Are there any benefits in gluing 1/2" MDF sheet and 1/2" plywood together to get 1" sheet material to use in constructing some floor standing speakers ?
I'm wondering if there's any sonic benefits of doing this v's just buying some 1" plywood ?
I'm wondering if there's any sonic benefits of doing this v's just buying some 1" plywood ?
I'd just go with plywood. MDF is heavy and bendy, which means the resonances will be pulled down in frequency, which in turn means they're more likely to be excited.
Plywood (especially the good stuff - PM me for a timber merchant that stocks birch ply and can cut to specs) is light and strong, which pushes the resonances up in frequency - more difficult to excite, and therefore less likely to be audible.
Chris
Plywood (especially the good stuff - PM me for a timber merchant that stocks birch ply and can cut to specs) is light and strong, which pushes the resonances up in frequency - more difficult to excite, and therefore less likely to be audible.
Chris
can you ensure a void free bond between the two? and glue messes from excess glue ooozing out can be a PITA?
if it's a touring box the weight is a bad idea...a permanent install that could be different...
why 1" plywood? when the virtues of 3/4" void free baltic birch's virtues have been talk about at length around here...ooops just noticed chris post!
if it's a touring box the weight is a bad idea...a permanent install that could be different...
why 1" plywood? when the virtues of 3/4" void free baltic birch's virtues have been talk about at length around here...ooops just noticed chris post!
I would make the box from ply and the bracing from MDF and fix the bracing with glue that doesn't set rock hard.
Technically speaking I think that results in a lossy (which is good) impedance mismatch.
Technically speaking I think that results in a lossy (which is good) impedance mismatch.
That much lead sheet would be expensive ! 😱🙂
I think i'm just going to go with a good quality plywood, rather than my twin layer idea.
There are unlikely to be any significant benefits if the glue is strong. Depending on the details of what you are doing 3/4" birch plywood may well be preferable.
If the cabinet handles midrange frequencies rather than just the low frequencies then the drivers banging about on the baffle will be driving resonances in the cabinet some of which are likely to be audible if not damped. A millimetre or two of effective damping material between the two sheets could do this in a constrained layer damping arrangement. Note that only one sheet will carry load so there will be a drop in cabinet stiffness compared to both sheets carrying load. Optimum performance will occur when both sheets are same thickness but this is a bit of a waste of material and so the constraining sheet is often thinner. Thinner and stiffer can shift things back towards optimum.
The speakers are going to be three way active, the bass driver is going to be a 10" Visaton TIW 250 XS, Satori MR13P-4 and the tweeter is undecided at the moment.
I was going to hard glue the layers with the hope of using or combining the best properties of both materials in one sheet but i was mistaken judging responses on here. I'd heard that some commercial speakers were doing some thing similar ?
I was going to hard glue the layers with the hope of using or combining the best properties of both materials in one sheet but i was mistaken judging responses on here. I'd heard that some commercial speakers were doing some thing similar ?
what's the old saying...only believe half of what you hear and none of what you read in promotional literature...
your idea/thinking has been the subject of many a thread...constrained layer damping for one...in most cases it becomes, " is the increased cost and complexity justified in terms of measurable performance gains?"
your idea/thinking has been the subject of many a thread...constrained layer damping for one...in most cases it becomes, " is the increased cost and complexity justified in terms of measurable performance gains?"
The driver that deserves the hard treatment is the W
You don't want any ghost sound ( vibrating panels, wood that let pass the sound )
The mid driver is another beast
The tweeter...tweets!
You don't want any ghost sound ( vibrating panels, wood that let pass the sound )
The mid driver is another beast
The tweeter...tweets!
I avoid MDF (althou it makes good vent spacers, and bases).
Use of your laminate will likely make it easier to finish (MDF on the outside), and it will have the benefit of 2 distinctly different layers, but i suspect that your heavy 1” thick material will not give as gooda sonic presentation as well braced quality ply.
I have yet to design a speaker that needs more than 18mm quality plywood. Using bracing can be more effective than making the box walls thicker. Most can be made using 15mm (i did an experiemnt using 15mm BB to illustrate how effective mounting the woofers push-push can be at significantly reducing the need of the box to be stout. I would suggest using 2 x 8” push-push instead of 1 10”. Or choosing 2x10” that work in a similar size box to your existing choice.
From my perspective, 2 x 8” in a 15mm thick (properly braced) box will outperform 1 10” in your 1” compositr material (even if well-braced).
How big a box are you building?
dave
Use of your laminate will likely make it easier to finish (MDF on the outside), and it will have the benefit of 2 distinctly different layers, but i suspect that your heavy 1” thick material will not give as gooda sonic presentation as well braced quality ply.
I have yet to design a speaker that needs more than 18mm quality plywood. Using bracing can be more effective than making the box walls thicker. Most can be made using 15mm (i did an experiemnt using 15mm BB to illustrate how effective mounting the woofers push-push can be at significantly reducing the need of the box to be stout. I would suggest using 2 x 8” push-push instead of 1 10”. Or choosing 2x10” that work in a similar size box to your existing choice.
From my perspective, 2 x 8” in a 15mm thick (properly braced) box will outperform 1 10” in your 1” compositr material (even if well-braced).
How big a box are you building?
dave
I'm going to stick with some quality 18mm ply that was recommended by Chris earlier on this thread.
I'm going to run it sealed and the design isn't finalised yet but at the moment it's W340mm x D225mm x H1025mm. It will be braced.
I'm going to run it sealed and the design isn't finalised yet but at the moment it's W340mm x D225mm x H1025mm. It will be braced.
Braces should always be oriented such that subpanels have a higher aspect ratio than the panel being braced. Optimally a brace connects (at least) 4 of the walls together.
dave
dave
The brace below the woofer is going to connect 5 panels.
Not sure about a brace above the woofer as the mid enclosure is going to tie the front and rear panels together, it won't be too much trouble to tie in the side/top panels with a bit of extra wood.
Not sure about a brace above the woofer as the mid enclosure is going to tie the front and rear panels together, it won't be too much trouble to tie in the side/top panels with a bit of extra wood.
Damping? A soft spring to isolate the driver from the baffle can work well if the reaction force from the moving cone on the body of the driver is sufficiently small not to move the body significantly. This follows from the ratio of the masses. This tends to mean yes for a tweeter, perhaps for a midrange but likely no for woofers which tend to benefit from the added mass of the cabinet.
Damping is needed to get rid of energy when it is in the cabinet in significant quantities at resonant frequencies. Away from resonances the small damping force will be negligible compared to the larger ones associated with mass and stiffness. It is only at resonance where the two larger forces cancel each other that damping has any significant influence.
A stiff baffle also keeps energy out of the cabinet which can be seen in the baffles of some of the pro companies.
What best properties?
Boutique audiophile companies do all sorts of technically doubtful things for marketing purposes. The objective is to come up with something that seems plausible and attractive to the unenthusiastic but uninformed which is their target market. If you want to see technically competent designs look more to the larger established pro companies. They tend to have a house style but within that the designs tend to give significantly more weight to technical performance for cost considerations.