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Is this the ultimate 2-way speaker design?

The Epos M12/M15 design that is. A hot-rodded version is the Verity Audio Parsifals. Both use polypropylene mid drivers which "eat detail" but add more body and weight to the sound than paper. Possibly bigger perceived dynamics as well. Both also let the mid driver roll off naturally above 5,500Hz.
The Epos uses a single bass/mid driver which rolls off without a crossover at 5,500 Hz. A single capacitor cuts off the tweeter below this frequency. Obvious advantages I see are:
1) no crossover in the vocal range of 100-500 Hz.
2) No crossover on the 3kHz region where the ears are most sensitive.
So there is no phase shift. Sound is time and phase aligned up to 5,500 Hz. Unlike a 1st order x-over, the speaker will sound good everywhere, not just in the sweet spot. The speaker should be very un-fussy about placement. Reviewers describe the huge soundstage and natural, seductive sound.
Maybe someone has the chart which shows which instruments play at what frequencies but I think 5.5 kHz is above the basic harmonics of most instruments. Most single driver (Jordan JX-92s and Tang-band W3-871s) designs get rough above 5kHz and beaming is also a problem because a larger driver is needed to reproduce the lower frequencies. So a tweeter solves these two problems.
But most designs use a crossover to do the job of integrating the 2 drivers. Crossovers eat power (an extreme example is the inefficient Thiels require with their complex 1st order x-over) and mask detail. So the beauty of the Epos design is one can use a low powered amp. Crossovers also reduce the dynamic range of a speaker. Reviewers have said the Epos is very transparent and even changes in cables are readily obvious. This is at least in part due to the absence of a crossover. So the Epos act as a sort of an active speaker. Except there isn't even a crossover before the power amps.
Most low powered amps sound better and of course, cost less. This is just my experience but higher power amps tend to sound harsher (bipolars vs. mosfets) and when an amp designers attempts to boost the bass, the high frequencies get harsh. Nelson Pass tried to resolve this with his XA amps.Off the subject, but 4 ohm speakers which require a high powered amp better have a pretty sweet high end IMHO.
Downsides to this design are limited bass extension and they cannot be played very loud without losing bass.If you turn up the volume they probably get shrill as the treble takes over in relative volume level. I also wonder, can a single mid/bass driver reproduce the detail compared to separate mid and bass drivers? How fast can a single driver move before it gets congested and starts smearing detail? Also there are probably higher levels of distortion, especially in the bass. Companies like B&W place a premium on low harmonic distortion (although there are other disortions than this!) and relatively high volume levels. So I can see why they don't make a design like this.
Maybe I'm showing my ignorance here but I would be interested in other's comments and their thoughts on what makes the best 2-way speaker design.
cdc
cdc OP
1,785 posts
 
Thanks Metralla. That was an interesting interview. I was NTO saying the Epos was the best 2-way. Just the design concept seemed better than most.
Revel uses the 2 mid/bass 1 tweeter on their Gems vs. M20 and Axiom does the same thing between M3ti and M22's. But from what I think I rememeber from reading about this design was the dispersion of the tweeter is compromised because of it's placement between the two other drivers. Or something like that.
cdc OP
1,785 posts
 
Esoxhntr, I could not say it any better than you did yourself:

"08-30-04: Esoxhntr
Tireguy:

Agree with you 100% - well almost ;-) These firefights serve no purpose in terms of enlightenment, "

Happy flaming :-)
cdc OP
1,785 posts
 
That interview with Karl Schuemann's (AudioMachina) had some similar points:

1) The way it ought to be is a single transducer. But in the real world, that hasn't been achieved yet. At least in terms of something that is practical and still a full range transducer

2) The three way system is always going to have a crossover in the places where your ear is very sensitive to such things. You can hear, if you are listening carefully, the transition from the woofer to the midrange. It is not only a spatial transition in the sense that one is above the other and your ear-brain system can detect that; it is also that I think the characteristics of the drivers themselves are fundamentally different. So, whatever colorations the woofer imparts to its particular sound—it may be a certain type of distortion; it may be a certain type of flavor that the cone adds to the sound—those are going to be different than whatever colorations the midrange contributes. You can detect the discontinuity between the colorations

3) having that entire continuum from the mid-bass on up through the midrange and through the low treble reproduced by a single driver, you get coherence.

4) Whatever colorations that driver is imparting to the sound, they are present more or less throughout its entire frequency range and there is no crossover in the way, so there are no phase shifts, no time problems, no location problems. All of those problems are simply eliminated by the fact that it is a single driver. No matter how good a designer you are, you are not going to make a crossover disappear. Your best bet is to eliminate it entirely if it bothers you that it is there.

I wonder what Karl would say about phase shifts from putting two drivers together like Epos or Verity Audio which roll off naturally. Would that help or hinder phase shifts?

Here's the part about the problem with D'Appolito configuration:

5) in combination with having to have the woofers very close together in the D' Appolito configuration in order to not get the dispersion problems that you see a lot of times in the D' Appolito designs, and the amount of offset that I needed to achieve time alignment between woofers and tweeters, means that you end up with this deep wave guide.
So he used a wave guide to reduce this dispersion problem and put the drivers close together which I would think would further create dispersion interactions between drivers.
vladimir
346 posts
 
Good two-ways vs. the rest. Hmm.. I don't have either the space or the money to buy those big floorstanders. What to do? This is a never-ending discussion and contrary to what was said, I find it very enlightening especially for those who are starting on this high-end hobby. They can have your cake and eat it too, in a way. Yes, even the best two-ways have their shortcomings but what reasonably priced three-way or floorstanding speaker isn't compromised?

For those interested, I have written two articles here that present one side of this discussion (scroll down to Minimonitors and subwoofers I and II). They need updating but the basis is still valid, IMO.
cdc OP
1,785 posts
 
Vladmir, as you said "what three-way floorstanding speaker isn't compromised" is one of the most frustrating parts of this hobby (to me anyhow). You spend more and the speaker is better in some ways but worse in others. So even spending more rarely gives you better in every way.
I agree with your comments about a minimonitor and sub. Like the part about most 3-ways putting an x-over between 100 and 400 Hz. Right in the middle of the vocal range. Then they put one around 3kHz - again right where the ear is most sensitive. What a mess!
I guess my ideal is a small 2-way monitor 1) put in a small room where the room provides the bass reinforcement so a sub is not needed and 2) play at 75 dB max so the driver's don't get pushed into distortion.
The question I have about the audiomachina is which is better, an intricate 1st order x-over to 1) preserve time and phase coherence and 2) perfect driver integration or no x-over which 1) minimizes amp power required and 2) allows the maximum detail and transparency because of less electronics in the way of the signal path?
Amp designers commonly try to remove as many circuits as possible from the signal path be it negative feedback or additional gain stages and them you've got the speaker crossover putting it all right back in again.
Maybe it's a wash, I don't know.
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