While for the I agree with your post, I wouldn't be that quick to judge a speaker based on the sheer width of its off-axis response. The smoothness - yes - a 1" tweeter will cause a flare in off axis response trying to mate to a 10" woofer. But things change if that 1" tweeter isn't splashing sound around the room.
But there are some pretty good speakers out there using larger drivers high in frequency - AJ's Soundfield 1812, Gedlee Abbey, Audiokinesis Planetarium, Vapor Arcus. And there are also some pretty good large panel speakers out there like that are pretty beamy (although they can have a lot of destructive interference as they basically become arrays)
Beaming done right isn't necessarily bad - IE LeCleac'h horns.
What is wrong, is a speaker to beam, and then randomly "flare" off-axis in the critical 200hz to 8khz range.
Yes, but the beaming of those speakers is because of uncontrolled cone break up and that's nasty.
This thread has had a lot of attention. I think this is because of the endless attraction of something for nothing.
It is understandable in these hard pressed economic times that people are looking for lower budget items.
As usual this thread highlights that there is eternal frustration with speakers.
So it is a good time to examine the issues, which relate to the inter related confounding variables that bedevil the loudspeaker designer.
Understandably of late their is a desire for high sensitivity speakers, to stretch the limitations of receiver amplifiers and avoid the expense of external amplification.
First we need to clear up again confusion over sensitivity and and efficiency.
Sensitivity of a speaker is the db level on axis at 1 meter, either with a drive of 1 watt or 2.42 volts. For an 8 ohm speaker the number will be the same, for a four ohm speaker the sensitivity will be 3 db higher for the 2.42 volt spec versus the 1 watt spec, and the four ohm speaker will draw twice the power of the 8 ohm speaker.
Now, the above measurement tell you nothing about the power delivered into the room.
Now lets take a speaker that really beams. Pretty much all of its power will be on axis. Now lets take a speaker of the same sensitivity but with wide dispersion. The latter speaker will deliver much more power into the room and be much more efficient than the speaker that beams even though they have the same sensitivity. The latter speaker will be more frugal of amp power.
So when considering sensitivity specs you must understand how it is specified. Manufacturers always conceal the sensitivity loss of four ohm speaker by specifying 1 meter with 2.42 volt five rather than 1 watt 1 meter.
You must also have an eye on the dispersion characteristics of the speaker, to get an idea of the power the speaker will deliver to the room.
The next issue is that as a cone break up the speaker generally has a peaking response. This raises the sensitivity rating by virtue of the peak and beaming.
The designer of the speaker in question has driven the 10" paper drivers through their break up zone, when he should not have.
For a speaker to have a balanced pleasing sound in room it needs to have its off axis response mirror the on axis response but with some HF roll off on axis.
Other issues that cause speakers to run receivers into trouble include impedance drops in the power band, especially when coupled with adverse phase angles between voltage and current.
Unfortunately few manufacturers supply the impedance and phase angles of their speakers. Worse many and may be most outright lie about the impedance of their speakers.
Now high sensitivity is a laudable goal as it not only conserves amplifier power, but reduces voice coil heating, and therefore thermal compression and driver failure.
Unfortunately this is where a confounding variable rears its head. There is an inverse relationship between flux density and therefore sensitivity and bass extension.
Now the above and other factors in modern speaker design has made thermal compression a much bigger problem than it was previously.
The complaints about mushy ill defined mid range voiced in this thread and others, are due I believe in the vast majority of "affordable" speakers being awash in thermal compression.
In order to minimize reflections and improve imaging cabinets have become narrower and drivers commensurately smaller. This results in a need to boost the lower frequencies progressively below the point where a speaker transitions from a half space to a full space radiator. This occurs at a higher frequency as the cabinet is narrowed. This is the baffle step response and requires compensation, called BSC.
So it is typical for a speaker I described for the baffle step response to kick in at 600 Hz, so the power has to be boosted by 6 db at 300 Hz, 12 db at 150 Hz and 18 db at 75 Hz. Now remember that for every 3db increase you have to double the power drive.
So, is it any wonder the voice coils heat. Heat builds by the square of the current not in linear fashion. This is especially true in the HT environment and especially aggravated by the limited dynamic range of the current pop culture. The voice coils can't get a break.
This heating pushes voice coil resistance through the roof, cutting power and upsetting the response as the crossovers can only be designed for one impedance, not a range.
Just consider the heat a 40 watt light bulb generates and you see the problem. At 1000 watt drive you have a toaster or electric fire in the voice coil gap.
Designing drivers that mitigate thermal compression is formidable feat of precision engineering and I don't see it appearing in budget speakers any time soon.
We really need a good alternative to the moving coil driver. Unfortunately I don't see one on the horizon. I don't see any easy way out of the confounding variables imposed by the physics of these drivers either.
We have not even got to the problems of crossovers and cabinet tuning and design, but its getting late.
The bottom line is that high performance speakers are likely to remain very expensive items for the foreseeable future.
There just are no simplistic solutions.
