Gents, starting cabinet build and BB ply is nearly impossible to find here in Brisbane. I am going for AA marine ply instead which leads me to my next question. I can only get 12 or 18 mm boards. Which should I go for... 12mm with a bit of extra bracing or 12mm as per MT design or 18mm with extra bulk and weight....? Given Brisbane is a city of 2.2 million it is amazing how little we have and how expensive it is. For example a 2440x1220 sheet of 18mm and 12mm cost 132 and 89 AUD respectively... Any advice appreciated. Thanks, Andy
Ps so excited about getting this project off of the ground
Ps so excited about getting this project off of the ground
Thanks for the responses everyone. There is plenty of structural CD/DD ply around which is far cheaper and of very course quality and not appropriate for this application. Little in the way of AB or BB (quality not Baltic Birch) ply to be found either as marine or standard ply...I'm happy to pay for something that will have a positive affect on quality but still need to be conscious of budget. The external dimensions also need to be considered which is the main reason why I'm posing this question. Thanks again
Andy,
Google search generated this link:
plywood sheets in Brisbane Region, QLD | Gumtree Australia Free Local Classifieds
I am in no way sure about the authenticity of the site/products advertised.
If the ply is mostly free of voids, has flat surfaces, and is relatively high in ply count (9 layers or more), should be ok for a build.
Rest of funds can go into the drivers...
Google search generated this link:
plywood sheets in Brisbane Region, QLD | Gumtree Australia Free Local Classifieds
I am in no way sure about the authenticity of the site/products advertised.
If the ply is mostly free of voids, has flat surfaces, and is relatively high in ply count (9 layers or more), should be ok for a build.
Rest of funds can go into the drivers...
Almost all Baltic birch is shop grade -- BB. There will be football patches on both sides. Finnish birch is pretty much NLA in North America. What I get is Russian birch, but for shop grade, it is good enough. I suspect the same for Australia. Anything graded AA or AB is going to be very expensive, or it will be furniture grade and 5-ply for 3/4" and loaded with voids. Decent sheet goods are getting increasingly hard to find. BTW do not under any circumstances buy any Chinese "Tigerply" Worst stuff I have ever seen.
Bob
Bob
I hadn't even thought about gumtree as a supply source until zman suggested it. I just assumed it would not be a legitimate source so thanks zman. I have found two types of 18mm ply advertised as "18mm thick Plywood Sheets 1200mm x 2400mm AAA Grade Russian Birch". Although these are both from the same supplier and the only quality items above C/ structural ply they appear legitimate at this point. Supplier response to my questions on quality and number of layers below:
"I have two types one with 11 veneers and another that has 8 which also has a sheet of mgo in the middle of the sheet. They are fire retardant and full Russian birch seriously good quality plywood marine grade. Retail would be over $120 per sheet - I supply this commercially for $65/ sheet based on a full container 600 sheets."
The only reason I'm posting this is due to the 8 layer with mgo option. I assume this is Magnesium Oxide and a fire retardant. Anyone willing to suggest if this would actually do a better job than the 'standard' 11 veneer ply. I have seen people talking about laminating different materials to create a dead cabinet. This type of plywood made me think of this and my brain started ticking again...
Having said all that an 11 layer 18mm ply Russian birch 2400x1200 sheet for 65AUD (52USD) sounds like a great option.
Thanks guys, this is a thoroughly enjoyable process. I can not believe how helpful the diyaudio forum is. Quite a different experience to many of the others out there.
"I have two types one with 11 veneers and another that has 8 which also has a sheet of mgo in the middle of the sheet. They are fire retardant and full Russian birch seriously good quality plywood marine grade. Retail would be over $120 per sheet - I supply this commercially for $65/ sheet based on a full container 600 sheets."
The only reason I'm posting this is due to the 8 layer with mgo option. I assume this is Magnesium Oxide and a fire retardant. Anyone willing to suggest if this would actually do a better job than the 'standard' 11 veneer ply. I have seen people talking about laminating different materials to create a dead cabinet. This type of plywood made me think of this and my brain started ticking again...
Having said all that an 11 layer 18mm ply Russian birch 2400x1200 sheet for 65AUD (52USD) sounds like a great option.
Thanks guys, this is a thoroughly enjoyable process. I can not believe how helpful the diyaudio forum is. Quite a different experience to many of the others out there.
Haha, I'm in no need of a boat! He had some spare sheets (about 50) so he's just offloading them at his sale price even though no volume.
I have attached a photo below of the 18mm ply. It has 6 plies of birch with about 4mm of MgO in the middle. I wonder if this would work as a constrained layer for dampening the cabinet...? MgO board appears to be very strong and stiff and is replacing a lot of traditional construction materials due to its properties and it is also far more environmentally friendly. Apparently.
Doesn't look to be made with great quality but I'm no ply expert. I can see the glue lines and they seem thick.
I may just stump up for some normal marine ply unless someone says this is a good idea. Just wanted to throw something interesting out there as I haven't seen it on the forums before.
I have attached a photo below of the 18mm ply. It has 6 plies of birch with about 4mm of MgO in the middle. I wonder if this would work as a constrained layer for dampening the cabinet...? MgO board appears to be very strong and stiff and is replacing a lot of traditional construction materials due to its properties and it is also far more environmentally friendly. Apparently.
Doesn't look to be made with great quality but I'm no ply expert. I can see the glue lines and they seem thick.
I may just stump up for some normal marine ply unless someone says this is a good idea. Just wanted to throw something interesting out there as I haven't seen it on the forums before.
I'd be inclined to a knee-jerk reaction to avoid this material- but if conventional joinery techniques / adhesives can be used to fabricate enclosures, it would certainly be worth an experiment on as simple an enclosure as Pensil, microtowers, etc.
My only concern would be precision of machining for driver cut-outs -particularly since the thick frames on most MA drivers require rebating for flush mounting
I concur. Routing rebates down into that MgO layer (if required) might get messy or annoying. But I'm just guessing, having never worked with it.
The other thing that I failed to mention in earlier post is that the face and cross band plies appear to be a very low grade large pore, soft "meranti" type - not well respected in the trades hereabouts for screw holding ability. There are special panel materials ( Thermax, Kerfcore, Rubber Ply, etc) that we use in the commercial trade for attachment to sturdy wooden or metal sub frames, but many would not past any type of underwriting certification if used by themselves.
All in all, I'd be inclined to avoid this particular material for speaker enclosures - if it has some properties that are reputed to elicit sonic advantages, (such as constrained layer damping) - there are well established methods of achieving the same goals.
All in all, I'd be inclined to avoid this particular material for speaker enclosures - if it has some properties that are reputed to elicit sonic advantages, (such as constrained layer damping) - there are well established methods of achieving the same goals.
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