chesky's 2.5 way, want to rediy anyone?

[torzsok]

Dear all,

David Chesky has been offering these interesting 2.5 way loudspeakers on his site for years. Is anyone interested in building something similar? Has anyone built something similar?

The original has a phase-coherent crossover network with very steep filters. I would prefer a pair of a wide/full range MB without crossover and super tweeter with only a high-pass filter.

[sreten]

Hi,

Its not a 2.5 way design. Isobaric seems pointless for that size box.
You talk about something similar then suggest something completely different,


/sreten.

[torzsok]

Oh well, there were quite a few who liked this box, and the designer says it's isobaric. Why doesn't it make sense then?

I thought I can trust the Absolute Sound reviewer who says:

"David Chesky...has just introduced a loudspeaker...a rather small two-and-a-half- way that had no right to sound as good as it did."

Is it the lack crossover that makes the difference between 2.5 way and my 'whatever' ? On the other hand I only said I would prefer a crossoverless design ... if there's nothing against it.

[sreten]

Hi,

Its not a 2.5 way, the quoted reviewer waffle as ever is wrong.

Its an isobaric loaded 2 way, difficult to find a driver that would
be suitable for isobaric loading in a typical floorstanding volume.
(some Dynaudio drivers are suitable)

Also a crossoverless design will sound poor due to lack of BSC (search).

/sreten.

[tinitus]

When you use two or more drivers there are no such thing as "crossoverless", there will be crossover slopes with or with out components, AND most of the related classic problems, more or less

That said I am working on something simple with FR125S/VifaXT19

[torzsok]

sreten, I appreciate your expertise, but could you be a bit more specific? What drivers are suitable and why?

tinitus, I know the drivers will need to have a certain overlap in their frequency response, I just wanted to suggest that at least the bass/midrange driver could get the signal with minimum/no filter. And again: it was just a thought.

The point of the topic is the following: is there anyone out there who wants to find out how this 2 way isobaric thing works? Does anyone have any design suggestions? Suggested literature, must see website, own experience you ant to share?

[tinitus]

Never heard of isobaric used in midrange

Heard someone mention phase problems related to inside mounted driver

[phase_accurate]

Maybe the inner driver is just used at low frequencies so there would be no problems (well, less at least .....) with acoustic delay between drivers.

It doesn't say that the crossover is phase-coherent but being more phase coherent than ordinary first-order designs BTW. Truly phase-coherent crossovers of high order are very difficult to implement without resorting to digital solutions.

Regards

Charles

[sreten]

Hi,

a web search will find some 2 way isobaric designs and the principle......

good a place to start as any : http://en.wikipedia.org/wiki/Isobaric_speakers

Once you understand the design trade-offs for isobaric designs
then you will find using it for a slim 2-way floorstander with a
necessarily small single mid-bass driver a very dubious choice.

For your design interests I'd go for a bipole 2 x WR125 + supertweeter.

http://www.planet10-hifi.com/sealed.html

/sreten.

[Landroval]

Originally posted by sreten
Once you understand the design trade-offs for isobaric designs

What are the trade-offs?

Is the efficiency of isobaric mounted woofers the same as a single woofer if wired in parallel? Or how does it work?