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Al, Could the problem relate to the stock tweeter which has a fairly poor upper frequency response and output above about 17kHz? By running the tweeter 'open' it may be an attempt to compensate for this response. I know that one cannot necessarily hear these high frequencies in isolation, particularly as one gets older. However, the harmonics and interaction with clearly audible frequencies will be readily apparent. I wonder if this problem would apply if the Selenium tweeter is used with its smoother, extended frequency response? Nick

Al, I think that you have answered why many are happy with the Beyma. We simply do not listen at ear splitting levels. A combination of family, neighbours, room size and individual tolerance to loud music. I know that in my listening room, a sustained level 100dB+ would be unbearable, that the room acoustics would make the whole experience intolerable - and I think that IM distortion would not be the major consideration. Nick

Al, Please help explain a few things as I only have a vague understanding of the measurements that you made: The frequency plots for the 5 drivers would indicate (to me) that the Selenium driver has the smoothest and most extended response, followed by the Beyma CP25. Am I correct, and is this extended resonse one of the reasons the Beyma was recommended over the K77? From what I can understand, the IM distortion plots show that the K77 is not too bad, and the Selenium is the best compromise unit for frequency response and distortion. The K77 distortion seems better than the Beyma (I think) - why did noone really notice this? I have the feeling, which is how you always qualify all your findings, that our hearing does deceive, but more importantly, IM distortion at most listening levels is concealed by music quite effectively except in very poor quality drive units. I have lived with 1st order crossovers - type A and the dhaxovers, homemade - for several years without being entirely happy. I recently moved over to your universal design and the khorns sound so much better at all volumes. Besides reducing drive unit overlap, I have the feeling that the steeper crossover on the tweeter is reducing distortion in the Beyma. Am I correct in thinking that a steeper crossover will help reduce IM distortion as less energy at lower frequencies is reaching the tweeter? Will the sensitivities of the B&C and Selenium units necessitate the use of your tweeter attenuator which I already own but do not at present find necessary with the Beyma? Al, I can see that you are going to cost me another pile of money in upgrades if you are correct. Nick

Al, No such problem. The sides are not a constraint at all as to how much the top can be angled. Keeping the sides makes it easier to finish the appearance with either a new top, potentially using the existing top panel but brought slightly forward in relation to its previous position, or to use a capping strip for better appearance. Whichever option will still be a lot less expensive and easier to implement than false corners if one has suitable room corners. Nick

This modification does not break the seal to the bass bin. If you look at the photos, the lower panel and recessed divider between this lower panel and the mid/treble section remains unchanged. I have only loosened the very top section for adjustment. You may have found that the manufactured layout is better if, as you say, the bass seal was broken. The other factor I have found is that the degree of angle adjustment required is probably less than one would apply for an ordinary box type speaker. There is also some scope for adjusting the vertical angle so the units can fire slightly downwards to the listening position. And all the changes are completely reversible with no detriment to the loudspeaker. Nick

And one last photo. Once I have finished off the top in some way, the khorns should look a lot better than false corners. The amount of toe in or out that is possible is more than enough for any room that I can imagine. I also like the idea of leaving the top open - it allows for easy access to the crossover for that final bit of 'emergency' crossover treatment...... Nick

Another shot.

A photo of the modified khorns. No top or capping is in place at the moment to give a better 'finished' look.

Al, Will your universal crossover need to be modified to handle the new driver? At present I think you have a 12dB slope at 6kHz on the midrange. With the K55 this is certainly alright as there is a natural drop-off above this frequency. My K55m seems to have little audible output above this frequency. Would a move to 18dB slope be better with the B&C driver to allow bettter integration with the treble (which already has an 18dB slope). Otherwise I can see that it may require your extreme slope crossovers. This is just speculation based upon the specs and frequency response of the new driver. Nick

Am I correct in saying that positioning the tweeter capacitor after the midrange capacitor - at its output - maintains the constant impedance characteristics of the dhaxover and alk universal crossovers. If the tweeter cap (or tweeter circuit in the alk) is connected before the midrange cap, the impedance will fluctuate by a certain amount in these crossovers. Nick

Jay, I did think about this option but decided to try the alternative as it would probably look better. Either method is possible and better than false corners in many circumstances. Hopefully either method will help khorn owners make adjustments to improve sound. The surprising thing is that it only takes a small degree of change in angle to bring everything into better focus. I will try and post some photos with toe in changes.

Al, The B&C driver looks very promising. Does the extended frequency range to about 10k offer an opportunity to set the tweeter crossover at a higher frequency. From my very limited knowledge of loudspeaker and crossover design, this may be a good thing.

Why can't Johnny 5 decide for himself which driver sounds better? Al has never claimed to have golden ears and, as far as I am aware, has never claimed that the B&C unit sounds better or will sound better. What Al has made quite clear, even for the simple minded, is that a driver with 118dB sensitivity will prove difficult to match - not necessarily impossible - with the other drivers in the Klipschorn. There are alternatives with a more suitable sensitivity. Otherwise a new design auto-transformer will be required with the necessary range of taps.

Having owned Klipschorns for nearly 20 years and not having ideally dimensioned listening rooms, I have found my enjoyment has always been tempered by the knowledge that I could never optimiise the toe in or toe out of the mid/treble horns. Adjusting distance and seating height showed the differences in sound that could be possible. I did not want to build false corners - too much like hard work and in any case, my room corners are fine. The solution I have recently implemented, and perhaps others have found, is so easy and flexible and has let me finally feel that the sound is not compromised. Firstly remove the top of the mid/treble unit. Unscrew the top unit from the recessed stand-off. You will need to unscrew the front panel that the treble and midrange horns are attached to in order to access all the fixing screws. Depending on toe in or out, leave only the appropriate front screw to the right or left. You can now adjust the treble/mid horn section to suit listening distance. you can also allow some vertical adjustment so the horns are slightly downward firing. Once positions are as one likes, replace some screws to fix everything in place. Packers may be needed if you have tilted the horns downwards. I will be making some matching capping strips to give a better appearance although a new top panel could be an alternative. Otherwise, the speakers look fine in my room and certainly better than false corners. (Present set-up is with Beyma cp25 and alk trachorn)