Flawed? Wilson's Aspherical Propagation Delay


I've always wondered about this...

Recently I read an interview with Alon Wolf who stated that separating drivers into boxes that are adjustable would not work for him because the crossover would need to be reworked or adjusted.

Wilson is proud of their adjustable cabinets in their upper models, but I'm wondering how, in technical terms, they avoid phase and time errors and as Alon pointed out, how the crossover deals with the drivers in different locations and different angles?

I've heard Wilsons set up before and there is a distinct advantage to the adjustable enclosures when they are setup optimally for the listener's height and distance from the loudspeakers, but is there a shortcoming or compromise in doing so?
If the dispersion of the drivers is uneven (as they are in many audiophile designs) then adjusting the tilt and toe in of individual drivers can certainly be used to accommodate for inadequate design, however, this all comes at the expense of increased edge diffraction. The ability to tweak is definitely a selling point within some market segments.
If the wavelengths at the crossover frequency are long relative to the adjustments that are made, the effect on system phase response will be negligible. Also, the adjustments may well be restoring ideal geometry for listening positions that are not at the height and distance the speaker was optimized for. I'm gonna side with Wilson on this one.

Gotta agree with Duke. If time master Roy Johnson uses adjusting speakers, there must be a way to do it right.
Flawed, yes. Its a business model thing. Think about it, the bigger the 'boxes', the higher the price you charge. The 'effect' of Wilson speakers can be purchased at one tenth the price they charge. Wilson prides itself on a bigger is better approach. It is a guy thing.
I own Wilsons-and love em. No other speaker is for me. With that disclaimer...

The OP seems to be transferring Alon's statement based on his speaker methodology (..."would not work for him b/c the crossover...") to Wilson's methodology. Wilson take this into account and his crossovers are specifically designed for the Aspherical Prop. Delay. It's a system.

Alon was talking about "his system" He makes good speakers to! Just in a different way...

Buconero117-sorry in advance here. But, ok well you forgot "successful" in your biz model quip...So if others can make wilsons for one 10th the price, why haven't they? I'd gladly buy Alexandria X2's for 1/10th the price-assuming the same performance level. Maybe the sum of the parts is greater than you may think? I always find it odd when folks attack Wilson for their business model. If you don't like the sound of their speakers, that's your opinion and your certainly entitled to it.

Their business model seems to be a success and that's why they sell and win awards... we all want successful business models in the high end because that funds r&d for better products down the road. And, at least in the USA, provides jobs, benefits and profits. Therefore helping our economy and our gov't with more taxpayers...I don't think this is a "guy thing" But this is just my opinion I guess...
Thanks for the response thus far...

To clarify, I am a Wilson fan and own their speakers. To my ears they are more fundamentally correct in reproducing music than just about anything else I've heard in my price range. I'm not trying to create a Magico versus Wilson thread, but I've always wondered about Wilson's propagation delay. Perhaps it's the best thing in the world and is a great part of why their speakers sound so good, but if there is a downside to this method, can anyone think of what it might be? Sounds like the adjustability may be hugely a positive with little to no negative, but does it have an effect on how the crossover operates? If the crossover and aspherical propagation delay is a "system" shouldn't the crossover be user adjustable too? Please correct me if I'm mistaken...
Designing decent user-adjustable crossovers would be a lot more complex than it sounds. Adjusting the array to restore the correct speakers-to-listener geometry makes a lot more sense to me.

The dowsides are greater diffraction, as Shadorne noted, along with higher cost, greater dependence on trained professionals for initial setup, and introduction of the opportunity to screw things up.

If Wilson used active crossovers then they could offer adjustable x-overs at reasonable cost.

Frankly I am with buconero on this one, at least in regard to the very large Wilsons. I have no beef with the triangular sloped baffle on the Watt Puppy - as this does look like a genuine attempt to adjust for dispersion & maintain good diffraction characteristics. It seems Wilson is doing much the same as any manufacturer at the ultra-high end of the product range: countless questionable additional benefits that justify an astronomic price tag. To be fair this happens with cars, skis, watches, electric shavers...you name it! So I don't want to imply that Wilson products are inferior in anyway - they both look and sound great!

02-20-11: Buconero117
Flawed, yes. Its a business model thing. Think about it, the bigger the 'boxes', the higher the price you charge. The 'effect' of Wilson speakers can be purchased at one tenth the price they charge....
Which "Wilson effect" are you talking about--low level resolution where you can hear the air coming out of the trombone's bell?
Frankly, I'm surprised that Mr. Wolf would say this.
For a speaker to be 'truly' phase correct, time function, being 'distance' in this context, would have to be correct also.
Time alignment, in the loudspeaker context, places the drivers in a position so that the sound from each, arrives, (without room interaction, which is impossible to do)at the same time. This preserves the 'unit body' of a multi-frequency/several octave tone, being played by multiple drivers. Preserving phase relationships is universally thought of as being a first order/6db per octave slope.
Wilson, by having adjustable enclosures, one's which allow for adjustments for the listeners height/distance, are giving a more accurate arrival signature.
If approximated time alignment, (think THIEL dating back to the late '70's early '80's) aligning the drivers so that the sound from each driver arrives at the listener at the same time (allowing for the concave/convex nature of the drivers)works, then EXACTING alignment would by default works BETTER.
THIEL used a minimum distance of 8' for their time alignment, without regard to the height of the listener, instead, approximating a 40"(?) height.
Many years ago, I was aligning a loudspeakers drivers for a listening session with my old friend Jim Thiel...I was being anal and Jim, more interested in getting to dinner said, "That's close enough Larry." Knowing how OCD Jim was about all of his work, I gently said, "You know, if approximate time alignment works, perfect time alignment works better," He just smiled and shook his head in agreement. Dinner would wait.
I'm thinking that Mr. Wolf is giving up some ground to Wilson on this by not making the necessary adjustments to his crossovers. Surprising given the incredible 'technical bent' that seems to be an important aspect of his designs.
Lrsky wrote:
"For a speaker to be 'truly' phase correct, time function, being 'distance' in this context, would have to be correct also"

According to JA, Wilson speakers are neither phase correct nor time aligned or coincident (Their midrange is actually wire out-of-phase).
I thought that physical time alignment happens when drivers physical location are aligned with each other , not to the listener... I mean, how exactly can you "time align" anything on an angle?

Looks to me that Wilson has to "tilt" his drivers simply because they are located to high for any reasonable listening position. It has nothing to do with time or phase alignment.

The big Wilson have the tweeter 2 high for the typical listening position, making the head adjustable allows him to tailor to such...

Say what?
To put things in a context that everyone can hopefully appreciate, I'll make a few comments then shut up.
You say that, "I thought that physical time alignment happens when drivers physical location are aligned with each other..." or words to that effect.
This is, not correct. I was simply making the statement about time and phase correctness, assuming as I should not have, that the implication was such about Wilson versus Mr. Wolf's product.

Time alignment has traditionally been, an approximation, of drivers' juxtaposition based on the 'averaged' or suspected location of a listener.
Vague, yes, as I used the word, approximation. Let's say that THIEL's were aligned for a listener who was 8 feet away from the face of the speaker, and sitting at an ear height of 36 to 42 inches. Approximately...
What if, and this is truly the question, one could measure the exact distance to the listener from a predetermined and mathematically correct 'launch point', AND have the exact height of the listener's ears...then we could set the drivers voice coils so that their position assured that the arrival time of all drivers 'to the ear of the listener', could theoretically be perfect. ALL DRIVERS INFORMATION COULD/WOULD arrive at the listener's ear at precisely the same time. Think Soundlabs (no, I don't work for Dr. West) panel pulsing all the 'in phase' information arriving in the same time domain, since it's essentially one driver releasing a unit body of frequencies at the same time.
So we have, theoretical perfection, 1) In phase 2) Unitary arrival.
The 4/5 way speaker with voice coils mounted at varying distances almost preclude this event happening this way, unless the manufacturer has, as Wilson has, made the drivers adjustable in terms of their 'launch point'.
Years ago, I sold speakers that were alignable (new word), in that, using one 'launch point' determined mathematically, from the front of the bass module...then all other drivers, (there were 5 in all) were lined up to within 1/16th of an inch, based on the distance and height of the listener's ears.
Given the time, technology of that day, this was the 'best sound' I had ever heard within the 'arrival time' context.
Let me be specific about the dramatic side of this.
At a show in Chicago...I went into a room in which this exact speaker was set up--I was asked by the manufacturer to assess their 'set up', which my own technician had worked on...after listening for about 10 minutes, I said, there's a problem with the left midrange. Of course, looking like a racing team pit crew three guys came forth and checked the left speaker. And, and I swear to all that is Holy, they measured and found that the midrange driver had been accidentally placed 1/16 of an inch too far away. You can chose to believe or not believe this last statement but its TRUE.
I'm not sure I still have those ears at my age, but the point here is not me, but the veracity of TIME ALIGNMENT...when it's right, it's magic...when you once hear it that way, you'll not soon forget it.

There was something truly magic, when the 'launch' was mathematically, provably perfect in terms of arrival, using distance and height of the listener.
Without knowing, as I haven't researched Wilson's site, I would have to think that they too would provide settings based on distance and listener height--without which no alignment, as I can imagine it being calculated, could exist with accuracy.
I hope this lengthy message reaches someone...I did not want to become embroiled in a debate like this, but my experience and love of audio trumped common sense, as it is want to do on this site.
Love all audiophiles!
The German Ascendo speakers have a movable tweeter by which
you need to first measure the distance between your ears
and the tweeter and then use an instruction diagram to determine the right distance of the tweeter. The designer
Prof. Scheuring developed a special crossover for the band
pass woofer & mid/bass driver such that both are in phase
as well as time aligned. Jonathan Valin wrote about the
version M-S Mk II (the most expensive one) in TAS ,November
2006.BTW he was very impressed.