Vanillasoap.
The heavily damped panel usually has the effect of softening the sound and dynamics.
Your panels look very nice ,so I presume you are good at woodwork ?
I have found that veneer is a good material ,I have an old 1mm 6x9inch veneer panel that peeled off of an old 40s draw ,the sound is very good and it has a response that goes down to about 130hz.
I did try and get a 1mm balsa basswood but they sent me 2mm ply.
I don't know much about veneer ,only what I have read on line, but if the veneer is too thin ,maybe two veneers glued together could be an option?
Steve.
The heavily damped panel usually has the effect of softening the sound and dynamics.
Your panels look very nice ,so I presume you are good at woodwork ?
I have found that veneer is a good material ,I have an old 1mm 6x9inch veneer panel that peeled off of an old 40s draw ,the sound is very good and it has a response that goes down to about 130hz.
I did try and get a 1mm balsa basswood but they sent me 2mm ply.
I don't know much about veneer ,only what I have read on line, but if the veneer is too thin ,maybe two veneers glued together could be an option?
Steve.
Steve,
yeah, I love working with wood, either by hand or with cnc milling/laser. I remembered I had some sheets of plywood, the high quality type, air-plywood used in model airplanes. tested both 2mm and 1mm, and yeah, holy **** they're nice. the 1mm sounded best I think. the sheets are not that big, only 300mm x 600mm, but still, these are indeed better sounding than the foamcore, I see what you mean by dampening. I do wish they were a bit bigger, I'm really considering getting larger sheets, just wonder how large they can be without flexing too much, humidity is an issue, and they are prone to bending. maybe a balsa frame could help add some rigidity. another challenge is how to mount them, either on some legs or with suspension. Have to look at some existing designs I think for inspiration.
yeah, I love working with wood, either by hand or with cnc milling/laser. I remembered I had some sheets of plywood, the high quality type, air-plywood used in model airplanes. tested both 2mm and 1mm, and yeah, holy **** they're nice. the 1mm sounded best I think. the sheets are not that big, only 300mm x 600mm, but still, these are indeed better sounding than the foamcore, I see what you mean by dampening. I do wish they were a bit bigger, I'm really considering getting larger sheets, just wonder how large they can be without flexing too much, humidity is an issue, and they are prone to bending. maybe a balsa frame could help add some rigidity. another challenge is how to mount them, either on some legs or with suspension. Have to look at some existing designs I think for inspiration.
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Vanillasoap.
There is a 1mm ply used for model aircraft ?
60cmx30cm is far larger than I need for the panels I use , but I would still test this size first.
The larger you make the panel the more flexible it will become, foamcore is also a very lossy material so HF does not like to travel across the panel.
The 5mm xps I am coating with epoxy is very similar to your panels .
The idea of the epoxy is to hopefully help the HF travel across the panel probably with the added bonus of a lower LF?
The panel size I am using is too large,but I want to compare with old panels I have lying around.
With foamcore panels you basically have three damping layers glued together.
I did think that the bass panel patent might work quite well with this or the xps panel ?
The plot that you made only shows 50db segments ,which is far too large,try 10db or 20db , the dip you mentioned at 55HZ is about 50db down !
And if you are not using a measurement microphone you could just be measuring your microphone response ?
Did your microphone come with a manufacturers frequency plot ,this could help?
Steve.
There is a 1mm ply used for model aircraft ?
60cmx30cm is far larger than I need for the panels I use , but I would still test this size first.
The larger you make the panel the more flexible it will become, foamcore is also a very lossy material so HF does not like to travel across the panel.
The 5mm xps I am coating with epoxy is very similar to your panels .
The idea of the epoxy is to hopefully help the HF travel across the panel probably with the added bonus of a lower LF?
The panel size I am using is too large,but I want to compare with old panels I have lying around.
With foamcore panels you basically have three damping layers glued together.
I did think that the bass panel patent might work quite well with this or the xps panel ?
The plot that you made only shows 50db segments ,which is far too large,try 10db or 20db , the dip you mentioned at 55HZ is about 50db down !
And if you are not using a measurement microphone you could just be measuring your microphone response ?
Did your microphone come with a manufacturers frequency plot ,this could help?
Steve.
Have been reading through some of the 3.6K posts in this thread. Have not read it all so excuse me if this is common or errant advice.
My 2 cents from building snowboards for a couple decades with epoxies. Sandwich construction where the skins reinforce light core is very familiar.
Roller coat the epoxy, if it was tinted with a pigment you would be able to gauge the thickness and evenness of the application. Transfer it from a throwaway surface as opposed to dumping a pool onto your panel and trying to spread it out.
Fumed silica as a lightweight thickener would give a body i.e skin stiffness at a low weight cost. Thicker is stiffer, filled with fumed silica is lighter. You can add any amount, from a little to a massive amount, making the thinnest fluid thicker than peanut butter.
Lastly glass veiling as reinforcement might be worth considering as it is the thinnest form of fiberglass available.
My 2 cents from building snowboards for a couple decades with epoxies. Sandwich construction where the skins reinforce light core is very familiar.
Roller coat the epoxy, if it was tinted with a pigment you would be able to gauge the thickness and evenness of the application. Transfer it from a throwaway surface as opposed to dumping a pool onto your panel and trying to spread it out.
Fumed silica as a lightweight thickener would give a body i.e skin stiffness at a low weight cost. Thicker is stiffer, filled with fumed silica is lighter. You can add any amount, from a little to a massive amount, making the thinnest fluid thicker than peanut butter.
Lastly glass veiling as reinforcement might be worth considering as it is the thinnest form of fiberglass available.
"Fiberglass Surfacing Veils are a lightweight, advanced, non-woven fiberglass veil incorporating 100% E-Glass fibers, approximately 1" in length, bonded together in a random fiber matrix. The non-woven construction allows a resin-rich surface that increases chemical stability and reduces the risk of micro-cracks forming in the composite surface. It has excellent formability and drape and wets out evenly.
Fiberglass Tissue can be used to provide a smooth covering for composite structures or to add stiffness with minimal weight gain and thickness. It is compatible with polyester, vinyl-ester and epoxy resins and is suitable for use in wet layup, vacuum bagging and resin infusion manufacturing."
Fiberglass Tissue can be used to provide a smooth covering for composite structures or to add stiffness with minimal weight gain and thickness. It is compatible with polyester, vinyl-ester and epoxy resins and is suitable for use in wet layup, vacuum bagging and resin infusion manufacturing."
Thanks stratoton.
I've already coated the panel as you can see in the photo's.
The first pic is the coating using the roller.
I could not find my small roller but came across this tape gun, which worked very well.
The coat is much smoother and thinner ,which I hope you can see in the photo, I've left the last couple of inches at the top and bottom as I did not want to over stretch the epoxy.
One thing I did notice is that the epoxy is still very flexible? Very similar to pva ,I was hoping for more rigidity ,something like cascamite but without the cracking.
Have I the wrong epoxy ?
Steve.
I've already coated the panel as you can see in the photo's.
The first pic is the coating using the roller.
I could not find my small roller but came across this tape gun, which worked very well.
The coat is much smoother and thinner ,which I hope you can see in the photo, I've left the last couple of inches at the top and bottom as I did not want to over stretch the epoxy.
One thing I did notice is that the epoxy is still very flexible? Very similar to pva ,I was hoping for more rigidity ,something like cascamite but without the cracking.
Have I the wrong epoxy ?
Steve.
Attachments
I want to order some materials to play with.... specifically carbon fiber and canvas. Really trying to cover full range (let's say from 40Hz up). I have a couple of questions:
- Is there a minimum L/W I need for the panel to physically play 40Hz? And should I stick to the 2:3 L/W ratio or is that no big deal?
- These panels might have to support the weight of 2 exciters (~540g total + wiring)- I can get CF as thin as 0.5mm but is that going to be too thin?
- Does the tension in stretched canvas panels vary much and is that something that can affect the sound (i.e. Fs)
I'm thinking about getting 400x600mm or 16x24" panels if I can find them. Stretched canvas is cheap at Walmart and I can find CF panels at prices I can stomach on Aliexpress. I ride a Chinese carbon bicycle so I think their CF is pretty good.
- Is there a minimum L/W I need for the panel to physically play 40Hz? And should I stick to the 2:3 L/W ratio or is that no big deal?
- These panels might have to support the weight of 2 exciters (~540g total + wiring)- I can get CF as thin as 0.5mm but is that going to be too thin?
- Does the tension in stretched canvas panels vary much and is that something that can affect the sound (i.e. Fs)
I'm thinking about getting 400x600mm or 16x24" panels if I can find them. Stretched canvas is cheap at Walmart and I can find CF panels at prices I can stomach on Aliexpress. I ride a Chinese carbon bicycle so I think their CF is pretty good.
Cheapvega.
As you know , my 30cmx42.5cm canvas panel with 6x4inch 2mm ply goes down to 40hz before roll off ,and that is with only a ten watt exciter, a more powerful exciter might improve on this ?
You could try a slightly larger canvas panel to see if this improves things, but nothing is garenteed and if too large could cause other problems ?
Because the canvas is quite lossy and also damps the panel to some extent,i would place the exciter in the centre to keep the balance for low frequencies.
If two exciters are needed for some reason ? You could use the nxt positions and still keep the balance.
540g seems a little too heavy to me, I would use some sort of brace at the back to support this.
When I tightened my panel the the roll off started higher at about 100hz.
There is no garentee of a better sound or frequency extention with Cf , but it would be interesting to find out ,if not too expensive?
What I would do with a 1mm Cf panel would be totally different to you and I'd be tempted to try the .5mm as well.
These would be small panels.
Steve.
As you know , my 30cmx42.5cm canvas panel with 6x4inch 2mm ply goes down to 40hz before roll off ,and that is with only a ten watt exciter, a more powerful exciter might improve on this ?
You could try a slightly larger canvas panel to see if this improves things, but nothing is garenteed and if too large could cause other problems ?
Because the canvas is quite lossy and also damps the panel to some extent,i would place the exciter in the centre to keep the balance for low frequencies.
If two exciters are needed for some reason ? You could use the nxt positions and still keep the balance.
540g seems a little too heavy to me, I would use some sort of brace at the back to support this.
When I tightened my panel the the roll off started higher at about 100hz.
There is no garentee of a better sound or frequency extention with Cf , but it would be interesting to find out ,if not too expensive?
What I would do with a 1mm Cf panel would be totally different to you and I'd be tempted to try the .5mm as well.
These would be small panels.
Steve.
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I missed this post somehow.
A good DML panel has no problems reaching 20k and above.
Some of the newer exciters do seem to have problems with the HF mainly the 30mm variety,I believe ?
My old 10watt 25mm exciters on a canvas panel will run from 40hz to 20k with excellent sound quality.
I have happily lived with my various DML panels for over 10 years now and have not been in the slightest tempted to go back to ordinary box speakers.
Even planar and electrostatic's sound boxy to me ,and beam heavily.
With DML you don't have to sit with your head clamped in the sweet spot.
I also don't sit there listening for that sweet treble anymore.
DML let's you hear the real instruments, and I have never listened to a real instrument and thought mmm,listen to that sweet treble.
DML has changed my listening experience ,I'm more involved and excited,thrilled even.
It's a shame more people don't know about this.
Steve.
I would agree with Spedge's assessment. My dodgy exciters aside, I can get them to play flat on medium grade (70) EPS all the way to 20khz with suitable EQ (miniDSP HD). The exciters I have been using have a definite treble droop. I'm sure higher density EPS and a better balanced exciter will be even better.
By rolling off below 300hz, the DML is spared the heavy bass juice and the panel can operate very effectively as a mid to treble with no crossovers in the midrange or treble regions. I fill in the bass with a winged OB 15in unit. I use asymmetric crossover points (LR24) and get a smooth bass to mid transition.
Having experienced the OB bass and DML mid/top combination, I have precisely zero desire to go back to boxed speakers of any description. I don't like the way they load the room, and their 'point and squirt' approach is unnatural to my ears.
The next phase of the project is to (a) refine the OB bass unit (asymmetrical wings, slightly taller, possible treatment to prevent front baffle reflections) and (b) experiment with different DML mounting systems (free floating with minimal attachment to a frame, perhaps attaching to a frame as per the old DMLBES method, etc. - I'm expecting the former to sound better).
At the last hifi show I attended before the plague struck, the two best systems I heard were multi-driver OB types.
lordtarquin.
Point and squirt 😂 I like it
I can't remember seeing many OBs at UK audio shows ? But that could be my poor memory .
My friend has OBs and was in the middle of experimenting with DML but he has had to put everything on hold.
I met him on a park bench a couple of days ago (first time for nearly two years)and he mentioned that he was trying out a very thin corrugated cardboard he had come across .
I was hoping to go to the September audio show ,but my friends don't seem keen at the moment,and I have to agree.
Steve.
Point and squirt 😂 I like it
I can't remember seeing many OBs at UK audio shows ? But that could be my poor memory .
My friend has OBs and was in the middle of experimenting with DML but he has had to put everything on hold.
I met him on a park bench a couple of days ago (first time for nearly two years)and he mentioned that he was trying out a very thin corrugated cardboard he had come across .
I was hoping to go to the September audio show ,but my friends don't seem keen at the moment,and I have to agree.
Steve.
HiFI Shows
Steve
I know what you mean re. shows. I would like to go again, but now wouldn't be wise. The Kegworth show is a good one - lots of user systems and not too far from me. Feb/Mar 2022 is probably the next one, but the plague is bound to get in the way. Writtlebury 2019 was the last one I went to. PureAudioProject speakers spring to mind.
Simon
Steve
I know what you mean re. shows. I would like to go again, but now wouldn't be wise. The Kegworth show is a good one - lots of user systems and not too far from me. Feb/Mar 2022 is probably the next one, but the plague is bound to get in the way. Writtlebury 2019 was the last one I went to. PureAudioProject speakers spring to mind.
Simon
PVC foam panel
Further to the discussion on PVC foam, I've found that the PalLight product is sold in an Australian Hardware Store (Bunnings) in 1200x900x3 mm. Comes in black and white, with white somewhat cheaper.
I examined it and decided not to bother. Its quite heavy (seems to be about the same weight as a 1200x800x4 sheet of marine plywood I helf in the other hand. In addition its very dead, quite bendy, plasticky and soft.
Further to the discussion on PVC foam, I've found that the PalLight product is sold in an Australian Hardware Store (Bunnings) in 1200x900x3 mm. Comes in black and white, with white somewhat cheaper.
I examined it and decided not to bother. Its quite heavy (seems to be about the same weight as a 1200x800x4 sheet of marine plywood I helf in the other hand. In addition its very dead, quite bendy, plasticky and soft.
Membrane panels
With Steve and others waxing lyrical about the sound from art canvas panels, I started read up a bit on how the physics compares with bending waves.
Anyhow, it just occurred to me that it's strange that membranes driven by exciters had not been much investigated until recently (or am I wrong about that?). At least, I've not seen much mention of them before the mention of canvas in this forum. With the precursor of electrostatics it would seem an obvious thing to have tried.
Can anyone give a summary of the history, what other membranes have been tried, who started the art canvas thing etc?
With Steve and others waxing lyrical about the sound from art canvas panels, I started read up a bit on how the physics compares with bending waves.
Anyhow, it just occurred to me that it's strange that membranes driven by exciters had not been much investigated until recently (or am I wrong about that?). At least, I've not seen much mention of them before the mention of canvas in this forum. With the precursor of electrostatics it would seem an obvious thing to have tried.
Can anyone give a summary of the history, what other membranes have been tried, who started the art canvas thing etc?
Hi Steve,
Do we have a reference design/build log/info to refer for a DML speaker ( and preferred panel material like using canvas/ plywood/ foam / ceiling tiles etc), to be used with or without subwoofer.
Generally from the messages in the forum, it seems to be still work in progress or experimental phase.
From the given exciters given in below link which one we may prefer:
Bass Shaker / Exiter
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I am at this very moment listening to the 5mm xps panel coated in epoxy.
Even though it was a bit of a bodge up ,I have to say I am enjoying the music so far.
I had a quick look to see the frequency response and there are a few issues that need to be sorted ,but as yet I have not heard any nasty sounds.
I'll give a full report when the panel has stopped hardening and I've got more of an idea what needs to be done.
But so far I am impressed with the low level detail and clarity.
Steve
Even though it was a bit of a bodge up ,I have to say I am enjoying the music so far.
I had a quick look to see the frequency response and there are a few issues that need to be sorted ,but as yet I have not heard any nasty sounds.
I'll give a full report when the panel has stopped hardening and I've got more of an idea what needs to be done.
But so far I am impressed with the low level detail and clarity.
Steve
Canvas Panels - edge constraints
Steve
It occurs to me that since the stretched canvas panels are secured to a frame, we may be seeing some of the edge constraint/clamping ideas as explored in some of the recently linked articles. I've noted your experiments with some ply attached to the reverse. I'm not sure whether the exciter should go centrally or in the usual 3/7 + 4/9 position though.
I was also speculating as to whether some 10mm UHD EPS may do in lieu of the plywood as attached to the canvas. I'm going to have a few sheets to play with soon and it may be worth my trying a pair of A3 (or 40x30cm) stretched canvas panels as well.
Autumn and winter are approaching, and it's the right time of year to be experimenting for me in preparation for musical accompaniment to my mammoth 35mm slide digitising exercise.
Steve
It occurs to me that since the stretched canvas panels are secured to a frame, we may be seeing some of the edge constraint/clamping ideas as explored in some of the recently linked articles. I've noted your experiments with some ply attached to the reverse. I'm not sure whether the exciter should go centrally or in the usual 3/7 + 4/9 position though.
I was also speculating as to whether some 10mm UHD EPS may do in lieu of the plywood as attached to the canvas. I'm going to have a few sheets to play with soon and it may be worth my trying a pair of A3 (or 40x30cm) stretched canvas panels as well.
Autumn and winter are approaching, and it's the right time of year to be experimenting for me in preparation for musical accompaniment to my mammoth 35mm slide digitising exercise.