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

I am playing the cello myself on amateur level, and I am actually spending more time on that than listening to my khorns+laScala setup. To Marvel, you risk to get hooked on it, and if you find it expensive to have hi-fi as a hobby, then you should try the cello... A very good site for cello lovers is www.cello.org with its chat rooms. I find personally that Starkers left hand is less impressive than his right hand, and as an extreme example you should try to compare his recording of Kodaly op. 8 with that of Paul Tortelier, I find the latter much better. There seems to be a certain geographical tendency to prefer the nearest, as the Americans seem to find both Starker and Rose as being among the best, where most of us here in Europe (sorry Greenland) find them to be among the nextbest. There are so many really good cellists who are less known, as also the classical music suffers from too much PR for a few names. The greatest in the last century was in my mind Emanuel Feuermann who was the equivalent to Heifetz on the violin, but he died much too young in 1942. A few lesser known names: Mark Drobinsky Arto Noras Erling Bløndal Bengtsson Truls Mørk Miklos Perenyi (spelling?) Milos Sadlo, whom I knew personally Then there are a lot of chamber music players, especially in string quartets and piano trios, who are just as good but mostly you do not know there names, only that of their ensembles. You should give it a try. Søren

There is a general confusion about the class T principle, and it seems to me that Leo and I in this forum are the only ones who have worked with it since it was introduced in the audio field. I might be wrong in the following due to much secrecy and complexity involved, but the following is as near to the truth as I can get it. It was created in the days where Shannon and Nyquist were developing information theory and the second world war further accellerated the evolution. The idea was to use frequency as the variable and keep the amplitude constant but not as in classical FM modulation, as the frequency variations are far bigger than the signal bandwith and the relation between signal and output is more complex. Used in a transmitter it had a strong cryptographic effect as there is no defined frequency where you can listen. In the class T version the frequency swing is somewhere between 100kHz and 2MHz. So I think it is easier to say what class T is not: It is not a PWM, there is no fixed clock frequency It is not even necessesarily a digital amplifier; but is a classical tape recorder with HF premagnetization digital? In the time domain yes, in the amplitude domain no. This is just to visualize that the difference between digital and analogue is not always obvious. What it is a little bit more, or behaves like, is a FM transmitter. You can easily hear it with a Short Wave pocket radio if the amp is not well screened against HF radiation; much care should be taken making the layout. ----------------- Some of us are fascinated by this way of thinking and try to take it to its full potential, I also have an idea of how Tripath could make it even a little bit better from a high-end audio point of view. I think that the most fruitfull way of thinking at it, if you want to understand its nature, is to use the thesis of Thevenin: That anything in this electrical world can be seen as an EMF in series with a complex impedance, and instead of thinking at the EMF as most peple do, you should think more at the nature of the impedance. Søren

To Larry and Leo, Larry has probably heard a Strad several times without realizing it, as most of the more important american orchestras each have several. It is estimated that Stradivarius made about 1200 instruments including lutes, gambas and other things. Today there is left after my memory 50-60 cellos, 12 violas, of which many of them have been planed down as they were too big for modern playing, and about 500 violins. But many of the important players today are also playing on modern instruments, as Fritz Reuter says: 'Stradivarius made new instruments', and I will add, that with a few exeptions they are all modified to modern playing, such as longer neck, greater neck angle, stronger bassbar etc. Stradivarius was highly estimated in his own lifetime, actually very rich, could always buy the best wood, and was in a good circle his whole life. By the way, was the necks on the two cellos equally long? That should be very visible also for an untrained eye. The good modern makers exist, and some of them also take money for it, more than 40 000 USD for a cello is not unheard of although more than average. Interesting information can outside one meter of my bookshelf be found at: www.cello.org Catgut Acoustical Society a special copy of Scientific American and many other places. In the last couple of years my biggest instrumental surprise has been the effect of using metallized rosin instead of the classical kinds. They are much more linear in the response, friction as function of pressure, so if you master it you can play with a bigger dynamic range, less noise and with more different colours. It is like a hi-fi problem, or as a car analogy, it is as going from a normal car to a Lamborghini, more possibilities but dangerous in inexperienced hands. Søren

Good post, Leo, as I understand it, Ma was actually not playing on two cellos, but a viola da gamba and a 'modern' cello. The principal difference between the two is that the former has no sound post (supporting pin) and the latter has. Thus the big difference between the sound of two instruments. The sound post, french l'ame - the soul, creates a nodal point at its two ends, and it has not directly a supporting function, although you should not take it away with full string pressure on the bridge. I have myself a J.C. Kloz (so he spelled it, without a t) from 1771 and it is near to a baroque cello, but is absolutely a cello, not a viola da gamba. One of the problems in the last couple of hundred years is that that kind of music went out from the small chambers out in the large concert halls, which has pushed the musicians, including amateurs, to go for more and more sound, sometimes at the expense of beauty and ease of playing. -------------------- This winter I was at a concert, or more correctly a public rehearsal, outside Paris, where Paul Katz who played 26 years in the Cleveland Quartet worked with the Castagneri Quartet on Schubert 163 C major quintet, first movement. This was the first and probably the last time in my life, where you could get this masterpiece exactly as you wanted it, provided you could define it! The Clevelanders had played it with many important cellists, Starker, Rose, Rostropovitch and latest Ma, and and an important point is, 'the foreign cellist should always play the second cello' if not, much more rehearsal time, less satisfying result. With Ma they rehearsed 3 hours per day over a long time, played it at 6 concerts, and went then into the studio in order to record it. The did as during 'my' concert: They first played the whole thing, then they took the whole thing down to single measures trying to agree about every note. A recording manager came a little late into the studio, was shocked, and asked the recording engineer: Have these guys ever seen each other before? The two cellists also tried to compare the two celloes for the different voices, both very good and very different. Free concert and free champagne after, and we provoked them to take the second movement at last. Søren

Good post, Leo, as I understand it, Ma was actually not playing on two cellos, but a viola da gamba and a 'modern' cello. The principal difference between the two is that the former has no sound post (supporting pin) and the latter has. Thus the big difference between the sound of two instruments. The sound post, french l'ame - the soul, creates a nodal point at its two ends, and it has not directly a supporting function, although you should not take it away with full string pressure on the bridge. I have myself a J.C. Kloz (so he spelled it, without a t) from 1771 and it is near to a baroque cello, but is absolutely a cello, not a viola da gamba. One of the problems in the last couple of hundred years is that that kind of music went out from the small chambers out in the large concert halls, which has pushed the musicians, including amateurs, to go for more and more sound, sometimes at the expense of beauty and ease of playing. -------------------- This winter I was at a concert, or more correctly a public rehearsal, outside Paris, where Paul Katz who played 26 years in the Cleveland Quartet worked with the Castagneri Quartet on Schubert 163 C major quintet, first movement. This was the first and probably the last time in my life, where you could get this masterpiece exactly as you wanted it, provided you could define it! The Clevelanders had played it with many important cellists, Starker, Rose, Rostropovitch and latest Ma, and and an important point is, 'the foreign cellist should always play the second cello' if not, much more rehearsal time, less satisfying result. With Ma they rehearsed 3 hours per day over a long time, played it at 6 concerts, and went then into the studio in order to record it. The did as during 'my' concert: They first played the whole thing, then they took the whole thing down to single measures trying to agree about every note. A recording manager came a little late into the studio, was shocked, and asked the recording engineer: Have these guys ever seen each other before? The two cellists also tried to compare the two celloes for the different voices, both very good and very different. Free concert and free champagne after, and we provoked them to take the second movement at last.

minn male42, I was trying to explain why my amplifier is more expensive than the cheapest although the price is maybe 15% of the more expensive amplifiers. 1) Try to find the cheapest product on the market where Elma based attenuators is used instead of classical potentiometers. I guess that it is in preamplifiers in the 3000 USD range, but try for yourself. That it, and some other things, has an effect could I see when I replaced an ordinary Tripath whith the one I am using now; I knew it was better but not how much before my wife without being asked said: "This is really, really good". It was on our primitive system in our house in France, a cheap but reasonable CD player + some DIY one way speakers with a 5" driver from Monacor in each. Really nothing to write home about. You can imagine the difference between that and khorns, Goldmund, Orthofon Rohmann, air cushion arm, a 20 kilogram DIY preamp and so on here in eastern Greenland where I live. 2) When you are buying a typical industrial product the price of the raw materials is in the order of 10% of the retail price. The rest is distribution, marketing and other things not related to the product itself. I can keep this relation to at least 50% but only if am using really high end components. Where I find it relevant and critical for the sound quality, I use very good and expensive components; much less when I find it unimportant, but often after having builded different versions of the same amplifier. 3) Something giving a little confusion here is that probably because there is only one supplyer of spread spectrum chips on the market, that technology is always associated with the same name and people think therefore that 'Tripath sounds like Tripath', which is not the case, not more than 'SS sounds like SS' and tubes like tubes. ------ I am planning to make a better - and more expensive - version in the future, but it will take quite a long time and I do not know if the differences will be audible. In the mean time I am offering this model for test. Unfortunately I did not reach to send it to Kelly when he had the Leok version, it could have been most interesting. Søren PS. The dollar is low for the moment, take that into consideration when looking at the price.

tgourlie, I think, that if you do not know if you prefer tube or SS in that price range, then you should give the Tripath solution a try. It is based on a spread spectrum principle and is not a PWM amplifier as many believe. Leok and I have been building theese shortly after they were commercially available, independent of each other and have builded them mainly for friends, and we have the same opinions about the special problems involved, although our solutions are slightly different. We are here talking of nuances. If you are interested, I can send you such an amplifier, and you can have it for, say a month, and then you will have either to pay it or return it. The price will be 1100 USD. If you find the price a little bit high, then it is because I try to make it as expensive as possible, such as using Elma attenuators instead of potentiometers for two reasons: First, I find the principle so good that it deserves to be surrounded by the best components; second because it takes even less time to produce, and I can and will not compete with the production from Taiwan. Until now it has been the most satisfying I have tried on my Khorns and the other equipment with which it has been tested; but here, it has not been tried with everything, and I am not the right person to ask although I know it very well. If interested, then send me a mail or write it here. Søren

One of the problems about double blind test is, that they can only inform about what your counscience knows. The musical values, whatever that is, is mainly working on the subcounscious level, which has a calculation power in the order of 10E6 times greater than that of the counscious part of the brain. Therefore your subcounscience can detect differences which you do not know directly, but it can be seen i your pleasure to listen to music, blood pressure etc. My point is in general, that DB tests are more than doubtful as a tool for selecting a system or a part of it. I have in many years tried to find other ways for doing it, based on some secondary reactions to auditive stimuli. Søren

Just a little comment: Tripath is not based on a PWM principle, it is based on spread spectrum principle. Regards Søren

Just a little question: How many 'normal' instruments do you know with an output below 40 Hz? Søren