, they probably should have one. I am not a fan of fuses in the signal path, and I have my reasons. Hopefully, someone will also test it for themselves and post their findings. DM

Yes, but the point is that the Jubilee crosses over MUCH higher than what is being discussed (200 Hz) and look at it! Is nobody listening to me? DM

Here's whats happening with the fuse thing... 1) any change in wire diameter to a smaller diameter and/or differing metalurgy increases resistance. Resistance (heat) is what the fuse relies on in order to work, and that means it has a resistance to current "built in" to start with. 2) friction-mounted fuses have an air-conductor boundary with MUCH less-than 100% electrical contact per area. Any air-to-conductor boundary adds resistance, as well as being subject to issues of humidity, dust, air quality, etc. Add to that the nature of conductivity in the steel holder and the ends of the fuse, not so hot and it's not copper, so you are jumping current from one conductive element with a certain set of coefficients to another from a solder joint via a friction fit to another and then to a solder joint and back to copper. Even so, simply replace the fuse with an short length of copper speaker wire (at least 12 awg; double it up if needed) and listen to the difference. That should get you started. If you have quality horns (like Klipsch, etc.), you should be able to tell. 3) additional solder joints (2) - you don't need them in the circuit, and the more solder joints in the circuit, the less conductivity, solder is not a 1:1 conduction compared to straight copper wire, but it's certainly better than a friction joint exposed to the air. 4) protect the woofer (that's where the fuse is) against what? Overdriving? Catestrophic amp failure? In 40 years of audio, this has never happened to me. None of the other commercial speakers I have ever owned (ADS, Kenwood, SL, KEF) have fuses in them. If they don't need it, why would Klipschorns? I think that fuses in the signal path are for PA and other high SPL work where fidelity is not the main concern. Don't simply take my word for it, try it for yourselves. I don't want to hear from those who haven't tried it for themselves but want to argue about it anyway. DM

Take a big thick piece of wire and jumper around the fuse and fuse holder, you don't even have to solder to make the determination yourself. Just use "good" speaker wire of decent diameter, 2 or 3" will be enough. Take the fuse out and replace with the wire. This will be enough for you to determine the difference. DM