well gentlemen, thanks for the help. I went for plywood. Birch, and quality or not I don't know: it's what they had in the shop. Next step will be assembling it (I was thinking to use glue and those wooden pins you find in ikea forniture, to stabilize it while glueing it) and paint (glossy white). I even found a guy with a CNC for making the hole for the driver 🙂
NB: I'm probably going to skip the bracing, but just because I'm a lazy bastard.
NB: I'm probably going to skip the bracing, but just because I'm a lazy bastard.
unfortunately I can't ask for other than the 2 holes for the drivers.. but if I will add some bracing later on, I'll just make rough holes, nobody will look in the speaker anyway.
(off topic comment)
I've been reading since 30mins about how the bracing is supposed to interfere with the resonance inside the speaker, and I ask myself (again): so why not to settle on a TQWT layout then? Doesn't it dump more than a MLTL with bracing? It's even easier to build..
(off topic comment)
I've been reading since 30mins about how the bracing is supposed to interfere with the resonance inside the speaker, and I ask myself (again): so why not to settle on a TQWT layout then? Doesn't it dump more than a MLTL with bracing? It's even easier to build..
If you're still talking about Pensils - the bracing needn't be as elaborate as the full length intersecting holey braces that are found on some of the drawings and build photos.
As Jeff notes humorously, at least some minimal bracing between the long panels on a tall quarter-wave resonant enclosure such as these is highly recommended. The important thing to remember is run them longitudinally - i.e. not X-type window panes, as that could affect the net CSA, and I think if wide enough, impact on the 1/4 action upon which this family of designs is based - and try not to place such that would divide the panels exactly in half.
There may be test data somewhere out there, but I've not built duplicate enclosures to personally assess every possible configuration of bracing (size/shape/location) - 'cause building more boxes than you really need would be silly, wouldn't it?
If built as suggested with removable back panel, it's not too difficult to add front to back braces later, but getting a good fit on side to side after assembly can be a bit more of a wrestling match - particularly on the Pensils for 70mm drivers.
As Jeff notes humorously, at least some minimal bracing between the long panels on a tall quarter-wave resonant enclosure such as these is highly recommended. The important thing to remember is run them longitudinally - i.e. not X-type window panes, as that could affect the net CSA, and I think if wide enough, impact on the 1/4 action upon which this family of designs is based - and try not to place such that would divide the panels exactly in half.
There may be test data somewhere out there, but I've not built duplicate enclosures to personally assess every possible configuration of bracing (size/shape/location) - 'cause building more boxes than you really need would be silly, wouldn't it?
If built as suggested with removable back panel, it's not too difficult to add front to back braces later, but getting a good fit on side to side after assembly can be a bit more of a wrestling match - particularly on the Pensils for 70mm drivers.
I don't think anyone has mentioned proper "marine" ply. Not just exterior grade normal ply.
It's more expensive but is as dense as you like and will machine well and finish well.
It's more expensive but is as dense as you like and will machine well and finish well.
Wow, i remember when i asked that question! Having gained experience and working with good birch ply 11 or 13 ply (if you count the finished veneers), my first opinions have changed, but not vastly.
A properly braced box will reveal the weakness of the material far less than in an unbraced duplicate.
Birch is harder, stiffer weight for weight, and its easier to finish (less sanding and sealing)
Birch also has a self tension, or that is my opinion at least (i don't know if im correct, but that's how i explain to myself)
So, when badly braced or unbraced, BB ply has a drummy tone, and resonates rather noticably.
MDF on the other hand, under equivalent circumstances, seems to my ear to have less of an issue. It still drums, but it SOUNDS softer. Some would say indistinct, wooly etc. but in not sure that's right, at least not totally.
But real wood, even good ply, is just so much nicer to work with. Excluding cutting that is. Cutting guy ripped out a lot of the best side �� quite easy to do if your a self taught novice woodworker. Admittedly i had to use filler to cover the worst of the tear out. But MDF dust and seal makes the birch worth it. Cost me twice what MDF wouldve.
A properly braced box will reveal the weakness of the material far less than in an unbraced duplicate.
Birch is harder, stiffer weight for weight, and its easier to finish (less sanding and sealing)
Birch also has a self tension, or that is my opinion at least (i don't know if im correct, but that's how i explain to myself)
So, when badly braced or unbraced, BB ply has a drummy tone, and resonates rather noticably.
MDF on the other hand, under equivalent circumstances, seems to my ear to have less of an issue. It still drums, but it SOUNDS softer. Some would say indistinct, wooly etc. but in not sure that's right, at least not totally.
But real wood, even good ply, is just so much nicer to work with. Excluding cutting that is. Cutting guy ripped out a lot of the best side �� quite easy to do if your a self taught novice woodworker. Admittedly i had to use filler to cover the worst of the tear out. But MDF dust and seal makes the birch worth it. Cost me twice what MDF wouldve.
even without the dust issues, anything which absorbs water, swells quickly and falls apart can be a problem - that said, I prize my beaverboard 1960's Karlson K12s😀 - particleboard was somewhat less rubbery than MDF
You are going to generate just as heated an argument over bracing as you will over MDF/BB. I do primarily MLTL's because they are 1) idiot simple to design and 2) they are very simple to construct. i use some window braces to keep the structure square and stiffeners on the long panels to raise the resonant frequencies.
Bob
Bob
Bob, how much fun would it be if we all agreed completely on everything? To mix my metaphors somewhat, because it's not much use for anything else, if I don't exercising my brain at least once a day contriving snarky retorts to something, I feel a bit constipated, and don't much care for prunes.
here at DIYAudio , we put the FU in fun with Full-Range, not like those guys at some other forums 😀
here at DIYAudio , we put the FU in fun with Full-Range, not like those guys at some other forums 😀
Lol but that isn't my intent. I was just speaking of my experiences and how i rationalise that experience, which isn't vast.
Oh and id agree that MDF and water don't mix.
Main Point being ive made good boxes out of both materials, as good as my heavyhanded hatchet approach allow.
Above all, id like to build with solid wood
ill give it a go one day. Ply had many advantages and i certainly prefer working with it. I just have to practice....
I wasn't being snarky........
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Hi all,
There was a programme on the tele about a lady who made a small house for £50k and inside she used OSB board Sterling OSB2 | Norbord | FSC Approved OSB, MDF & Chipboard The claims on the web page make it look better than both MDF and Ply.
The house looked really good inside it glowed with the warm light reflected from the OSB.
Cheers - Jim
There was a programme on the tele about a lady who made a small house for £50k and inside she used OSB board Sterling OSB2 | Norbord | FSC Approved OSB, MDF & Chipboard The claims on the web page make it look better than both MDF and Ply.
The house looked really good inside it glowed with the warm light reflected from the OSB.
Cheers - Jim
Well I don't about that, I'm away in a good mood........
Chrisb, no-one ever uses MEDEX here? gesh it's so much better, less dust, cuts better, paints better, etc. I'm out of it now, but going to order a few more sheets soon.
Chrisb, no-one ever uses MEDEX here? gesh it's so much better, less dust, cuts better, paints better, etc. I'm out of it now, but going to order a few more sheets soon.
There are different manufactures of the product, I'm getting the same as last time I ordered, very, very nice, a joy to work with. Way stronger than mdf also.
Just spent the last 12 hours cutting mdf, pretty gross. If you need to use it, don't try to machine a lot of the parts, cough-cough.
Just spent the last 12 hours cutting mdf, pretty gross. If you need to use it, don't try to machine a lot of the parts, cough-cough.
There are more than enough brand/ trade names and now with the trend to NAUF, LEEDS etc , special adhesives etc for "MDF / HDF/ MDO" sheet goods to make it very confusing. And don't get someone in the trade started on the FSC boondoogle.🙄
as with plywood , not all "MDF" is created equal
MEDEX is a registered trade name for a particular and somewhat specialized product by Sierra Pine. It's a perfectly fine material, but perhaps not as widely distributed as "normal" MDF, and even at bulk quantities to the trade, at a premium price ( $12 ea more for a 3/4" 4x8 ft in our case) .
as with plywood , not all "MDF" is created equal
MEDEX is a registered trade name for a particular and somewhat specialized product by Sierra Pine. It's a perfectly fine material, but perhaps not as widely distributed as "normal" MDF, and even at bulk quantities to the trade, at a premium price ( $12 ea more for a 3/4" 4x8 ft in our case) .
i feel the most cost effective method is using good plywood for the large/long panels, MDF for short panels or bracing.
when you're building really big boxes, it can get seriously expensive using Baltic Birch ply.
when you're building really big boxes, it can get seriously expensive using Baltic Birch ply.
My largest to date, 5cu.f golden ratio cabinets, required 3x ~45$CAD sheets of 5'x5' 18mm ply and I went double-thick on the front and back baffles. Of course, one is then not too likely to be using a couple of closeout drivers in such projects, so I see it as not a good place to skimp on building material. 🙂 Ply cost me about half a woofer, or a full tweeter in this case, easily justified.
Seeing how Vb will grow faster than enclosure surface area, I think it is economically best the larger the box. 😉
IG
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actually, what I'd consider proper "bracing" as opposed to panel tuning cleats (such as in AudioNote E enclosures), is probably the last place I'd use MDF - it lacks the stiffness
a small dimensional piece of solid hardwood such oak, maple or birch, or even spruce 2x4 stud would likely yield better results as a minimal stub brace than a much larger fin / windowpane of MDF
a small dimensional piece of solid hardwood such oak, maple or birch, or even spruce 2x4 stud would likely yield better results as a minimal stub brace than a much larger fin / windowpane of MDF
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