Eric in section #3 you mention the coincidence frequency being higher in thin panels. /what happens in a case when the panel is for example one inch EPS but the panel is gradually tapered to the edges to lets say 1/4 inch thick?
I guess it is the same as with a regular speaker elements. Some even make liquid cooled elements, but when compared to perceived volume, temperature will rise very suddenly. 3dB more volume, and they have to handle double the power, so probably adding heat sinks will make a very marginal effect in how loud you can play before overheating. You probably have to make them nitrogen cooled to make a significant difference, and that is if they don't start distorting or reaching xmax before they melt in that case
In pro audio when trying to get as much output as possible from each element, a more common solution to the problem nowadays is having a temperature sensor that will limit the voltage to avoid overheating. That way you can make sure to squeeze every last dB out of each element without melting them. It is cheaper then advanced cooling, and in practice it more efficient to first make sure you can confidently use every last dB, rather than increasing the dB that can be produced.
I think in this case the question is really about why some exciters get hotter then other with a multi-exciter setup. I destroyed a couple of plates driving them too hard and then the styrofoam had melted more behind some exciters, but not sure if there was a pattern as to which. But I did constantly check temps and did not notice that some exciters started heating up before others. After playing with the same output level all night all exciters was cool, and then suddenly after changing DJ in early morning, although mixer output was looking fine and apparent volume seemed the same, I noticed the exciters getting warm, and really hot on a couple of plates with too much epoxy.
So if there is a effect where some exciters get hotter in a multi exciter setup, it is either avoidable with a centre cluster or the effect is very marginal and will not affect the power handing of the plates in a significant way.
Audiofrenzy posts recordings on YouTube.
But they are always deleted after a short while.
So there is nothing there to listen to now 😭
Which is a pity.
Steve.
Steve would you please share the info on this speaker? Canvas size, exciter model and if the exciter has a mounting plat if so what material and dimensions and how you mounted the cling film please. These for me are going to be the first of your small panel designs that I want to build to have as a reference. These sound simply stunning to me. Thank you for posting.
find a shop with a thickness sander and have them and it to the desired thickness.
have you considered coatings on the spring area such as PVA without and or with additives such as graphite powder or diatomaceous earth or coating with shellac?
have you considered routing an X grid of shallow cuts into the area of the exciter mount surface which extend just past the vc mount so air can vent there at the back side of the panel. even it it makes a little noise you are not going to hear that from the front side. just a thought.
Thank you for your kind words.
I'm glad you liked the "stunning" sound this panel produces .
I have videos of this panel (I think) on YouTube, but not construction.
That is on this forum somewhere 🤔
This is a very easy build panel, as all the hard work is done for you.
I purchased the canvas panel from my local diy arts store.
I purchased 4 panels on special offer, for a ridiculously low price.
Did you read the patent of this type of panel?
The polythene helps take this panel to the next level of detailed sound.
Steve.
Hi moray.
Is this the correct (preferred)name for you ?
You have to remember that I have not been experimenting with dml panels for about a year now.
At the time I had about 4 different projects on the go.
Mainly to improve rigid heavy panels, for other people.
I found it fun solving these problems.
I had put my very light eps on hold for this reason
You have been bringing up old footage and recordings on this thread which I had but forgotten about.
Christian has been tempting me to start experimenting again (my wife will be very happy, NOT !)
I am very happy to continue to talk on PM or other methods for advice but it takes a lot to get me moving in my room again.
I can't remember, but did you post the patent with grooves cut into the panels and panel strengthening in this area ?
Steve.
Is this the correct (preferred)name for you ?
You have to remember that I have not been experimenting with dml panels for about a year now.
At the time I had about 4 different projects on the go.
Mainly to improve rigid heavy panels, for other people.
I found it fun solving these problems.
I had put my very light eps on hold for this reason
You have been bringing up old footage and recordings on this thread which I had but forgotten about.
Christian has been tempting me to start experimenting again (my wife will be very happy, NOT !)
I am very happy to continue to talk on PM or other methods for advice but it takes a lot to get me moving in my room again.
I can't remember, but did you post the patent with grooves cut into the panels and panel strengthening in this area ?
Steve.
if you have a link or the patent number you mentioned I would appreciate reading it. thanks.
Thanks Steve yes moray is my first name and james is my second name campbell the last.
after Highwood Audio I started moray james cables and designed and built cables until I had my stroke. We might be best discussing via email or PM regarding modifications so as not to clog up the thread. The other thing about email is I think it is a more secure place to store information. which ever you like.
no it was not me who posted the patent about the grooves.
after Highwood Audio I started moray james cables and designed and built cables until I had my stroke. We might be best discussing via email or PM regarding modifications so as not to clog up the thread. The other thing about email is I think it is a more secure place to store information. which ever you like.
no it was not me who posted the patent about the grooves.
you are right a video clip is not in person listening but for me at least it tells me if I need to be interested or not I would love to hear your work. thanks for posting.
no reason that you could not emboss your own foil pattern. thanks for posting.
But...don't forget about these threads too:
https://www.diyaudio.com/community/...r-dml-design-and-analysis.383567/post-6954047
https://www.diyaudio.com/community/...ing-of-dml-speaker-panels.394465/post-7234486
https://www.diyaudio.com/community/threads/dml-pa-systems.390363/post-7124792
Thankfully they are much shorter!
Eric
https://www.diyaudio.com/community/...r-dml-design-and-analysis.383567/post-6954047
https://www.diyaudio.com/community/...ing-of-dml-speaker-panels.394465/post-7234486
https://www.diyaudio.com/community/threads/dml-pa-systems.390363/post-7124792
Thankfully they are much shorter!
Eric
Moray,
To be sure I have never done that (tapered a panel), so I can't be sure. But here is what I think "should" happen (theoretically):
The speed of bending waves (for thin plates) is proportional to square root of plate thickness. So bending waves travel a bit faster in thicker plates and slower in thinner plates. So, for a tapered plate, I would imagine that a bending wave would slow down as it moved from the thick section of the plate, to the thinner section of the plate.
For the panel of constant thickness, the wave speed should be constant across the length of the panel for a particular frequency. So the entire panel should have the same coincidence frequency. But for a tapered plate, since the wave speed varies as the wave traverses across the plate, for a particular frequency, the thick part of the plate my be above coincidence, while the thinner part would be below coincidence. Hence, any transition in sound radiation that happens at coincidence would happen less abruptly for the tapered plate than for the constant thickness plate.
Eric