I, for one, an very glad to see you went back and edited your original post (as captured by Irv's quote of it) to include IMO! You are indeed entitled to your subjective opinion, and if you had stated it as your opinion in the first place, you would not set off so many audioholics' BS meters (and saved yourself from having to be defensive and attempt to reframe your statements from a "freedom of speech" platform).
But to the content of your post, I agree that using multiple tweeters has the potential to increase dynamics, but am not so sure about multiple drivers improving extension - can you point me to a link?
Also, this doesn't really have so much to do with your dealership status. Your original statement of this as if fact was unprofessional. Dealer or not, it would still be a baseless claim.
I am curious what caused you to delete MTM speakers from your statement. Can you elaborate?
No, adding multiple drivers does not add to extension. The lower limit will be just that.
However a tweeter is a slightly different case. Generally they operate above 2 KHz. However in music, power demands rapidly decrease with increasing frequency.
So a single tweeter may be power limited below 2.5 kHz for instance. Now if you add more tweeters the power handling is increased and you could then achieve your power demands with a crossover at 1.8 KHz for instance that you could not do with one. That is not added extension but at a cursory glance could seem like it.
When it comes to woofers you can use all the drivers you want and Fs and therefore F3 obtainable will not change.
When it comes to multiple drivers, there are as usual there are swings and roundabouts.
The ideal is a full range point source. As you add drivers in a vertical array, you do get comb filtering, that is undeniable, the spacing has to cause reinforcement and cancellation which is frequency and driver spacing dependent.
Now the advantage is obviously increased power handing and lowered distortion and increased horizontal dispersion and limited vertical dispersion.
So now we get down to what sort of sound stage you favor, and the presentation in the room you want to convey. This is where science meets experience and art. For me this makes speakers eternally fascinating.
So where do I stand. I have only found vertical arrays acceptable in very large spaces never domestically.
For many years I just used single 4" JW full range drivers TL loaded. As you added drivers the power went up, but the sound was much less defined and accurate in fact. The single drivers were fine in student digs and resident quarters. I still have the speakers I built for my resident room.
When I moved to North America and larger spaces, a pair of 4" full range drivers did not have the power. Adding drivers was never entirely satisfactory. The speakers now my rear backs used four JWs per side as a mid array and a vertical tweeter array, as there was no ferrofluid then. The sound was powerful but somewhat over full and lacking refinement and detail, with poor depth of focus.
So in 1984 I changed to the current arrangement.
That improved matters greatly after a lot of work getting the crossovers right.
Now the MTM arrangement is a design, that IF designed correctly, can work.
The trick is to skillfully design the lobing patterns, so you have what is close to a point source. However, unlike a point source, horizontal dispersion is increased and vertical dispersion is reduced. At the same time power handling in the all important mid range is doubled.
Would I have made the design choices that RBH have, no. I personally prefer to use less, more expensive drivers with greater power handing and less thermal compression. In my room here I have no trouble achieving all the spl I need without distress from the speakers. In fact the rig can produce a massive wallop when required.
I understand why RBH could make the choices they did. There are some, may be many who like the presentation of that type of speaker layout, I'm just not one of them.
Changing gears a little, it so happened I watched a program last night that is apropos this tweeter discussion and a lot else besides.
The "amateur" university of Waseda, Tokyo, symphony orchestra performed at the Philharmonie Berlin recently. Now these are all unpaid university students. It is not a youth orchestra which are have students training as professional musicians. However DO NOT let the amateur status of this vast number of enthusiastic youngsters put you off.
The
concert is up free on the BPO Digital concert hall site. You do have to register for free.
Go to the work at the bottom, Mono-Prism by Maki Ishii.
This is the most wild extravaganza I have ever seen. I just can't begin to describe it. It has the largest percussion section I have ever seen, with some of the strangest instruments besides. It will really give your tweeters are work out, and everything else besides. There is a huge array of Japanese drums beaten senseless by a large collection of very muscular young men.
I should mention that you will have to advance the volume more than usual. The engineers wisely reduced the average spl in order to deliver the enormous dynamic range of this program.
It goes without saying that the video is stunning and the audio spectacular.
After watching that I have no desire to spend 3K on diamond tweeters.
I do encourage all to watch this and comment. There are also some encores following this work. The normally somewhat staid German audience went wild. They just could not get enough of these youngsters.
