Okay, the gloves are off. Let the fur fly

THE THIRD ALTERNATIVE... To follow up Zaikesman's excellent post of 4-01...the real world factors" that put very serious considerations on the SOUND LABS "conquror of the boxes"...IF you can afford...IF your wife likes the new furniture...IF you can find the proper placement (room size factor)...IF your favorite amp will accept the demanding low ohm load...too many "IFS" for me at this point in hobby and life..the 3RD alternative for me is choosing the SUPERIOR drivers you would like in your design...and not having to buy the "commercials" that choose for you...IF the "POPULAR" labs put the drivers i mention in a design their markup brings us into the SOUND LABS price range..and we don't want to go there..21ST century drivers are : FOCAL midwoofers and midrange,PHILIPS RT8P isodynamic tweeter,ESg1,ESg2 ribbons,RAVEN1,2,3 ribbons,MENGER full range,TRIANGLE full range...with a good designer you can put together a far superior speaker for alot less than whats offered in your local hi-fi shop..these drivers with superior xover components (HOVLAND,SOLEN etc) would better the SL's is some aspects, the one factor that comes to mind is the price differential $1500 to $2500 VS. $8K and UP UP...AWAYYY! AND i get to keep my amp of choice. To complete the full range of frequencies we will need a superior sub that makes the intergration work, FOCAL WX11 WX13 WX15. This kit choice is just a possible 3rd alternative,not for everyone, but for me it's the only way to go.

Fascinating thread! However, I can't grasp the out of phase comment in Twl 0402 post: if, say, a multidriver speaker is out of phase, the musicality & timing (prat?) will be lost -- irretrievably? I mean, even if I reverse the polarity at single driver(s) or speaker level, I won't get the phase/timing corrected, surely -- rather, something has to be done @ crossover level? Or am *I* irretrievably confused (most probable)??? Cheers!

Greg, now you're getting somewhere. One can correct a lot of the problems of a multi-way system simply by getting rid of the passive crossovers or at least minimizing them down to the bare essentials. This is what Israel Bloom does with the Coincident's.

However, one still has to look at how the individual drivers will sum at a specified distance, play with their positioning on the baffle and then study the lobing / cancellaton / reinforcement that takes place. Then re-position accordingly and study some more until you've got everything as good as you can. This becomes even more critical if you aren't using any crossover at all, since you now have to select drivers that will have complimentary frequency response curves and roll-off rates. VERY tough to say the least.

To take things one step further, you can remove ALL electronics from between the speakers and use an active crossover. This gives you direct drive ( just like an amp driving one driver ), greater efficiency from the amp, FAR more detail, impact and lucidity than with a passive crossover, etc...

Then all you have to do is make sure that you've got all your amps gain matched, use good quality amps and crossover, take into account the lobing and positioning of drivers, etc... This is a LOT of work, but it is also probably the highest fidelity that your going to achieve if done correctly. Obviously, this is strictly my point of view and others may / may not agree. Sean
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Greg, the phase problem you mention is only one of the many phase related problems. Phase induced distortion/coloration is another. Sure, there are methods of addressing these problems. My contention is that the cure is generally worse than the original illness. If I told you that your system would sound better if you would just wire-in a few transformers and capacitors into your speaker cables, you would think I was crazy. And you would be right! That is essentially what a crossover network is. Except, it is calculated to achieve the blending of drivers in multi-way speaker systems. Sometimes it is done very well. Most times it is not. When high end mfr's. tell you to wire-in transformers and capacitors into your speaker line, nobody thinks they are crazy. How come? Do you ever remember hearing a small table radio or old car radio that sounded really good, even though it was small? Alot of that "goodness" can be attributed to the simple speaker setup, driven direct with no other drivers or parts. Now table radios(boom boxes) and car stereos(rolling boom boxes)sound like crap, but they have plenty of bass. Such is the case with 98% of the multi-way systems today. There is a significant segment of purchasers who will place bass response over all else, and buy the "least offensive" big-bass speaker, and claim it sounds great. Maybe it does. This is subjective. I'm quite sure that the owner of the pulsating Nissan that reverberates subsonic shock waves through my house every morning on his way to work, thinks his car stereo sounds great, too. Now that I think about it, I could probably get rich designing a new single driver system utilizing a 24" driver that produces high SPL and only responds from 10HZ-150Hz. This is the only part of the frequency range that seems to matter these days, anyway. Maybe I could name it the "Seismic Oscillator" or "Primal Thump". Any takers?

LOL, Twl, the "pulsating Nissan"; what a beautifully accurate image! The Primal Thump (or Thud) is a killer product, indeed!
Among the best thud machines IMO, are industrial washing machines and factory bottling lines: they keep a steady rythm AND offer bonus sound effects, well into the KHz region!

To link onto Sean's post and yours above, and deepen my confusion...
To reiterate the obvious, in striving for correct phase across a speaker's spectrum,we are limited by having to:
a) coordinate drivers between themselves (in the case of multiple drivers) AND the enclosure,
b) coordinate vs. a specific listening position,
c) coordinate vs. a given room's/chamber's/space's acoustics.

An electronic c/over may help tame some of the room/chamber related inefficiencies and allows for better use of power, as Sean notes. But, do we have correct phasing within the whole spectrum of each (or THE) driver? Or is it too much to ask that the driver reproducing (fortuitous example) 150-3KHz provide correct "musical timing" at both ends and @ 1,5KHz?

Because if it doesn't or even "sort of" does, no amount of speaker positioning or engineering seems likely to completely correct the phasing. I mean, what can one do? Slow down the 1,2-1,8kHz fundamentals so that their 600/900Hz harmonics can catch up? Or speed up the cello sound so it can catch up with the violin?
I'm coming to realise that a lot of engineering is necessary to trick my ears into believing in the reproduced sound of the symphony orch. that emanates from my pulsating multidriver boxes, and it's NOT only a matter of dynamics...

Case in point: the Genesis V (dipole/bipole) I'm now using combine a 4th order quagmire of capacitors (c/over as per Twl) for the mid-highs, with an electronic crossover controlling the built-in sub (as per Sean). One of the controls on the electronic c/over is "phase", expressed in degrees, 0-180. This *does* mean phase & not polarity.

So I can correct for time-related problems in the sub's 20-110Hz area (the c/over point is my choice). So far so good. However, even if we assume that the phasing is correct from 85Hz down(my present c/off for the sub), the harmonics reproduced, par exemple, by the woofers are NOT necessarily always in phase with the fundamentals coming from the mid-high section. So, where's my timing? (I might as well dispense with the expensive Mr B. Walter altogether :))

Furthermore, when we use many drivers (and the enclosure, of course), the speaker becomes a system. So, as Sean suggests, we'll have to tune/engineer the c/over accordingly in order to accomodate the combination of drivers... Probably in relation to the slowest transducer in the system -- it being rather difficult to speed up a driver unit to reproduce its core frequencies in phase with the rest. Then, we will have some overlap between drivers. Assuming the room has no reflections that excite certain points in our reproduction system (as per Murphy's law, the weak, c/over points of course), we're in business.

...A nightmare. I apologise for the long, confusing diatribe; the only excuse I can proffer is, I'm not an engineer!
I'm off, as many others in quest of the sound that will defitively seduce the omnipotent ear, to purchase the next $20-200k speaker.
Cheers!