Magic Matt Posted September 9, 2014 Share Posted September 9, 2014 I've seen everyone recommending "void free Baltic Birch" plywood, but this seems to be hard to get hold of, and very expensive. This is my first build, and I've never done a cabinet before, so I expect to make a mistake or 10 along the way... hence I'm a little concerned about spending a fortune on wood. If this is a relatively small cab (120 Litre) will it make much difference to the sound if I were to use relatively cheap plywood, 12mm, and brace it? I was thinking of putting a + across each face (except the font obviously) and possibly ++ across the back. I realise the finish may not be as good, but then with my currently very novice skills I'm expecting to cover or paint the cab anyway, hence the wood itself wont really be visible. Quote Link to comment Share on other sites More sharing options...
JPJ Posted September 9, 2014 Share Posted September 9, 2014 I'd go for a good construction grade exterior plywood. This comes in various grades and the better ones are almost void less without the expense. Honestly, I don't think that void less ply makes that much of a difference, a bit like gold plated jack plugs Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 9, 2014 Author Share Posted September 9, 2014 That's what I was thinking - certainly on a first build anyway. I think the time to be looking at expensive grades of ply etc. is probably second or even third build, if I decide to, when I've got a better idea of what I'm doing. If it were a big cab. where there's larger panels to resonate I can understand it might make a little difference. Gold plated plugs just look cool... that's the only reason I buy them, lol Quote Link to comment Share on other sites More sharing options...
JPJ Posted September 10, 2014 Share Posted September 10, 2014 I don't think manufacturers specify voidless ply for their production cabs. The best way I've found of bracing and changing the resonant frequency of panels in bass cabs is to inset strips of softwood using a router and strong adhesive. This way the bracing doesn't affect the cubic volume of the cab but has the desired effect. Quote Link to comment Share on other sites More sharing options...
ahpook Posted September 10, 2014 Share Posted September 10, 2014 I'd be interested in how you get on. I've generated a lot of ply off-cuts working on my kitchen, which are begging to be put to musical use. Quote Link to comment Share on other sites More sharing options...
6v6 Posted September 10, 2014 Share Posted September 10, 2014 [quote name='Magic Matt' timestamp='1410272477' post='2547699'] I've seen everyone recommending "void free Baltic Birch" plywood, but this seems to be hard to get hold of, and very expensive. This is my first build, and I've never done a cabinet before, so I expect to make a mistake or 10 along the way... hence I'm a little concerned about spending a fortune on wood. [/quote] I think it'll be fine provided you avoid the really cheap stuff which will probably just fall to bits and/or be hard to joint strongly, particularly if you go 12mm vs 15 or 18. If you're using something with voids in you probably want to use something like reinforced butt joints with a batten in every corner, as then the joint doesn't rely so much on the integrity of the ply core vs something like biscuit joints or glue/screw butt joints where you screw into the core of the ply. I see you're in Portsmouth - I imagine you can get birch ply there (try Covers at Hilsea), but FWIW I got some excellent quality 15mm birch ply from Totton timber, it wasn't all that much more expensive than the cheap Wickes stuff and IMO it was easier to work with, particularly as they have a fairly accurate panel saw there and cut it all to size for me. Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted September 10, 2014 Share Posted September 10, 2014 (edited) For a first build I'd definitely go for 18mm board unless you are really fetishistic about low weight. It only adds a couple of kilos to the cab because the speaker weight is a given and you need less bracing. I've used a lot of marine and exterior ply with success. If you really want to keep costs down then it is worth thinking about using chipboard, it comes in different grades depending upon the compression they used when making it and look for stuff with graded particles so the outside has finer particles. Sonically it makes a better cab though it is usually a little heavier and isn't so resistant to bumps and scrapes, unless you cover it. Less than half the price and just as good if this is only a prototype. Reinforced butt joints are good too, especially if you don't have access to good clamps whilst glueing as the screws pull everything together and hold it whilst the glue sets Edited September 10, 2014 by Phil Starr Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 10, 2014 Author Share Posted September 10, 2014 (edited) One of the main objectives of the self-build is to come up with something lightweight. I already have a 1x15" combo (Peavey 115S) that I like, it's just a bit heavy carrying up the steps to the flat after a gig. I'm not expecting to best it, but I'd like to at least equal it in sound, just lighter. I also fancied giving it a go and making something totally unique looking. Anything else I can achieve with the cab is a bonus. The local timber merchant stock Birch Ply. I asked if they stocked "void free Baltic Birch or similar" and got this as a quote... 12244122BIRPLY 12mm 2440 x 1220 Birch Plywood BB/BB £31.49+VAT Not sure if that qualifies as really cheap stuff, but the ends looked pretty good. I've not bought it yet - I probably wont until I know what size panels I need, as I'll need them to slice it down to get it in the car. I've bought a set of Mr. Fitzmaurice's rather excellent looking Simplexx 12 plans. I will probably follow those, but possibly vary a little to add batons in the corners, just purely for the sake of compensating for the lower quality ply. His plans have bracing on the panels already and use 12mm (1/2") ply. The main issue I'm going to have is cutting 45 degree angles on the ducts... just have to practice on some scrap with the hand tools! [Quote] [indent=1]Do not use ¾ inch plywood, or MDF. Commercial cabs use ¾ inch material with no bracing, as that reduces labor costs, and MDF, because it’s cheap. The S12 built from ½ inch plywood with bracing is 30% lighter than an un-braced cab made of ¾ inch, but is as vibration resistant as one made of 2 inch. MDF is heavy and not durable, so it has no redeeming qualities.[/indent] [indent=1][/quote][/indent] I think I'd add to that in that MDF is also butt-ugly, annoying to work with, and toxic. The only good thing I've seen with MDF is the "Bendy-MDF" that I thought might be good for flares on bass ports, but even then I'm doubtful. Edited September 10, 2014 by Magic Matt Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted September 10, 2014 Share Posted September 10, 2014 (edited) [quote name='Magic Matt' timestamp='1410365239' post='2548616'] I've bought a set of Mr. Fitzmaurice's rather excellent looking Simplexx 12 plans. I will probably follow those, but possibly vary a little to add batons in the corners, just purely for the sake of compensating for the lower quality ply. [/quote]Battens are a waste of wood and weight, as the corners of the cab are the strongest point of the cab. Suggest you join my forum to post any questions, and be forewarned that if you suggest any alterations there you will be told in no uncertain terms that there are three rules that you must not violate. They are: 1. Follow the plans. 2. Follow the plans. 3. Follow the plans. They'll also be able to tell you where to source your plywood. Edited September 10, 2014 by Bill Fitzmaurice Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 10, 2014 Author Share Posted September 10, 2014 You mean I'm not annoying enough here, you want me over there too!? I'm working my way through reading the stuff in the FAQs etc. before I register, but I certainly will when I come to building the speaker. Thanks! Quote Link to comment Share on other sites More sharing options...
LawrenceH Posted September 11, 2014 Share Posted September 11, 2014 [quote name='Magic Matt' timestamp='1410365239' post='2548616'] The local timber merchant stock Birch Ply. I asked if they stocked "void free Baltic Birch or similar" and got this as a quote... 12244122BIRPLY 12mm 2440 x 1220 Birch Plywood BB/BB £31.49+VAT [/quote] That is a decent price in my experience. I've never seen birch that was voided enough to worry about, presumably it's a bit silly wasting expensive birch to produce nasty gappy stuff. Quote Link to comment Share on other sites More sharing options...
Marvin Posted September 11, 2014 Share Posted September 11, 2014 [quote name='Magic Matt' timestamp='1410365239' post='2548616'] The local timber merchant stock Birch Ply. I asked if they stocked "void free Baltic Birch or similar" and got this as a quote... 12244122BIRPLY 12mm 2440 x 1220 Birch Plywood BB/BB £31.49+VAT [/quote] If that's actually Baltic Birch then it's a good price. Just bear in mind (and I'm likely to offend someone here, but it comes from personal experience) when it comes to dealing any company that has 'merchant' in the title you have to be very specific and make sure you're not fobbed off with something else. Personally I'd pay for the Baltic Birch. It has a nicer finish and is better quality all round. It may be your first build but you may find you make a really good job of it and think afterwards 'oh arse I wish I'd made it out of BB' Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 11, 2014 Author Share Posted September 11, 2014 True... I may be cheeky and ask if they have an offcut I could take as a sample, and see what it's like. I have to really try not to rush into doing things and take my time over this. I'm keen to get started, but I don't want to waste money by being too eager. Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted September 12, 2014 Share Posted September 12, 2014 Grade BB/BB ply may have fairly extensive filling/patching on the surface veneers and some of the stuff around at the moment is tending to splinter a bit when machined. This is pretty much what I used recently when I sourced it from a builders merchant, it wasn't very flat either. On the plus side it is a good price. I was prototyping so was less bothered. The stuff they are selling at Wickes and B&Q is better quality but denser. Builders merchants tend to spec on the structural qualities of ply for it's use in building. http://www.lathamtimber.co.uk/icmeditor/HTMLEditor/images/Literature/Latham%20Brochures/Birch%20Plywood.pdf Quote Link to comment Share on other sites More sharing options...
discreet Posted September 12, 2014 Share Posted September 12, 2014 (edited) Thing is if you get a void that has loose material in it, the cab will buzz in use and there will be nothing you can do about it. If you take your time and build in logical stages there's no reason why you shouldn't end up with an A1 cab. Edited September 12, 2014 by discreet Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 12, 2014 Author Share Posted September 12, 2014 Still tempted to put some small 12mm baton on the inside of the corners... because then I can trim the outer edges with 12mm quadrants and get a really nice look... just done it on a lid for the aquarium and I really like it. I'm not too worried about the appearance of the wood faces, as I intend to cover it anyway, but obviously I don't want any voids. Surely it would have to be an exceptionally bad piece of ply to have voids so large that loose material inside actually rattles and can be heard? Quote Link to comment Share on other sites More sharing options...
JPJ Posted September 12, 2014 Share Posted September 12, 2014 [quote name='Magic Matt' timestamp='1410522586' post='2550317'] Surely it would have to be an exceptionally bad piece of ply to have voids so large that loose material inside actually rattles and can be heard? [/quote] Agreed! I've used an awful lot of plywood in my time in building, boat building and cabinet building and have never come across loose material inside the ply's. Considering the way plywood is made, I struggle to understand how this could happen? Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted September 12, 2014 Share Posted September 12, 2014 [quote name='Magic Matt' timestamp='1410522586' post='2550317'] Still tempted to put some small 12mm baton on the inside of the corners... because then I can trim the outer edges with 12mm quadrants and get a really nice look... [/quote]Follow the plans. Even when radiused at 3/8 inch, which is standard for protective corners, the edges of the cab don't require any reinforcement. If they did [i][b]it would be in the plans[/b].[/i] Quote Link to comment Share on other sites More sharing options...
LukeFRC Posted September 12, 2014 Share Posted September 12, 2014 [quote name='Bill Fitzmaurice' timestamp='1410525588' post='2550373'] Follow the plans. Even when radiused at 3/8 inch, which is standard for protective corners, the edges of the cab don't require any reinforcement. If they did [i][b]it would be in the plans[/b].[/i] [/quote] do you have a hotkey set up on your pc to just paste that in? Quote Link to comment Share on other sites More sharing options...
discreet Posted September 12, 2014 Share Posted September 12, 2014 [quote name='LukeFRC' timestamp='1410532646' post='2550496'] do you have a hotkey set up on your pc to just paste that in? [/quote] When in made my first BFM cab I thought I knew better too. I didn't. Bill stresses that you need to follow the plans because if you don't you will end up with an inferior cab. Bill knows what he's talking about. Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 12, 2014 Author Share Posted September 12, 2014 (edited) I can't afford to buy a router and a table saw... how would I radius the edges without a router!? Everything is going to be done with hand tools, bar some stuff with a cordless jigsaw and a cordless drill/driver. Will there really be no reinforcement needed if being assembled by a slightly cack-handed monkey? Edited September 12, 2014 by Magic Matt Quote Link to comment Share on other sites More sharing options...
JPJ Posted September 12, 2014 Share Posted September 12, 2014 [quote name='Magic Matt' timestamp='1410539620' post='2550590'] I can't afford to buy a router and a table saw... how would I radius the edges without a router!? Everything is going to be done with hand tools, bar some stuff with a cordless jigsaw and a cordless drill/driver. Will there really be no reinforcement needed if being assembled by a slightly cack-handed monkey? [/quote] Lots of places like B&Q offer a panel cutting service (first x cuts free etc) which can make buying from them a lot more cost effective. Turn up with the cutting list from Bill's plans and they'll cut your sheet down into the required pieces that will be square cut with square edges. This should make assembly a lot simpler and result in nice tight joints. As for radius'ing the edges, you can do it using a batten, your jigsaw and some sandpaper. Use the jigsaw on the angle (most have adjustable bed plates) to chew off the meat of the corner (say 60 degrees from each side) then smooth the radius with a sanding block and sandpaper. Use a baton either clamped or screwed to the cabinet to keep the jigsaw running in a straight parallel line with the edge you are trimming. Quote Link to comment Share on other sites More sharing options...
discreet Posted September 12, 2014 Share Posted September 12, 2014 (edited) You don't need a router or a table saw. I made mine with a circular saw and a Workmate. And radiused the edges with a small block plane by hand. Edited September 12, 2014 by discreet Quote Link to comment Share on other sites More sharing options...
6v6 Posted September 15, 2014 Share Posted September 15, 2014 [quote name='Magic Matt' timestamp='1410539620' post='2550590'] I can't afford to buy a router and a table saw... how would I radius the edges without a router!? Everything is going to be done with hand tools, bar some stuff with a cordless jigsaw and a cordless drill/driver. [/quote] You can radius the edges with hand tools (plane, rasp, sandpaper) quite easily, it'll just take longer than with a router. FWIW I bought a router from Aldi recently for £25 and it's perfectly serviceable. Quote Link to comment Share on other sites More sharing options...
bartelby Posted September 15, 2014 Share Posted September 15, 2014 [quote name='JPJ' timestamp='1410540188' post='2550598'] Lots of places like B&Q offer a panel cutting service (first x cuts free etc) which can make buying from them a lot more cost effective. Turn up with the cutting list from Bill's plans and they'll cut your sheet down into the required pieces that will be square cut with square edges. This should make assembly a lot simpler and result in nice tight joints. As for radius'ing the edges, you can do it using a batten, your jigsaw and some sandpaper. Use the jigsaw on the angle (most have adjustable bed plates) to chew off the meat of the corner (say 60 degrees from each side) then smooth the radius with a sanding block and sandpaper. Use a baton either clamped or screwed to the cabinet to keep the jigsaw running in a straight parallel line with the edge you are trimming. [/quote] You need to be careful with B&Q cutting service though. They may not be as accurate as you'd like. Quote Link to comment Share on other sites More sharing options...
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