More Epic DML #3 - Adding BMR "Tweeters"
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- Опубліковано 11 вер 2024
- Upon discovering that my acrylic DML panels aren't outputting as much high frequency as I'd assumed, I'm looking for the best solution to tackle the high end.
In this video I explain the measurement error that had caused my misunderstanding in the first place, and try out a pair of balanced mode radiators (BMR) in lieu of actual tweeters.
This might not be a permanent solution, or it might be. I also have another type of driver to test (next video) so I supposed time will tell!
Beautiful build!
Around 10:27 you mention the BMR & DML acting as dipole, which you commented on in the video.
DML panels operate as bipole in that front/back radiation is in phase. There is a reduction in output to the side of DMLs because of a lack of output from the edges of the panels and not not due to cancelation. A BMR acting as DML in high frequencies experiences this, but as frequency lowers and pistonic action takes over, those frequecies are dipole. So, a BMR has a mechanical "crossover", if you will, where low and high frequencies use different mechanics to produce their sound. It's not too different from a driver with a whizzer cone.
Keep the videos coming!
Thank you! And thanks for the clarification.
The Tectonic boys call it diffuse dipole, so I guess that means it’s a bit of both. From an engineering standpoint it can’t be bipolar, as it’s a single surface and at any single point on the panel a plus on one side is a minus on the other and visa-versa. However because the modal behaviour produces a diffuse wavefront in the air, they aren’t prone to destructive interference patterns you would expect from a traditional source making predominantly coherent wavefronts. The traditional terms are kind of inadequate to sum up DML, because you have to specify the level of analysis to avoid contradiction… that said diffuse dipole/pseudo bipole both kind of work.
Thanks for this! Have you considered reversing the polarity of the subwoofer or chasing the phase at the crossover point?
So reversing the polarity would result in a 180° change in phase, but with the DSP I can control that more precisely via the delay on the panels. Unless I'm misunderstanding your idea.
I was curious what effect you would be looking for by taking those actions?
I wonder how it would work out using 2 of those on each panel. Maybe go with one on each top corner and you could put some sort of cover that goes across to make it look more uniform.
Also I think all of this is awesome!
Dome tweeters have great dispersion. They're a dome, after all.
They do not, mainly because of beam-forming due to comb-filtering as waves leave the surface of the dome. That's why some dome designs have a phase guide to help with dispersion.
Nope sorry. A dome tweeter has a physical size to work, combined with it’s pistonic mode of operation that dictates the off axis interference pattern at any given frequency. DML/BMR don’t suffer from off axis interference in the traditional sense.
Are the next tweeters gonna be Air Motion Transformers?
I've got a pair of planar magnetics with an open back ready to test once I've had some listening time with the BMRs, but I'm also interested in the AMT drivers they look really cool.
@@TypicalBenYThave you tried mounting the tweeters on stainless steel plate? You would only need a 300x300 mm square for each.
noice
Dude, your volume is all over the place in this video, mainly so low not audible... at least for me.
Oh man. Sorry about that. It sounds ok to me on my PC and on my phone.
@@TypicalBenYT you can try to record sound from your listening space. It will be much more audible for all
Can I ask what you guys are listening on? I listened again and it seems ok no matter what device I use but I'd like to improve it for others if possible.
@@TypicalBenYT FWIW, I don't hear any issues with the sound. Thanks for posting your experiences and things you've learned on your journey.
@@jisozaki great thank you.
noice