Personally I would not use mdf for bracing, it is less stiff than ply and needs to be sealed all round as it does not take well to moisture. I hope you know that you will need a dust mask for any woodworking, but for mdf especially so. A proper half mask with replaceable filters should be the minimum, the disposable masks don’t create well enough a seal.
If it was me, I’d use 3/4 everywhere but the front baffles. Use 1 inch there, and you’ll have to use a router to remove material from where the volt mounts to get it down to 20mm. Or, use 3/4 all around (18ish mm) and build up the area around the volt to 20mm.
I used 18mm 3/4 on my fronts. When you add thickness of the vaneer, and a 1 mm gasket, it should work out perfectly. YMMV!
I used 18mm 3/4 on my fronts. When you add thickness of the vaneer, and a 1 mm gasket, it should work out perfectly. YMMV!
Ok thanks. Is there a reason why the original cabinet design calls for 22mm? Using 18mm instead seems way off to me, considering the design calls for 22mm which is not a common plywood thickness found in the wild. There must be a good reason non-standard plywood thicknesses were use so I'm hesitant to use 18mm.
Other than weight, is there a downside to using 24mm instead of 18mm for all sides?
If I use Baltic Birch for the inside pieces instead of MDF, the closest thickness I can get is 15mm and not 16mm.
Does using standard ply thicknesses mean I have to re-calculate different dimensions for the cabinet than the ones found in the guide? Are there by chance any diagrams with dimensions matching the standard thicknesses? I'm guessing the original build was done using a planer or something to get precise thicknesses.
Also, layering 2 pieces of plywood would potentially introduce air pockets no? I though a strong press was required to bond them.
The Baltic Birch thicknesses available to me are 15mm, 18mm, and 24mm.
Other than weight, is there a downside to using 24mm instead of 18mm for all sides?
If I use Baltic Birch for the inside pieces instead of MDF, the closest thickness I can get is 15mm and not 16mm.
Does using standard ply thicknesses mean I have to re-calculate different dimensions for the cabinet than the ones found in the guide? Are there by chance any diagrams with dimensions matching the standard thicknesses? I'm guessing the original build was done using a planer or something to get precise thicknesses.
Also, layering 2 pieces of plywood would potentially introduce air pockets no? I though a strong press was required to bond them.
The Baltic Birch thicknesses available to me are 15mm, 18mm, and 24mm.
I think all the comments so far have given opinions on most of the above.... this is DIY—pick an approach and go! You can't get it wrong. Keep the inner volume close to project spec as detailed in the paper—don't go nuts about it.
The offset of the Volt driver and the fact that Matthias built his cabinets from solid wood and what was available to him where he lives and the desired aesthetics is what informed his material choices (besides all the maths and insane work involved in the speaker design!). He can chime in if I got that wrong. He also lined his cabinets with aluminum. I chose not to do that due to cost mostly. I used nominal 3/4" sheet materials for my build. I added a gasket (cork and rubber blend, nominally ~2mm) to the Volt to get it flush with the front. The driver is huge, and heavy.
Nominally "Russian" ply, or "Baltic" ply is in a 5x5' sheet and nominally ~19mm (my sheets in the shop are around 18.5mm). It's also available in a ~1/2" thickness. It has no voids—it's very dense and heavy has lots of plys—and at least one furniture grade face. Where I live (upstate NY) Home Depot sheet goods are laughable (and expensive), Lowes has much better stuff—and it's still not even close to what you get from a larger cabinet making oriented supplier.
The argument for using MDF for the interior bracing is that it's sonically neutral (way more than plywood anyway). You don't need to seal it in any way.
I recently got to hear some original RCA LC-1A, no crossovers, in an open barn, vinyl, CDs, tape as sources. All I can say is wow that sound—but it was also VERY familiar in sonic quality....Like what I have at home!! I was amazed since the design approaches are very different (to me) also the RCAs are 15" FR drivers. (incidentally the signal path was all esoteric tube stuff, but at the end of the session the hosts fired up a pair of ACAs! They held their own—fantastic in context. Super fun!)
The offset of the Volt driver and the fact that Matthias built his cabinets from solid wood and what was available to him where he lives and the desired aesthetics is what informed his material choices (besides all the maths and insane work involved in the speaker design!). He can chime in if I got that wrong. He also lined his cabinets with aluminum. I chose not to do that due to cost mostly. I used nominal 3/4" sheet materials for my build. I added a gasket (cork and rubber blend, nominally ~2mm) to the Volt to get it flush with the front. The driver is huge, and heavy.
Nominally "Russian" ply, or "Baltic" ply is in a 5x5' sheet and nominally ~19mm (my sheets in the shop are around 18.5mm). It's also available in a ~1/2" thickness. It has no voids—it's very dense and heavy has lots of plys—and at least one furniture grade face. Where I live (upstate NY) Home Depot sheet goods are laughable (and expensive), Lowes has much better stuff—and it's still not even close to what you get from a larger cabinet making oriented supplier.
The argument for using MDF for the interior bracing is that it's sonically neutral (way more than plywood anyway). You don't need to seal it in any way.
I recently got to hear some original RCA LC-1A, no crossovers, in an open barn, vinyl, CDs, tape as sources. All I can say is wow that sound—but it was also VERY familiar in sonic quality....Like what I have at home!! I was amazed since the design approaches are very different (to me) also the RCAs are 15" FR drivers. (incidentally the signal path was all esoteric tube stuff, but at the end of the session the hosts fired up a pair of ACAs! They held their own—fantastic in context. Super fun!)
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Has anyone built these in Canada recently? I'm guessing it would be near the $6000CAD mark and maybe more when considering shipping and duties/fees, so getting the dimensions of the case with perfect math is essential. I'll revisit these again in the future but not certain this is the best 1st build for someone with no speaker experience such as myself. I don't know how to calculate the volume and would need to go down the rabbit hole to learn more about it if I change the original design. ( or rely on someone else to do it for me, which is not really DIY! )
Made more steady progress on the cabinets today. Very grateful to have a friend with ability and willingness to help! Still much to do, backs, fronts, plinths, and all of the holes!
@SkyPirate - the third picture shows what looks like a recessed area where I assume the front panel will connect. It look like you either have an extra layer of plywood or else routed out the edge to create the recess
What did you do?
What did you do?
That’s impressive routing, with those thin remaining walls. Wondering how you got the rear panel into the same shape, with those rounded corners?
@maximax77 - Great question.. Haven't decided yet if we will chisel out the corners so that the rear panel will have square corners, or attempt to cut a radius in the back panel that will match.. Leaning towards chiseling out the corners..
I'd not try to chisel the corners out. There's a risk to destroy the plywood by separating the layers. Rounding off the corners of the back panel seems a lot easier to me. Even easier would've been to route the side panels before gluing them, so the router would have take off all the material in the corners (but it's too late for that).
Rounding the corners of the back panel is a fairly easy task for someone with that workshop setup. A template, a handheld router (or even a table router), and it’s done.
When I first saw the recess, I visualized a panel made of a different wood type or finish. If you get the combination right, it will surely look great!
When I first saw the recess, I visualized a panel made of a different wood type or finish. If you get the combination right, it will surely look great!
Ok! @mbrennwa and @dptucunduva, thanks for the opinions! This is my first speaker build and I’ll take the wisdom! Rounded corners it is!
Absolutely not with a chisel. An oscillator saw (Fein Multimaster et al) should be able to get it done if you are careful. But the walls are too thin for my liking, especially if you intend to screw the back as opposed to gluing it all together. Taking out the rounded corners will make them too weak. If you want to glue after all, you could use epoxy which unlike glue can fill voids. In that case you can just bevel the corners and fill the gaps with epoxy. But you might have to install the Basotect before gluing the back into place.
Thanks, @maximax77.. We will stick with the rounded corners. Not planning to glue the back panel in place. I'd like to be able to easily access the inside of the cabinet at sometime if needed.
