D-MAN

Gil brought up another great thought-provoker concerning corner loaded mouth size: I figure that the apparent mouth to be 1/8 the calculated size of a straight horn mouth when corner loaded. This is a kluge, but seems to work. Normal straight horn rules-of-thumb get kind of "seriously modified" when it comes to folded corner horns... However, I have read that corner loading produces EIGEN-TONES which are supposedly not good. What the heck is THAT? Khorns sound great to me... am I missing something? DM

Hi, again. Gil was right: As far as placing the 2-driver throat openings further "up" the horn as compared to the single driver version, as long as the cavity opening effectively doubles the orig. single opening at the appropriate expansion point in the horn, the geometry and expected performance of the horn is retained. So this does not alter the horn's fc. I was wrong on that point. 2 drivers doubles the efficiency which is reported in the single driver version to be approaching 30% if I remember correctly. So effectively, you have to double the midrange and tweeter horns and drivers to keep up with the bass output. Maybe that's the reason PWK didn't manufacture these! The back chamber volume is up in the air for me... since we are not enlarging the throat area or the horn geometry then I assume that no changes are required for the back chamber since its effect is to match the resistance of the air in the exponential horn itself to provide equal motion of the cone front and back. So perhaps no changes are needed here, too. The doubling of efficiency would have an apparent effect on the rolled off bass freqs, but the overall response curve of the horn would not change. It would just be louder at the same given wattage, and by being louder, the "rolled off" low freqs below the fc would also be twice as loud. But they still get rolled off below fc proportionally. Altering the horn geometry to lower the fc is the only way around that. I would also estimate the 2-driver version to have far more PUNCH (twice as much) compared to the single diver unit and with a double set of upper horns, the transients could kill. Perhaps that is what you want as there is not much lower bass available on most music source material that is not single-note bass (for cars) or "noise" and/or "sound effect" on a movie soundtrack. I'm sure that the 2 driver version would definately kick some serious tail from here to next week. BUILD THEM and THEY WILL COME... DM

Well, dudes, take this all with a grain of salt. GIL: You are usually right about things (and might be, after all), but I feel the need to explain and clarify my point and in this case, (GASP!) refute yours. I have read numerous times that the LF waveform is propagated most efficiently by a slow (for a low fc) and mathematically steady expansion rate from a given throat size (which is integral in determining the expansion rate and efficiency for a particular fc) and the subsequent length of the horn to the mouth and one cannot shorten the horn by simply moving the throat opening around and get the same result; if it worked that way, the Khorn itself would be quite a bit smaller in size as would all horns. Of course, the size of the throat would have to be increased at the point that we are considering for the 2-driver version, but the cone size in question would be the controlling limit on that. I think that the horn area cross-section at that point is larger than the available cone area. I am assuming an unaltered Khorn dimensioned horn, as dimensions are not specified in the diagram. None-the-less, I will stay with what I said in the previous post. But as always, you bring up a good point, so I will have to chew on it awhile and do some research. MUNGKIMAN: Agin, just a guess, but if you go with dual 15" drivers, you should theoretically be able to just power your way past the low freq cutoff point to a certain extent at least more than a normal Khorn does. PWK published an article about horn low fc as not being an absolute limit. But I don't think that you can find a good pair of 12"s that could for as little investment. My final bit of reasoning: If it out performed or even came close to the performance of the Khorn, and it is certainly easier to build, then why did PWK continue to manufacture the more difficult design. I rest my case. DM

Don't think that I am against this project, as I am not. I am just postulating some possible performance issues based on some experience with building and researching horns on my own... Some more thoughts about the 2 driver version... There are a couple of drawbacks to this approach; it appears to be a modification of a previous and proven design, and is not a true "purpose-built" design from the ground up. It has cut some corners, in other words (pun intended!). I'm guessing but the possible results of this could be (and this is probably a worst case): (1) a "less" smooth response in that the remaining exponential horn is not as long as the expansion rate would suggest. Essentially, the expansion rate is for a longer horn and this design just "chops" the front part off. This usually produces "peaky" or uneven bass response. (2) higher low-frequency cutoff (fc) due to a throat/length/mouth mismatch due to expansion rate and length of horn not being "correct" for a 40Hz fc horn (which I believe that the horn mouth and expansion rate would suggest). (3) higher modulation distortion due to restricted size of back chamber ; however, insulative material can effectively increase the "apparent" size of the BC by a factor of 1.4 times as large as it really is, so that might be used to counter this effect. In the 2 driver version, I wouldn't think that the back chamber volume is capable of supporting the use of 2-15" drivers as the effective throat area would also be doubled (I believe that the formula concerning this is in the patent, too); rather it may be better with 2 - 12" drivers otherwise the fc of the horn would be raised even higher (when too small of a back chamber area is used) considering the throat opening sizes on the 12" drivers to be substantially smaller. Additionally, more mid-bass and mid-range waveforms will be transmitted through the horn in that is is shorter (than the traditional 1-driver version) and has less FOLDS to contend with. Also when using 12" drivers, this could/would be even more exagerated as they would probably have a higher natural upper-frequency cutoff (or ability) than a 15" would. This would, in turn, effect the design of the crossover points and efficiencies of the upper frequency lashup employed. Thirdly, where would you get a pair (or 4 total) of 12" drivers that can perform adequately in the horn? The 15" has historically won out on this point... in that the Klipsch K33E is $130.00 each. I wouldn't want to settle for less than nominal Khorn performance if building such beasts- they are already the same size, etc... But, I am all for DIY projects! Please proceed and let us know about it! It does look very interesting! DM

Howdy... The point of the patent's 2-driver version was to provide an increased power-handling capability (and output) than the single driver approach. Remember that the patent was from 1946 when tube-driven wattage was expensive (it still is!) and the ability of drivers to dissipate heat was limited compared to todays standards. I think that special mention was made in the text to provide a more-powerful version intended for theater and large format use. In the patent, PWK also mentioned using a single larger driver but the patent drawings seem to all feature the 12" variety. The drawings faithfully represent what we know today as the "Klipshorn" which survived 50 years without serious design changes. Many other designs have been attempted and marketed; but they have all gone extinct... In the case of the 2-driver version, the shortening of the exponential horn would theoretically raise the fc of the horn, i.e., it would not go as low as the single driver version which utilizes a longer horn but having double the throat/cone area and the natural coupling of 2 woofers would more than make up for that in raw output horsepower. Since the bass output would be greater the midrange and tweeter setup would also require higher output to keep up with it, again not intended for smaller spaces. Within the bandwidth that it would reproduce, it would be louder than a single driver, of course, and have twice the power-handling capability of a single. DM

Just a guess, but I would think that if you were "slappin" the cone against the motor board hard enough to prevent cone movement to the point that it was going to overheat, you would definately hear it slap before it eventually fried the VC... but then again, who knows, that would be some LOUD stuff anyway, so you may not hear it first... I would also guess that the cone itself would display some marks of the compression against the motor board in such a case... but then again, who knows... Its the age of the woofer that I am keying in on. Things get weird when you (and your speakers) get old! DM

Gil, you are right. I always wondered where Klipsch got the extra back chamber area (I've read approx. 4800 cu.in. total) but couldn't see how if the baffle board did not have cutouts in it. I've only seen the SpeakerLab plans until now. Good observation! DM

Mike, looks like Western Washington state... Oh, hell, it could be anywhere, but looks familiar. DM

There are a couple of reasons that the woofer could bite it: 1) there is a physical obstruction in the air gap. This is the bain of DYI, sawdust or some other obstruction although typically you would (or should) first HEAR bad things before it truly fried. But not always. 2) the insulation on the woofer voice coil wire will eventually fail due to age, that is why most older tube amps require new transformers (they fry) when heated up after a long dormant period. The definitive test involves an Ohmeter check. If the voice coil measures anything other than 3+ Ohms then it is either shorted or open. If open it may be due to an obstruction or scraping. If shorted, probably an insulation failure. (Those are guesses). Whether obstructed motion or age-induced insulation failure, it would explain the reason that the mid and tweeter remained unaffected by the source signal which most likely was within nominal operational conditions and had nothing to do with the woofer biting the dust. DM

Oops. Messed up; the Hartsfield patent was 1957, not '59 as I stated previously. Sorry.

I'm a believer in speakers requiring a break-in period. As a matter of experience, I figure horn midrange compression drivers take the longest (about 48-72 hours total) using normal music at normal volume. They usually sound quite harsh at first but will eventually smooth out a bit; I think it is entirely mechanical break-in. I figure about 2 weeks of "normal" listening periods, that is, not leaving them running overnight, etc. Tweeters are not as intrusive to me as the midrange sqawkers. I don't think that they move enough air to be much of a problem. I regard the break-in on horn tweeters as negligible. The woofers don't seem to be effected much, although they mechanically move the most. Maybe the bass-end of things are not as easy to hear as the uppers. I've heard of people putting the speakers face-to-face out of phase so they cancel each other out and running the same cd track set on auto-repeat overnight at loud levels and stuff. Never did it.

Hi, ENDOVER Forgive me, guys, I am going to make some GENERAL STATEMENTS about feedback and lack thereof, and these are ONLY my opinions, so take with a grain of salt: One simple thing to remember about amplifier operating "class" is that in most cases (except A), negative feedback is applied to reduce distortion at a given wattage output and promote a wider frequency response than would be possible without it. The relationship of frequency bandwidth, distortion level and overall output gain (wattage) are all modifiable via the use of feedback depending on the circuit type and design, so cannot be assigned as either good or bad. There are some cases where class A (which has no feedback) is not capable of 20-20kHz or wider response without producing more distortion than other classes of operation. This is not necessarily a bad thing; tube amp distortion is regarded as much more acceptable than other operating class distortion in some circles; however, in regards to Class A such as a Tube SET amp the distortion will typically be higher than another type of amp with the same bandwidth capability. These things all trade off. The AB class operation typically produces the most usable wattage with the widest frequency bandwidth at the lowest distortion for a given output stage and is therefore the most popular. It is also the most stable in that the stage is not driven beyond its operational limits in "normal" operation. I am not saying that one is better than the other, only that these elements make up an engineering compromise (i.e., a balance of things) that like all things in our hobby are more a matter of taste and application than "hard and fast" rule. DM

Some food for thought... I may be all wet on this, but here's my experience with irritatingly bright frequency response. If you move around and the sound changes drastically or sounds better in one place than another, its the room, not the system (if the sweet spot is not where it should be, etc). Granted it ALWAYS will sound different if you move around, but we are talking about the "sweet spot", i.e., where you sit and expect the sound to be the best. If your system is ACTUALLY producing (or preproducing) harsh sound electronically then it will be more "harsh" spread around the place a bit more than would be expected. I would not think that this would be the case, although Khorns will certainly reproduce a harsh waveform as accurately as any thing else. I run my corner horns "flat", i.e., zero bass or treble boost and/or cut and "treat" the listening environment to prevent upper frequency reflections as much as possible, which are probably the problem especially if you are noticing a "bite" or harshness to the upper frequencies; another indication of this is an indistinct "sound stage" or indistict "imaging". Actually rather than trying to boost the bass end which is not going to cure any of the above, I would try to reduce the mid/tweet REFLECTIONS first. This could be a simple mechanical issue that has to due with room absorbtion characteristics, reflectivity and modal effects due to architechural elements in the listening area including the dimensions of the listening space itself (reflection induced mathematical frequency doubling or halving, aka: "modes", etc). If you can't control the room first, then how can you control the speakers? I think horns tend to be particularily touchy about environment more than other types of speakers due to 2 things: (1)dispersion characteristics (they are designed for max coverage and sit against a corner and therefore are more subject to wall reflections due to the combination of proximity to each wall and wider dispersion than most direct radiating speakers) (2)efficiency (they are much more efficient so tend to exagerate the rooms deficiencies sound-wise) So I have found that I tend to try to "equalize" the room rather than the system... Good luck DM

Craig, keep it up! Six or seven years (I forget) ago I bought some mail-order-only Sound Valves M60 (60w ea 6550 switchable) monoblocks that look very much like yours (except all metal chrome chassis, metal cage, and the guts, of course). The company apparently is now out of business, I think, at least the URL is dead. The amps, however, are still very much alive. Granted that they were/are not hand-made and therefore may not be as good in quality of performance as yours, but I paid $1000 each at the time, so that is right on the money with "your" competition (I presume your pricing is for a pair - forgive me if I'm wrong) based on raw wattage. They later went up to $2500 a pair. It is sort of risky buying a completely unknown product, but I wanted big watt glass and couldn't afford anything else, so I took the risk and it worked out. So there are people like me who take these risks out "there". If you offer a money back guarantee for a given period (I would say 30 days), then I would think that you could sell enough of these things to make a living, especially with an internet site of your own taking visa cards, etc. I for one would be interested; hand made is a good thing. Sort of like buying a painting when you know the artist; makes it all the better. Best of luck and keep on going. DM

DUDE, I got a rant about CD players here: the price range in question limits you to the dreaded and infamous "CHEAP JAPANESE CONSUMER ELECTRONICS" of which I would recommend staying away from if at all possible. I have read the hype about the Marantz something63, etc., checked them out and thought they were irritatingly shrill and nasty (on otherwise good gear) with NO ABILITY to reproduce "depth" or anything approaching "sound staging"; it was so bad that I knew that the hype was a just marketing ploy. Really, go out there and compare this japanese stuff in a good stero shop (i.e., not at the GOOD GUYS) where you can hear the differences between them as compared to something at the 1500 dollar range using the same CD on the other wise same gear as a reference. Another example, I had a new $500+ PIONEER ELITE cd player that crapped out and died within 2 months out of the box. Drawer wouldn't open, etc. That was the last piece of JAPANESE "product" that I will ever buy! I will guarantee that you get far less than you pay for. Ok, I'm done now. I would recommend buying used ENGLISH, AMERICAN or CANADIAN if you can. Way better sound and build quality. Even on the budget stuff. DM

The anti-freeze CD pre-soaking worked better when it was still POISONOUS, I think... Oh, for the good old days! DM

Hi, John. I agree with Greg. I got an McIntosh setup for stereo (my listening priority) and an additional cheesy AV receiver for HT that has a pre-amp out on it (Denon - cheap). That way I can run the AV pre-amp out to the Mc preamp for the 2 mains without hassles. The straight stereo gets much more use with me also, so like Greg said (more-or-less), I would spend my money on the stereo first with an eye towards as much quality as I could afford. HT receivers are pretty lousy for quality listening, in my opinion, with the possible exception of Yamaha which seems to have a better build quality than the other imports. DM

Yeah, Gil. The highlights of the patent were that a single full range driver was available that used a metal horn "adaptor" to mate with the bass horn mouth as a rear-loaded lower cost version that could be upgraded by the owner at a later time by purchasing the midrange/tweeter driver and horn along with the larger woofer to be monted directly in the bass bin. The patent also specified that damping material was installed inside of the metal adapting horn to prevent upper frequencies from being transmitted. This was a major point, but only effected the rear-loaded version. The patent-version Hartsfield looked like a nightmare to build, but it is an exceptional example of ingenuity and market savy. I took some of these qualities to heart when I did my design. I ended up with a top-loading Khorn (more or less) that could do the same thing so I could experiment and tweak. Don't know of anyone else that has them! Hell, I would have bought a Khorn flat kit, but couldn't find one. I don't think that I'd want to try a Hartsfield flat kit... But a Khorn flat kit - Why aren't any of you guys selling those?! DM

3d-zapper, It is my guess that, in general, woofers are more apt to fail for exceeding excursion limits in a "normal" baffled-type direct radiator enclosure where the cone is free from restriction. In the case of a Khorn, its probably a combination from being prevented from excessive forward excursion by hitting the motor board on the front (I've heard this called "slapping") and over-excursion towards the basket in the other direction; the result is that heat build up in the voice coil will eventually fry it unless cone tearing occurs first. Whether the failure is to the cone, spider, or over-heating voice coil or all of the above is up for grabs. I have temporarily clipped 300 watts into my Khorn K33E's although they are only rated at 150 watts without any apparent damage (luckily). Tweets and mids are also fine. I wouldn't want to repeat it. If it doesn't damage the drivers, it certainly will damage your ears. DM

Picky's right. My Fridge turning on causes line noise on my house circuit. Electric heaters, fans, Freezers, welders, etc. all cause noise. Just imagine what a REALLY BIG noise-makin' load like an aluminum plant does on the local grid. If you think that you can't hear any noise, have you ever noticed that your stereo sounds better late at night? There you go. I've decided that ANY available filtering is a good thing. DM

Hi Guys, I have a couple of thoughts and blatherings concerning the Khorn as compared to the Hartsfield... Please bear in mind that I have not heard a Hartsfield per se but have studied a little about it. The Hartsfield was patented in '59 especially to compete with the plethora of horn-type encosures in vogue at the time (including the arch-rival Klipsch patented in '45). To avoid paten infringement, it features a more complicated folding of the exponential bass horn than a Khorn which (of course) has the tendency to color and/or limit the upper-mid-bass frequencies that it can produce. It is typically operated as a two-way whereas the Khorn is typically a 3-way. Patented as a "convertible" corner horn speaker, a single back-loaded driver version was offered to allow for the end-user to "step-up" the the full 2-way front-loaded horn version at a later time and for more money. Note that the Hartsfield lasted in production for about 10 years, and the Khorn is still in production after 50; nuff said about the labor and material costs involved as the end result did not apparently justify the means in the market place. The Hartsfield has a completely enclosed exponential horn all the way to the mouth, which the Khorn does not (it uses the walls to "approximate" the horn mouth. I say approximate because technically the Khorn begins unloading the horn as soon as the top is "cleared" by the expanding waveform which reduces the pressure and starts to unload the horn. The addition of "wings" on the top of the Khorn will serve to maintain the pressure on the expanding wave extending the horn mouth for another 8 inches (or so) on each side until the sides of the cabinet are cleared. This can be done with a single triangular sheet of plywood placed on the top of the bass bin and below the upper cabinet. This will enhance the bass response of the unit, and I believe that when done this way, the length of the Khorn exponential horn is longer (which is better) than the Hartsfield. Another favorite tweak of the Khorn is to strengthen the back reflector with extra bracing as it is only 1/2 in thick and is liable to vibrate which absorbs accoustical output at various frequencies. This mod tend to "clarify" the bass and present a more "solid" and clean bass performance. Accurate sealing of the cabinet to the walls by using foam rubber gasketing material is also recommended. The Hartsfield is shorter and wider than a Khorn and that does have an effect on the listening position to a certain extent. At a shorter distance from the speaker (i.e., closer than I would sit with a Khorn), I would think that a Hartsfield would probably sound better in the mid and upper freqs than a Khorn. But at an appropriate distance for the height of the Khorn upper-frequency cabinets and their dispersion characteristics, the Khorn would sound better than a Hartsfield at the same distance. So listening environment and especially listening position is of course important to the overall effect when making a comparison. I would also imagine that the Khorn is slightly more efficient than the Hartsfield in that the Khorn bass horn has less foldings to navigate when the same drivers are used. The Harsfield also used/uses a novel aluminum horn attachment that looked like some sort of a wave guide protruding in front of the upper frequecy horn. Note that this is no longer available; I wonder about its sonic value, but it gave the Hartsfield a distinctivly cool look. But cool looks aside, it still went extinct for a reason. One more element of comparison; the back chamber area of the Hartsfield is substancially smaller than the Khorn (I am assuming a 15 in. driver). This would indicate a higher Fc than perhaps one would expect in such a case (read that in a Klipsch patent). I would guess that pound-for-pound a fully tweaked Khorn can successfully compete with the best there is and do it for a lot less wallet. DM

It sounds like an intermitant connection that is subject to environmental conditions (vibration, humidity and/or temperature). To actually track down and pinpoint the problem will take some experimentation. To look for the cause, if it is temperature related, does it happen more or less when the unit is "warmed up"? If it is humidity (harder to track down) related, I would expect that the snapping occurs less with higher humidity (i.e. better conductivity across physical gaps). Voltage would also effect it as again higher voltages should jump physical gaps more easily. Some general electronic stuff: 1) corroded i.e., oxidized solder joint ; this is the most probable culprit. Lead solder oxidizes faster than copper wiring. It can act like a cap, with current building up and then arcing across the oxidation (dialectric) exactly like a capacitor. Determining its location will be the hard part. Look for wiring points on the output end of things, start at the speaker connections and work back from there. The fix is to clean the joint down to the bar wire and re-solder. 2) Capacitors can be induced to discharge inappropriately when old or when an oxidized solder joint was involved (the oxidation changes the resistance). Old oil caps are the worst. The fix is to replace, but I would go there until I was sure that the problem wasn't a oxidized solder joint. However, if a cap itself is bad, it should snap constantly, it should not be intermitant, so that's probably not it. 3) Potentiometers ; used as trimmers, these can change dimension with age, oxidize (or both) and become more susceptable to environmental conditions and thus change resistance, which could induce a cap discharge when it is undesirable; this would be more difficult to determine. Volume pots can also be subject to dust, which is a conductivity problem in itself. Blow out all pots with a vacuum on reverse. This will clean dust out of the chassis too. Dust is always bad. 4) Oxidized wires ; that's right, copper or any of its alloys oxidize even under a rubber coating due to contact with oxygen. This creates resistance when there should be virtually none. Rare, but if I couldn't find anything else I would go there next. Good luck DM

here's some possible issues worth chasing down: 1) grounding issues - if you are using a different outlet, it could have the ground wired incorrectly providing that your EQ has a 3-pronged plug. In such a case a 75 cent two-prong adapter can eleviate a questionably grounded outlet. Ground the chassis independent of the outlet in such a case (or just let it "float"). Except for surviving a lightning strike or other such electrical mayhem, it will work. I have an amp that is very touchy about grounding, but the rest of my components don't seem to care (some only have 2 prong AC plugs anyway). I have one more question about the outlet in question: is it nearer to the refridgerator or other source if AC noise in the house circuit than the previous one? This could be a source of noise, but not usually humming. Just a thought. 2) cabling problem - perhaps a susceptable interconnect cable is placed too near a source (usually a power transformer, wall wiring, ect.). A worn or broken cable can become "suddenly" susceptable to outside interference. Try different cables and placements thereof. 3) apply a ground wire to the chassis of the humming component if it doesn't have one already. Ground it to real ground such as a drain pipe if your outlet ground is in question. This need not be permanent but can serve to indicate where the problem lies. Good luck. DM

In my experience, most solid state amps can accept the 16 ohm load without problems, even when a 16 Ohm tap is not present. That is, "most" SS amps. If you actually are contemplating driving the amp full out, the extra power handling of a series hook up is a safe approach from the speakers point of view, although the actual accoustic output will be somewhat lower than a single 8 Ohm lash up. It doubles the power handling capabilities of the speakers. To see if the amp is going to have problems, I would check to see if the amp has a "direct" out or uses an output transformer. In the latter case, there might be a problem because the 16 Ohm load will draw more current from the amp, causing excessive heat in a mismatched output transformer. Probably not a problem at reasonable volume. If no output transformer is present then the output transisters connect directly to the speakers and match the impedance. It would be rare (but possible) for direct coupled output transister stage to find a 16 Ohm load unnacceptable. Try it and check for increased heat at the output stage as you will be running double the current that an 8 Ohm load uses. If it doesn't get excessively warm and it sounds good, then you are good to go. If there is any degradation the the sound quality, or it starts to smell "hot", turn it off immediately or it is going to fry something if it hasn't already (itself or the speakers or both). It should take some time to ensure that the heat-level remains constant and you feel that it is indeed "safe". The 16 Ohm lash up is common amongst musicians for mixing and matching PA and music amps to a variety of speakers for exactly the same reasons. However, you may find that a 16 Ohm lash up is not required; I have 150 watt rated speakers and they can take 300 watts in short bursts with applomb. Good luck, DM

Howdy, I have the Monster "one-eye" job that I like, but only for the video gear and audio pre-amp. I bagged using it on the CD player and it really is inadequate and inappropriate for the main power amp. However, as long as you do not run a power amp with it (it limits the available current) I would recommend virtually any conditioner as better than a simple power strip. Note that you may hear a very frequency "thing" ; I cannot accurately describe it, but it is there. It seems to me that a slight "whitening" in the high end occurs that I find annoying but regard the surge-suppression capability as a valuable commodity. DM