High eff speakers? Sonata III, Super III, OR ???

Tvad - I think I saw that one already, maybe not. I did see one wherein Duke was telling you stuff about matching the amps impedance or something... I've read so many things these past few weeks my eyes are rectangles... and my ears are worn out... and both PCs are in critical care units.

Duke. "sonatina" or Sonata?

I got the impression from what i've read the Di applito config gives a great dispersion, laterally, and vertically. If done right. but it's a tricky thing to do right. I'm assuming Mr. Bloom figured it out.

Like I said above, neither Alans' nor Israels' units are ones I'm strickly looking at.. just there's some press on each. More on Alans. Bill Cowan who did the review on the coincidents and I e'd some on that topic and given my tastes he said to ensure I stuck with the fabric dome tweets. Suits me. Though I know even fabrics can be tuff just like metal ones. sometimes.

RE: impedance matching of amps
What's what there? I mean how can anyone really know what numbers to look for on amps output impedance when you ain't sure if 'EVERYONE' measures those numbers the same? Some amp makers don't even post those numbers.

...and if they are posted, how do you choose one vs. another given speaker makers aren't all measuring the same either...??? Should I send everything to John Atkinson first?

Jim, I meant "Sonata" - sorry. I put one too many syllalables in the word.

In general, the greater the size discrepancy between the drives, the greater the radiation pattern discrepancy at the crossover frequency. The midbass drivers in an MTM array have a much wider horizontal than vertical radiation pattern, and in my opinion this is undesirable if you use a dome tweeter.

Let me try to explain why I think the radiation pattern matters. I'm evidently in the minority on this; most designers don't go out of their way to deal with it, so don't take my word a gospel.

Okay, the ears derive timbre not only from the first-arrival sound, but also from the reverberant sound within the room. At listening distances of more than about five feet, most of the energy that reaches your ears is reverberant sound. Now your ear/brain system suppresses directional cues from this reverberant sound, but you're still picking up loudness and timbre and ambience cues from it.

One characteristic components of live music is, a natural-sounding reverberant field. Live voices and instruments even sound natural from the next room, where there is no line-of-sight to the instruments and therefore no direct sound; only reverberant sound. In contrast, very few loudspeaker systems sound convincing from the next room. One reason is, their "power response" (summed omnidirectional response) is very uneven. I believe this is one of the major causes of the perceived difference between live and reproduced music.

Let's look at why the power response of most speakers is uneven. No doubt you're familiar with "beaming". As an example, let's take a 6.5" two-way speaker, crossed over to a 1" dome tweeter at 2.5 kHz. The woofer's radiation pattern is wide wide at low frequencies, but then it starts to narrow as the wavelengths shrink to where they're comparable in size to the diaphragm's dimensions. So the pattern has narrowed to maybe 90 degrees in the crossover region. Then the tweeter takes over, and the radiation pattern blooms out wide wide again. Eventually the tweeter also starts to beam, but usually not until the very top octave.

The problem region is the lower end of the tweeter's range, roughly 2.5 to 5 kHz. In this region the speaker may well be putting out 8-12 dB more energy into the reverberant field than at most other frequencies. And this just happens to be the region where the ear's sensitivity is the greatest. So what happens is, the extra reverberant field energy in this region makes female vocalists sound a bit harsh, and the eventual result is often listening fatigue (I could explain why if you want).

Now the MTM format's vertical radiation pattern on the M's side of the crossover will be comparable to that of an oval driver the width of one of the midranges but the height of the whole MTM stack. So in the vertical plane, the radiation pattern will be much narrower than in the horizontal plane. The result will be a significantly greater net radiation pattern discrepancy in the crossover region than if we just had a single midrange driver.

Of course there are advantages to MTM's. Much better pattern uniformity in the vertical plane with odd-order crossovers; higher power handling; and reduced floor-bounce reflection energy due to the narrowed vertical pattern (though the vertical pattern will usually be wide once again in the 4 kHz region, where the ear's sensitivity peaks, because that will be produced by the tweeter).

So it's a trade-off. Surprise, surprise.

I'll try to comment on impedance matching later.

Duke

Hmmmm. thanks duke.

With the addition of the Thor MK II preamp, the degree of naturalness in my system has been elevated to no small affair. It's scary good... and as my office/equipment room is immediately adjacent to the listening area, the sound I'm getting from the office is as good or better in terms of realism. really. Not as dynamic to be sure, but mighty authentic sounding.

I've said it before on other issues, I'll say it again. Design topology or configurations is not my forte. neither am I influenced by them. if someone could put together a couple pieces of PVC pipe and a tennis ball, and make it sound super, I'd buy it/them... probably. they'd need painting though.

See, that's what I'm shooting for now. More presence past that which I am getting from soloists and vocalists. I'm mighty close to the I'm there deal... now I want them to be here, sort of deal. hence the notion of the SET approach.

Not hearing any so far, just the Thor PA 30s, but doing a bunch of research on them, I'm positive the richer harmonic textures and filled out imagery are it's mainstays. Suits me. I'm in.

My primary reservation is my tastes in musical genres. I'm prone to more than one or two genre specific arenas. Currently I enjoy immensely large jazz ensembles, same for blues, and R&B, along with the more pallid simplistic virtues of lite jazz, vocals, and acoustical music. So I like a lot of things. ...and yes, even gangsta bluegrass.

BTW... how did you compute the projected SPL vs. Sensitivity of the speakers & power output of the amp? that's a handy item to know. I didn't mean to sound previously like I knew what I was doing. I don't usually, that's why I ask all these dumb questions all the time. I do have the capacity to learn however... and I am.

Duke, Sorry about that 'dirty' word, I didn't mean to imply that the posts were accompanied by nude pictures. Quick and simple always works best for me, especially simple. Since your explainations were intelligible to me I thought they would be easy for anyone to understand. :-)