Posted by Duke [ 208.98.184.17 ] on November 16, 2007 at 14:25:16:

In Reply to: Re: Schizophrenic woofer? posted by valveman on November 15, 2007 at 16:10:00:

Right now I'm still waiting for prototypes, which will probably take several more weeks. Then there's testing (which may involve an outside laboratory for some of the measurements), perhaps minor changes perhaps not, and finally the production run itself.

I have been playing with a simple 8" hemptone driver for several months now with encouraging results, and am excited to see what will happen when we put a JBL-quality magnet system on a larger hemp cone. Unfortunately, JBL-level cost is also involved. I don't have the exact numbers yet, but this is not going to be a cheap woofer. I have let the engineers know that I do not want to compromise for the sake of saving a few bucks. After our initial conversation about the dual voice coil concept and crossover point, they told me that meeting my targets would be a piece of cake - would I like to take it even further? Of course I said yes, so this woofer will go beyond what my initial targets were.

The dual voice coil feature itself is not really an innovation. It has been used in subwoofers for many years. Dual voice coils were also incorporated in regular woofers and midwoofers made by Focal and offered to the DIY market back in the 1980's, and at least one of the engineers working on my custom woofer owned a pair and liked them very much. Typically, people would just run the second coil in parallel at low frequencies to get 3 dB of bass boost at the expense of halving the impedance. I think Joseph D'Appolito used them in one of his MTM systems, either written up in SpeakerBuilder magazine or sold as a kit (can't remember which). I don't recall anyone driving the second coil with a separate amplifier, but then I don't think plate amps were available to the DIY market at that time.

I don't like to do "me too" speakers that have to rely on marketing to differentiate themselves from their peers. I like to do stuff that's different enough in some way to make it interesting all on its own. The "mainstream" is already being done - what's not being done yet??

Duke

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