Moray.
The crate ply is a very flexible panel , in one direction only.
Although the rigidly in the other direction is not very rigid.
I presume this material is similar , maybe, to flexible ply ?
As I have said before, I like flexible light panels.
The sound of this panel is similar to my eps panels, but is still a little too heavy for that ultimate sound that I like.
And thanks for liking my recordings, much appreciated 👍
Steve.
The crate ply is a very flexible panel , in one direction only.
Although the rigidly in the other direction is not very rigid.
I presume this material is similar , maybe, to flexible ply ?
As I have said before, I like flexible light panels.
The sound of this panel is similar to my eps panels, but is still a little too heavy for that ultimate sound that I like.
And thanks for liking my recordings, much appreciated 👍
Steve.
Steve: I look forward to the results of our experiments. I had another thought about your comments on thicker EPS panels getting in the way of the high frequency energy emanating from the exciter. This may or may not be original but that's ok. Here are a couple of ways to make sure that the exciter energy is transferred evenly from the rear of a thick panel to the front. First one id to mark accurately on the back side of the panel exactly where the exciter mount is going to be, once done you would mark out lets say eight evenly spaced points on that circle where the VC former will sit, At these point you would insert penny nails (the kind with a flat head). To do this you would drill a hole the next size larger than the nail, then yu would insert some epoxy into the hole and then fit the nails into the hole. The nails should be long enough to reach as far as the front of the panel. This will provide a direct transmission line for the high frequency to penetrate the foam panel and should result in more high frequency being emitted on the front side of the panel, you might not require a tweeter hard to say.
The second way to do this is to use a hole saw which is the same diametre as the exciter VC. Once again the centre of the desired location needs to be marked on the back side of the panel. Once marked use the hole saw to drill out a plug from the panel. Carefully remove the plug from the hole saw and then with epoxy re -install the plug back into the panel. The saw has a kerf so the plug will be smaller than the hole by the thickness of the saw itself, this gap between the plug and the panel will be filled with epoxy which will turn into a hard cylinder which will serve the same purpose as the nails in the above suggestion.
This would be a good place to consider using add mixtures to your epoxy to harden it such as graphite powder or diatomaceous earth. Hope this is of interest.
The second way to do this is to use a hole saw which is the same diametre as the exciter VC. Once again the centre of the desired location needs to be marked on the back side of the panel. Once marked use the hole saw to drill out a plug from the panel. Carefully remove the plug from the hole saw and then with epoxy re -install the plug back into the panel. The saw has a kerf so the plug will be smaller than the hole by the thickness of the saw itself, this gap between the plug and the panel will be filled with epoxy which will turn into a hard cylinder which will serve the same purpose as the nails in the above suggestion.
This would be a good place to consider using add mixtures to your epoxy to harden it such as graphite powder or diatomaceous earth. Hope this is of interest.
using the same brace material but placing it horizontally rather than vertically (ie shorten the brace) will result is a stiffer brace with a resonant point much high up in frequency.
I am just guessing but I think that you could control the level of a whizzer via the degree of coupling it has to the panel. A hard coupling ought to translate into a higher energy transfer while decoupling the whizzer cone by using a softer coupling should decrease the energy transfer from the panel resulting in a more subdued level from the Whizzer. Does that seem reasonable?
suppose you could add a heat sink(s) to the back of the hot motors they don't have to weigh very much, or see if you can find locations which work as well but don't get as hot.
wow Steve that sounded excellent. So can you tell me what the spacing is between the film and the canvas and how you space the film (is it air tight))? How do you keep the film from rattling? kling film is a very generic description but generally they are a stretch type soft film have you tried any different films? I know from experience that stretch and shrink films are not reliable so far as long term stability go but for the moment that is not a concern.
do the exciters on these panels have ply supporters under them? These sound very good Stece these make me re-think other panels these are so simple to build.
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.