Alaska129.
while waiting for the exciter glue to dry on my card panel, i put up my canvas only panels(no ply) and thought i would make a recording for comparison to the other two recordings of another cup of coffee.
there was a dent in the larger canvas panel ,from leaning on another panel i wiped it with a wet sponge and it tightened strait away .
the other smaller panel has a very loose canvas , i did try and tighten it but it was not easy with the exciter already attached !
these both roll off below 300hz but i let them go down to 120 as there is still some useful output .
the TLS roll off at 300hz as usual .
steve.
while waiting for the exciter glue to dry on my card panel, i put up my canvas only panels(no ply) and thought i would make a recording for comparison to the other two recordings of another cup of coffee.
there was a dent in the larger canvas panel ,from leaning on another panel i wiped it with a wet sponge and it tightened strait away .
the other smaller panel has a very loose canvas , i did try and tighten it but it was not easy with the exciter already attached !
these both roll off below 300hz but i let them go down to 120 as there is still some useful output .
the TLS roll off at 300hz as usual .
steve.
Sadly the DIY stores here only carry the 5mm Revolution Ply that Veleric used in post #838, and 6mm poplar. Due to the shortage of 3mm birch right now, the Meranti 1088 ply in 3mm is what being used by a lot of the CNC folks. It is a light wood so maybe closer properties to poplar. And it's Cheep
Pete
Pete,
As it turns out, the 5 mm Revolution Ply is quite well suited to the "high aspect ratio" approach that I have been investigating. The dashed green line below is the frequency response I got using a 14.25" x 50" revply panel. This is among the best (if not the best) response of all the hundreds of DML responses I have measured.
Revply is unusual in that it is stiffer in the direction perpendicular to the face grain than it is in the direction parallel to the face grain. That results in a particularly high density of natural frequencies when used as a high aspect ratio panel with the face grain running in the long direction of the panel.
The panel is mounted to a frame with 1/2" wide 3M 411 tape around most of the perimeter.
I'd be happy to share more details if you are interested in building something like it. The image below is of a similar construction, but using a different but similarly sized panel.
Eric
That seems very odd. I had no problem.
I found the site and company because the site DesignBoom profiled it at: https://www.designboom.com/technology/hidden-sound-thin-speakers-hifi-audio-07-15-2022/. They also have a Facebook page at: https://m.facebook.com/hiddensound.ch
Hidden Sound has two DML sizes. One the "size of a smart phone" and the other the size a a piece of A4.
Some quotes from the site:
...
...
A couple of images:
Some quotes from the site:
Compact but powerful DML home audiophile speakers, which through magical thinness and cutting-edge 360-degree acoustic innovation, offer a
mesmerising listening experience.
...
Swiss, Smart and Sustainable.
Swiss quality, hand-crafted sound systems made from sustainable materials, changing the laws of physics.
An only 4mm thin first layer of sustainable balsa wood, harvested from reforested plantations, uses sophisticated micro vibrations to generate digital sound, covered by a uniquely engineered second layer of 4mm thin acoustic foam.
Held in minimalistic 8mm thin frames with an incorporated tabletop / bookshelf stand, created from machined, hard coat anodised, recycled aluminium.
...Hidden ECO System Specifications (small one)
Frequency response
50Hz-16kHz
Sensitivity
90 dB/W/m
Total RMS power
120 WRMS
...
Hidden EVO System Specifications (A4 size)
Frequency response
40 Hz-18 kHz
Sensitivity
93 dB/W/m
Total RMS power
200 WRMS
A couple of images:
Aagas,
Interesting find. I didn't have any warning about the site, but I'm wary of anything they describe like this.
Eric
aagas.
The larger of the canvas only panels in the left photo has had its dome dust cover pushed in somehow?
The smaller canvas panel in the second photo , which has the looser material .
This was an old canvas picture frame my daughter gave me many years ago , I think it is more a plastic than canvas ?
On the recording this is on the left.
It is only 14x8inches.
Steve.
The larger of the canvas only panels in the left photo has had its dome dust cover pushed in somehow?
The smaller canvas panel in the second photo , which has the looser material .
This was an old canvas picture frame my daughter gave me many years ago , I think it is more a plastic than canvas ?
On the recording this is on the left.
It is only 14x8inches.
Steve.
Attachments
The use of "acoustical foam" seems odd to me. Typical damping materials for dml panels "damp the nasties" by dissipating energy when they are deformed (stretched/compressed/sheared) due to the flexing of the panel. But acoustical foam "normally" is used to absorb sound waves in air, not mechanical waves in a panel. And 4 mm of foam is only thick enough to absorb sound waves over about 20 kHz. So technically it doesn't make much sense. Of course, depending on what they are calling "acoustical foam" it could be something completely different from what I am imagining.
I agree with Steve about overdamped panels. Only thing worse is underdamped panels.
Eric
Let's not forget that light panel materials don't need a lot to overdamp them.
Heavy panels take a lot more.
If the so called acoustic foam is just hanging in front of the panel then there is probably not mush damping.
But if it is glued on and with what glue ? , then damping will probably take place.
I always even took my speaker grilles off of speakers, because of the dulling of the sound.
Steve.
Heavy panels take a lot more.
If the so called acoustic foam is just hanging in front of the panel then there is probably not mush damping.
But if it is glued on and with what glue ? , then damping will probably take place.
I always even took my speaker grilles off of speakers, because of the dulling of the sound.
Steve.
My egg Whites panel is still drying , but I am listening to them at the moment, and they sound OK.
I will not do any serious listening and measuring until tomorrow, to give the hf a chance to settle down and improve.
But at the moment it is at least going down to 160hz at 3m.
Lower at 1m.
Let's see what tomorrow brings.
Steve.
I will not do any serious listening and measuring until tomorrow, to give the hf a chance to settle down and improve.
But at the moment it is at least going down to 160hz at 3m.
Lower at 1m.
Let's see what tomorrow brings.
Steve.
+ @Alaska129
Thank you for those information. I didn't know this wood (thought it was a brand...).
I found some information from a french "data base" : meranti light red
Poplar : density 450kg/m³, E = 10GPa
Meranti light red: density 500kg/m³, E = 13GPa; Some other Meranti are heavier.
Here is for Lauan. It is from the same wood family as Meranti (see the scientific name)
Pete, in the different possibilities you listed, it is the one I find the most interesting. I would go for the 2.7mm thickness.
For a quick start, hanging panel is a possibility but for more long term design, I am in favor of a framed panel with a foam suspension. I know this is a topic which don't have a full consensus but 2.7mm is a low thickness subjected to warping if fully free.
Eucy, the white color of light wood seems a general rule. The color might be given by a varnish.
Christian
Thank you Aagas
The web site has few technical information. The panels are not very large, about 200x330mm and as you said from balsa wood. they are powered by 2 exciters. It is all I found.
The style is pretty nice.
From the same source : "the exact thickness and length of the panels are what makes the sound "omnidirectional"." The smoke curtain is thick (not sure this sentence has a meaning in English to say the reality is hidden...).
I like also the idea of "the molecules of sound" in the same link.
What makes more sense is how the sound fills the room, the fact you can forget the speakers, how people react the first time... this is the essence of DML.
"The smoke curtain is thick" comes pretty close to a number of American-English idioms. Your point comes across very well.
The quote from the website that I found the hardest to swallow (another idiom - e.g., read or take in):
"Swiss quality hand-crafted sound system from sustainable materials, changing the laws of physics."
Switzerland hosts The Large Hadron Collider, which seeks to identify evidence of the laws of physics, but gee, now we have a little Swiss company making DMLs, that is by their own assertion: "...changing the laws of physics".
Either, (1) something got lost in translation or (2) the scientists who built the Collider should try and get their $5 billion returned because HiddenSound can just adjust the laws of physics for them. EasyPeezy!
Christian..
Meranti has more of a pale to mid brown colour, and the silvery look I mentioned is actually like a mild silvery glistening effect within the brown which is mainly noticed after clear coating...it's unusual and not something I like much
The ply was used a lot for varnish ready interior doors. The strip timber for architraves and skirting boards until being largely superseded by cheaper coated customwood (compressed fibreboard) products which are ubiquitous now in new Aus house builds (unfortunately)
Eucy