Sapphire,
Wow, big LF bump with the baffles. Nice to see data! Can you share any pics of the panels and baffles? I've never tried baffles but have always wondered about whether simply making the panel bigger (self baffling) would achieve the same or better result than adding the baffle. Any thoughts?
Eric
Hey Moray,
I could be wrong but I'm not sure that you can really do much with localized application of CLD. Frankly, I'm skeptical of any treatments attempting to address individual modes, and even more skeptical of treatments for individual antinodes. I prefer a more wholistic approach like I described in an earlier post tonight.
One possible exception would be the use of local weights for the purpose more evenly distributing natural frequencies along the frequency spectrum. I have not tried this myself, but for me this would be similar to using shape, or aspect ratio, or elastic properties to tailor the distribution of natural frequencies. But it would take modeling capabilities (like LISA or better) to do decently.
Eric
I used some scrap chipboard to make an L that I mounted to the back of the frame. It's about 15 inches deep and runs a bit further than the length of those 2 sides. I used duct tape around the entire panel-to-frame gap for a seal but I don't think that worked very well so I'll have to figure something else out. The frame is made of 2x6 so it's already got at least 6" of baffle built in all the way around. This was my first test and I haven't had time yet to experiment with baffle sizes. Building a driver brace is a higher priority right now, as is my day job...
Bracing the two short ends of the panel made an improvement by itself but it was a bit lumpy. The baffles added more and smoothed it out.
I never really thought about baffles in the past because the panel itself looks like a baffle (self-baffling), but there's a lot of interaction between the front and back near the edges. The smaller the panel the more intense that is. You can feel it in the air with your hands near the surface and hear the weirdness with your ears if you inspect the edge of an unsecured panel while it is playing. I figure that baffles should dilute that front-back interaction resulting in higher efficiency and less distortion.
Moray James.last tom waits
xrk971.
on the first recording ,take it with me ,i had to lower the volume of the veneer panel as the piano was setting off the problems with splitting and cracking surfaces .
but then i noticed that something else was also distorting , the low frequency from the TLS was causing at least 2 items in the room to start buzzing (still not located ).
so ive had to lower the TLS which only run below 300hz,so his voice does not sound as deep(would you believe )as it would, which i think is much nicer and gives more warmth and closeness ?
the second recording, filipino box spring hog,i recorded to show that i wasnt just playing soft music , because the panel could not handle it.
i had one finger in one ear and turned my head to one side when playing this, and i was well back in the room, as it was quite painfully loud
obviously you do not have to listen to it this loud
sorry they are in the wrong order, i had to change ,take it with me , to 128 , as it was too large, even though at my end it said it was not ?
steve.
I would not worry about not having enough DBs from small panels.
This recording of Filipino box spring hog , is a torture track for any type of speaker ( not just because it is Tom waits 🤣)
As I explained in this post, I was playing the track very loudly, far louder than I would ever normally listen.
It is a very raw recording, and he is shouting most of the time.
There is no compression or strain from the panel, so it is hard to tell just how loud I am playing this track, from listening to this recording.
Believe me when I say, I was in pain listening at this level, during the recording!
Steve.
Panel size does not influence efficiency, only the bottom end cut-off.
Efficiency, loudness, is a function of panel density and stiffness. A very light panel made of EPS is probably more efficient than any other material, but it's extremely mid-range heavy. A large EPS panel can have very nice bass, but you will have to do something about the HF.
Hi Moray
No... Just a radius to the corners...I visualise this stuff a lot, and if you point load a flexible membrane like cloth (ignoring the effect of the added stiffening in this case), then the least energy deflection shape is circular, so forcing a rectangular shape causes distortion at the corners, which can be reduced by adding a radiuses fillet to each corner of the frame. This in the will allow the sharp peaks in Andre's stiffening to be reduced/modified
Eucy
I also found this thread very interesting and is still valuable. Unfortunately it came to an abrupt end.
https://www.diyaudio.com/community/...ndwich-dml-panel-construction-project.300581/
https://www.diyaudio.com/community/...ndwich-dml-panel-construction-project.300581/
I did a test tonight with the panel mounted in my 2x6 frame with baffles mounted, and then I carefully removed the 15" deep long side baffle without disturbing anything and retested, and the results were almost the same. Only tiny differences. My previous tests by hand must have skewed the data. Either that or the frame's built-in 6" baffle is enough and adding 15" to one side is insignificant.I used some scrap chipboard to make an L that I mounted to the back of the frame. It's about 15 inches deep and runs a bit further than the length of those 2 sides. I used duct tape around the entire panel-to-frame gap for a seal but I don't think that worked very well so I'll have to figure something else out. The frame is made of 2x6 so it's already got at least 6" of baffle built in all the way around. This was my first test and I haven't had time yet to experiment with baffle sizes. Building a driver brace is a higher priority right now, as is my day job...
Bracing the two short ends of the panel made an improvement by itself but it was a bit lumpy. The baffles added more and smoothed it out.
I never really thought about baffles in the past because the panel itself looks like a baffle (self-baffling), but there's a lot of interaction between the front and back near the edges. The smaller the panel the more intense that is. You can feel it in the air with your hands near the surface and hear the weirdness with your ears if you inspect the edge of an unsecured panel while it is playing. I figure that baffles should dilute that front-back interaction resulting in higher efficiency and less distortion.
ok so level is not going to be an issue do you find any difference in terms of the amazing 3D spatial sound between a small 6x9" panel and a larger one say 9x12" ? thanks.
I think there are a couple of factors that contribute to the "3D spatial sound".
First of all of course the phase incoherent waveform patterns that is emitted rather a single waveform, making it sound spacious and encompassing.
The second is that transients are very pronounced, which makes stereo imaging very good, which otherwise would be a bit unexpected for a more diffuse signal.
I don't think there is a big difference in neither spaciousness or imaging between reasonably sized plates. My impression is that larger plates can have a bit longer decay times, and smaller plates sounds a bit tighter, but both still sound very much DML.
Also something I suspect, but have not confirmed, is that the cluster of four exciters have better spatial imaging than using a single exciter. We use initial transients to determine direction of a sound, and they come from the piston action introduced by the exciter. And with a single exciter, the area emitting that is only the area in the mounting circle of that exciter. If you have four exciters close together, not only do you have four times as much area that is directly following the exciters movement, and hence producing transients, but the area in between them becomes coupled and makes it like one large ring.
First of all of course the phase incoherent waveform patterns that is emitted rather a single waveform, making it sound spacious and encompassing.
The second is that transients are very pronounced, which makes stereo imaging very good, which otherwise would be a bit unexpected for a more diffuse signal.
I don't think there is a big difference in neither spaciousness or imaging between reasonably sized plates. My impression is that larger plates can have a bit longer decay times, and smaller plates sounds a bit tighter, but both still sound very much DML.
Also something I suspect, but have not confirmed, is that the cluster of four exciters have better spatial imaging than using a single exciter. We use initial transients to determine direction of a sound, and they come from the piston action introduced by the exciter. And with a single exciter, the area emitting that is only the area in the mounting circle of that exciter. If you have four exciters close together, not only do you have four times as much area that is directly following the exciters movement, and hence producing transients, but the area in between them becomes coupled and makes it like one large ring.
your comment about four close exciters makes me wonder about multiple single exciter panels. if one were to use say four panels (two per channel) does anybody have any experience with doing this? if so do the two panels per channel present a larger sound field if spaced closely or wider apart? Thanks.
I use four panels per stack to be able to deliver enough power, but I would think that the ideal is one source of transients. If you have multiple, if they arrive at exactly the same time we should interpret the signal as coming from the middle of the sources. But if you are off axis and have different arrival times, the transients would be a bit smeared.
In practice I found the imaging amazing also with multiple plates, but if you don't need that much power I would think a single plate should offer the best imaging.
In practice I found the imaging amazing also with multiple plates, but if you don't need that much power I would think a single plate should offer the best imaging.
thanks very much for your input I would expect that room acoustics will play a major factor in using multiple panels per channel especially so if the panels are space apart.
At a guess I would expect a pair of small panels in front of you to the left and right similar to a conventional stereo set up along with a second set of stereo small panels set up farther away from you (to increase arrival time from the front pair of panels)
with some tweaking in the set up I would expect a larger perceived sound field than with a single pair of small DNL panels, especially if the second set of panels can be situated to the back side or to the rear of the seating position. This is however mere speculation on my behalf at this time.
At a guess I would expect a pair of small panels in front of you to the left and right similar to a conventional stereo set up along with a second set of stereo small panels set up farther away from you (to increase arrival time from the front pair of panels)
with some tweaking in the set up I would expect a larger perceived sound field than with a single pair of small DNL panels, especially if the second set of panels can be situated to the back side or to the rear of the seating position. This is however mere speculation on my behalf at this time.
I have been further researching Mycelium Board, where straw from Rice and Wheat is a substrate, there is also Coffee Waste being referred to regularly as well.
Boards Density is at present being seen to double across the designs being produced, with a Kg per m/3 ranging from 57Kg to 99Kg.
This will offer at the lightweight end of the scale a 1000mm x 1000mm x 10mm board at 0.57 Kg ( 20oz) per / m2
A 5mm thick Board which I assume will be the go to thickness is 0.285Kg (10oz) per / m2.
Mycelium Boards using the above production materials are becoming popular at thicknesses between 25mm - 60mm as a Insulation material.
The Market is growing, expect to see this product in broader use and a increased variety of Board Thicknesses.
Boards Density is at present being seen to double across the designs being produced, with a Kg per m/3 ranging from 57Kg to 99Kg.
This will offer at the lightweight end of the scale a 1000mm x 1000mm x 10mm board at 0.57 Kg ( 20oz) per / m2
A 5mm thick Board which I assume will be the go to thickness is 0.285Kg (10oz) per / m2.
Mycelium Boards using the above production materials are becoming popular at thicknesses between 25mm - 60mm as a Insulation material.
The Market is growing, expect to see this product in broader use and a increased variety of Board Thicknesses.
At the moment the most common work is being done in Countries where a concern is being expressed for Circularity in the Economical Strategies.
Holland and Spain along with Scandinavia, this is early doors and the interest is growing, unfortunately the coverage on the Web is Sporadic.
I will search out any Mycelium Boards being produced in the US, there might be University producing product, I was once in communication with a American University about their producing Delignified Translucent Wood Panels as a Glass Substitute.
Holland and Spain along with Scandinavia, this is early doors and the interest is growing, unfortunately the coverage on the Web is Sporadic.
I will search out any Mycelium Boards being produced in the US, there might be University producing product, I was once in communication with a American University about their producing Delignified Translucent Wood Panels as a Glass Substitute.
This most recent find might be of interest.
https://www.etmm-online.com/innovat...-speakers-a-5ef4a9e16cdb80e626083af0a6ff611f/
https://www.etmm-online.com/innovat...-speakers-a-5ef4a9e16cdb80e626083af0a6ff611f/