RE: Acoustat intermingling - Ferrstein 12:37:12 11/11/09 (1)
 RE: Acoustat intermingling - CineDave 08:29:45 11/13/09 (0)

The Spectra 2+2 frankenspeaker is a cool idea. The problem is the Spectra 3300 interface you have isn't designed for four panels. You can run four panels without damaging anything, but I fear you might have too much bass. Just to confirm, your interface should have a label that says 2123 somewhere on it... meaning it can be used for either a spectra 22 or 33. The 2146 interfaces, on the other hand, were designed for the Spectra models 44 (basically spectra-ized 2+2s) and 66 (two Spectra 33s stacked atop one another). For each interface, there is a tap on the transformers that corresponds to the number of panels. The 2123 has a tap for the 22 and a tap for the 33. The 4146 has a tap for the 44 and a tap for the 66. To get proper bass response, the correct tap must be selected. Having said all that, you may find the bass response of a four panel speaker driven by the 3300 interfaces (set to the three panel tap) to be very acceptable.

Another hurdle you need to jump is the fact that Spectra panels are "split" down the center electrically. This is easy to duplicate with five-wire panels. All you need to do is go the the center-most stator loop at the top of the panel (there is one each front and back) and cut the wire. You'll want to separate the ends and shrink-wrap them. Be VERY careful with a heat gun around these panels. If they are three wire panels you'll also need to run a return wire from each stator as Acoustat did. For that you need to pluck the end of the wire at the bottom of each stator and carefully strip, solder, and shrink-wrap the wire to the loop.

Once you have four spectra-ized panels around, you need only wire 'em up correctly in the frames. Picture it like this: with the panels split in two, you have four halves of a panel on each level of the two plus two. From the inside of the speaker, you want to use the output taps of the spectra interface as such: Inside-most half: midrange and below. Next half moving out: fullrange. Next half moving out: midrange and below. Outside-most half: bass only. The top two panels are wired identically to the bottom two.

Now... an opinion that you didn't ask for (sorry, I like to type). The 33s are probably better than the 44s (or spectra-ized 2+2s). Unless you have a strange room configuration or are just bugged by the lack of HF while you're standing, the wider Acoustats have always sounded better to my ears. Now if you could make some 66s, that'd be interesting... but you'll need to source some 2146 interfaces first.