rk7 Posted January 28, 2016 Share Posted January 28, 2016 Great work! Keep it up! RK Quote Link to comment Share on other sites More sharing options...
stevie Posted January 28, 2016 Share Posted January 28, 2016 Just for information, here's a graph of the bottom-end performance of one of these drivers in a similar cab. It doesn't go very low, but that is clearly what some people want. [IMG]http://i63.tinypic.com/8yt2yh.jpg[/IMG] Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted January 29, 2016 Author Share Posted January 29, 2016 (edited) Allowing for the different scale, that's not far from the modelled response. I'm aware that the output of these is limited lower down, but I've had other cabs which behave similarly and I'm pretty sure they'll work for me. If my needs change somewhere down the line there are quite a few other drivers which would work in these boxes too - not least the Beyma used in the design diary thread, though with any luck I'll be quite happy with the Betas. Edited January 29, 2016 by Beer of the Bass Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted January 31, 2016 Author Share Posted January 31, 2016 (edited) I've been bashing on with these, as I'm determined to have at least one up and running for a gig in a fortnight's time. Today I cut out holes in the baffles for the speaker and ports. I used one of these cheapy fly-cutting tools for the port holes. It made nice neat holes, but it's not a tool I could say I enjoyed using. It came with blunt blades which I had to sharpen and was a bit scary in use. It's generally advised to use them on a pillar drill at low speed but the pillar drill in the workshop doesn't have a low enough speed setting, so I used it in a handheld electric drill. This seemed to be quite taxing on the drill, which got a bit hotter than it ought to so I took a break for it to cool down before doing the second cab. I cut out the holes for the drivers with a jigsaw, which is probably the wrong way to do it! I stayed slightly shy of the line so that I could finish it up more precisely with a rasp until the drivers fit snugly. There was still a little more to come off when I took this photo but hey, it looks a bit like a cab already! Although I was talking about making the baffles removable, I might just glue them in. It seems like it would make the cab a touch more rigid and in some ways it would be simpler than faffing about with woodscrews and gasket tape. It might make lining the cab a little more tricky, but as long as I fit the lining before the ports are glued in place I should be OK. Edited January 31, 2016 by Beer of the Bass Quote Link to comment Share on other sites More sharing options...
rk7 Posted February 1, 2016 Share Posted February 1, 2016 Great work! Glad to hear you are finding some tools scary. I thought it was just me. I'm terrified of my hand held router, even when it's unplugged. thank you please RK Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted February 1, 2016 Author Share Posted February 1, 2016 I realised when doing the second baffle that some of my trouble with the fly-cutter was down to me not using it correctly, rather than any problem with the tool. It uses two blades, one with the flat side outwards and the other facing inwards. Initially I had the inner blade badly adjusted, just a little too far from the line cut by the outer blade. If the inner blade is too far from the outer one, the waste doesn't chip out as easily and the drill has to work much harder. After adjusting it so that the inner blade was closer to the outer one it cut much more easily and didn't need nearly as much torque from the drill. So I guess that's a thing to watch out for with these. Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted February 4, 2016 Author Share Posted February 4, 2016 Further plywood news! I cut out the holes in the back for the connector plates; I drilled the driver mounting holes and fitted the T-nuts by pressing them into place with a G-clamp. Having found T-nuts irritating in the past, I reckoned this would be easier than doing them when I fit the drivers. You can see that my driver cutout is not the neatest, but everything is hidden by the front edge of the driver. I should really have made up a circle cutting jig for the router to cut these - maybe next time. Then I glued the baffles in place using woodscrews to keep everything in place. When the glue is set I'll take these out and fill in all the holes with dowels. I'll round the corners off at the weekend, then it'll be on to cutting the port tubes to length and checking the tuning, then painting, lining and making the grille frames. Quote Link to comment Share on other sites More sharing options...
mcnach Posted February 4, 2016 Share Posted February 4, 2016 Looking good! Quote Link to comment Share on other sites More sharing options...
Jakester Posted February 4, 2016 Share Posted February 4, 2016 [quote name='Beer of the Bass' timestamp='1454601926' post='2971259'] Then I glued the baffles in place using woodscrews to keep everything in place. When the glue is set I'll take these out and fill in all the holes with dowels. [/quote] At the risk of exposing my naivety, why would you remove the screws? Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted February 4, 2016 Author Share Posted February 4, 2016 [quote name='Jakester' timestamp='1454612972' post='2971377'] At the risk of exposing my naivety, why would you remove the screws? [/quote] Recessing the screws and using filler in the holes would be a viable option. But the paint I'm going to use doesn't stick to filler very well, so I'm trying to avoid using too much. If I fill the holes with wood and PVA, the paint should adhere to that just fine. Quote Link to comment Share on other sites More sharing options...
Dad3353 Posted February 4, 2016 Share Posted February 4, 2016 (edited) [quote name='Beer of the Bass' timestamp='1454613473' post='2971394'] Recessing the screws and using filler in the holes would be a viable option. But the paint I'm going to use doesn't stick to filler very well, so I'm trying to avoid using too much. If I fill the holes with wood and PVA, the paint should adhere to that just fine. [/quote] ... and wood weighs less than metal, too..! Edited February 4, 2016 by Dad3353 Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted February 6, 2016 Author Share Posted February 6, 2016 I rounded over the corners this morning. After trying a couple of times on scrap, I figured out that out of the bits I have available, a 1/4" roundover bit was the closest match for the chrome corner protectors I'm using. I used the router table in the workshop - I haven't spent a lot of time using table mounted routers, and I was so focussed on retaining the correct number of fingers that not only did I forget to take any pictures of the process but my tea went cold too! I've just realised that the gig I want to use them for is a week today, which seems like a scenario from one of those cheesy home improvement challenge programs on TV. Will I make it in time? Who knows... Quote Link to comment Share on other sites More sharing options...
mcnach Posted February 6, 2016 Share Posted February 6, 2016 [quote name='Beer of the Bass' timestamp='1454768465' post='2972795'] I've just realised that the gig I want to use them for is a week today, which seems like a scenario from one of those cheesy home improvement challenge programs on TV. Will I make it in time? Who knows... [/quote] Nailbiting stuff! Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted February 8, 2016 Author Share Posted February 8, 2016 (edited) I decided that before I bash on with painting and grilles, I should pop a driver and port tubes in one just to check that it's a functional cab. I haven't glued the ports in yet, they're just pushed into the holes with a little tape around them to ensure a seal. First I ran a test signal (from a function generator app on my tablet, plugged into my GK MB200 head) through it to determine if my port tuning was as expected. One low-tech way of checking port tuning is to place a few grains of sugar on the cone with the speaker lying on its back, sweep the frequency of the test signal across the expected range and look out for the point where the sugar dances about the least, which should correspond to the port tuning. This makes sense when you look at the cone excursion graph on the last page, as the excursion is smallest at the port tuning frequency. The process was a bit less precise than I anticipated as there is a certain amount of guesswork as to exactly where the minimum is. With three ports 21cm long, the tuning is certainly very close to the expected 50Hz, though I think the minimum may actually be in the upper 40s. The sugar starts dancing around more strongly below the mid 40s and when you get above 52Hz or so. I'm calling that close enough! Here's my improvised test setup: I then tried playing some bass through it. I haven't spent long enough with it to evaluate the sound in a detailed way, but it works! I wasn't getting any rattles, buzzes or windy noises so I guess my cabinet construction is OK. I also tried plugging one port to lower the tuning and as Stevie predicted, the difference in sound is so small as to be almost undetectable in practice. However, there is visibly more cone movement in certain parts of the range with the 40Hz tuning. I think I'll keep all three ports open. Edited February 8, 2016 by Beer of the Bass Quote Link to comment Share on other sites More sharing options...
scojack Posted February 10, 2016 Share Posted February 10, 2016 (edited) Really enjoying this build Beer ...just wish i knew wtf you are talking about most of the time Edited February 10, 2016 by scojack Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted February 10, 2016 Author Share Posted February 10, 2016 I'm not totally sure I know what I'm talking about myself, TBH! I'm probably picking up quite a lot as I go along. I'm going to give them the first coat of paint later, hoping they come out looking OK... Quote Link to comment Share on other sites More sharing options...
stevie Posted February 10, 2016 Share Posted February 10, 2016 The first coat of paint is when it really starts looking like a cab. Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted February 10, 2016 Share Posted February 10, 2016 Well done on this, I'm confident you'll be pleased with the sound. I ended up with a 50Hz tuning too so I think that will be the best decision. Can't wait until you've tried it. Quote Link to comment Share on other sites More sharing options...
GarethFlatlands Posted February 11, 2016 Share Posted February 11, 2016 Very cool, you make it look so easy even I'm thinking I could put one of these together! Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted February 11, 2016 Author Share Posted February 11, 2016 [quote name='stevie' timestamp='1455133377' post='2976345'] The first coat of paint is when it really starts looking like a cab. [/quote] Here we go: This was taken after two coats, and I've just done a third. I'm using Turbo Blue Tuff Cab paint. After a bit of experimentation I found that I much prefer the smoother foam rollers that came with my pound shop paint tray to the honeycomb textured ones which Blue Aran sell with the paint. The cheap foam rollers produce a nice fine texture, while the texture from the Blue Aran rollers reminds me a little too much of Artexed ceilings! The paint is quite pleasant to work with - it dries within an hour or two but gives you enough time to roll it to the texture you want, it doesn't have an objectionable smell and it cleans up with water. It looks a bit more blue than this in decent light, but I'm painting in a dingy store room under a couple of fluorescent strips. I was almost tempted to go for a brighter colour, but I hope to be using these for quite a few years to come and I didn't want something I would have second thoughts about. Quote Link to comment Share on other sites More sharing options...
Merton Posted February 12, 2016 Share Posted February 12, 2016 These look ace! Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted February 12, 2016 Share Posted February 12, 2016 [quote name='Beer of the Bass' timestamp='1455225513' post='2977323'] Here we go: After a bit of experimentation I found that I much prefer the smoother foam rollers that came with my pound shop paint tray to the honeycomb textured ones which Blue Aran sell with the paint. The cheap foam rollers produce a nice fine texture, while the texture from the Blue Aran rollers reminds me a little too much of Artexed ceilings! [/quote] I agree, I managed to get a linen like effect with the cheap foam rollers. The Blue Aran ones are meant to give you the effect the big boys get by spraying their cabs. It's worth trying longer pile rollers too, the ones designed for emulsion paint, they give you a texture in between the two. Quote Link to comment Share on other sites More sharing options...
stevie Posted February 12, 2016 Share Posted February 12, 2016 What's wrong with Artexed ceilings I'd like to know! Quote Link to comment Share on other sites More sharing options...
EBS_freak Posted February 12, 2016 Share Posted February 12, 2016 Looking good. Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted February 12, 2016 Share Posted February 12, 2016 [quote name='stevie' timestamp='1455281383' post='2977733'] What's wrong with Artexed ceilings I'd like to know! [/quote] Hmm wonder if Stevie would like his cab in white Quote Link to comment Share on other sites More sharing options...
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