A Study of DMLs as a Full Range Speaker

[spedge]

Moray.
I have talked about the pros and cons of listening to the sides of the panels.
I think burntcoil also talked about this, using his blond panels, I think?
I probably might have made a recording also?
I also talked about this over on nxt rubbish, using my 7ft eps panels.
But where on this forum i do not have a clue 🤔
What is it you wish to know?
PM me if you wish.

You keep sending me likes of lots of my recordings, and I end up going down memory lane, listening to them again.
Making me want to get them out and listen to them again.
I agree, that the recordings do sound very good.
Steve.

 

[twocents]

Moray, it was Burntcoil's Snow White panels. See
https://www.diyaudio.com/community/...s-as-a-full-range-speaker.272576/post-7147457
and
https://www.diyaudio.com/community/...s-as-a-full-range-speaker.272576/post-7147993
Points 9,10,11

 

[Andre Bellwood]

The extension in bass is impressive! How is the sensitivity (you get nothing for nothing?)? Does the canvas around the solid panel act as an extension of the panel - like the panel is abruptly thinned out and very flexible?
Very interesting but also hard to grasp what could be happening - like everything related to dml panels afaik.
Greetings, Hans

From about 500Hz the sensitivity is actually better by a few dB than my general average, but the HF drops quickly above 4kHz. This means, like other low-density panels, that the midrange is rather strident.
I think the canvas around the panel acts like a standard speaker surround, and allows the panel itself to move freely, but in a controlled manner.

 

[Andre Bellwood]

maybe during the test try holding onto the back of driver, or add a mass to the back of the driver (maybe doubling it's weight), to see if it has any significant effect on that peak.

The driver resonant frequency by itself, is below 100Hz, and there are virtually no harmonics above this frequency that can be transferred out through the back. if one restrains the back of the driver, then this might effect frequencies up to maybe 200Hz if you measure very carefully.

My first thought when you cut the hole was that the back of the driver is out of phase with the panel and it now has a clear and direct path for that opposite wave to interfere.

Also, just a thought, but maybe that's not a peak at 9kHz, maybe it's a dip from 2kHz - 8kHz

Yes, there's definitely a dip between 5kHz or so up to the peak.

But the above applies only to Albasia. I don't get the same problem on other materials.

 

[Andre Bellwood]

... I have one more test to try boost the top end on this cardboard. If it doesn't work as I would like, then it's back to the Nidaplast.

I tried filling up the honeycombed cardboard with a resin puck directly in front of the driver, and while it did reduce the broadband peak around 3.5k, it did not give me the HF extension I was looking for. In fact, this seemed to reduce the sensitivity of the whole panel.