habeeb,
The efficiency of PS foam is indeed impressive, but I've never been able to get rid of the echo. Others have, or maybe it doesn't bother them, or maybe they don't hear it. I tried the PVA coating to no avail. I doubt curving it will make a difference either but don't let that stop you from trying it!
For me, plywood is the better solution. With 2 panels and 2 exciters per panel you can get pretty decent volume, especially if you combine it with a sub for the low end. As for birch, it's a bit on the dense side as wood goes, so if you can find something a little lower density you should get a little more efficiency (but still nothing like PS foam). If you can find "revply" or "sureply" (which is underlayment plywood, roughly 0.2" thick), it is lower density and plays a bit louder.
For getting more full range sound, you should try mounting your plywood panels to a frame that surrounds the perimeter, with a soft foam between the frame and panel, like shown here. You may like it better. You can put the foam around the entire perimeter if you want, or leave the corners free like I did here.
The efficiency of PS foam is indeed impressive, but I've never been able to get rid of the echo. Others have, or maybe it doesn't bother them, or maybe they don't hear it. I tried the PVA coating to no avail. I doubt curving it will make a difference either but don't let that stop you from trying it!
For me, plywood is the better solution. With 2 panels and 2 exciters per panel you can get pretty decent volume, especially if you combine it with a sub for the low end. As for birch, it's a bit on the dense side as wood goes, so if you can find something a little lower density you should get a little more efficiency (but still nothing like PS foam). If you can find "revply" or "sureply" (which is underlayment plywood, roughly 0.2" thick), it is lower density and plays a bit louder.
For getting more full range sound, you should try mounting your plywood panels to a frame that surrounds the perimeter, with a soft foam between the frame and panel, like shown here. You may like it better. You can put the foam around the entire perimeter if you want, or leave the corners free like I did here.
Jaxboy.
My recordings only go up to 10k becsause of the microphone response and drops like a stone after that.
So if they sound OK I wouldn't worry about a tweeter too much.
If you have an equaliser
You could play a track full range and then play the same track again but with the frequency restricted to 8k and see if you can tell the difference .
If you can hear a difference then increase the frequency response until you can't hear a difference.
This will at least give you an idea of what you can and can't hear.
Steve.
My recordings only go up to 10k becsause of the microphone response and drops like a stone after that.
So if they sound OK I wouldn't worry about a tweeter too much.
If you have an equaliser
You could play a track full range and then play the same track again but with the frequency restricted to 8k and see if you can tell the difference .
If you can hear a difference then increase the frequency response until you can't hear a difference.
This will at least give you an idea of what you can and can't hear.
Steve.
Sanded down the front of one xps panel to a nice curve, cutting the edges down from 1" to about 1/3", and yep it didn't help at all. If anything it may have made it worse. At least if I ever get into model planes I'll have a nice wing to start with?
The plywood is definitely impressive though and with a quick and dirty FR test it was surprisingly accurate from around 150hz to around 11khz, but while the dropoff after was noticeable just by ear the microphone I was using definitely didn't help. There's still some distortion but not so much to make it unpleasant and I would buy the idea that it'll reduce over time. Still planning to try some other kinds of wood but for now I'll try to work out some mounting.
For those of you that run DMLs alongside other speakers, do you find that it helps to run separate amplification/potentially different eq to keep everything balanced?
The plywood is definitely impressive though and with a quick and dirty FR test it was surprisingly accurate from around 150hz to around 11khz, but while the dropoff after was noticeable just by ear the microphone I was using definitely didn't help. There's still some distortion but not so much to make it unpleasant and I would buy the idea that it'll reduce over time. Still planning to try some other kinds of wood but for now I'll try to work out some mounting.
For those of you that run DMLs alongside other speakers, do you find that it helps to run separate amplification/potentially different eq to keep everything balanced?
For now I am using Audirvana with some software EQ as plugins. I am trying to 'customise' my different headphones and will profile the DMLs once they are on line.
Attachments
habeeb.
im a little confused ,you say you can hear echo ,do you mean the artificial echo machine is too prominent ,or something else.
these panels are heavily damped (for me over damped)with pva and vinyl so have not a lot of self noise.
ive done another recording with the same track but a little closer to the panels to reduce the room echo ,does this help in any way ?
steve.
im a little confused ,you say you can hear echo ,do you mean the artificial echo machine is too prominent ,or something else.
these panels are heavily damped (for me over damped)with pva and vinyl so have not a lot of self noise.
ive done another recording with the same track but a little closer to the panels to reduce the room echo ,does this help in any way ?
steve.
I have a feeling this is to do with ears, hearing an echo when music (sound) is loud.
Mpte.
I havery seen them but have no idea how they will sound.
Those excites look quite heavy and have what looks like a fairly robust spider ,so wold think they might do well on something like ply or one of the more expensive type of honey cone materials?
Look forward to your opinion of them.
Steve.
I havery seen them but have no idea how they will sound.
Those excites look quite heavy and have what looks like a fairly robust spider ,so wold think they might do well on something like ply or one of the more expensive type of honey cone materials?
Look forward to your opinion of them.
Steve.
Sorry for the imprecise language. By "echo" with the xps I meant the hollowness in the produced sound. I had tried adding some damping to no effect and I thought that I heard the same hollowness in your recordings. I did buy a few panels from home depot so I was able to test that each had more or less the same hollow-sounding quality seemingly regardless of the surface treatment. To me it sounded like hearing music through a thin wall and happened at both low and high volumes as well as with single and multi exciter set-ups. I was mostly surprised not because some materials might sound better than others but because there were several builds which I followed as closely as possible with the exact brand/size of xps which the original builders alleged sounded great but to me just sounded horribly muddy and imprecise.
Habeeb.
That's ok , now I understand.
You hit the nail right on the head yourself.
1inch thick xps IS a wall,it has high sound damping properties.
This was mentioned many years back on NXT Rubbish.
One of the members mentioned something like, everything seemed to be going on behind the panel in the next room !
This was one of the reasons I carved a cone shape in front of the exciter area,this gives a more intimate presentation,which is the opposite to a lot of suggestions to thin the panel towards the edges ,but helps bring the sound around to the front of the panel.
I also purchased the 5mm xps to reduce this problem too,but also carved the cone in the centre to help the sound penetrate the panel,and have only just now, added a make shift dome.
I also believe xps has a problem with hf being blocked by it's sound deadening properties?
Does turning the panel around cure the problem ?
Thin card panels with a dome in the centre also reduce this problem I have found, which is basically a flat paper cone
Steve.
That's ok , now I understand.
You hit the nail right on the head yourself.
1inch thick xps IS a wall,it has high sound damping properties.
This was mentioned many years back on NXT Rubbish.
One of the members mentioned something like, everything seemed to be going on behind the panel in the next room !
This was one of the reasons I carved a cone shape in front of the exciter area,this gives a more intimate presentation,which is the opposite to a lot of suggestions to thin the panel towards the edges ,but helps bring the sound around to the front of the panel.
I also purchased the 5mm xps to reduce this problem too,but also carved the cone in the centre to help the sound penetrate the panel,and have only just now, added a make shift dome.
I also believe xps has a problem with hf being blocked by it's sound deadening properties?
Does turning the panel around cure the problem ?
Thin card panels with a dome in the centre also reduce this problem I have found, which is basically a flat paper cone
Steve.
For those who might be interested.
I've taken some pictures of the response of the panels with integrated dome tweeters .
This was at about 12inches, before the room affects the performance and drops off , I accidentally got my metal tape measure stuck to the tweeter at one point,so a little damage was caused
If you compare the response with the panel without domes on post 3174 you can see the response drops rapidly above an 8k peek.
With the dome there is still a peek or resonance ,but with a very small ball of blu tack placed on the dome the resonance has gone(a little too much) but the hf has been extended to 15k before rolling off.
And this is with my thrown together affair.
If done properly 20k is easily reached,if wanted of course.
The panel still sounds over damped but I would think it would sound the same as putting a tweeter on a heavily doped mid and bass unit,which was done in the past ,and probably still is ?
a Very smooth sound not my favourite .
Steve.
I've taken some pictures of the response of the panels with integrated dome tweeters .
This was at about 12inches, before the room affects the performance and drops off , I accidentally got my metal tape measure stuck to the tweeter at one point,so a little damage was caused
If you compare the response with the panel without domes on post 3174 you can see the response drops rapidly above an 8k peek.
With the dome there is still a peek or resonance ,but with a very small ball of blu tack placed on the dome the resonance has gone(a little too much) but the hf has been extended to 15k before rolling off.
And this is with my thrown together affair.
If done properly 20k is easily reached,if wanted of course.
The panel still sounds over damped but I would think it would sound the same as putting a tweeter on a heavily doped mid and bass unit,which was done in the past ,and probably still is ?
a Very smooth sound
not my favourite .Steve.
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Im definitly going to try xps and maybe ply.
Ihave an idea for a sheet of aluminum with magic eraser foam glued to the back for damping. Also its possible that would allow me to mount that to a wall if i want to .d I was thinking foam blocks glued to the whole back or just the perimeter.
What thickness of aluminum sheet would be good for an 18x24" panel expiriment?
Ihave an idea for a sheet of aluminum with magic eraser foam glued to the back for damping. Also its possible that would allow me to mount that to a wall if i want to .d I was thinking foam blocks glued to the whole back or just the perimeter.
What thickness of aluminum sheet would be good for an 18x24" panel expiriment?
Mpte.
OK, but it would be very helpful if you could let us know if the frequency response from the opposite side of the exciter is improved in anyway?
Hopefully having a bolt on both sides of the panel would be similar to having an exciter on both sides?
I do think this could be ideal for my ply panels ,if you find it worth it?
Also for aluminium, I only used very thin sheet aluminium and glued them together with spray mount ,this gave internal damping and stopped ringing .
I use this same method with my card panels except I use pva glue instead.
I still have some sheets down the garden somewhere , if you would like me to measure them ,let me know.
Steve.
OK, but it would be very helpful if you could let us know if the frequency response from the opposite side of the exciter is improved in anyway?
Hopefully having a bolt on both sides of the panel would be similar to having an exciter on both sides?
I do think this could be ideal for my ply panels ,if you find it worth it?
Also for aluminium, I only used very thin sheet aluminium and glued them together with spray mount ,this gave internal damping and stopped ringing .
I use this same method with my card panels except I use pva glue instead.
I still have some sheets down the garden somewhere , if you would like me to measure them ,let me know.
Steve.