Sound Dynamics 300ti specifications?

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.

thanks for the informative reply Johnny.

I don't know how JM Reynaud got away with a 3800hz crossover (plus an unusual dual crossover in the woofer) for it's Trente speaker which has a 1.1" tweeter and a 7" woofer. But it is really good sounding and the thing about the fundamentals struck me because that speaker had presence in spades.

I am always curious about speaker design and the fact that someone is actually using a 4" midrange (in the 300ti)peaks my interest, I would bet you are close with your 550Hz and 2500Hz reply though. It does not seem the midrange driver is working too hard.

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.

thanks Johnny.

I think you are about right on with most of the specs. In the last few weeks I have searched the web and they do have a 3/4" tweeter, 4" mid and 8" woofer. I just wonder how much of the midrange the 4" unit handles, for instance if it went up to about 3800 hz before the tweeter kicked in it would cover most of the fundamental tones of acoustic instruments (at least in the upper range). I do have them at home now and they are pretty good, certainly excellent for the price, with terrific detail, a neutral tone and the bass is impressive - down to the mid 30s seems right.

BTW I am driving them pretty well with my 8wpc SET so they are fairly efficient, I thought I read 90db but that is a small matter and also a spec that can be meaningless based on how they do it but in this case they are easy to drive.

thanks!

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.