Are you (open) baffled yet?

[DJNUBZ]

could someone post a link to this luilui speaker?

I was wondering what effect would using a curved baffle have on an OB speaker. Top view, Front- ( -back

[fdegrove]

Hi,

They look absolutely fabulous.

Still undecided on how to finish the inside surface of the wings.

Same as the outside?

Congratulations, a beauty!

Cheers,

[Erik]

Linesource asked:

What measurements have you made on your dipole woofer, and what compensations have you added to your crossover? Does the tapered-pipe loading should show up in the measurement?

I'm looking for help in doing some measurements. Exactly how does one measure a dipole sub? Nearfield measurements don't give the picture, Farfield measures like mush, and gated is right out!

Right now I'm just going by ear. I built an active cross that provides a 2nd order crossover with variable gain, frequency, dipole correction and hi-pass filter. Current setting are for a 2nd order lowpass between 75 and 100 Hz. Configured for 8 Ohms, the Lambda 15s have a QTS of .9, so I can make do with a small amount of boost cutting in at about 75 Hz.

Critical listening does not indicate any bad resonances within the pass-band, so I'm hoping I lucked out with the design and can avoid a notch filter.

Until I can measure this thing correctly, I can't really judge the effect of the k-slot, but subjectively, the bass seems quicker and better integrated than the same drivers mounted on a rectangular baffle w/rear wings.

Nuuk asked:

You went for the budget versions then Erik! Do you use one or two of those?

Hehe. Yah, the drivers were purchased before I decided on dedicated sub. Kind of a waste of bandwidth, but they do sound GREAT.

I am only using one. I cringe thinking of building another. This thing is BIG. One provides more than enough SPL, and the ear cannot located the sub.

I actually have the material to build another. Anybody want one?

[Gridstop]

Erik, I've been thinking about dipole bass as well recently.

How do you calculate the dimensions for such a subwoofer, especially for the slot-loading 'wings'.

Speaking of which, how do you BUILD the wings?


Also, with the two drivers out of phase, doesn't that tower rock at all? I'm interested in building one of those with Tumult drivers (requires lots of EQ because of low Qt, BUT has incredible displacement and very low distortion) The motors are extremely heavy (50 pounds) and the moving mass is about 4 times that of the Lamda dipoles.

[Erik]

Gridstop -

All dimentions were derived from the drivers. I purchased plywood 1/2 cylinders just big enough to contain the drivers, which was a 20.5 inch diameter pipe of 5/8th plywood.

The construction was complicated. I have a gallery on AudioCircle that has a pictoral walkthrough of the construction.

http://www.audiocircle.com/circles/m...view_album.php

The baffle hardly moves until the woofers are cranking through an inch of travel. The wings vibrate slightly with increased air motion. I'm probably going to dampen them eventually. That's why I'm unlikely to veneer more than the top most portion of the inside wings.

DJNUBZ -

Take a look at the speaker that lauched a dozen clones...


Scroll down halfway.
http://www.dietiker-humbel.ch/micromag.htm

[Gridstop]

Hmm, I wonder how available (and expensive) those cylinders will be in my area. (Western Wisconsin)


The curve you traced on the wings... is that a particular ratio or anything? Or is it one of those things where, there probably IS an ideal, but even just winging it will get you close enough you'll notice a benefit?


I tend to paint, not veneer, so that simplifies things a bit for me


Couldn't you build two simicircles to support the wings between the two drivers? (Mostly hollowed out of course)

[The Paulinator]

Where do you get these Supravox drivers I keep hearing about. Must admit I've never heard of them.

[Erik]

GRIDSTOP -

West coast distributer for the 1/2 cylinders in Anderson International Trading (www.aitwood.com). They stock a 20.25 diameter by 102 inch piece that can be cut in two and shipped UPS. This is the equivalent of the two pieces I picked up on the east coast.

As a subwoofer, the eliptical opening is far to small to have any sound reinforcement effect, so the curvature is not critical. Mine was sized by using the maximum length and leaving a one inch gap between the panels.

For me, the dampened baffle and the rigid coupling to the base is enough to contain the motion of the drivers. If your moving mass will be much greater, you should consider a more elaborate bracing system.

Couldn't you build two simicircles to support the wings between the two drivers? (Mostly hollowed out of course)

You mean like this?

[Gridstop]

Ahh yep, that is what I was thinking of.


Anderson International also sells fibreboard cylinders. I wonder if they are closer to MDF or to particle board. If they were more dense like MDF perhaps with some bracing (like you pictured) they would work. Save a lot of money as well.

I'll call them up sometime this week. Also need to call Dan at Adire and ask him about dipole Tumults. I'll let you guys know if anything comes of this


EDIT: Ahh ,my mistake. I see what you mean, you bought a single 102" long half cylinder (180 degrees) and had them cut it in half so you had two 51" long halves delivered. Only $135 as well, not bad at all.

[catapult]

Gridstop,

Tape Ease in Wisconsin has the 1/2 cylinders. It's a good place to buy veneer as well.

http://www.tapeease.com/2rounds.htm