Thiel Owners

Bluetone - Yes, it would be instructive and helpful for me to test those midranges as a baseline reference standard. Since I don't have an anechoic chamber, my curves will not match the other published curves, but it will be a step toward progress. The rest of the parts can wait; I am really not ready to take on the 3.5 as a project. Please send a PM to exchange shipping information. Thank you.

I have ordered some test equipment to do some measurements of the mids of my 3.5 and will compare the specs to some alternative drivers. I'm interested in tri-amping each speaker with digital active cross overs and incorporate fir and peq  filters for equalization, as many of the eq of the 3.5 have become repair prone. It's a different approach then the original, but I'm just curious about the pros and cons of this adaptation. Still researching this area but it looks promising.

Rules - Go for it! I mentioned way back that Jim's first focus and indeed we built early prototypes of active speakers. At that time the market would not accept the concept; now, the time has come. There are many details to tame. I hope that you stick with first order slopes to get time coincident and phase coherent output. 

Please share your driver rig and results. Get your primary curve from free air mounting in a large wall - infinite baffle.

A huge pro of the active approach is taking the guesswork out of cables and amp responses, along with lower cost of low power crossover components.

Keep us informed, please.

Tom, thanks for the encouragement. Infinite baffle, is that doable with 8x8 wall. As I have a farm and can do outside measurements, been looking for some scaffolding. How high?

The larger the baffle the lower the frequency of the baffle step where the wavelength drops off the edge of the baffle. You can calculate where the 8x8 glitch will occur. Circle is cleaner than square. Put the driver in the middle of the baffle. Now, there's the floor (ground) bounce to copy with; so, if possible, tilt the baffle parallel to the ground, firing the driver upward with the mic 1 or 2 meters away (whichever protocol you use.) Firing up does lots of stuff right if you can manage the particulars. We also used an infinite baffle or ground plane. Hole in the ground with known-sized insulated box in the ground. Compare and subtract low frequency enclosure back pressure against open air performance. That ground-plane "sandbox" provides zero baffle step response, which is what you want to know. Correct the curve for box pressure rolloff and you have the true infinite baffle measurement.
I will repeat that measurement series after 10 feet of snow melts from my neighbor's flat field. Or we can rent the Bell Labs anechoic chamber in New Jersey for perhaps $1K / half day (guessing).