S11 OB - Desktop Open Baffle with Seas 8" and Tangband Full-range

Drivers: Seas L21RNXP, Tang Band W3-1364s (bamboo fibre cone)
Frequency: 40Hz-20kHz. Designed to be listened near field (ie. not much SPL).

Build process here.

The speakers are really small as seen above. Very pleasing.

About the bass... the optimum compromise between distortion, listening level, and excursion is 40Hz. That's pretty deep, dipole or not. The woofers are working hard. Some 30Hz can be felt but not respectable. Below 30Hz is just asking for trouble. These metal cone makes horrible sound when bottomed. It's simply just physics and there is no way I could get more, except putting again a pair of 15" on my desk.

The distance to rear wall is about 35cm. I could not hear any faults. Phantom image is convincing, almost like the speakers making no sound and the music comes out from behind the wall.

I have small clip taken using my mobile phone in YouTube.




Update 14/7/12
- Migrate ASP to DSP
- Baffle strengthening

Next:
- To document the project

S10 OB - Seas L21RNXP on Open Baffle

After completing my last iteration, I really don't feel the need to experiment with different speakers / OB topology. Any improvements I thought, would come from the drivers themselves which unfortunately is about $$$, not engineering. I should also start to make a PCB and perhaps paint the speakers or something like that :)

But when I saw someone is selling a pair of Seas L21RNXP really cheap on ebay I couldn't resist having a go at rigid piston driver. The Seas drivers are beautiful indeed, and this is not even the magnesium series. They were old types of drivers but never used. The newer ones are L22RNXP.








What I would like to gain from this one are:

- Ability of the midrange to cross lower than P13WH. Let's say 120Hz, presumably better integration with the woofers.

- Transparency of rigid cone drivers. Is the claims true?

- Much higher SPL level

And some drawbacks I would expect/investigate:

- The need to cross the mid to tweeter lower, possibly straining the tweeter.

- Would the increase of baffle from 19cm to 24cm affect the polar response in a really bad way?

- Metal cone resonance

Build process is discussed at diyAudio. See interesting finding here. Measurement data available and discussed here.