There's no doubt that there will be interference. Is interference necessarily bad? Waves reflect off every perimeter of a panel (especially one with free edges) and interfere with the original wave and each other. In fact, the interference of all those reflections is what creates the modes that make a DML a DML. If interference has to be bad, why are free and undamped perimeters (which result in more interference) good?
I suggested watching at 1/4 speed. Is it my fault if you don't do that?
It shows exactly what happens, and no more, no less.
And if we would see "the waves move up and down in frequency" (or something that looks like that), why would it indicate a necessarily bad result at normal listening distances?
Eric
Lawnboy.
The closest panel size i have to the one you mention is 17inches 13 inches I made this from strips of 3mm ply from crates .
The second picture is from 3m into the room I believe and the third is at 1m if I've got them the right way round.
Everything below 50hz is traffic noise and my big feet 😁
The closest panel size i have to the one you mention is 17inches 13 inches I made this from strips of 3mm ply from crates .
The second picture is from 3m into the room I believe and the third is at 1m if I've got them the right way round.
Everything below 50hz is traffic noise and my big feet 😁
Attachments
It is the reason I prefer the sound of one exciter and not two, as I have said before it muddies the water (pun intended ) if you do not care if the problem is there Or not , there seems no point in me showing you it.
I do not know how to change the speed of your recording and like you I can not be bothered to find out.
I will leave it there , believe what you like.
I will carry on trying to help people build great sounding panels, but not necessarily on this forum as YouTube seems to be a much better way of demonstrating panels.
Steve.
Hello Jaxboy,
Of course more evidences are always welcome
I guess yes, unless there is an other natural mechanism that increase the level. Applying the technique shown by Eric on different panels should learn a lot on this topic.
This is the richness of the forum... and also part of the challenge
Christian
Hello Steve
Thank you for the proposal. Yes, it would be interesting to increase the knowledge of materials against that. The distance of the edges should be mentioned also
Could you add proplex in those tests?
I will plan to do the same... not this week, I don't have my measurement tool for now.
@Veleric : which material was your test?
Christian
Why not both? If You Tube offers a wider public and is dedicated for video, the concentration of passionate DIYers at good level is here.
Please keep us inform here to what you publish there.
Christian
Thanks , I have found similar items in the UK on Amazon.
I'm looking at the fabric of the lamp and thinking canvas panel type panel.
Maybe using perspex ?
The other half would not even know they were there, hehehe.
Steve.
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Hi Christian.
The proplex is a very good panel ,but the problem is I cannot find out anything about the round fluted panels on line only square flutes ?
So if it is not available anymore it seems a bit pointless perusing testing ?
Steve.
Hello Colin,
Have a look here Github DML page. The first document is a kind of history file. There is a table summarizing some canvas realizations. Extract :
Not sure it was the result of deep design investigation but more obviously copies... Canvas for painting are also mainly easy to find in rectangular shape. The canvas being identical in both directions, a square shape is not a good idea leading to have modes with the same frequency.
My current choice is DAEX25-4FHE. It is 4 ohms. I would have preferred 8 Ohms not because of the amp but because of the cut off frequency due to the inductance with the voice coil inductance. I won't worry about the impedance viewed by the amplifier. About the legs, no experience. What we read here is they are generally cut.
As for the proportions, there are not so much variants of this design so few experience. In mine, it is rectangular. The variant is to be with real balsa. It works but the others are light plywood. In posts with Spedge, we understood what he thought to have bought balsa was in fact basswood... probably a good choice.
My dream also when I started to build DML... I am afraid there is no real hope on this way. The rear wave has the same energy as the front one so very difficult to absorb it. Depending of the damping material, some energy will be reflected and combined with the front. Easy to test. Let us know your results... just don't start with a permanent attach method!
Same, low deviation from the original one... The canvas is probably not working on exactly the same physics as DML (vibration in a membrane versus in a plate), the common point is modes; Being at the centre, the force coming from the canvas tension is balanced in a better way for the voice coil.
My experience in EQing is to low to understand really your question. DML are suitable for EQing as they are based on modes. Due to the possible dispersion between panels (material, tension, exciter placement) some individual EQ could make sense. As first step, I would build them and then test them with REW each being at the same location to evaluate the similarities or differences.
Christian
Hello Steve,
It would be even a good reason to do it! As you got a material with good results, even if not available, why not trying to figure out more of its characteristics. to help for the next choices.
Christian