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




14 comments:

Anonymous said...

Wouldn't you get substantially better OB sound if you made your (non)enclosures larger?

gainphile said...

No. With OB there is always a tradeoff. Larger baffles do give lower bass, but at the same time very poor off-axis reponse.

Smaller baffles give smooth off-axis response which contributes to excellent imaging. The bass problem can be equalised electronically.

See here for unequalised measurement showing excellent response up to 2.5kHz

http://farm4.static.flickr.com/3497/3943649882_3e8f2cd5fa_o.gif

Franz said...

Why not combine it with a 15" woofer in OB?

Just mount a baffle on the backside of your desk between the two legs, like I do it with my 2.1 nearfeald setup.

Links are in german language, but just look the images:

http://www.rahaso.de/foren/msg.php?f=audiotreff_selbstbau&idx=50344&

http://www.rahaso.de/foren/msg.php?f=audiotreff_selbstbau&idx=50341&

Franz

boris said...

How about a trapezium baffle? Then you'll have a narrower upper baffle for the tangband and a wider baffle for the SEAS woofer.

boris said...

Also, will I get better bass (at the expense of clarity) by placing open-cell foam on the back of the baffle?
I think I'll be able to get an apparently larger baffle by doing so.

audiotring said...

Is your 1.5 KHz crossover active or passive?

Can you proved its details?

gainphile said...

The 1.5khz xo is active LR4. It's op-amp based.

Geddam said...

Really a good endeavor,, very simple design!!

bad klopfer said...

As the Tangband is also not available anymore I wonder if the TB W3-1878 is a good alternative. As it is very expensive do you have another alternative?
Thanks.

gainphile said...

Klopfer, any 3" fullrange would do fine. If cost is a concern perhaps try Hivi B3N or the round variant. But you have to deal with the cone breakup.

bad klopfer said...

Hi gainphile, by searching through various websites I got the idea that you used the W3-1364s - not 1346s as you said in the blog. Am I right? The 1364s is still available and would be my first choice then :-).

gainphile said...

Hi Klopfer, you are correct! They are W3-1364. I see the price has risen dramatically, it was only $20 when I bought them few years ago. Must be the neo magnet cost.

Colin Wen said...

Hi Gainphile
I link to your blog from stereo.net (my id is uglykidwen).
When I saw your desktop OB speakers, I feel like to try it by my own.

Need some advice here.
I only have a small amp 2x2W (Qinpu Q-5), I use it to run a computer speaker before.
I wonder if there is any value fullrange driver can run by this one?
And any theory about the size and material for this baffle?
I googled around alreaedy, but if you can give me a head-up (like where on line shop or website) will be appreciated.

Cheers
Colin

gainphile said...

Small fullrange drivers are normally not very sensitive. Perhaps 88db if lucky, so no 2wpc amps are definitely not enough. 25 to 50 watts would be the norm.