Hello Eric .
Isn't this what I have been saying for years now.
I have never been keen on rigid panels.
Have you finally come around to my way of thinking ?
There is a sweet spot somewhere between flexibility and stiffness, this all depends on the flexibility and size of the panel.
Even my 1inch large eps panels are too rigid if used for small panels.
Even HD grades of eps I find has a rather harsh sound caused by its rigidity.
Rigidity in a panel has never been a desire for me, my small card panels are a good example of a fairly flexible small panel that works very well ,and is free if old cereal boxes are used.
Steve.
Isn't this what I have been saying for years now.
I have never been keen on rigid panels.
Have you finally come around to my way of thinking ?
There is a sweet spot somewhere between flexibility and stiffness, this all depends on the flexibility and size of the panel.
Even my 1inch large eps panels are too rigid if used for small panels.
Even HD grades of eps I find has a rather harsh sound caused by its rigidity.
Rigidity in a panel has never been a desire for me, my small card panels are a good example of a fairly flexible small panel that works very well ,and is free if old cereal boxes are used.
Steve.
Yes!... But it seems that "stiffer is better" is wrongly engrave in the DML design rules.
Christian
Christian.
Maybe someone believed the computer, rather than their own ears 🤣
Steve.
Maybe someone believed the computer, rather than their own ears 🤣
Steve.
Christian.
On a more serious note, all the nxt patents I read seemed to concentrate on showing that dml worked.
The quality of the panel material being used didn't seem to matter or the exciter for that matter.
If only they had built a decent sounding panel instead of selling franchises, maybe dml would be more well known and popular.
As you know, My cousin popped round the other day when my wife was out , and he was amazed at all the panels I brought out and played.
He had never heard of dml panels, and he could not believe how good they sounded.
I gave him the small card panel for him to hold in his hand, he walked over to the proplex panel that was hanging on the other side of the room, he put his head between the two panels and said it was like listening to headphones, giant headphones.
When I compared the sound of the panels to my headphones, he said he preferred the sound of the panels.
This was without any special setting up , I just hung up the panels and played music.
He now wants to build some panels.
The picture shows what my room looked like after he left.
I had a devil of a job trying to tidy up before my wife came back home.
🥵
Steve.
On a more serious note, all the nxt patents I read seemed to concentrate on showing that dml worked.
The quality of the panel material being used didn't seem to matter or the exciter for that matter.
If only they had built a decent sounding panel instead of selling franchises, maybe dml would be more well known and popular.
As you know, My cousin popped round the other day when my wife was out , and he was amazed at all the panels I brought out and played.
He had never heard of dml panels, and he could not believe how good they sounded.
I gave him the small card panel for him to hold in his hand, he walked over to the proplex panel that was hanging on the other side of the room, he put his head between the two panels and said it was like listening to headphones, giant headphones.
When I compared the sound of the panels to my headphones, he said he preferred the sound of the panels.
This was without any special setting up , I just hung up the panels and played music.
He now wants to build some panels.
The picture shows what my room looked like after he left.
I had a devil of a job trying to tidy up before my wife came back home.
🥵
Steve.
Attachments
I was supposed to be testing my 6ft rigid mounted panel on the wall ( the panel on the left in the picture I last posted).
But my cousins surprise visit put a holt to that.
The rigid ply panel acts like a stud wall when mounted on a solid wall, I did not get a chance to add some sound damping material behind the panel , this I would have hoped would have improve the sound even more.
Stud walls usually have rockwool insulation between them ,something similar would probably be better than nothing.
It's all put away now ,so it will have to wait for another day.
Steve.
But my cousins surprise visit put a holt to that.
The rigid ply panel acts like a stud wall when mounted on a solid wall, I did not get a chance to add some sound damping material behind the panel , this I would have hoped would have improve the sound even more.
Stud walls usually have rockwool insulation between them ,something similar would probably be better than nothing.
It's all put away now ,so it will have to wait for another day.
Steve.
I guess it is convenient to look at stiffness primarily since the tricky part is finding a material that is stiff enough in relation to weight. Flexible and light is easy.
For low frequencies I think that below a certain point suspension becomes more important, at least if you want a defined a tight bass. To move enough air, and to fit modes for low frequencies, plates need to flex a lot and be big. If you instead have a suspension that allows the plate to work as a piston element, you can have a smaller plate with tighter bass.
And for high frequencies it seems like the reproduction does not depend as much on material flexibility either, but rather compressive strength in relation to weight?
The mid is by far the most important part though, and where DML really shines. But usually when a material is bad is when it is too flexible or soft, which means it doesn't go low because of inability to have the plate act as a piston element, and dampening the highs by not being hard enough. Polycarbonate, which is not very flexible, had a strong HF response but not so much mid. However it is not stiff in relation to weight anyway.
Are there any examples of materials that been tested and rejected for bad performance that are stiffer in relation to weight compared to materials like EPS and nomex/carbon sandwich?
Oh, yes, I can't believe I missed that one!
But, also, as you are aware, the negative of low stiffness (at least according to Dave's attached paper), is that the high frequency cutoff due to the "ring" effect with a typical exciter is lower when panel stiffness is reduced. As we can see with Pettals, that cutoff can easily be within the audible range.
Eric
Since early in my investigations I understood stiffness to be a compromise (that's how engineering works!). Stiffness contributes to sensitivity, but forces the use of larger (or thinner) panels. More recently I came to understand that there is even a second level of compromise: Stiffer panels have a higher (better) cutoff frequency (due to the exciter ring effect) but a lower (worse) coincidence frequency. Finding the best compromises is what makes DML speakers challenging and fun.
Eric
Which one are you talking about Steve? I don't see anything mounted on the wall, but I do see tall panels on the left and right in (pine?) frames. But I can't tell what the panel is. Is that what you meant to be testing? Or something else?
Eric
If you cure the problem within the exciter coil foot area , even my soft low comprehensive eps panel can reach 20k with no problems .
Adding weight to the exciter area by using a disc or foot extension only complicates things as pointed out in the paper you last showed.
I found this paper lacking in so many ways, similar to NXT patents.
Steve.
I have posted pictures of these panels many times over the last 15years .
This is another picture for clarity.
The only place in my room to test the panel up against the wall was longways behind the settee which was quite interesting.
These rigid ply panels seem to work OK up against walls acting like a stud wall , I did not get around to adding sound damping material behind the panels as I was interrupted by a visit from my cousin.
These panels have warped and screws have loosened over the years as I did not permanently glue everything together as they were an experiment.
I made videos on WhatsApp for Christian but no recordings for this forum.
I even played a recording of Big Ben which I recorded from my very small card panels played over my surround sound system.
And still it sounded fantastic.
As if it was the original recording.
DML , even after being recorded twice still sounds so realistic, showing how good my original card panel recording sounded .
This I posted on this site years ago.
No-one seems to listen.
Steve.
This is another picture for clarity.
The only place in my room to test the panel up against the wall was longways behind the settee which was quite interesting.
These rigid ply panels seem to work OK up against walls acting like a stud wall , I did not get around to adding sound damping material behind the panels as I was interrupted by a visit from my cousin.
These panels have warped and screws have loosened over the years as I did not permanently glue everything together as they were an experiment.
I made videos on WhatsApp for Christian but no recordings for this forum.
I even played a recording of Big Ben which I recorded from my very small card panels played over my surround sound system.
And still it sounded fantastic.
As if it was the original recording.
DML , even after being recorded twice still sounds so realistic, showing how good my original card panel recording sounded .
This I posted on this site years ago.
No-one seems to listen.
Steve.
Attachments
Hopefully everyone will use a good pair of headphones to listen to this recording.
Playing over ordinary speakers will not do this justice .
Steve.
Playing over ordinary speakers will not do this justice .
Steve.
Hello Steve, what is your last solution for the voice coil foot area problem, especially regarding EPS panels? If I remember correctly you thinned the EPS in a dome shape and made a small hole in the center of the exciter area and filled it with sound deadening material, am I right?
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In which ways Steve?
My main question with this analysis is why the concentrator experiments failed so dismally.... The mechanism appears to be more complex than that covered in this paper.
Eucy
Hello Eucy,
For me also, all the tests of concentrator failed... I have the same question. In the list of what remains unclear for me coming theory is the role of the local mass (voice coil and concentrator).
Christian.