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rdrysdale wrote:

The bass driver will play to about 8 khz…

OK, this dose make some since, become I understood you that it droops after 300Hz.

I wonder what made you to select the 300Hz as a crossover point – the currently existing horn of the actual evaluation which driver sounds better at upper-upper bass? The reasons why I asked because of you said  “actually sounds quite good up to that frequency” (that I doubt as I feel that a good midrange driver should be more alive at upper midrange). Did you consider letting your bass horn to run way upper then 300Hz? I went over those experiments few years ago and I detect that 200-500 Hz are one of the most important frequencies where most of the fundamentals live and where is better do not have any driver’s ambiguity.  Also, there is another VERY important point. If you have your midrange driver to operate down to 300Hz then your midrange horn should have rate somewhere around 170Hz. This is a big ass horn and conspiring that you go for the fairly LF-heavy midrange the sucker should be really heavy. Contrary, pretend that you let the MF driver to run down to, I would say 500Hz. Now you can do away with a manageable 300Hz horn. The beautiful part is that that this smaller horn will be substantially shorter. As the result, the MF will output more HF (never hurt) and the most important the dissipation pattern will be WAY wider. You really might want listen 300, 500, and 800Hz produced by bass channel vs. MF channel and find out which sounds better. If you do find that the upperbass horn does better at HF then you defiantly need to match the MF horn to ~50%-70% off of the MF driver’s cut off. This is very important as if you have the MF horn too large than you loosing dissipation, loosing HF and gaining some boomy heaviness. If you have the MF horn too small then you have honk combine with aggressive and sharp sound….

rdrysdale wrote:

A bent horn does very much concern me, I think Jeffery is on the right track with a straight bass horn, maybe one could be built to exit into the room, and dive under the floor for most of it's length, but then there would be no adjustment for location.

A bent horn should not concern you: it should not be used. To go over all hassle you are going, to make own driver and to stick it into a bent horn is similar to us catching Osama Bin Laden and appoint him as president of United States. Oops, sorry - the bad example: if it happens then hardly anything will be changed in Washington….

rdrysdale wrote:

We didn't know what to expect from the carbon fiber, the original RCA drivers were made with phenolic resin and very thin silk cloth. We haven't been unable to get any suitable samples of phenolic resin to try, and since I have a patent using carbon fiber in the aerospace industry, we decided to give it a try. The very first diaphragms that we made actually sound better than the phenolic and produced slightly higher frequencies. The .carbon fiber is lighter than the phenolic, and is a little stiffer, plus there is no noticible ringing when the diaphragm is tapped. There may be other materials available that perform even better, and we will always look for these, but right now we are very happy with the carbon.

I do not know – I kind off agree with Jeffery: I should not label all carbon fibers the same. Perhaps there are some carbons out there that would not behave like …. Sorbothane. I personally hate carbon fiber in tonarms and this all that I experienced in Sound. Still if I did something like you do I would try some marinated paper, and yes, the marinated fabrics as the outer suspension.  Many good drivers with good tone use fabrics for externals suspension. We kind of never know what will work in there but to change the recipe of the marinate is always easier then to manufacture a new cone… I would be fun if you conclude that the best result you got if you soak a cellulose cone in 29-year-old Scotch…  :-)

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