[fredpb]

Quote:

Originally posted by Joe Bloggs Hey, if open headphones are such a successful design, why don't we have open speakers too? Like, three-way speakers with just the minimum structures required to hold the drivers at the right heights and maybe just a plastic / wooden frame to enclose the drivers and prevent damage.

Some speakers are made to work with an open design. Usually panel speakers (huge flat surfaces that vibrate minutely, but with a large surface area). They can be electrostatic or magnetic (I had Magneplanars like that).

As far as cone type speakers go (non-panel). Driver/cone characteristics are critical. You need to compensate for backwave, resonant frequency, cone rigidity, and other factors.
You have to do this for each driver. Like woofer, midrange, and tweeter (those that are not backless in design). Some enclosures act like capacitive reactance (sealed, acoustic suspension), some like inductors (bass reflex/ported), and resistive (aperiodic). Then there are radiation patterns of the drivers, box volume. Then to top that off, the design and size dictate what is best for speaker placement in the room.

I found planar types to be a pain in the a*s for positioning in my room. Plain box speakers are easier (except for height, base, and distance from wall). My current Vandersteens are of a complex design, and I had to really compromise on my placement.

In short, panel/bipolar speakers are made to be open. But placement and nearby furniture placement are critical. Radiation patterns for these have to be understood because they are quite different from box speakers.

Each speaker just can't be placed anywhere. My speakers even have a back tilt adjustment for the whole speaker.

Open speakers. Not the most practical units in the world.
I often thought of making my own units. But the complexities and cost make it prohibitive.

My favorite speakers I have owned: OLDEST-Dynaco A50's circa 1970. Fulton Tempos (circa mid 80's). Now-Vandersteen IIce Signatures. These are not the only ones I have owned, but just the ones I used in my main system over the years.

These do not represent the "best", only the ones I could afford, and could get.

 

[Hirsch]

At least one other Head-Fier and myself (I won't out him

) had some of our first "high end" experiences in the same store, listening to Bose 901 direct/reflecting...one speaker pointed forward and eight aimed at the rear. The store had two pairs mounted together from the ceiling...the effect was surprisingly good. I remember thinking for years that was going to be the ultimate system I would one day own

Oh well, I was young

 

[nebuchadnezzar]

joe, listen to a pair of martin logans! amazing speaker....and not too pricey

www.martinlogan.com

 

[skippy]

if you're really interested in open baffle speakers, linkwitz has an open baffle design on his site. it's pretty good reading material. www.linkwitzlab.com

 

[Neruda]

Quote:

Originally posted by Joe Bloggs Is this quite ideal? I don't understand this reinforcement thing really--how do you design the enclosure to reinforce certain frequencies? In physics terms if possible And wouldn't the resonance from the enclosure be out of phase with the sound produced directly from the driver?

Read a book

regarding the picture, that's a single fullrange driver on an open, cloth-covered baffle. the back is empty, the front is empty, the driver is doing everything on its own. this speaker has to be placed in a corner to improve bass response.
Quote:

joe, listen to a pair of martin logans! amazing speaker....

the only problem with martin logans, and many other electrostatic speakers, is that the "sub" is being crossed at a whopping 500Hz! waaaaaaaaaaaay too high! no good. then again, I've never heard a pair. Still, I have very little faith in a design like that, since so much of the crucial midrange is not being produced by the electrostatic element.

 

[Dusty Chalk]

Quote:

Originally posted by Neruda the only problem with martin logans, and many other electrostatic speakers, is that the "sub" is being crossed at a whopping 500Hz!

Well, you did say "many", so I'll cut you some slack, but electrostatics come in many flavours -- there's even some that are full-range. In fact, that's usually one of the biggest differences in price -- where the crossover is. The lower, the better, the higher the price. Usually.

 

[kwkarth]

There's not much good to say about Martin Logans except for the CLSII which is a real purist's speaker. The other models are terrible compromises from what they could be...

You can't argue with the success of their marketing department though!

 

[Neruda]

Quote:

Originally posted by DustyChalk Well, you did say "many", so I'll cut you some slack, but electrostatics come in many flavours -- there's even some that are full-range.

Don't worry, I'm plenty aware of that. There's audiostatic for one, then Martin Logan's CLS IIz as kevin pointed out, and plenty of others...