Audio Note speaker design

[Feanor]

RGA and others,

RGA's passion for Audio Note speakers is very well know and long standing. Apart from RGA's flat assertion that they sound better than anything, there are the eccentric and questionable aspects of AN's designs. It's not fair to dismiss AN models out-of-hand just because they flout industry trends; but neither is it obvious that any one or combination of them automatically suggests an AN superiority in theory.

If everyone, especially RGA, is up for it, I would like to review ANs divergences from popular practice with a view to possibly revealing the AN phenomenon.


Broad (and sharp-edged) baffles:

There is one advantage of a broad baffle the I'm aware of. That is, the gain that occurs when the baffle is wider 1/2 the wave length of the sound; obviously this occurs at a lower frequency with a wider baffle.
On the other hand I have heard it said that the optimal width of the baffle is not much wider than the aforementioned 1/2 wave length. So to the extent that this true, the wider baffle wouldn't favor the AN tweeters even if it assists the mid/bass driver. You'll notice that in some designs, the cabinet is shaped to be narrower around the tweeter than the mid/bass drivers.

Tweeter placement:

AN's practice of placing the tweeter on the vertical axis isn't so much against current practice as against best practice. It is true that response spikes cause by the cabinet's edges are less if the tweeter is placed at different distances from each edge, (right/left/top/bottom). As mentioned above, the shaping of the cabinet around the tweeter in some non-AN designs which will usually reduce defraction. Alternatively, some use a semi-horn or "controlled dispersion" surround for the tweeter; Paradigm designs their grills to control dispersion.

Large mid/bass driver:

The frequency at which a driver will begin to "beam" rather than disperse the sound is 1/2 the wave length at that frequency. Thus an AN 8" mid/base with an effective driver diameter perhaps 6" will begin to beam above around 1100 Hz. The more typical 6.5" driver with an effective 4" width will start to beam around 1700 Hz. Thus AN's 8" and 10" drivers are disadvantaged with respect to dispersion assuming the crossover is, as one would expect, above 1100 Hz.
[edit] Of course, a larger driver will typically go deeper than a smaller driver; it will also play louder versus a single, smaller driver. Vendors today, likely because of narrow baffles, offset the loudness aspect by using multiple, smaller drivers. [/edit]

Under-damped, resonant cabinets:

AN's cabinets are made of plywood, both more resonant but less predictably so than the more common MDF. Contrary to usual practice, which is to reduce resonance as much as possible, AN cabinets are supposedly design to resonate. I guess in theory you could design a cabinet that resonates in such a way as compensate for speaker drive irregularities. However this would seem to require such extremely tight tolerances in both cabinet and driver as to be unachievable in practice.

Near-wall or corner placement:

No doubt placement near-wall, or more so. corner placement will boost bass. Also, it will reduce the need for "baffle shelf compensation" which relates to baffle width effect as discussed above. Thus AN's recommended placement and baffle width both tend to increase efficiency.
I suspect that the near-wall/corner placement must tend to less predicable over-all frequency response and bass humps however. This no doubt the reason most designers today design for placement 1-3" from the wall.

Model differentiation based on crossover components:

There are boutique speaker makers who offer different, optional grades of crossovers, but none to the extent that AN does where a single, basic design can see a several-fold price increase as the supposed quality of the crossover increases. The significance of wire and crossover component quality for sound quality is debatable, (though no doubt better is better), but there is certainly diminishing returns and AN seems to away over the top in this regard.

Thus AN uses a combination of good and dubious practices. The practical success of their approach can be judge only by listening, but on balance what they do doesn't presuppose a superior speaker.