Size of Midrange Drivers

Some of the more important reasons why we rarely see midrange drivers above, or even approach 7-8" in the typical regime of "hifi" speakers seem dictated by the use of direct radiating dome tweeters and their lack of <2kHz handling, as well as a common demand for midrange drivers to co-act as low fs bass units in 2-way systems, where 6.5" driver would see limitations in speed and agility starting already in the upper bass and lower mids. Even "dedicated," smaller midrange drivers (up to ~5") in 3-ways systems seem to emulate almost the design of the more typical hifi bass drivers, certainly going by their efficiency and overall specs, making you wonder what is gained by the smaller diaphragm diameter when this again limits the preservation of energy (and not least its nature) that comes through added, sheer displacement area. My own speakers sport a 12" bass/mid driver (crossed at ~1.3kHz to a 12" compression driver-driven OSWG waveguide) with a relatively lightweight paper cone and moderate sensitivity of about 94dB, and though this sits close to the beaming wavelength of the effective cone diameter the audible outcome is nonetheless more dynamic, natural, relaxed and uncolored than most mids I encounter from other, even much more expensive speakers with smaller, more "exotic" midrange drivers. Perhaps the best mids I've ever heard comes from 3' diameter fiberglass JMLC-horns (300 - 3.5kHz) driven by compression drivers as well - go figure.

Bombaywalla --

What's to learn, exactly - that 12" units can't do midrange? To clarify: 700Hz er certainly part of the midrange (indeed the lower part of the central mids), and voices typically contain a lot of energy even lower in the frequency spectrum. Upper bass sits below 300Hz, not at a high 700Hz.

12" units can do wonderful midrange, but you wouldn't expect an 88-90dB, fs 20-30Hz hifi bass ditto to do this job; it's supposed, or certainly restricted to do bass only. There are other 12" units to come by with higher efficiency, higher fs, and lighter cone movements, and there's good reason to seek out their qualities in the mids department as opposed to the smaller diameter alternatives - depending of course on the design they are to be implemented.

What's to learn is oftentimes to unlearn, keep an open mind, and be willing to go against accepted (read: rigid) norms.

Bombaywalla --

To reiterate from an earlier response of yours (to the OP):

The Tannoy Kingdom Royal has NO MIDRANGE driver contrary to what you seemed to allude to.
Their new HF compression driver tweeter is doing all the midrange.
Like you seemed to indicate - Tannoy is not foolish & they wouldn't put a 12" midrange! The 12" unit does upper bass to 700Hz & the lower bass unit does the bottom-most octave.

Well, the Tannoy Kingdom Royal has got a midrange driver (sorely needed to play midrange) - that is, not only one but two of them: the 12" unit for the lower mids, and the compression driver for the rest above 700Hz.

In your reply to me:

no dispute here Phusis. I was not stating otherwise. Merely stating that the bulk of the midrange freq is handled by their new tweeter. Yes, freq below 700Hz is handled by the 12" mid driver which seems to be more suited to the lower freq. Tannoy smart as they are did not try to do any more midrange with the 12" driver - that was my point.

Given the choice of two well-implemented speaker systems I'd not necessarily choose the one where a compression handles midrange duties from 700Hz up (which, in effect, would likely be a 3-way setup, or more) compared to a 12" unit handling the mids up to 1.3kHz (which, crossed over to a compression driver, could be a 2-way ditto).

You seem fairly adamant in claiming that a 12" can't do midrange much above 700Hz; I say it can - and certainly the beaming limit for a unit this size (with an effective cone diameter of ~10") is not yet reached, even at 1kHz. In the case of the Tannoy's mentioned I do believe they made the right choice crossing over the 12" unit no higher than 700Hz, also being that the compression driver here is augmented by a "supertweeter."

You continue:

good advice Phusis. I keep an open mind while keeping Physics in my mind at the same time. Hopefully you do the same....
Timlub tried to explain some of the physics to you but it went over your head. I tried too in my very 1st post & it looks like that went over your head as well.
Well, you can take a horse to water but you cant make it drink...

I find the writings of Mr. Timlub enlightening, indeed there's something to learn here, but while I appreciate your addressing "physics" I believe you adhere to them in a rather non-flexible fashion that cares more about numbers than, it would seem, actual listening impressions - or at least you're without the positive experience of a 12" playing midrange above 1kHz, in which case I respect. I just don't share the same experience.

Something went over my head? I don't think so, but while I'm glad to learn I have no problem going contrary to stated physics if my ears tell me otherwise, and in my case and with my speakers there's no seeming dissonance between what I hear and what physics should imply.

Johnnyb53 --

...

Finally, the name of the game isn't just radiating area; it's air displacement. A 4.5" driver has a radiating surface of 15 sq. inches. My Mag 1.7s have a radiating surface of 456 sq. inches. Yet, a premium 4.5" midrange might have a maximum excursion of .2", which amounts to around 3 cu. in. of displacement. My big panel, if its excursion is .01" (I'm guessing here, but it's probably in the ballpark), displaces about 5 cu. in. of air even though it's spread over a wider area. So two of those 4.5" midranges would displace about the same amount of air at full excursion.

This is an interesting aspect. My impressions is that it's not without audible importance how a given amount of air is moved; either "gently" via a larger area, or "forcibly" through a smaller ditto. My preference - if it is indeed explained fundamentally through this aspect - is for the former, and this goes for the whole frequency spectrum.

Moreover, the number of point sources (convering the same frequency span) is also a factor. With regards to bass (and the rest of the sprectrum), generally, I'd rather have one unit covering what two or more units equaling the same radiation are can muster.

Bombaywalla --

I have a fair bit of world-wide listening experience & have listened to a lot of speakers (& a lot of electronics) yet to but yet to have a positive experience of a 12" midrange playing midrange. If you look at my systems I do own a Tannoy DMT10Mk2 which has a 10" playing midrange all the way up to 1.4KHz. It sounds good for the most part & is just fine for the use that I've put it to but when I had a time-coherent speaker with a 4.5-5" Eton midrange, the Tannoy was nowhere near that quality.

Having not heard the Tannoy model you own I still believe what you hear could be categorized under 'preference' with regard to certain aspects of sound. Take 6moons review of the Austrain WLM Diva Monitor speakers (for a hopeful illumination):

(excerpts)

10-inch paper cones with hard cloth surrounds simply sound different than 5-inch Beryllium or ceramic cones that are hung off loose butyl rubber. The former are more natural, relaxed and full to my ears. In turn, they're not as overtly 'resolved'. The sharpness and leanness often associated with accuracy is missing.

...

It's a speaker that will tweak certain people because it lacks what they consider prerequisites for a hi-end worthy design - narrow baffles, small midrange drivers, exotic diaphragms, famous tweeters. WLM gets by with apparently lesser ingredients. Still and to my ears, the end result is a more inviting, tastier dish. What that really says about current high-end hifi sensibilities you may ponder yourself in some spare time.

...

As our own Jeff Day reminds us, there's a music lover's perspective which deviates from the studio monitor credo of 'warts'n'all'. Music lovers first and foremost insist on an emotional connection with the music. Secondly, they insist -- very sensibly if you ask me -- that all of their music and not just a very narrow selection thereof be enjoyable. The Diva Monitor conforms perfectly to this omnivorous demand. It's a tone monster. That makes it a fabulous addition to the retro/vintage sector of loudspeaker design where large paper cones with pleated cloth surrounds remain en vogue. Those counter the over-articulated 'starving super model' ideal that's pursued to excess elsewhere. It returns us to the earthy curves of a Sophia Loren, the power and brio of Classic Rock and the soulful tone of a Mesa Boogie.

http://www.6moons.com/audioreviews/wlm/divamonitor_4.html

Time coherency of definately an important factor in sound reproduction, but it's a singular aspect attainable in many forms with many variables. The WLM Diva's are one way to get there, and going by the floorstander version of the Diva's it's a sonic imprinting I enjoyed immensely. In other incarnations though, despite being time coherent speakers, it could be an entirely different matter - to my ears at least.

Bombaywalla --

They take an interesting approach, Brodmann Acoustics, and seem fairly priced. Never heard them.

One of the more memorable sonic demoes I've had came from the Peak Consult Kepheus at their home facility in Denmark. The twin Audio Technology 5" midrange units presented some of the most natural (and dynamic) mids I've encountered - certainly coming from cones - just as they are beautiful and coherent sounding overall. Although steeply(!) priced it's beyond me why these handcrafted speakers aren't referred to more often, if at all in the "audiophile arena;" it can't be the high price, for that alone seems to have its drawing power all by itself. One suspects that what sounds natural simply isn't interesting enough..

But in the end, to my ears, nothing trumps the ease, tone, clarity and relaxed power from a well-implemented waveguide/horn, preferably conical variants, and larger cones. This sums it up nicely:

I am amazed today that 99% of all "audiophile" speakers are the basic "monkey coffin" cones and domes in a box that have defined the industry for the last forty years. This is fine for general consumer stuff, but, no matter what the price, you can only get so much out of a 5" cone midrange and a 1" dome tweeter, and it isn't enough, in my opinion, for even modest ambitions. It's just the physical nature of the elements involved.

http://www.newworldeconomics.com/archives/2013/111713.html

"It's just the physical nature of the elements involved" - indeed...