BD15 Subwoofer as Open Dipoles (BD-Design)
by soundcheck 
, Germany, Friday, September 01, 2006, 15:07 (6453 days ago)
Hi Bert.
I finally took the pictures.
As I mentioned earlier. I finished recently my 2*2*BD15 Subwoofers.
And I am more than happy with it.
Clean, Rocksolid, Black all positive things you like.
And small - very small (36*44*44cm w,h,d)
Very limited interaction with the room.
Two in parallel gives you 103db/w/m and 8R. That's fun for every amplifier.
And that was one of the key issues why I had chosen the drivers.
Linkwitz and Ridthaler are working with a much lower sensivity, which does
Not match high sensitive mids and tweeters.
I am crossing them over with a DCX2496 48db/oct at 100Hz. That cleans up
your lower mids.
It is a Linkwitz based design. There is also Ridthaler who claims
a patent on this design.
As long as its DIY for your own purposes its of course not an issue.
Front:
![[image]](images/uploaded/image129.jpg)
Side: (Bert: your labels are still attached 
)
![[image]](images/uploaded/image130.jpg)
Back
![[image]](images/uploaded/image131.jpg)
Not more to say.
Ah wait.
Currently I am driving them with 2 Icepower 1000ASP.
(Leftovers! Were replaced by T-AMp 2020 to drive my Mids/Highs)
My Subwoofer Chain is not batterypowered as everthing else in the chain.
Klaus
BD15 Subwoofer as Open Dipoles
by jeno , Saturday, September 02, 2006, 00:22 (6453 days ago) @ soundcheck
edited by unknown, Saturday, September 02, 2006, 01:17
Hi Klaus!
This looks very interesting!
Just a couple of questions:
Do you really have 103 dB efficiency with this design?
If so, how low and loud does this bass go?
Are there any information, messurements etc on this design on the Internet?
Edit: I found this on the diyAudio forums
BD15 Subwoofer as Open Dipoles
by soundcheck , Germany, Saturday, September 02, 2006, 19:01 (6452 days ago) @ jeno
Hi Jeno.
Interesting link! Thanx.
It made some things clear to me. At least I hope it. I am not that deep
into electronics theory.
Lets see if i can put a quick storyline together.
The effiency of the BD15 drivers according to Bert is 103db if connected in parallel.
If you put it in the U-baffle you loose -6db.
If you put it in the Ripole design (according to above link) you got -12db.
So you are down to 91db/W/m. Which should be its actual sensivity!
My T-Amp has a voltage gain of 12. The icepowers have a voltage gain of 27.
If I calculated it right that's 6db in difference.
With my U-dipoles (mids/highs) rated 98db, I have 7db difference on the sensivity. The difference is compensated by the higher gain of the icepower amp.
Thats probably why the DCX2496 stands on neutral - No gain added.
Perhaps somebody can correct me if above assumptions/calculations are wrong!
I do not hope that this is complete nonsense.
Would help me to improve my therotecial understanding of the whole stuff.
I'll try to take some measurements next week. I am just setting up my old
PC for it. (Another challenge)
You will not find that design or better - construction plans with the BD15 on the internet. I did it by myself. (On my own risk.) The design of course is according to the Ripoles look to get the sub and its chambers as small as possible.
How low and loud? Hmmh. FS of the driver is 38,9. I hope I'll get it down to at least 30Hz, with this design. As said i'll try to measure it next week.
Klaus
Hi Klaus!
This looks very interesting!
Just a couple of questions:Do you really have 103 dB efficiency with this design?
If so, how low and loud does this bass go?
Are there any information, messurements etc on this design on the
Internet?Edit: I found this on the
diyAudio
forums