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.
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.
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
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
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.
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.
Yes, there's definitely a dip between 5kHz or so up to the peak.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
But the above applies only to Albasia. I don't get the same problem on other materials.
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.
thanks I had forgotten about this post great looking loudspeakers. Glad to now make note of this and the info here in. /there are some other posts as well on this topic and I would like to find them as well.
And now for an almost different subject altogether...
A piece of board (any board, EPS, cardboard, polycarb, PE, etc etc) has a bass response which can be improved by gluing it into a framed canvas panel. I suspect this improved bass response has something to do with the 'surround' created by the space between the inserted board and the hard edge of the frame, and which allows the board to vibrate as a piston at its fundamental frequency.
1. This construction possibly creates a very high QTS driver (consisting of exciter motor, board, surround and frame) which is exactly what is required for open baffle woofers.
Indeed, I tried taking TS parameters using REW, and it seems like the little A3-sized panel I'm testing, with good bass response down to 60hz, has a Qts of 12. This is either very important, or it's wrong.
2. Resonant frequency can be controlled by board weight and canvas tightness. Qts can be controlled by the damping of the surround.
This should make it possible to adjust Fs to the natural frequency of the board by itself, or maybe to that frequency between between the first few modes where you get that inevitable notch on the bass response.
There's much to think about.
A piece of board (any board, EPS, cardboard, polycarb, PE, etc etc) has a bass response which can be improved by gluing it into a framed canvas panel. I suspect this improved bass response has something to do with the 'surround' created by the space between the inserted board and the hard edge of the frame, and which allows the board to vibrate as a piston at its fundamental frequency.
1. This construction possibly creates a very high QTS driver (consisting of exciter motor, board, surround and frame) which is exactly what is required for open baffle woofers.
Indeed, I tried taking TS parameters using REW, and it seems like the little A3-sized panel I'm testing, with good bass response down to 60hz, has a Qts of 12. This is either very important, or it's wrong.
2. Resonant frequency can be controlled by board weight and canvas tightness. Qts can be controlled by the damping of the surround.
This should make it possible to adjust Fs to the natural frequency of the board by itself, or maybe to that frequency between between the first few modes where you get that inevitable notch on the bass response.
There's much to think about.
The problem is that you will have two surfaces which, when resonating, will flap against each other and cause massive odd-harmonic distortion.
Hi Andre, I was thinking a similar thing, with the canvas surround the panel at low frequency would be pistonic and the whole thing is similar to a traditional woofer. I wonder if anyone has experimented with different surround materials in a similar manner to the canvas. I can't remember off the top of my head.
Thinking a tensioned (could be adjusted somehow) rubber surround could be used to give forward back flex but also edge damping. I may try with bicycle innertube around a panel in a frame to see if it works.
If I remember correctly people have tried circles and they aren't ideal for DML modes?
Thinking a tensioned (could be adjusted somehow) rubber surround could be used to give forward back flex but also edge damping. I may try with bicycle innertube around a panel in a frame to see if it works.
If I remember correctly people have tried circles and they aren't ideal for DML modes?
How odd that you should mention this now .. I've been mentally churning along this path for many months, and I'm partway thru an experimental build... It's a bit different to the above and I've no idea how it will go yet but I'll let you know either way
Eucy