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cv wrote:

Well, the Cogent (Steve Schell and Rich Drysdale) boys are building just such a beast: field coil magnet, (possible) permendur polepieces for >2T, Fs 70Hz, throat - dunno, but at least 3" dia, reduced compression ratio relative to midrange units. They tried various diaphragms, phenolic originally but I believe have decided that carbon fibre is king [cv ducks for cover...?]. I've seen pictures of the internals of the drivers and they certainly *look* incredible. A very, very early prototype of the smaller midrange unit may be seen at: http://www.oswaldsmill.com/id29.html but you've probably seen that already.

Yes, I have seen them; never head what those guys do though. I had some concerns about that project. I read somewhere that they were planning to put this drive all the way up to 10Khz, equipping it with some kind of phase plug and so on. I do not think that it would be good idea. The base theory of horn loudspeaker contradicts the wide frequency operation. I would personally love to have such an upperbass driver optimized from 70-80Hz to sub 1000Hz, which would perfectly fit into the 4-way installation.

Anyhow, no one never knows why those compression driver sound in the way how they sound. We get pretty much sound “as is” from those drivers and try to make out of it something. All drivers that I like of use do not do well on the specks. The very same S2 driver has very ordinary datasheet. Go figure how they all will sound!

Anyhow, I was argue (my normal state of mind) with someone of Cogent boys in past about a necessity to use a paper cone for mid bass driver (even compression). At that time they were big on the metal cones. So, you said that now they have decided that the “fibre is king”… Dose it mean that I won and now I can pat my ego :-), or perhaps to have the driver to try? Also, I hope that this drive will not come with a digital EQ… :-)

cv wrote:

As for JMLC, I don't have his email address, but you should be able to find his details on the web. That musique concrete site that Jan attached was very interesting - a French fella by the name of Marc Henri did some interesting research on the damping properties of different horn materials. He uses a similar flare horn as I have for the S2, but made of plaster of paris IIRC.

I do not really think that different horn materials are so important. The horns obviously should not be made with the Coca-Cola cans (courtesy to Altec-BL-Klipsh-EV-Vitavox and many others). A proper horn should have above critical mass that should be projected to the lower cut off frequency (LF push to mass). If is it heavy enough then the material become irrelevant but if a horn is too light for the given lowest frequency then the material maters. I think in those concrete horns the material is very secondary (they have enough mass and it is all the they should have). The really interesting thing in those concrete horns is not the concrete itself but the finishing surface. I have paid attention that the more “hairy” and granular horn’s surface is that more “interesting” the horn sounds. With a glossy horn sound juts “slips” vs. the “hairy” horn sound “flows”. John Hasquin once taught me to pain horns with structured paint to make them not smooth but abrasive. All his horn made this way. I tried to do the “structured paint” on some of my prototype horns and get very good and very predicable result. I think that the beauty of those concrete horns is in thier structured, abrasive surface that Marc Henri mistakably recognized as the “contribution of material”

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