Sound Dynamics 300ti specifications?

It's been about a dozen years since those were discontinued. I mostly knew about them from Audio Advisor selling off the last of the production run, which went on until about 1999. I recommended them to several people who bought them and who liked them a lot. In a couple cases the buyers really caught the audiophile bug and upgraded their electronics and source components. Now I wish I had one of my old Audio Advisor catalogs to answer your question. Sound Dynamics was the economy line of Audio Products International (API) of Canada, makers of Mirage and Energy speakers. When home theater became a bigger part of the market, API dropped the SD line and started the Athena line, originally targeted specifically at HT.

As I remember it, the "ti" designation indicated that it had a titanium dome tweeter. I have several pairs of Mirage speakers with their cloth-surround titanium tweeter and it's a very good unit. I believe the 300ti's midrange is 4" and the woofer is 8" and ported. Frequency response was around 37-20K Hz. Sensitivity was rated at about 89dB and power handling is around 150-175 watts.

I'm sort of guessing here, but I believe the crossover points were around 550Hz and 2500Hz.

I'm pretty sure that the crossover would not be as high as 3800 Hz for a 4" midrange. It would cause an in-room suckout as the midrange started beaming a half octave before the crossover point. That's what causes the so-called "cupped hands" midrange, which the 300ti's definitely don't have. It's a function of the frequency wavelength relative to the diameter of the diaphragm generating it. One reason API speakers sound so good in-room is because they pay very careful attention to dispersion patterns throughout the frequency range.

These design decisions are based on API's research at Canada's National Research Foundation and applies to all their speaker lines--Mirage, Energy, Athena, or Sound Dynamics.

The JM Reynaud speaker manages to be a 3-way with only two drivers. As you said, the woofer has two voice coils. If it's anything like Reynaud's Twin Mk III, then both woofer voice coils kick in below 600 Hz while one of the voice coils stays active up to the 3800 Hz you mention. However, it's not a straight handoff from woofer to tweeter, or you'd get the midrange suckout I was talking about. Rather, the tweeter is not crossed over until around 1K Hz, meaning the woofer and tweeter overlap throughout the most sensitive part of the midrange, 1KHz to about 4KHz. The woofer would add overall volume and energy while the tweeter supplies the wider dispersion.

The measurement charts on the page I linked to show how this works, so there's good energy and uniform dispersion throughout the midrange.

I'm pretty sure the 300ti uses a more conventional approach. Now that I think about it, I'm pretty sure they used second-order, 12 db per octave crossover slopes throughout, though they may have gotten a little more creative.