stevie

I have a couple of those 3012LF drivers here - so I'm quite familiar with them, although I've never pushed them to the limit. It's probably the best driver Eminence makes. They're fairly insensitive and need a large cabinet (and a separate midrange driver) but they do extend low, handle oodles of power and sound very dynamic. The crossover on your cab is 2kHz - 24dB per octave.

Make sure you don't wreck your driver. It looks to me like you're hitting 10mm excursion. If you hit 17mm, the driver dies. I'd expect the suspension to stiffen up before you get to 17mm, but 500 watts of bottom E string is a lot for a single 12.

The kind of grille Pete has needs to be supported all round - otherwise it could rattle. Rubber feet would work but only on a heavy grille.

This is excellent work, and just goes to show that you can calculate till the cows come home but nothing beats a practical test. I carried out lots of tests on the cab (including using it live) but didn't carry out any stress tests. The obvious solution to the problem is to increase the height of the picture frame grille support. The "lip" around the cab is 25mm - so we have plenty to play with. I looked for some suitable batten ("stripwood") and found some from Wickes. I believe Wickes has a national distribution network - so it shouldn't be too difficult to source. You can always try your local timber merchant, of course. Wickes have 10 x 18mm and 12 x 21mm batten, which will raise the grille by an additional 3mm or 6mm. https://www.wickes.co.uk/Wickes-Pine-Stripwood-Moulding-PSE---10mm-x-18mm-x-2-4m/p/121255 https://www.wickes.co.uk/Wickes-Pine-Stripwood-Moulding-PSE---12mm-x-21mm-x-2-4m/p/121260 I suspect that 3mm will be plenty but will wait to see what Pete discovers in his tests. Both Pete and I now have the 15mm batten installed in our cabs. So we're going to have to figure out what to do now. Foam strip might work but there is the problem of the foam poking through the holes in the grille, which we want to avoid. The alternative is some neoprene rubber sealing strip, which is available in a variety of thickesses from Ebay for about £6 delivered. That is enough to do two cabs. Ebay item no. 261725424586. Pete, if you can figure out what thickness of strip we need, I'll order some and send half of it on to you.

Sounds like a plan to me. My workbench has an 18mm birch plywood top that has suffered years of abuse and is still performing well. If you decide not to use the worktop (although I don't see why not) you certainly wouldn't need to double up on the plywood. Very nice shed. I'm envious. I can recommend LED battens for the lighting.

I'll need payment when I have to fork out for the cabinets and the compression drivers - that's too much for me to fund on my own. However, I don't want to sit on anyone's money unnecessarily. So I'll let you know in good time.

Quick update. I've fitted the corners, feet and handle - with sticker - to the cab but can't do much more until I have the etch primer to paint the aluminium grille. It's on order and should be with me this week. I'll cut and paint another expanded metal grille as soon as I can so that we can compare the two options visually. The dark grey paint looks stunning against the black fittings and the black and red badges - so I've decided to paint the aluminium grille satin black. I've notified the CNC company of the minor changes needed and confirmed the order for 10 kits. They have said two to three weeks, which will give me time to build the crossovers.

The aluminium one (shown in the parallel thread) weighs 400g.

Agreed - that wouldn't be a good idea.

I've just measured up. The distance between the highest point of the cone and the top of the foam surround on the chassis is 5.5mm. The gap between the top of the foam surround and the grille is 4mm. So, the cone can travel 9.5mm before is just starts to touch the grille. If this were a problem, the solution would be to to move the grille further away from the driver using thicker foam on the picture-frame support, as Pete suggests. Or try to find some 11 x 19mm batten, although I don't think that's a commercially available size. As it stands, if the cone is audibly hitting the grille, it's a sign that you're about to wreck the driver. The above calculations only work as long as the grille remains flat. If it sags in the centre, you'll lose some clearance. That's why I like to provide an additional support for the centre of the grille. You'll see a central support in commercial bass cabs too, usually just a screw and a washer through the grille into the cab. It's very unlikely that this grille will sag in the middle unless it's pushed in. The purpose of the central support is to prevent that from happening. The foam strip that Pete referred to earlier was supposed to go on the top of the chassis to push the grill out slightly and hold it there. The trick works really well and is invisible in practice on most types of grille, but the one Pete is using is quite open and I can see that it would look odd if it pokes through.

Good job you mentioned it then. 🙂

Yes, top right is where I'd put it - sorry Stew. Definitely not top left because that will alter the frequency response of the horn. Its presence above the port is unlikely to have any effect on what's coming out of the port. You could always try it on the bottom or centre if you like. By the way, the badge doesn't look blue as in funkle's photo. The background is very dark blue, almost black. Given your contribution to this project, Luke, I think you deserve to have serial no. 002. It's yours.

Well thank you all very much! It's true that a number of Basschatters have provided valuable input that has made it possible to give birth to this cab, and I have tried to mention everyone along the way. However, at this juncture, I think a special vote of thanks is due to Pete (funkle). A cabinet building beginner by his own admission, he has worked under the glare of public scrutiny to draw our attention to the mistakes that lie in wait for the unwary - by making those mistakes on our behalf. Not only that, but the descriptions and photos in this thread provide an excellent guide for those who will follow in his footsteps. Now, about those T-nuts.... 😀

Anodising is definitely a professional job, unless you're happy pouring sulphuric acid in your bath and putting an electric current through it. The cost could be acceptable even for small quantities, but for a one-off you'd pay a minimum charge, which as far as I can tell, would be £50+. The same goes for powder coating. It's cheaper than anodising but I'd estimate at least £20 for a single speaker grille, unless you can persuade a friendly powder coater to stick a speaker grille in with something else they're coating at the same time. Spray Bike looks very interesting, but if you read the small print they say it needs a primer coat. So, I can't see any way round buying a can of etch primer and painting the aluminium grille yourself. I tried painting a corner of my grille with some normal spray paint, but it comes off easily. I'm going to get the weights of each of these grilles and will post the info later this week so that builders can choose the best option for them. There's also the option of a fabric grill, of course, with Fender or Marshall cloth, and if you decide to do that, be sure to post the info on the thread.

The way I understand the problem, Phil, is that the bolt has been cross-threaded and has jammed in the T-nut. Turning the bolt has forced the T-nut round, gouging out a circle in the rear of the baffle. So the T-nut is now spinning round but not gripping anything, and the bolt is stuck in the T-nut and won't come out.

Phil's suggestion of pulling the T-nut out to re-engage the spikes is definitely worth trying. However, I suspect that the bolt is tightly jammed and the T-nut might not hold. If you can get the mole grips to grip the T-nut tightly - you'll need to experiment with the adjustment a bit - jam the handles of the mole grips against the side of the cab. Then turn the bolt. When you get the bolt out, you'll need to fill the bit of the baffle that the T-nut has gouged out. Unfortunately, the Everbuld wood filler you have is only meant for use in thin layers, although it might work depending on how much wood the T-nut has removed. Two-pack wood filler or car body filler will work and will allow you to reinstall the T-nut. Araldite is another option. With any of these fillers, you'll need to re-fit your T-nut before they set hard. I think that repairing the hole will be a lot less work than filling all the existing holes and drilling new ones. If you need another T-nut, I can send you a couple on Monday - just let me know. When you've removed the offending T-nut, there's nothing to stop you finishing off the cab and trying it out. Just stick some Blutac over the spare driver hole.

Oh dear, just as you were nearly there!🤨 It looks like you've cross-threaded a T-nut. Drilling out the bolt is absolutely a last resort. What I suggest (and others who have some experience of jammed T-nuts might like to comment) is trying to grip the offending T-nut from the rear with a pair of pliers or, better still, mole grips. It depends how far in the bolt is, but you might be able to lift the driver up enough to get your hand in behind it. If you're lucky, you could even swing the driver out to improve access. Failing that, slide your arm in through the hole for the horn and try to get to the T-nut that way. You can get a lot of leverage on the bolt with an Allen key. This is ideally a two-person job. One person gripping the T-nut and another person trying to undo the bolt. While you're deciding what to do, put some lubricating oil on the bolt and let it seep into the thread on the T-nut. That should aid removal. Don't give up now!

Yes, that's definitely an option. I have a specialist aluminium powder coater not too far away from where I live and I'm planning to ask him for a quote - although I suspect a one-off could be expensive. That doesn't really help anyone else though, unless they can find a local powder coater who does aluminium (I believe aluminium uses a different powder coating process to normal steel). So I'm still going to look for a spray can that would do the job. It wouldn't need a thick coating - it's just to stop the aluminium tarnishing with age.

I think that's basically what the foam roller does in fact. It just speeds the job up and makes it easier to achieve a consistent finish.

Mine's 007.🤩

I am indeed. And there will only be one serial no. 001 - the one you are watching being built right here.🙂

I agree, it could be a nice look. I'll be hammering Google this weekend to find some kind of spray coating that works. Then we can all see how it looks.

I'm leaving my cab to harden up a bit overnight. It's dry now but the paint still seems a bit soft. I'm not sure it's a great idea to load it up just after painting it.

The difference in price between the steel and aluminium grille isn't that great - it's the cost of the primer that makes the aluminium one so much more expensive. However, Luke has just pm'd me with the idea of keeping the aluminium look (he keeps sending me these neat ideas). So if we can find a clearcoat to spray over the aluminium to stop it tarnishing, that could be a solution. Depends on how an aluminium grille looks, of course.

The expanded metal grille isn't that heavy, although obviously heavier than the aluminium one. I expect the punched mild steel one will be the heaviest, although I haven't actually weighed any of them.