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It is possible that the oft-cited coherence advantage of a single driver has more to do with its relatively benign off-axis response than with its superior phase response. My understanding is that the ear is relatively insensitive to phase anomalies. Not that they aren't audible, but they are a relatively subtle effect. In contrast, frequency response anomalies are generally a lot more obvious. Most two-way systems have a pronounced off-axis response glitch in transitioning from the midwoofer (which is beaming) to the dome tweeter (which has a wide pattern). Since most of the sound that reaches our ears in a normal room setup originates with the off-axis response, we hear that glitch, and it's right smack in the crossover region. I believe this response glitch is far more audible than phase shift in the crossover region.Fullrange drivers do not have that sort of off-axis response discontinuity, so there is no corresponding frequency response glitch for our ears to take notice of. I believe that one subjective effect of this is superior coherence.
Interesting theory. I completely disagree. We are very sensitive to phase anomalies. When a set of speakers exhibits phase differences we get accustomed to the sound. When the phase differences go away, it sounds much better. But it's not only phase that a crossover messes up. The fidelity of the electrical signal is compromised. Send a square wave to a mid/woofer through a crossover and there's no chance that the speaker output will look anything like a square wave. Remove the crossover and a good woofer will output something that resembles a square wave. Phase effects sound localization (imaging) and coherence.
Virtually all mid/woofers start to show off axis response differences around 1 to 2K region. One of the advantages of a multi-driver system is optimise off-axis response. Normally the tweeter will just raise the frequency of this off-axis depression.
Your previous post, while being non-representative of the situation, sums up the problem for me. The $830 Seas driver has 13dB difference between response at 400Hz and 17KHz. The plot for off-axis response is even uglier than on-axis. What price single driver? I know there are drivers with more reasonable on-axis freq resp, but with out the whizzer cone they probably have much worse off-axis performance. I think I'd go for the freq resp and aim the speakers at me.
It is possible that the oft-cited coherence advantage of a single driver has more to do with its relatively benign off-axis response than with its superior phase response.
In talking about listening on-axis and freq resp, I was referring to full range drivers. As a novice to full range speakers, I find the freq resp graphs of many to be a nightmare. I would also contend that the Focal speaker you selected is not necessarily representative of 2-way speakers. Whatever, the Seas full range response looks horrible on or off axis. What's the point of using a full range if the response needs correction? Without active EQ they need passive filters or a zobel.It seems to me that losing the crossover is indeed the benefit of using a full range. The problem is finding a driver capable of doing it all. Some speaker systems talked about in this circle are not really full range systems. I have a set of speakers that have a woofer with flat response to 4KHz. I can run the woofer w/o any passive filter and use a high pass on the tweeters. I still consider them 2-way speakers even though they would qualify as full range. It seems to me that something like this might be a more viable candidate. Notice the off axis response starts to diverge around 2K, like I said initially.http://www.madisoundspeakerstore.com/approx-8-fullrange/fostex-fe203en-s-special-8-full-range/neo
This artisan driver is a onetime production and Madisound has been allocated 25 pair for the US market. The FE203En-S posses remarkably high sensitivity and is optimized for use in a folded horn enclosure. It is engineered to deliver effortless sound reproduction with a very dynamic character, and do so even with very low input amplitude. The result is a driver that performs exceptionally well from low to high listening levels. Limit one pair per customer. This driver is a value at $600/pair.
In talking about listening on-axis and freq resp, I was referring to full range drivers. As a novice to full range speakers, I find the freq resp graphs of many to be a nightmare.
I would also contend that the Focal speaker you selected is not necessarily representative of 2-way speakers.
Whatever, the Seas full range response looks horrible on or off axis.
What's the point of using a full range if the response needs correction?
I've had occasion to hear a couple of models of Fostex's "special" series, and they can certainly sound dynamic and musical, although few would argue they're without some degree of "personality" (i.e. coloration). Further, keep the following from Madisound's website in mind:
Yes, but the on-axis response is only a small piece of the puzzle, and because fullrange drivers are inevitably beaming a lot more than a 1" dome would, their nasty graphs are only applicable within a narrow angle. Move off-axis a bit and that on-axis curve is no longer representative of anything that reaches your ears, being now blended in with the off-axis energy, and making only a small contribution thereto.The Focals use a stiff woofer cone that behaves closer to a rigid piston than most (which includes beaming more severely), and they also have a fairly flat on-axis response, and so illustrate my point well. Many designers introduce an on-axis dip at the lower end of the tweeter's range to offset the off-axis pattern flare; that is a design choice I would have made. If you have offsetting peaks and dips in the off-axis energy, the net result sounds a lot better than if you have a big energy ridge. Dips that are not offset are fairly benign. That upper-frequency "hash" doesn't sound nearly has bad as it looks to the eye; the ear tends to "average out" peaks and dips that are within 1/3 octave of one another.Correction circuitry may offend the purist, but if it's a net improvement, I see nothing wrong wtih using it. My first commercial speaker was an augmented Fostex fullrange driver (augmented by a built-in sub and rear-firing supertweet), and I believe the correction circuitry I used made a significant improvement.
This is all very interesting. Not sure on-axis / off-axis is of much importance to the way I listen to music. I seldom set down just to listen. I like to have music in the background while doing other things. Still the music must sound good, be easy to listen to and not be tiring. At this point I am thinking off the Tekton Lore. Just over $1,000 shipped plus any wood veneer over paint.
