Corner Dipole Woofer (CDW): info? anyone tried one?

[AudioLapDance]

Hi everyone, I just moved into a new place and my listening room is:

11 ft wide by 7.75 ft high by 13.5 ft long (~1150 cubic feet).

Because of furniture restraints, I will be sitting quite close to the front wall with places me at 45 degrees from the corners.

Hmmm … corners … 45 degrees … that reminds me of something … I know, that weird corner baffle posted on the linkwitz site:

Discussed briefly at question #30

http://www.linkwitzlab.com/faq.htm#Q30

Picture here:

http://www.linkwitzlab.com/images/gr.../corner-dp.gif


I want to use it from 40Hz to 200Hz. I will have one (or two) Audax PR170MO with super tweeter on an open baffle covering from 200Hz up.


Does anyone have any info on the CDW?

Has anyone tried them? How are they?

Thanks for the help,
Jeff

[planet10]

very interesting....

if you try it, let us know how well it works.

dave

[dwk123]

I'm playing around with similar but not identical ideas. The setup in Linkwitz drawings will have nulls at +` 22.5 degrees from the walls. Unfortunately, my listening position is at about 20-degrees, so it won't work.

I did do some quick experiments with a flat baffle coming straight out of the corners at 45-degrees. This actually sounded really good, but bottomed my woofers (nht 1259's - for testing, not expecting them to 'work' in the final setup) really easily. Not surprising, as the 'd' parameter gets 'foreshortened' by the sin of the angle of tilt, so the effective baffle width is pretty small in this case. I believe the setup Linkwitz illustrates will have the same problem, although keep in mind that you do get a boost of sorts by firing into 1/8 space which partially offsets the shorter baffle.

My next test was to place the flat baffle about 3' up the wall tilted at 45 degrees back away from the listening position. This formed a resonant chamber (since my speakers were on a platform on top of the dipole baffle) behind the driver, and didn't work too well. I'm guessing that if youi can go 3' up the side, a conventional H baffle would be the best idea.

If you have enough displacement - an Avalance 15 or 18 per side (or two!), I think the corner dipole thing can work ok. I'm trying to figure out a good way to use two 15's in my 'flat baffle' approach. Something like the 'ripole' idea (basically a modified W baffle) might work, but might be physically cumbersome to squeeze into a corner.

BTW - I'm crossing at around 80 right now. I dont' know that this type of approach will work up to 200Hz. Woofers that have enough volume displacement to make this work may not work that well to 200Hz, even apart from the dipole resonances etc that may show up.

[LS]

Hi,
The CDW @ SL's site[faq30] is my invention,

the low pass Fdt{F dipole transit, eff Lambda/2 rear to front},
lower bound is ~= (6780/center of woof to baffle edge),
the Single baffle Corner Bisector form is generally more usefull,

http://www.geocities.com/larryselmer/DRL.htm

LS

[jdunham]

Jeff,

>I want to use it from 40Hz to 200Hz. I will have one (or two) >Audax PR170MO with super tweeter on an open baffle covering >from 200Hz up.

>Does anyone have any info on the CDW?

>Has anyone tried them? How are they?

Yep, and very good they are too!

See:

http://www.kingdom.uk.com/jdfiles/si...right_full.jpg

http://www.kingdom.uk.com/jdfiles/in...lose_full1.jpg

They dipoles are high passed at 160hz, and are pretyy flat to 30hz, rolling off rapidly after that.

I did try the final piece of baffle into the corner as per LS diagram, but to be honest it didn't really add anything.

The only other issue I would say, is that you have a failrly small room, and you may well have problems with a dipole mid, especially if they are used tight into the corners. I much favour the directive mid/high's as provided by the front horn than a dipole mid.

Regards,

Jonathan

[LS]

Hi, Find any intel on CDWs ?

LS

[Rudolf]

Reanimating a very old thread (but the only one related to the issue imho).
There is a new contender for the most ingenious dipole concept:

More info and pictures on the Gradient Helsinki website

Some speculations regarding this alien speaker have already started at audioasylum

[inrank]

i would like to see what happens with this thread, as i have a similar sized room, (11ftx11ft) but with a large bay window, and i currently have open baffles placed near the corners about 1-2ft from each.

[Geoff H]

I'm signing in too. 3.5 x 5.5 metres. OBs reign, but I keep walking into them. I have thought of somehow combining a w-baffle into a corner, without arriving at anything yet.

Geoff

[jdunham]

Its seems still that I am one of the few to actually have tried these. I've been really happy with my set up for a couple of years.

Come on guys give it a go, it doesn't take much. Don't just wait to read about others trying these things, give it a go yourself!

Regards,

Jonathan