Wilson Gets Another Cover!!!!

[ack]

The negative polarity of the midrange unit ensures that when the phase response is also considered, the outputs of the drive-units sum in phase in the crossover region to give a flat amplitide response on the intended axis.

...

Because then the drive-units would not sum in-phase and you would get a large and very audible suckout in the crossover region. Pathologically poor design.

So the drive units sum up in phase in the crossover region - fine; but isn't then the midrange driver always out of phase within the rest of its operating range, ie. within those crossover points? And isn't that a bad thing? The response above seems to imply that a midrange (in a 3-way design) must always be wired in reverse polarity and that no one can design a crossover with them in-phase and avoid suckouts?

It feels like I am missing something here...

 

[Stereoeditor]

So the drive units sum up in phase in the crossover region - fine; but isn't then the midrange driver always out of phase within the rest of its operating range, ie. within those crossover points? And isn't that a bad thing?

It doesn't appear to be. The ear is relatively insensitive to phase differences.

The response above seems to imply that a midrange (in a 3-way design) must always be wired in reverse polarity and that no one can design a crossover with them in-phase and avoid suckouts?

I wasn't making a general point, just that the crossover topology chosen by Wilson mandates that the midrange unit needs to be wired with the opposite acoustic polarity to the woofer and tweeter in order to give a flat amplitude response on the design axis. If Wilson had chosen 4th-order LR filters, then they could have wired all 3 drive-units in positive polarity and got a flat summed amplitude response.

It feels like I am missing something here...

You can't just look at the polarity of the drive-unit wiring and declare that it is good or bad design. You need also to take the crossver into account and I also forgot to mention that the slope of the baffle needs also to be considered. This introduces a time delay to the tweeter and midrange unit relative to the woofer that will also affect the system's behavior in the time domain.

John Atkinson
Editor, Stereophile

 

[DaveyF]

"I wasn't making a general point, just that the crossover topology chosen by Wilson mandates that the midrange unit needs to be wired with the opposite acoustic polarity to the woofer and tweeter in order to give a flat amplitude response on the design axis. If Wilson had chosen 4th-order LR filters, then they could have wired all 3 drive-units in positive polarity and got a flat summed amplitude response."

John, do you have any idea as to why Wilson would take this route vs. go with a 4th-order LR filter and use positive polarity throughout? What would be the perceived benefits

 

[audioguy]

the way to end up with a small fortune in this industry is to start with a large one.


Or be Dave Wilson.

Can I hear another "amen" to that. (both pieces).

While I have not been a great Wilson fan (owned some and heard many others), I absolutely love his success and since (I assume) he isn't breaking laws, he should be applauded. The long-term survival rate in this business is abysmal. Most companies either fold or merge into some other entity (can we say The Harmon Group). He has managed over a very long time to run a reasonably successful company in a very fickle business, with great marketing. I love the cosmetics of most of his product line and I wish him continued great success. And to the extent he can get on the covers of audio magazines, more power to him.

A true American business success story.

 

[Stereoeditor]

"I wasn't making a general point, just that the crossover topology chosen by Wilson mandates that the midrange unit needs to be wired with the opposite acoustic polarity to the woofer and tweeter in order to give a flat amplitude response on the design axis. If Wilson had chosen 4th-order LR filters, then they could have wired all 3 drive-units in positive polarity and got a flat summed amplitude response."

John, do you have any idea as to why Wilson would take this route vs. go with a 4th-order LR filter and use positive polarity throughout?

I'm sorry, I have no idea. If this were a price-constrained design, then the extra parts costs for a 4th-order LR topology might well be a factor. But I doubt that was a factor here.

John Atkinson
Editor, Stereophile]

 

[Gregadd]

Jim WIney of Magnepan ts probably a better business model. Solid value for a reasonable price.

 

[ack]

I wasn't making a general point, just that the crossover topology chosen by Wilson mandates that the midrange unit needs to be wired with the opposite acoustic polarity to the woofer and tweeter in order to give a flat amplitude response on the design axis. If Wilson had chosen 4th-order LR filters, then they could have wired all 3 drive-units in positive polarity and got a flat summed amplitude response.

From your experience, can you get just as good results from either design? There must be pros and cons with either. Perhaps the crossover is simpler (overall sound more transparent) with a reversed-polarity midrange but with the midrange being phasey (and you said the ear does not appear to be sensitive to that - I am not too sure, the ear is such a sensitive organ that I would be amazed if it wouldn't be able to perceive this), and perhaps phase is correct with same-polarity midrange but the crossover is more complicated (thus perhaps the overall sound more veiled??? and to make it just as transparent the cost of parts in the crossover increases significantly???)...

Just pondering some thoughts... I have a feeling there is much more to all this... What I am really thinking up here is reasons for me to stay with electrostatics/panels, or at least 2-way full range designs, where the list of problems appears to be smaller...

 

[audioguy]

Jim WIney of Magnepan ts probably a better business model. Solid value for a reasonable price.

I don't know about better business model but most certainly MUCH better value proposition. MUCH MUCH better.

 

[vinylphilemag]

"I wasn't making a general point, just that the crossover topology chosen by Wilson mandates that the midrange unit needs to be wired with the opposite acoustic polarity to the woofer and tweeter in order to give a flat amplitude response on the design axis. If Wilson had chosen 4th-order LR filters, then they could have wired all 3 drive-units in positive polarity and got a flat summed amplitude response."

John, do you have any idea as to why Wilson would take this route vs. go with a 4th-order LR filter and use positive polarity throughout? What would be the perceived benefits

Robert Harley has some very interesting things to say on this topic (i.e., crossover orders in general; not specifically the Sophia) in the speaker chapter of his book, The Complete Guide to High-End Audio. Well worth checking out.