Soeren Basboell

JJK, I have been visiting DEW-4 a couple of times some 30yrs ago, so maybe we know each other without knowing it... I think you could have got the whole station for free if you promised to take it away and then you could have installed it in Ohio. The electricity we use here in Tasiilaq (Ammassalik) and everywhere in Greenland is 230V 50Hz. Maybe Thule Air Base is still using the american standard. Søren

First, I would say do not use money on it before you have found the problem. My khorns are from 1975 and I have not made any modifications on them so far and they sound very, very well. Like another person on the forum you have a serious problem so faultfinding is the solution. A minor problem I had 25 yrs. ago was no sound from a tweeter; I quite simply looked at the crossover network, loosened and cleaned all the spade connections and tightened them again, one after one. Problem solved. So that is a good thing to do, specially if you got them second hand (I bought mine as new). Remark that most of these low-tech errors will show up in some kind of assymmetry. If I understand you right, then you have: left and right, no middle and no bass; that is the perfect description of a reversed polarity. Try to change the polarity of one of the speakers, and see what happens. I have have heard of one case, where the polarity was wrong from the factory. The bass from khorns and Jubilees is different from the bass from nearly all other speakers, I will describe it as massless as there is almost no cinetic energy stored in the moving mass of the speaker. When the signal stops, the sound stops. This is opposite to what is going on in a 'normal' direct radiator. Once you have made them work properly, then think about sealing in good corners, crossover updates and so on, but for the moment your problems are of a much more basic nature, and they should be solved first. Good luck, Søren

Rodrocket, where did you get the plans? I am dreaming about building a pair for our house in France. Cheers, Søren

Jorjen, which plans did you use? Søren

I have plenty of GZ34 Philips about year 1960 +- something which I would be happy to give away, as there are fare more than I and my tube friends can use for the rest of our lives. I do not want money for them, but there will be some freight to pay. What is a little disturbing for the moment is that the Icelandic volcano has closed our airports, but if you can wait we could find a solution. And by the way, GZ34 do not last forever if they are under a heavy load. Cheers Søren

I do not know why some of you think that the solution to the problem should involve a khorn, maybe it was because I wrote a '(k)horn in a 4-dimensional corner', but that was only intended as a 'khorn inspired' horn. We all agree that a khorn is an ingenious solution for a 3-dimensional corner, but it is not for a Pi/4 corner. The question is: How should a horn be designed being optimized for a Pi/4 corner? I find that there in life is nothing more practical than a really good theory, so I am starting there. Søren

I think that I now have found a qualitative solution to the problem. First, the situation is as William described it, which means that the roof is going down to the floor in an angle of 45deg, and the end walls are vertical. If we look at a Jubilee in a normal position there is a vertical symmetri plane and the corner walls would make an angle of 45deg to that plane. Now we could reduce that angle to 22.5deg and change all the elements correspondently. It would probably be necessary to use 4 x 6.5" speakers in order to get the right flare in the beginning of the horn, delicate mounting, but probably possible. Then the whole thing is turned 90deg and placed on the floor with some spacers in respect to the horizontal symmetry. The whole thing has to be (re)calculated, but that is a minor problem. Søren

JJK, funny, we might have met in Kulusuk without knowing each other. My question is not about how to get the optimum performance from a set of khorns. I have such at set and a laScala here in Tasiilaq where I live, 20km from Kulusuk. Actually I did not really ask a question, but if there is a question, then it is of a mathematical nature: Can it be proved that there is or is not an existing mathematical solution to the problem? And if there is a mathematical solution to the problem, is there an elegant solution to the foldings which can be realized in real life (it does not have to be easy)? William is closest to understand the problem. I have no photos of the room, and I will first go to France in september. The thread was mostly started as a philosophical reflection over what would PWK have done if he had had such a room, i guess that he would have gone for the maximal radiation resistance. A khorn was impossible before PWK made it... Søren

Another thought, as the distance between the two corners is relatively small, 3 meters I guess, I am tempted do design it a little inspired by JBL Paragon in the sense that it could be made as one stereo speaker but it will be linked to that room. Anyway it is only an idea in my head, trying to transform a drawback into an advantage. Do the line separation (enter) work? I am using Linux. Søren

Thanks for the answer, but I my approach differs a little bit. My main argument is that every time we reduce the radiation angle by a factor 2 the radiation resistance goes up by a factor 2. Thus: Free air - 4Pi Traditional corner - Pi/2 '45' corner - Pi/4 The idea is that in a '45' corner the radiation resistance is 16 times greater than i free air where it is 'only' 8 times greater in a normal corner. In other words, if such a horn can be made, it could either go a little octave deeper for the size of a khorn, or it could be considerably smaller for the same low frequency performance. I am personally convinced that if PWK had lived in such a room for some time, his thoughts would go in the same direction. Søren

I am a little disappointed that nobody seems to be interested in this problem or solution. In this forum we normally have a set of khorns, how do we create two corners? Here I have two corners twice as efficient as normal corners, how should the horns be designed in order to benefit from it? Søren

In 'my' room in our house in France one of the walls goes down to the floor in an angle of 45 degrees. That space can not be used for much, but since we made that restauration of the old house, I have thought of theese corners with a room angle of Pi/4. So now I am obscessed with the idea of designing a (k)horn for a room angle of 45deg allthough it is doubtful if I will ever realise it. Søren

It strikes me that the problem could be of a completely different nature. Have you tried to listen to the signal coming from the power amp through another pair of speakers or even headphones? In surprisingly many cases where I have helped people with trouble shooting bad connections or even a turntable without RIAA correction. If I am reading the previous posts correctly, you have not controlled that the output from the power amp is healthy. K-horns are extreme 'live' speakers but they have to be fed with a healthy signal. I too have had them sound lifeless, but the problem was long before the speakers and easily solved. Søren

In my mind by far the best solution is a class T amplifier as among others Leo and I are making them. They are very stable and easy to use which is not the case with valve amplifiers (which I also love and build), and they are on a very high level. Other amplifiers might be different, but none better. Room threatment is important too, but it is really the electronics which make you loose you appetite for music as the brain can not correct for the more nasty kinds of distortion found in amplifiers opposite to room resonances. All these thing you can play with when you get more experience, but you are completely correct when saying that for now it is the electronics and program source which count. Be sure that the horns are tight in the corners. Søren

I prefer the primitive Antex with or without a vario transformer. Like some of the others they can deliver a lot of heat without raising the temperature, which I find is a problem with the thermostat controlled systems at least from my experience. They are very cheap too. If you are building hardwired tube amplifiers, then chose a big tip, buy a little collection of different tips. Søren