OK...first of all let me say this....
For years before I was even considering DIY audio, I bought a pair of ACI (Audio Concepts Inc) Sapphire III's from my little brother.
Probably the most impressive thing about these speakers were the cabinets, they were made from 1 inch HDF! (High Density Fiber board.) The knock test on these makes everything else seem amateur!
To make a long story short when I decided to build my own speakers, naturally I wanted HDF! But we had huge problems there.
The problem wasn't just not being able to find it, nobody even knows what it is!!!! But with a diligent internet search and a LOT of CREATIVITY I found the hands down solution to building speaker cabinets with HDF !!! No JOKE!
Let me clarify right here I am working out some details but my first test seems like it will work WITHOUT improving anything from my first trial.
Okay so here goes.
I am currently building the popular Elsinores project. And in one post Joe mentioned one of the biggest improvements you could make to the cabinet was to build just the front panel out of HDF!
"But the thing that I believe would improve the box most is the most simple (and yet difficult at the same time), take a look at the newer Dynaudio designs, that baffle of theirs made of high density fibre board. I have heard a pair of Lenehan ML-1 speakers in both standard and 'Signature' versions and this was the only difference. Make the front part of the box structure out of this material and I believe the improvement would be greater than anything I have covered so far, no kidding!" (http://www.diyaudio.com/forums/multi-way/97043-elsinore-project-thread-15.html)
So I have spent the last several weeks...not to mention several years trying to source HDF! But it wasn't happening! You can get it but you have to buy a few thousand dollars worth of inventory!
But I did find something called "hardboard". And as it turns out it is the same thing as HDF, but it's just come is thin sheets.
So I got the idea of laminating several sheets together to make the thickness needed to build a cabinet!
So I bought a sheet of it, ripped the sizes I needed and this afternoon laminated them together...and all I can say is WOW!
WOW, WOW, WOW!!!!
On a single 9" X 4' panel the knock test hurts your knuckles! I am not kidding! It is like concrete, without any bracing of even a structure! For speaker building I think it was the smartest move I've made!
I used 7 total 1"x 4"s with braces behind them and my test piece is not as straight as I'd like. Which I am sure once even thing is put together would not be a problem, but tomorrow I'm going to get a half sheet (4' x 4') of 1/2" hardwood plywood and make a "former" to keep the rest of the laminations straighter!
I'll update when I have more to tell...and pictures.
For years before I was even considering DIY audio, I bought a pair of ACI (Audio Concepts Inc) Sapphire III's from my little brother.
Probably the most impressive thing about these speakers were the cabinets, they were made from 1 inch HDF! (High Density Fiber board.) The knock test on these makes everything else seem amateur!
To make a long story short when I decided to build my own speakers, naturally I wanted HDF! But we had huge problems there.
The problem wasn't just not being able to find it, nobody even knows what it is!!!! But with a diligent internet search and a LOT of CREATIVITY I found the hands down solution to building speaker cabinets with HDF !!! No JOKE!
Let me clarify right here I am working out some details but my first test seems like it will work WITHOUT improving anything from my first trial.
Okay so here goes.
I am currently building the popular Elsinores project. And in one post Joe mentioned one of the biggest improvements you could make to the cabinet was to build just the front panel out of HDF!
"But the thing that I believe would improve the box most is the most simple (and yet difficult at the same time), take a look at the newer Dynaudio designs, that baffle of theirs made of high density fibre board. I have heard a pair of Lenehan ML-1 speakers in both standard and 'Signature' versions and this was the only difference. Make the front part of the box structure out of this material and I believe the improvement would be greater than anything I have covered so far, no kidding!" (http://www.diyaudio.com/forums/multi-way/97043-elsinore-project-thread-15.html)
So I have spent the last several weeks...not to mention several years trying to source HDF! But it wasn't happening! You can get it but you have to buy a few thousand dollars worth of inventory!
But I did find something called "hardboard". And as it turns out it is the same thing as HDF, but it's just come is thin sheets.
So I got the idea of laminating several sheets together to make the thickness needed to build a cabinet!
So I bought a sheet of it, ripped the sizes I needed and this afternoon laminated them together...and all I can say is WOW!
WOW, WOW, WOW!!!!
On a single 9" X 4' panel the knock test hurts your knuckles! I am not kidding! It is like concrete, without any bracing of even a structure! For speaker building I think it was the smartest move I've made!
I used 7 total 1"x 4"s with braces behind them and my test piece is not as straight as I'd like. Which I am sure once even thing is put together would not be a problem, but tomorrow I'm going to get a half sheet (4' x 4') of 1/2" hardwood plywood and make a "former" to keep the rest of the laminations straighter!
I'll update when I have more to tell...and pictures.
Even though MDF and Hardboard is supposed to be homogenous in that it is consistent in density which should theoretically make it the best material to use for speakers I like the idea of laminating it as you are doing. I think that step adds a bit of strength to it so that it helps prevent warping and sagging. MDF is also prone to absorbing moisture as I bet HDF is but not as much. I think after building anything with MDF it should be sealed someway before any other process takes place.
I like the idea of laminating MDF with plywood for that reason.
However
I like the idea of laminating MDF with plywood for that reason.
However
I used to use HDF. One of my mentors did just what you did some 40 years ago… multiple thin layers laminated together under a 10 ton press. You are making a plywood. Even cheap MDF gets better if you use thin layers and make plywood.
MDF itself is not a good material for making speaker cabinets.
I find quality plywood even better. The best sheet material we have used is stranded bamboo plywood.
dave
PS: note that most do not know how to interpret a knock test.
MDF itself is not a good material for making speaker cabinets.
I find quality plywood even better. The best sheet material we have used is stranded bamboo plywood.
dave
PS: note that most do not know how to interpret a knock test.
Two layers of MDF bonded together with viscous rubbery glue or a sheet of rubber in between for CLD may work even better the HDF by itself. I don't know but I recall someone measured differences between materials somewhere.
Laminated bamboo flooring panels (5in wide) can be used if bonded together. Might be cost effective.
I have seen solid 1in thick plate glass as speaker cabinet material as well as granite, concrete, and Corian counter tops.
Laminated bamboo flooring panels (5in wide) can be used if bonded together. Might be cost effective.
I have seen solid 1in thick plate glass as speaker cabinet material as well as granite, concrete, and Corian counter tops.
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one of my 1955 Karlson K12 walls and wings are made of 1/8" hardboard laminated to 5/8" fir plywood with a Formica covering = pretty stiff - perhaps just something laying around in one of their 7 "factories" as other cabinets were 3/4" plywood
IIRC the above mentioned "sandwich" is for side panels. I have also read that using a sandwich of two different materials like one layer HDF and one layer of ply might possibly be even better.
For baffles what I understand is that more rigid the better. IIRC from the Elsinore thread Joe Rasmussen advocates making the baffle stiff and strong, specially around the tweeter area.
Calusen,
Gluing up on thin panels sometimes leads to a bit of bend. You can have a look at some quality multi-layer plywood too if available. Bamboo laminates look and feel very nice - light and strong.
CLD isn't just for side panels. The baffle is the most important part that benefits - CLD panels don't lack stiffness - they just absorb vibrations better through shear forces.
That is an understatement. Even measurements with accelerometers glued or screwed to cabinet walls are hard to interpret. Sound transmission measurement isn't that simple with home and kitchen appliances.
Formica is also great for re-doing older particle board boxes. The stiff and dense Formica really transforms the material's behavior. And the patterns are better than almost all wood-grained vinyl. White is good for kitchens and labs. Stupid people put drinks on your speakers? Who cares!
My Gedlee Summas were the deadest speaker I've ever owned.
When I took them apart to test them, I was quite surprised by what they were made of.
(Hint : it's not the same material that Geddes currently uses.)
Re Knuckle Test:
Means sod all..... wrap your skull, hurts knuckles no?
Simple answer is to make speakers from whatever you want / can get / afford and go enjoy.
CLD 'damping' does NOT need to be the 'whole panel' btw 😉
Means sod all..... wrap your skull, hurts knuckles no?
Simple answer is to make speakers from whatever you want / can get / afford and go enjoy.
CLD 'damping' does NOT need to be the 'whole panel' btw 😉
For sure, HDF is a step up from MDF, but Benelex or better yet, Spauldite is a major leap, so where you want t be if not using either welded up heavy gauge sheet metal or braced void free 11-13 ply BB apple or similar plywood. The high cost makes the latter the preferred choice for most folks though.
GM
Thanks! I would have, had I known, but I've been away from high tech construction since '94 so woefully now out of date.
GM
I know...I'll build these speakers out of sheet rock! How's that sound!
All I was hoping for here was a..."yeah that might work, let us know how it works out"...
Like Clint Eastwood's character said in one film..."opinions are like A$$holes, everyone has one, and everyone thinks everyone else's STINKS!"
All I was hoping for here was a..."yeah that might work, let us know how it works out"...
Like Clint Eastwood's character said in one film..."opinions are like A$$holes, everyone has one, and everyone thinks everyone else's STINKS!"