@sns wrote:
With the modded Khorns hard pinned info really extends into room, but at the same time I have a wonderfully deep center sound stage which can also extend out into room. I’ve had narrow baffle box loudspeakers in the past which made speaker disappear, with the large Khorns this really not possible. One of the great benefits of my mods is that I’ve been able to achieve much better time alignment of drivers. With the free standing mid horn and tweeter I can set tweeter baffle back from front face of speaker, result is high freq much more in balance with mids, when Khorns were stock sound stage was much more in your face and hot. I can also toe in or out both mid driver and tweeter without disturbing the corner placement/seal which is required for the folded horn to perform best.
What you describe confirms what I’ve expected, that the performance of the Khorns can be seriously "elevated" upgrading the midrange horn/driver and tweeter ditto - incl. of course the crossover. I previously owned a pair of Simon Mears Audio Uccello’s, which are an homage to the Klipsch Belle speakers built completely from ground up with CNC-machined stacked plywood Tractrix horns, B&C midrange (DCM50) and tweeter (DE10) drivers, the cast frame 15" Crites woofer (1526C) and (modified) ALK crossovers. Lovely speakers and beautiful craftsmanship. They produced some of the best midrange I’ve ever heard and that tuneful front horn-loaded bass that’s a treat, but eventually the truncated bass horn resulted in upper bass colorations (and the lack of proper physical height of the speakers made for a fairly low acoustic center), which - initially just as an experiment - made me seek another, actively configured main speaker option. However, modified Khorns would be another great path to pursue, though I’d go with active config. that also offers delay settings and minute frequency response corrections/notches and other PEQ’s.
No doubt horn material matters greatly, far more natural sounding vs. plastic or the metal mid my Khorns originally had. Shape of horn also matters in that it directs the sound, tractrix far superior to exponential.
Solid wood is one of the best choices of material for horns, for sure. Apart from the horn profile, as mentioned earlier, its size (in relation to the profile) is also an important sonic determinant and factor and what it means for proper power response and energy coherency, not least in the vital crossover region centered in the lower to central mids.
Finally, in order to achieve a more refined or natural sound quality from horns a quality crossover is required, using quality caps, inductors, resistors if used and wire can go a long way in achieving this.
In addition to ways to tweak the overall nature or gestalt of the sound with the filter components and cables used and their own, specific sonic particularities.
As for amps, pre’s, I think SET is great match for most high efficiency horns although push pulls can be very nice as well. SET may be more immediate/up front but the lovely 300B with no negative feedback and it’s even order harmonic distortion is sublime.
The 300B’s were a great combo with the passively configured Uccello’s mentioned above. With my current, actively config. high eff. speaker setup I prefer topologically similar (though power differentiated) class A/B SS amplification by MC² Audio from the top all the way down into the subs.