AUDIO ELEMENT FIFTH ANNIVERSARY CELEBRATION

[DaveyF]

@metaphacts - you are obviously closely associated with Wilson, and perhaps you are an employee, so let me ask the same question: how can two out-of-phase drivers be time coherent?

+1

 

[KeithR]

So why no D'Appolito for Wilson? Dave spent his life pursuing the proper alignment in time of the full signal's arrival at the listening position. His pursuit has been measured and documented since Dave experimented with adjustable drivers mounted above his speakers some 50+ years ago. It has really been in the last 15 years, since academic studies bore out just how easily people hear time arrival differences and just how short those audible intervals are coupled with the WAMM Master Chronosonic project with the extensive research it entailed that Wilson designs began to take those intervals down close to, and in the case of the WAMM, below the audible threshold of the typical person. However, to accomplish this precision, the drivers must be capable of being pulse aligned at a given listening position (distance and ear height). But once the drivers move from a physically symmetrical array on the vertical axis, they cannot be termed D'Appolito by definition.
Bill

Bill, it was nice to meet you Saturday morning briefly (I was in the wheelchair hogging the room!)

follow up question - if time alignment is so important based on Wilson's studies, why invert polarity in the crossover?

 

[KeithR]

Ron - thanks for the great write-up!

I spent an hour basically unfettered with the Sasha DAW as I was the store early bird. In particular, I enjoyed the DAW sound on the AMG analog rig and, when asked, did not request to hear it on the Monaco as Lyra isn't my cup of tea either (I owned the Delos). The DAWs seem more coherent than prior iterations. As my WBF friends know, I have been critical of the Alexia 1 and Alexx in particular on this note and it has improved in the Sasha DAW. Soundstage was excellent and there wasn't any brightness. I had heard the Yvettes on the same VTL rig in that room before and think transparency was kicked up a notch this time around - probably due to the WAMM drivers. Luke Manley and I played with the rear door to dial in the bass, and that room definitely required it half way open to prevent bloat although it still didn't seem perfect- these speakers were only 3 days old so take it with a grain of salt.

As far as the digital rig sound, I can't say the dCS Bartok front end helped things. I found the sound a bit hifi and mechanical in nature. I certainly would like to hear an MSB front end on that front.

As always, Brian Berdan is a gracious host and his store is excellent. Audio Element and Alma Audio are my favorite dealers in the LA area and if you are in SoCal visiting, highly recommend a trip to each!.

 

[Folsom]

Interesting. Can you elaborate on this subject? As far as I see it, most of the time the digital is converted by a DAC and the cutter is analog driven.

Cutters use a DAC, yes, but the dots are connected in an analog fashion as it goes from one point to another. The cutter "fills" between in a mechanical way, where as a DAC has to do it electrically. Obviously you could probably design cutters differently to have slightly different sound profiles based on how it adjusts from point to point. You can adjust the cutter to not be sensitive enough to try and fill end information above the audio range as well, so you don't get tons of RF. (phono stages are meant to be fairly immune to it, and cartridges are necessarily good at reading it)

 

[metaphacts]

Bill, it was nice to meet you Saturday morning briefly (I was in the wheelchair hogging the room!)

follow up question - if time alignment is so important based on Wilson's studies, why invert polarity in the crossover?

Hi Keith,

You seemed quite in your element (pun intended) listening and other than my noisy reunion with Mark Goldman, I hope I didn't interrupt too much.

Let me come back to your question after work please. I have only 2 days in Utah before I go back out on DAW and WAMM presentations the remainder of the month.

Bill

 

[microstrip]

Cutters use a DAC, yes, but the dots are connected in an analog fashion as it goes from one point to another. The cutter "fills" between in a mechanical way, where as a DAC has to do it electrically. Obviously you could probably design cutters differently to have slightly different sound profiles based on how it adjusts from point to point. You can adjust the cutter to not be sensitive enough to try and fill end information above the audio range as well, so you don't get tons of RF. (phono stages are meant to be fairly immune to it, and cartridges are necessarily good at reading it)

Thanks. You are saying that the cutter acts as an additional filter, because of mechanical inertia of its parts and the cutting process, complemented by the reading process. IMHO there is no dot connection at all in an analog fashion - just a different way of filtering the DAC, with lots of added coloration and noise. Also as far as I know cutting systems accept an analog filtered signal , not DAC steps, although it could be implemented - for example a DSD directly driven cutter. I never read about such system.

 

[Folsom]

I was just trying to illustrate. Yes the cutter receive analog but it is a filter. Analog cutting of vinyl existed before we had anything remotely high sample rates. It simply doesn't translate the hash that a DAC on a CD player will.

 

[microstrip]

I was just trying to illustrate. Yes the cutter receive analog but it is a filter. Analog cutting of vinyl existed before we had anything remotely high sample rates. It simply doesn't translate the hash that a DAC on a CD player will.

So all we have to do is implement a proper electro-mechanical filter between DACs and preamplfier to have great analog sound in our systems?

 

[Jeffy]

I'm in agreement with Ron. I've never liked a Lyra cartridge that I've heard at audio shows or show rooms. I never had one in my system. The sound always came off brighter and thinner than I liked.

 

[tima]

I agree that listening isn't the same as measuring. However, we can measure coherence in time. The impact of time coherence is where the listening comes in.

I imagine the Daws are coherent sounding, as many speakers are. I've heard many Wilsons, and they don't sound particularly disjointed. But, to my knowledge, they aren't time coherent.

Wilson, like every company, has their marketing terms, and they seem to be eyeing time coherence as a feature of their speakers. I don't see how it's actually possible though. And again, they've been measured to be not coherent in time.

I'm just wondering how they can say they are, and people back them up, when the speakers are obviously not.

We can also experience time coherence.

Let me ask you this: how do you think a time coherent speaker sounds? What are the sonic characteristics of a time coherent speaker?

 

[DaveyF]

I'm in agreement with Ron. I've never liked a Lyra cartridge that I've heard at audio shows or show rooms. I never had one in my system. The sound always came off brighter and thinner than I liked.

Interesting, and this is certainly a reputation that these cartridges have received. Unfortunately, I think they are getting a bad rap!
Having heard the whole line now, I can tell you that they are a serious microscope on the whole chain. If you have not maximized your upstream gear and/or your downstream gear ( compatible tonearm that has the CORRECT compliance and has excellent bearings, typically not a unipivot design) , plus your set up isn’t spot on...you will certainly hear the results that you describe. I noticed this when a friend who owns an Atlas demonstrated the differences that just a very minor adjustment made in Azimuth set up.
These aren’t ‘Forgiving ‘ cartridges, like my old Benz was as an example.( that would sound very good with a number of variables not 100% dialed in).
But if all of the parameters are hit, IMO, they are top rung.

 

[lordcloud]

We can also experience time coherence.

Let me ask you this: how do you think a time coherent speaker sounds? What are the sonic characteristics of a time coherent speaker?

I can tell you what I've heard in time coherent speakers, versus what I've heard in all others. Though it also takes into account, speaker set up. Which I think is incredibly crucial, and even more crucial when it comes to time coherent speakers.

For me, when set up properly, I can see instruments and the space they're played in much easier. They're easier to listen to, even if they're very detailed. Images are denser.

Most speakers sound flat to me. Time coherent speakers tend to sound more dimensional. Less boring.

 

[NorthStar]

Sidebar 2: Aspherical Group Delay

Wilson claims that its Aspherical Group Delay technology is as effective harmonically and texturally as it is spatially, helping to precisely reintegrate, at the listening position, the frequencies that have been separated by the crossover and sent to the various drivers.

To do this, each of the three drivers in the Alexandria XLF's MTM array can be independently adjusted fore and aft, as well as rotated on its polar axis. Of equal importance, once the appropriate position has been found, each module can be rigidly locked in place with tether bolts of various lengths, secured with wing nuts. Each module is moved along a pair of rails, each with a center notched track. There's one set of rails atop the woofer box, and one set each atop the lower-midrange and tweeter cabinets. There's also an assortment of spikes of different lengths. It's a major feat of mechanical engineering and precision manufacturing that needs to be seen to be appreciated.

All you have to do is measure the distance of each drive-unit from the listening position, and the height of your ears when you're sitting down, and Wilson's charts tell you into which numbered notch each spiked module should sit, and which length of tether bolt should be used to set the module's elevation. But no, you don't do any of this—your Wilson dealer will.

The goals are to time-align the drivers so that the combination of their outputs produces the equivalent of a single point source, and, by adjusting the modules' polar axes, to precisely focus the sound propagation on the actual listening position—not at a theoretical point a set distance from the speakers dictated by a design that might not suit the realities of the room. It's sort of like the difference between cameras with fixed and adjustable lenses."—Michael Fremer
_____

Taken from the Stereophile's review of the
Wilson Audio Specialties Alexandria XLF loudspeaker
Michael Fremer | Dec 28, 2012

 

[lordcloud]

Sidebar 2: Aspherical Group Delay

Wilson claims that its Aspherical Group Delay technology is as effective harmonically and texturally as it is spatially, helping to precisely reintegrate, at the listening position, the frequencies that have been separated by the crossover and sent to the various drivers.

To do this, each of the three drivers in the Alexandria XLF's MTM array can be independently adjusted fore and aft, as well as rotated on its polar axis. Of equal importance, once the appropriate position has been found, each module can be rigidly locked in place with tether bolts of various lengths, secured with wing nuts. Each module is moved along a pair of rails, each with a center notched track. There's one set of rails atop the woofer box, and one set each atop the lower-midrange and tweeter cabinets. There's also an assortment of spikes of different lengths. It's a major feat of mechanical engineering and precision manufacturing that needs to be seen to be appreciated.

All you have to do is measure the distance of each drive-unit from the listening position, and the height of your ears when you're sitting down, and Wilson's charts tell you into which numbered notch each spiked module should sit, and which length of tether bolt should be used to set the module's elevation. But no, you don't do any of this—your Wilson dealer will.

The goals are to time-align the drivers so that the combination of their outputs produces the equivalent of a single point source, and, by adjusting the modules' polar axes, to precisely focus the sound propagation on the actual listening position—not at a theoretical point a set distance from the speakers dictated by a design that might not suit the realities of the room. It's sort of like the difference between cameras with fixed and adjustable lenses."—Michael Fremer
_____

Taken from the Stereophile's review of the
Wilson Audio Specialties Alexandria XLF loudspeaker
Michael Fremer | Dec 28, 2012

All this is saying is that Wilson Audio says that if you move the drivers around and into the correct positions relative to the listening position, time coherence is achieved.....

So we're back to, it's time aligned because Wilson Audio says it is. Even though the crossovers are high order, and the drivers start and stop at different times.

I've not read or seen anything that shows how the signal from their drivers actually arrive at the listening position coherent in time, even though they don't leave the speakers that way.

 

[NorthStar]

For that particular speaker, read the review online, they use the Aspherical Group Delay Technology. Yes each driver's enclosure is adjustable to reach the listener's ears @ the same time, and with various adjustments in its rear, like phase, level, damping, etc.

_____

Dunlavy, Vandersteen, Thiel, Reference 3a, Tannoy, Quad, and few more employ "time coincident" technology with all the drivers in the same polarity and with individual driver responses arriving at the ears at the same time, sometimes called "time/phase coherent.

The crossovers in other loudspeakers are electrically phased tuned/corrected.
Some use low order crossovers (6dB per octave) to achieve best integration between the drivers. Speaker's design is an art, and it's also a science. Magic is obtained between our two ears.

Each speaker designer use more or less similar methods.
Which method is best? ...Vivid Giya G3, BeoLab 90? I have no clue; some use DSP, with FIR and IIR filters in their crossovers. Whatever sounds great is the aim.

I wouldn't mind give those a test drive, in addition to the Sasha DAW.

And a good setup in an acoustically tuned room is everything.
I can think of few speakers which would benefit and be @ ease to please two ears.

 

[lordcloud]

For that particular speaker, read the review online, they use the Aspherical Group Delay Technology. Yes each driver's enclosure is adjustable to reach the listener's ears @ the same time, and with various adjustments in its rear, like phase, level, damping, etc.

_____

Dunlavy, Vandersteen, Thiel, Reference 3a, Tannoy, Quad, and few more employ "time coincident" technology with all the drivers in the same polarity and with individual driver responses arriving at the ears at the same time, sometimes called "time/phase coherent.

The crossovers in other loudspeakers are electrically phased tuned/corrected.
Some use low order crossovers (6dB per octave) to achieve best integration between the drivers. Speaker's design is an art, and it's also a science. Magic is obtained between our two ears.

Each speaker designer use more or less similar methods.
Which method is best? ...Vivid Giya G3, BeoLab 90? I have no clue; some use DSP, with FIR and IIR filters in their crossovers. Whatever sounds great is the aim.

I wouldn't mind give those a test drive, in addition to the Sasha DAW.

And a good setup in an acoustically tuned room is everything.
I can think of few speakers which would benefit and be @ ease to please two ears.

I feel like you know that Dunlavy, Thiel, Reference 3A, and Vandersteen are very different than Wilson when it comes to claims of time coherence, and that designers that aren't using first order crossovers and physically aligned drivers, aren't doing it at all like the others (Tannoys aren't time coherent).

Many speaker manufacturers aren't even attempting time coherence, and they also usually give their reasons why they don't think it's important. But like you said, whatever sounds great is usually their aim. Nothing wrong with that.

 

[tima]

I can tell you what I've heard in time coherent speakers, versus what I've heard in all others. Though it also takes into account, speaker set up. Which I think is incredibly crucial, and even more crucial when it comes to time coherent speakers.

For me, when set up properly, I can see instruments and the space they're played in much easier. They're easier to listen to, even if they're very detailed. Images are denser.

Most speakers sound flat to me. Time coherent speakers tend to sound more dimensional. Less boring.

Yes, dimensionality improves with time coherence. It's ancient - when the twig snaps behind you, you've got a pretty good idea. The vast majority of your standard audiophile sonic attributes contain or involve time dependencies. It takes a time accurate source and time coherent speakers properly set up, along with amplication that minimally screws up (smears) the signal passing through it.

All this is saying is that Wilson Audio says that if you move the drivers around and into the correct positions relative to the listening position, time coherence is achieved.....

So we're back to, it's time aligned because Wilson Audio says it is. Even though the crossovers are high order, and the drivers start and stop at different times.

I've not read or seen anything that shows how the signal from their drivers actually arrive at the listening position coherent in time, even though they don't leave the speakers that way.

I'd say you don't need to rely on Wilson to tell you. Listen. The upstream example is the easy experiment. Use a newer Wilson speaker with finely stepped module alignment, properly vowled-in using the standard WAS setup technique by a competent installer (eg Bill, Peter, John.) Changing the stepper position can walk you in and out of coherence. You can hear it. You can read specs all day but it only takes a few moments to prove using your ears.

 

[microstrip]

For that particular speaker, read the review online (...)

Bob,

Although you have good intentions, most of the time reading reviews on line concerning specific technical aspects that are being debated only adds noise to the discussion, unless the reviewer is a technical expert, something that M Fremer is not. He will just reproduce what he has read somewhere else, without a proper reference.

As usual, most of our debate is on semantics - manufacturers use the terms concerning time coherence rather freely with different meanings. We can not expect that the so called "scientific community" will hep us on this aspect - I quote from the F. Toole book :


They assume it is audible, but only expresses preference, not accuracy.

If people really want to know about Wilson Audio opinions on that matter, IMHO the best way is looking at David Wilson patent https://patentimages.storage.googleapis.com/a4/13/e8/793f8aea3369b7/US4450322.pdf Adjustable speaker system and method of adjustment . And yes, I know most of the time patents are like cooking books, they protect the recipe, but do not tell us of the science ...

IMHO - I have no access to privileged information - time alignment is just one part of the whole of a Wilson Audio speaker, and it is the more often referred. However it is only meaningful when connected to many other specific aspects of their speakers, such as frequecny response , dispersion and delayed resonances.

Although the measurements at the optimum listening position can be used used for assembling the system, IMHO the system is created to have a well defined behavior of the time alignment (or misalignment ) when movig out of the sweet spot.

BTW, some recent reviews of the WAMM system include interesting comments on time alignment, including the influence of the driving amplifier.

 

[metaphacts]

Bill, it was nice to meet you Saturday morning briefly (I was in the wheelchair hogging the room!)

follow up question - if time alignment is so important based on Wilson's studies, why invert polarity in the crossover?

Hi Keith,

As has been said in later posts in this thread, there are numerous effective ways to design a loudspeaker. In focusing on both the spectral and temporal, Dave made (and documented) choices that for many traditionalists were less than conventional. Certainly the separate enclosures that facilitate simultaneous arrival times based on listening distance and height are an expensive way to skin that cat, but there was no other so effective. The crossovers he designed require that some drivers be hooked up in different electrical polarity for the best acoustic and measured impulse performance at the listener. Note too this varies by Wilson speaker/crossover. Dave felt he was pushing an envelope he first observed in the venerable Dahlquist DQ10.

Does it work? Clearly Wilson has many fans (and engineers) who believe it does. We have no issue with demonstrating the importance of alignment at the listener and do so on a regular basis.

But the 6dB/octave crowd believes it does not and that's ok too. You pay your money, you take your choice, and hopefully enjoy your music.

Bill

 

[metaphacts]

BTW, some recent reviews of the WAMM system include interesting comments on time alignment, including the influence of the driving amplifier.

As mentioned earlier, we have measured the group delay of various amplifiers used on the WAMM. From those measurements, very precise setting offsets are calculated to compensate for them.