Advantages and Disadvantages of a 3-Way vs. a 2.5 Way Speaker??

[parimento1]

Hi there, I was wondering what the advantages and disadvantages of either speaker type are? I never understood the 2.5 way design exactly...

[curtis]

3 way = separate driver (or set of drivers) for treble, mid, and bass.
2.5 way = separate driver for treble, another driver that handles mid and bass, and separate driver for bass.

The simple differences are the 3-way separates the frequencies into separate drivers. and the 2.5 way gives you two drivers to deliver the bass.

It is all about the implementation, but for me, I would rather have the mid and bass separated to different drivers, rather having two drivers handling the bass.

[RicardoJoa]

hm..
well, three way has dedicate driver for the mid range , while the 2.5 will still have one driver producing bass and mid like curtis said. Three way will have its own enclosure to seperate it from the bass enclosure, some time is built in the driver itself. 2.5 way usually are easier to implenment, they add sensitivity over a 2 way or a 3 way with three drivers. Of course that would be assuming to be using relatively similar sensitivity drivers.

[GirgleMirt]

You have an example here of a 3.5 design which will give you a good idea of what it looks like: http://www.zaphaudio.com/ZDT3.5-FR-IMP-individual.gif

Red: tweeter
Dark yellow: Mid
green: 1st woofer
pink: 2nd woofer
In blue is the sum of both woofers.

[DougMac]

It is all about the implementation, but for me, I would rather have the mid and bass separated to different drivers, rather having two drivers handling the bass.
I'm far from qualified to speak definitavely on the subject, but there are some considerations to be made.

I agree that it seems that designing drivers to handle certain frequency ranges optimally is a smart way to go. However, from my understanding, the more drivers, the more problems to deal with. Crossovers are more complex and you have to deal with the non linear nature of crossover components. I would also think you have to deal with time delay and wave interference of the drivers.

Because of this, there's a camp that thinks the efficiencies gained by multiple (3 or more way) designs is offset by problems that can't be completely addressed. For them a 2 way design with an 8" woofer is considered optimum. The Sierra is an excellent execution of their theory.

This did make me think of some great vintage speakers that I had the pleasure of hearing - Bozak Concert Grands (http://www.stereophile.com/historical/1005bozak/index.html). They were the cat's meow back in the late '50's and early '60's, with four 12 woofers, two midrange drivers and eight tweeters! In 1961 they cost $2k each which is >$20k a pair in today's money. Compare their specs to Sierra Towers and the Sierras spec out much better and I'm sure sound much better.