I am happy for you to see progress like this Wes...
And they look freaking good!!!
BTW I see a lot of chatter on the screw countersinks....tell the machine guy to run it slower and higher feed, so the tool bites into the material.that way no chatter.
I had the picture centered on the screen and moved the mouse wheel fast up and down...boy what an optical illusion
you see the same driver all the time but the surroundings change hehehe
Never mind my eyesight. Those look really nice, must have high WAF too...
Danny
And they look freaking good!!!
BTW I see a lot of chatter on the screw countersinks....tell the machine guy to run it slower and higher feed, so the tool bites into the material.that way no chatter.
I had the picture centered on the screen and moved the mouse wheel fast up and down...boy what an optical illusion
you see the same driver all the time but the surroundings change heheheNever mind my eyesight. Those look really nice, must have high WAF too...
Danny
I'll tell myself next time . You do realize these were made with a drill in a stand, a jig-saw and a router in a table?
The drill stand doesn't have that good of a stop on it, I tried different speeds and couldn't get the better results. I'll work on a better stop on the stand. I don't mind though as it is not a visual feature like the driver holes that came out pretty good for a simple router job.
. You do realize these were made with a drill in a stand, a jig-saw and a router in a table?The drill stand doesn't have that good of a stop on it, I tried different speeds and couldn't get the better results. I'll work on a better stop on the stand. I don't mind though as it is not a visual feature like the driver holes that came out pretty good for a simple router job.
I have a dilemma about soundproofing my enclosure. I already have the materials to dampen the back wave. But would I benefit from using a CLD on the walls of the enclosure? Birch Plywood has a higher resonance frequency than MDF for example. Putting a layer of glass fiber weave plus epoxy will put that even higher. A CLD on the wall would bring that back down, but would I benefit from it?
I'd go for about 25% coverage and put the CLD tiles (the automotive ones made from butyl with a thin layer of aluminum on top) in the middle of unsupported walls/braces.
So what do you guys think? You can get the tiles in 2mm and 4mm thickness.
Yay or nay?
I'd go for about 25% coverage and put the CLD tiles (the automotive ones made from butyl with a thin layer of aluminum on top) in the middle of unsupported walls/braces.
So what do you guys think? You can get the tiles in 2mm and 4mm thickness.
Yay or nay?
Haldor: Constrained Layer Damping. I have used it extensively in my car.
Danny, Dynamat is basically the same as I plan to use. I've had good results with Silent Coat. It's a bit more affordable than the Dynamat brand. It does very well in various tests I've seen on automotive forums.
So it's a Yay from you Danny?
Danny, Dynamat is basically the same as I plan to use. I've had good results with Silent Coat. It's a bit more affordable than the Dynamat brand. It does very well in various tests I've seen on automotive forums.
So it's a Yay from you Danny?
True, I don't know the answer here...
Stiff materials move the resonant frequency higher... CLD tiles would lower the resonant frequency (as adding mass would do).
But would I want to do that? I have a stiff, relatively light construction here. Moving resonant frequency up. Should I rely on the inside damping (the fluffy kind) to eat up the rest? So nothing gets exited? The problem is it is a full range speaker and I got to combat all of those in one space.
Stiff materials move the resonant frequency higher... CLD tiles would lower the resonant frequency (as adding mass would do).
But would I want to do that? I have a stiff, relatively light construction here. Moving resonant frequency up. Should I rely on the inside damping (the fluffy kind) to eat up the rest? So nothing gets exited? The problem is it is a full range speaker and I got to combat all of those in one space.
Hi Wesayso.
Fantastic work.
The internal structure of my speakers is not a million miles away from yours. I have used internal baffles to break up the rear waves, the principal is similar to a cars muffler or a guns silencer. By far the best sound I have achieved is with no additional damping material. The addition of any damping material gives a woolly sound with notable muted dynamics. Of course have fun experimenting to find the best solution.
Still the best speaker thread on the net.
Niffy
Fantastic work.
The internal structure of my speakers is not a million miles away from yours. I have used internal baffles to break up the rear waves, the principal is similar to a cars muffler or a guns silencer. By far the best sound I have achieved is with no additional damping material. The addition of any damping material gives a woolly sound with notable muted dynamics. Of course have fun experimenting to find the best solution.
Still the best speaker thread on the net.
Niffy
The internal shape has already a great deal of diffraction of rear waves, but we do want to dampen those waves further. The best suggestion I can give would be BlueLogic Ultratouch recycled denim insulation. 3.5" thick has an absorption factor of greater than 1 above 100Hz. This is neccessary to kill off surface waves on the cone transmitting back through the cone and adjacent drivers cones. These delayed retransmitted waves produce various distortions that negatively affect image by time smearing the transient and phase distortion that impacts response. Over dampening the bass makes it less dynamic and slow sounding but we aren't dealing with that in these line arrays.
The auto dampening sheets AL faced would help somewhat but would do this secondary. Internal baffles are a good idea but must be modeled for proper placement.
I have ofter heard people claim that dampening makes a speaker "less dymamic", this is a misnomer. The artificially overdynamic undampened is really nothing more than these colorations adding a false sense of dynamics.
The auto dampening sheets AL faced would help somewhat but would do this secondary. Internal baffles are a good idea but must be modeled for proper placement.
I have ofter heard people claim that dampening makes a speaker "less dymamic", this is a misnomer. The artificially overdynamic undampened is really nothing more than these colorations adding a false sense of dynamics.
I have to agree here with Greebster... What I want damping wise in the enclosure is to have just enough to absorb what is possible of the scattered back wave. Not sure yet if I will measure that with my test box and an impedance measurement or a frequency measurement. Or a combination of both.
But these arrays will play quite a broad range. I couldn't find the Bluelogic Ultratouch demim here in my side of the world. Fibreglass insulation seems to work best with broad frequency ranges as far as I can tell. The more exotic Angel Hais seems to work wonders with very little needed in midrange frequencies but not sure about the lower range.
Another idea on panel damping that surfaces a lot on here is braces that are coupled with an elastic material to the walls. Not a rigid mount but one of the permanent elastic materials.
I'm not sure I need to add any panel damping though. But I also don't want to remorse the fact that I didn't think about it.
But these arrays will play quite a broad range. I couldn't find the Bluelogic Ultratouch demim here in my side of the world. Fibreglass insulation seems to work best with broad frequency ranges as far as I can tell. The more exotic Angel Hais seems to work wonders with very little needed in midrange frequencies but not sure about the lower range.
Another idea on panel damping that surfaces a lot on here is braces that are coupled with an elastic material to the walls. Not a rigid mount but one of the permanent elastic materials.
I'm not sure I need to add any panel damping though. But I also don't want to remorse the fact that I didn't think about it.
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After thinking it trough and reading some old Magico articles(*) that used Birch Ply I think adding CLD tiles would be somewhat counter productive. With the stiff, well braced cabinet using a stiff material (Birch Ply) you push the resonances up in the frequency band. CLD, as said, would lower that again (counter productive?). Birch Ply is known for low energy storage.
Adding extra weight and not stiffness would add storage by lowering the resonance.
Does that reasoning sounds valid?
You either move the resonance up or down. If you move it down (like BBC dampened thin wall cabinets) you hear the resonance less due to our hearing at lower frequencies. It moves out of the mid frequencies that way. If you move it up in frequency it would make more sense not to excite the resonance by taking care in how you reduce the resonance from the baffle to the enclosure (that part I did look at already with my chosen path) and internal damping material so the enclosure does not get exited as much because you can damp a higher frequency much better than a lower one with longer wave lengths.
If I'm not satisfied I can look into CLD etc...
Question remains if I glue the real wool felt to the walls and if I do with what glue...
(*) = I only found out about the resemblance of my speakers to the Mini's much later than I made the plans for my own speakers. Someone pointed them out to me. I had not noticed them before, probably because they were already being replaced with the Q1's. I had selected aluminum baffles to have something sturdy to mount my drivers to. But there's no harm in looking at what they did back then to learn and get inspired, is there? I loved to see and read about those Mini's in particular and have saved many pictures of construction etc. in my project folder.
P.S. I can notice a big difference in frequency where I have the baffle (the one without drivers at this moment) screwed to the enclosure and where there are no bolts yet. It gets much higher in frequency by tightening the bolts. So I guess I need to stay true to that philosophy...
Adding extra weight and not stiffness would add storage by lowering the resonance.
Does that reasoning sounds valid?
You either move the resonance up or down. If you move it down (like BBC dampened thin wall cabinets) you hear the resonance less due to our hearing at lower frequencies. It moves out of the mid frequencies that way. If you move it up in frequency it would make more sense not to excite the resonance by taking care in how you reduce the resonance from the baffle to the enclosure (that part I did look at already with my chosen path) and internal damping material so the enclosure does not get exited as much because you can damp a higher frequency much better than a lower one with longer wave lengths.
If I'm not satisfied I can look into CLD etc...
Question remains if I glue the real wool felt to the walls and if I do with what glue...
(*) = I only found out about the resemblance of my speakers to the Mini's much later than I made the plans for my own speakers. Someone pointed them out to me. I had not noticed them before, probably because they were already being replaced with the Q1's. I had selected aluminum baffles to have something sturdy to mount my drivers to. But there's no harm in looking at what they did back then to learn and get inspired, is there? I loved to see and read about those Mini's in particular and have saved many pictures of construction etc. in my project folder.
P.S. I can notice a big difference in frequency where I have the baffle (the one without drivers at this moment) screwed to the enclosure and where there are no bolts yet. It gets much higher in frequency by tightening the bolts. So I guess I need to stay true to that philosophy...
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CLD would certainly help but in your case how to apply internally poses a serious problem due to the alternating wave pattern. Appied uniformly would require being sprayed on with a LPHV spray gun. Think more along the lines of sprayed on truck bed liner. Then a layer of glass mat over that.
Now you might have already thought OMG Noooo!
The alternative is done external, which leaves us with another, OMG Noooo!
CLD Bracing is a good thought, to incorporate would require many. But just how to while minimizing part count is difficult to answer. Perhaps a single three point brace for every two to three drivers. The other question is where to brace and would we also want to dampen the motor at the same time killing two birds with one stone? It's questions like these that make my head hurt. Mainly because I would test, mockup, test some more, trying several materials, mockup, test more, pull hair out, retest...
Suggest finding some thick plush microfiber towels cut into strips and held in place with velcro has worked quite well in my cld sonotube mltl. This can be formed (folded) into a vertical wave like curtains hang. For your line length two or three towels should be plenty. I buy these at Target, automotive dept. They have a thinner plush blue towel and a thicker plush bronze colored towels. Suggest taking some time to do an ear test wherever you find similar.
Now you might have already thought OMG Noooo!
The alternative is done external, which leaves us with another, OMG Noooo!
CLD Bracing is a good thought, to incorporate would require many. But just how to while minimizing part count is difficult to answer. Perhaps a single three point brace for every two to three drivers. The other question is where to brace and would we also want to dampen the motor at the same time killing two birds with one stone? It's questions like these that make my head hurt. Mainly because I would test, mockup, test some more, trying several materials, mockup, test more, pull hair out, retest...
Suggest finding some thick plush microfiber towels cut into strips and held in place with velcro has worked quite well in my cld sonotube mltl. This can be formed (folded) into a vertical wave like curtains hang. For your line length two or three towels should be plenty. I buy these at Target, automotive dept. They have a thinner plush blue towel and a thicker plush bronze colored towels. Suggest taking some time to do an ear test wherever you find similar.
I think if you apply CLD to a structure that already has high resonance freq, it will damp those frequencies rather than to lower the resonance frequency. It depends on the relative mass and stiffness that the CLD has. But given that the flexible contact between the substrate and the top layer on the CLD, the stiffness of the CLD doesn't matter.
If you de-compose this into a 1-d time dependent lumped element dynamics model: the basic spring-mass-damper system of the birch ply is modified by soft spring contact between the main mass and the CLD top plate mass with a damper attached in between the two masses. The solution of this two body (mass) problem is dominated with a pole located at the original frequency of the birch structure (massive) and a small much lower amplitude pole at the resonance freq of the CLD top sheet. The damping and spring in between the masses now serves as an energy sink in addition to the self damping of the materials.
For how massive and stiff the birch ply enclosure is, I really don't think you need to worry about resonances. My work with the TC9FD in very resonant structures made from foam core has shown that the structure can be prone to resonances, but these are very light relative to the birch. I have found that CLD in foam core can cut HD by up to 15 to 20dB. Absorbing the back wave has to do more with using a good amount of open cell foam combined with felt, denim padding, polyfill, etc. I find a layer of 1in thick open cell foam on all internal walls does a very good job.
If you de-compose this into a 1-d time dependent lumped element dynamics model: the basic spring-mass-damper system of the birch ply is modified by soft spring contact between the main mass and the CLD top plate mass with a damper attached in between the two masses. The solution of this two body (mass) problem is dominated with a pole located at the original frequency of the birch structure (massive) and a small much lower amplitude pole at the resonance freq of the CLD top sheet. The damping and spring in between the masses now serves as an energy sink in addition to the self damping of the materials.
For how massive and stiff the birch ply enclosure is, I really don't think you need to worry about resonances. My work with the TC9FD in very resonant structures made from foam core has shown that the structure can be prone to resonances, but these are very light relative to the birch. I have found that CLD in foam core can cut HD by up to 15 to 20dB. Absorbing the back wave has to do more with using a good amount of open cell foam combined with felt, denim padding, polyfill, etc. I find a layer of 1in thick open cell foam on all internal walls does a very good job.
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Just found this link again, had seen it before but almost forgot about it:
zelfbouwaudio.nl
These results (berken= Birch multiply) seem to indicate that what you say is true.
If you look at the result of strengthened birch ply with glass wool the results are very good. But adding CLD damping could improve it even further, lowering the amplitude of the resonances that are left.
The CLD should help in lowering the remaining resonances of a stiff birch ply structure.
I'll think about what route to follow. The posts up to now seem to indicate 2 Yay, 2 Nay and one not necessary
The testing done on DIY Mobile Audio seems to confirm a more rapid decay in time of resonances. Although this is used on a metal skin it is obvious there is a reduction of resonances especially the after-ringing at all frequencies:
http://www.diymobileaudio.com/forum/member-reviews-product-comparisons/146403-sound-deadening-cld-testing-11.html
Lots of CLD materials were tested, very interesting read.
zelfbouwaudio.nl
These results (berken= Birch multiply) seem to indicate that what you say is true.
If you look at the result of strengthened birch ply with glass wool the results are very good. But adding CLD damping could improve it even further, lowering the amplitude of the resonances that are left.
The CLD should help in lowering the remaining resonances of a stiff birch ply structure.
I'll think about what route to follow. The posts up to now seem to indicate 2 Yay, 2 Nay and one not necessary
The testing done on DIY Mobile Audio seems to confirm a more rapid decay in time of resonances. Although this is used on a metal skin it is obvious there is a reduction of resonances especially the after-ringing at all frequencies:
http://www.diymobileaudio.com/forum/member-reviews-product-comparisons/146403-sound-deadening-cld-testing-11.html
Lots of CLD materials were tested, very interesting read.
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Thanks for that link. I don't read Dutch but am guessing that this is 18mm birch plus 11mm viscous damper plus 18mm MDF plus fiberglass?
Very impressive reduction.
Very impressive reduction.
An externally hosted image should be here but it was not working when we last tested it.
