Full Range Dipole Designs - Any Advice?

[Forster]

Hello,

Having just completed building the superb TLB transmission line speakers, I am looking for a new project.

What I am looking for is a dipole full range design which would utilize four Fostex, or similar full range speakers.

Frankly I am not sure that many designs could better the sound given by the TLb's which is astonishing, but I am willing to try!

Thank you for your time.

Forster

[Dumbass]

Check out the reference project thread:
diyAudio Full Range Reference Project
and see if anything strikes your fancy.

Lots of good bipolar TL designs in there.

[LineSource]

Hi Forster,


Multiple even modest diameter full range speakers will have combing effects since the center-to-center spacing is larger than the highest wavelength. The low Xmax of most Fostex speakers also limits the SPL unless a very large baffle is used, or the Fostex is crossed to a woofer. You've probably seen these three Fostex dipole designs.

1) The BassZilla Evolution (October 2003) By Dick Olsher - a 3 way using ribbon + Fostex + sealed bass

http://www.blackdahlia.com/html/tip_41.html


2) Adding Siegfried Linkwit's H-frame or W-frame dipole woofer crossed at 100-200 Hz above a Fostex full range on a large'ish open baffle


3) There is a Fostex design that hinges together three tall, narrow, panels to look similar to a room divider. The center panel is a sand filled sandwich with a baffle board for the speaker. Open-up to get good dipole bass effiency. Fold-up to better use the room space.

[Dumbass]

Point of clarification:

Do you mean dipole or bi-pole? In the most generic sense, those two terms mean the same thing, but in our little world "dipole" typically means a single driver in some sort of open baffle, so signals are out of phase, while "bipole" means a pair of drivers mounted back to back, but wired in phase.

I assumed you had meant bipole, i.e. two drivers for each stereo channel mounted back to back.

[Forster]

Dumbass,

Yes, I did mean bipole, many thanks for your correction.

Best regards - Forster

[Dumbass]

Originally posted by Forster
Yes, I did mean bipole, many thanks for your correction.

Do check out the reference project thread. The simplest build would be the simple vented ("mass loaded") transmission line (MLTL), because it's just a box. But the thread also has some interesting variants.

As shown in this picture, any monopole MLTL can be turned into bipole by adding the back driver and doubling the enclosure's cross-sectional area: