Volti does it again!

@doyle3433 +1.  Greg did that demonstration at the first or second Capitol Audio Fest that he exhibited at.  It's a pretty compelling demo.

I have doubts that something like a 2” throat diameter is the secret sauce to superior horn performance.  Horn behavior has been studied for many decades and a dizzying array of designs have been tried.  
i like the Volti speakers and its compression midrange driver and horn are good compared to most modern varieties, but, I prefer a number of vintage horns and compression driver combinations, none of which employ a 2” throat.  I particularly like WesternElectric horns and drivers, replica Western Electric drivers, and other vintage horn/drivers that followed Western Electric principles.  

@larryi  I have a recovered single horn and folded cab that I pulled out of an old theater. It was made and installed by International Projector Corp. The drivers from what I understand were actually made by Jensen. The horn compression driver weighs like 60lbs by itself. The horn array is multi-celled a is quite large, it's coated on the outside by some sort of spray or paint on dampening material. When I cleaned it all up and sanded/sealed the bass cab. (also some fresh wire and a thorough clean of the Altec Xover), the darn thing sounds amazing! Too big for the living room so it lives in my second garage playing anything I want, sometimes at warp factor 12. 

When I listened to the new Lucera at FLAX there was a jump in midrange smoothness and coherence for sure compared to my RAZZ. (Hence my burning desire to bring a pair home). What I understood from Greg on this new model was some mid driver xover work along with a larger woofer. It sure sold me!

IPC made terrific gear.  In particular, I like their IU 1000 compression driver that has a diaphragm just like a Western Electric 555 diaphragm.  This driver was made in the 1930's and 1940's and I would put it up against any midrange driver made today. 

I don't think that Volti, or any other modern builder has access to compression drivers as good as these old drivers.  The modern ones that sound very good are VERY expensive, such as Goto, ALE and Cogent drivers.  I do think that modern manufacturers can make good horns for their drivers--either new designs or replicas of old horns.  I've heard a few such modern horns.  Volti appears to be quite successful with making practical horns that can be fitted into reasonably sized cabinets.  Still, there is something about the "weight" and sense of authority of a larger format horn that makes one dream of owning such systems and the room that can fit those monsters.

I run a smaller vintage horn (KS12025) which is a two-foot wide by 6-inches tall metal sectoral horn.  It is a straight horn which makes it too big to fit into a practical cabinet (it sits on top of the woofer cabinet).  My compression drivers are Western Electric 713b's.  The sound is quite good and is free from excessive horn coloration, but, when this driver is put on large format horns, it is evident that size does matter in horn-based sound.  I don't have the room or the money to even think of an upgrade.  That has left me with upgrading the crossover which I am in the process of doing.  

Please understand that these are just my own thoughts on this subject. It’s not like I was tutored by the man himself about this. But based on my experience in designing and building midrange horns, here’s my thoughts on the Klipsch K400 horn used in the La Scala and Klipschorn loudspeakers.

In the beginning, Mr. Klipsch had a terrific folded horn design (Khorn). Compact and fitted in the corners of just the right sized/proportioned room, these bass horns produce solid bass down into the low 30’s and have a way of surrounding the room with bass that I’ve not heard from any other speaker. The Khorn bass horn cuts off naturally at about 400hz on the upper end, no crossover needed. Mr. Klipsch needed a midrange horn/driver combination that could reach down to 400hz to integrate with the bass horn. He chose a midrange horn size that would fit comfortably under the tophat design of the Khorn and then manipulated the design to lower the Fc of the horn by lengthening the throat of the horn, creating a long, narrow pathway for about half of the length of the horn. It is obvious to me that the unusually elongated throat of the K400 is ’pushing’ the horn beyond it’s ’comfort zone’ and causing the characteristic honky, colored, and harsh sound that the horn is known for. But it does reach down to 400Hz! The goal was met, but at a cost.

Twenty years ago or so, someone was building midrange replacement horns for La Scala and Khorns that had the same mouth size/shape to be a direct replacement. The horn was much shorter though. Still with a 1" throat, but not elongated. I tested and listened to a pair of these in my Khorns, and indeed they did sound less colored and harsh than the stock K400 horns. However, there was a problem. They didn’t extend down to 400Hz, leaving a ’hole’ in the response between the mid and the folded bass horn. Could be overcome somewhat in La Scalas, which have bass horns that can extend up higher than 400Hz to meet the midhorn with the higher Fc, but no chance with the Khorns. This exercise demonstrated to me how Mr. Klipsch took a ’normal’ exponential horn design and lengthened the throat to lower Fc. The replacement mid horn with a shorter/normal throat would get down to 600Hz and the longer throat K400 down to 400Hz - but at the cost of sound quality.

Nowadays, modern compression drivers are much more capable than they ever were. Machining tolerances, modern materials, and modern manufacturing processes enable compression drivers to produce lower mid frequencies with very low distortion. A modern compression driver with a 2" outlet and 3-1/2" diaphragm feeding into a 2" throat horn is capable of covering low-mid frequencies in a typical listening room with much greater ease. It is no longer necessary to push the design Fc of a horn by constricting the throat. A shallower design with a 2" throat that fits under the tophat of the Khorn can cover down to 400Hz with ease, and with no unwanted colorations, glare, or harshness that plague older and lesser quality designs. Think of it this way, the modern compression driver can cover more of the load, not requiring the horn to do as much.

Why does Klipsch still use the K400 horn in their speakers? It really is one of the worst sounding midrange horns ever produced. I just did the demo today for a customer who visited here to listen to my speakers. I spoke through the K400 and then spoke through my V-Trac horn. The difference is night and day. Charlie left here today with a pair of Lucera speakers in the back of his van and a big smile on his face. The demo of how different horns can sound I’m sure had a little to do with that. It certainly didn’t hurt.

So why? Perhaps it is because the Khorn has an iconic sound that Klipsch simply cannot change. People are used to a certain sound from the Khorn. Making a big change to the sound would be kinda like making Wonder Bread into a healthy slice of bread that you can no longer squeeze into a little ball in your hand. lol. Is Wonder Bread still made? Or how about New Coke? Remember that one? How did that go over?

I don’t know, it’s a theory.

Greg