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The “best midrange comes from compression drivers”. I see somebody like Haralanov would be very much opposed to this comment. The irony is that I would be opposed as well to this comment.  I would say that the best midrange at over 107dB sensitively is the simplest to get from compression drivers. I did heard very good non compression driver but they were good 10-20 less sensitivity then good compression drivers, not to mention that non compression driver will have a lot of difficulty to work with a good upperbass horn, and this is not a laughing matter as a proper upperbass horn with a right compression driver is the winning tandem, not the MF compression driver itself.

 The whole business of having something “best” is a bit tricky and it has to be understood properly. The best is not an absolute criterion but rather the best balanced criteria. The best compression driver is like a woman. Women know own best and worse properties of appearance and they use different tools of dressing, make up, behavior and etc… to hide the less attractive element of own appearance  and to highline on the most reactive properties. Would we consider that a women that does it most successfully might be considered the “best woman”? I do not think so but the compression driver it appears to me works in the very same way. It looks like it is very easy to capitalize on the best what a compression driver doe the best and it looks like it is relatively easy to deal very effectively with problems of compression drivers. So, I would not call that the best midrange comes from compression drivers but I would say that as a ready to go package the compression drivers are more optimized to get the best MF as they are.

Another subject that I would like to point out that in upperbass horns there are very narrow margin what would be the best size of upperbass horn.  Your MF mush be fast opening horn, this is not arguable and if you are in MF with exponential horn then you are ether deaf of a Moron. Either Tratrix or La-horn are fine, or it might be any other fast opening profile.  If you go for 120Hz upperbass then you most likely would like to stay with fast opening, it looks better and it has some sonic advantages, the sonic advantages are arguable however for 120Hz horn.  Still, 120Hz horn is 36”, and then we have let say 12” of MF horn. A half of 12” is 6” and we do not want the upperbass and MF overlap. So, 36” of upperbass and half of MF horn make 42” of the MF driver height. Jorge said that MF driver has to be at hears level, which is about 42”. So, we just concluder a proof that that 115-120Hz is the maximum possible size for upperbass horn. Sure you might put your upperbass above your MF but then you need to paint your horns in red, green, yellow and blue stripes in order everyone see that you are a Moron. Now let to see what happened with the upperbass length.  If you have 35”-36” diameter then the length will be dictated by the diameter of your throat. If you go for 1.5” as WE and the imitator do then your horn will be an ugly snake that you will never time-align with MF driver. If you go for 6”-8” throat that Bruce so like to make for his mostly idiotic customers then your upperbass will act mostly as a direct radiator and will not have the necessary equalization. If you sit with a 3D modeling software and begin to slide the throat up and down and to preview the desirable upperbass length in order to have the sufficient horn EQ, the easy of time aliment and the proper esthetic appearance foe your acoustic system in your frame then you very fast discover that 34”-37” is the very optimum length that makes upperbass to have 4” throat. A simple calculation will inform you that with 4” throat Tratrix blowing into 35” mouth will yeald for you +6 dB gain at the horn lover cut off. Congratulation, you just reinvented the basic Macondo geometry! Another 10 years of experience on the subject and you will reinvent what I leaned – a design of proper horn installation must start from design of horn supporting frame, but this is whole another subject…

A few words about a subject that Jorge missed. The loading of the amp or amps that drive MF and upperbass is super important. If you use tubes then more loading of output stage gives you more gain, more power, more harmonics, better diaphragm damping. Letting the output tube to run more idle give you faster transient response, less distortion, shorter decays. It is not necessary to multi-amp your MF and upperbass if you would like to mitigate the individual loading between the channels, you can do it with a single amp as well. Still, loading is VERY powerful tool, in many cased more powerful then a change of the drivers.

About the upperbass horn, upperbass horns are not panacea in my view. There are other topologies that can deliver very good upperbass results. The infinite baffle or VERY large open baffles in my estimation do very well. The problem with large open baffles is that they do not accept any channels under bottom, nothing will work with them. There are other problems with large open baffles, like large vertical surfaces destroy imaging and many others problems.  The upperbass horns in contrary not only sound well but as they do not deal with acoustic shorting as the result they accommodate proper bass support.

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