S16 - Constant Directivity Dipoles

[454Casull]

Originally Posted by CLS

Some considerations (guessings):

1. With DE250 on the WG, you have the opportunity to remove the rear cap to have some rear-firing HF. Maybe good, maybe not. But at least it's very easy to try.

That would probably kill the low end of the tweeter.

[roflynn]

Second attempt at Pics for gainphile, finger trouble missed the pics.

[jerome69]

Nice job with the WG300s and the scanspeak. I would like to see a response curve after the tweak.

[Radugazon]

...and polars to compare with what Rudolf did once with a front and back firing combo.

BTW, Russel that's really well done

[gainphile]

Originally Posted by roflynn

Second attempt at Pics for gainphile, finger trouble missed the pics.

Thank you very very much Russell!

That is a very interesting approach. What are the WGs and how big are they? It would be interesting if they can hold directivity down to 1.5khz... That would be "solution to a problem" indeed

Edit: .. found it, Monacor waveguide!

[roflynn]

The purchased waveguide is 168mm. The outer edges of the guide are 89mm apart, and the gap is (was) filled to smooth the edge and increase the diameter hence cut off frequency. The purchased waveguide was close enough to my analytic prototype derived target: a 240mm OD toroid with 120mm diameter cross section, and oblate speroid transition to the dome. The doe is at the front, and the acoustic cavity at the rear appears trivial - ref below.
I used paper mache to form the torroid for the proto tests, as it has worked (for me) the next step is making the toroid for the tweeter and the mid in a more visually appealing structure. The mid also has a torroid like form, rather than a circular cross section it has an 90 x 54mm elipse, and the ellipse rotates so that it forms a moebius, for aesthetics. I am making it by using thin plywood sections set on a central frame then fill with foam, shaped and covered; like a model airplace wing mated with a surfboard.
The measurements I have are here amongst hundreds of spreadsheets of single points data. Making one plot that would make sense to another person is not on my list of pleasurable activities so I will decline the offer of producing a report. My data analysis discounted higher volumes (I only have a small apartment and rather than an SL like 90 dB I settled for 87) and my hearing is second rate above 13KHz. Others might find something where I wouldnt have looked.

[gainphile]

Thanks again. I'm very interested with this approach.

2 pairs of WG300 is on delivery, and I will report back

[keyser]

Very nice indeed! Keep us posted, guys!

[thunk303]

Just trying to understand the photo of the 2904 in the waveguide, specifically what "might" be the back photo with what looks like the motor structure with a series of holes around the edge.

Is this the motor?
How much output can one expect from those tiny holes compared to the front dome?

Great work
Cheers
Dean

[DeonC]

Hi guys

I read briefly through this post (reading it on a cellphone, so it is difficult to see everything), and one thing came to my mind: a lot was said about the B&G Neo3 at the beginning of the post, so has anyone thought of maybe loading both the front and the rear sides directly with two Dayton waveguides (10-inch WGs maybe)? Mounting this structure on a baffle might be tricky, and I am not sure how this loading will affect the Neo3, but then you'd have true DI-pole (as opposed to BI-pole) loading. Any thoughts?

Enjoy,
Deon