stevie

That's the finish you get from the foam roller without trying too hard. (The badge looks great!) The shine on the bottom left is from the flash.

Best I can do right now, as the grille's not finished.

Flush mounting the handle is a nice idea but I think it looks best surface mounted because the edges are rounded rather than straight - you'd have an odd gap. I thought about fitting rear wheels and a retractable handle, but they cost the earth.

I hope you haven't spent your money, @stewblack because things are progressing more quickly than I'd expected. The cab kits are likely to be here early next week - probably before everything else is ready. If you can collect, you can probably have your kit next week if you don't mind waiting for the other bits and pieces.

But just wait till you see my grey one with the aluminium grille.......

That looks the business - and certainly outshines some commercially built cabs. "What, you built that yourself? You're kidding me!"🤩

On the question of a HPF on the GK, the measurements show that there is one but it's quite mild and is negated by the bass boost. It looks better with the tone controls set to optimally flat.

I'm not an expert on compressors, but as far as I can see, you need to set the compressor to catch and squash that initial transient.

This has been bugging me all weekend. There's no reason why the cone should have touched the driver on Pete's cab. There was a gap of 4mm between the driver frame and the grille, which means the speaker was moving 4mm beyond the frame. That's quite a lot of movement, to put it mildly. It's worth mentioning that exceeding xmax isn't necessarily a disaster, and exceeding xmax on transients is probably something we all experience regularly when we're playing loud. However, it shouldn't have happened in this instance because Pete says he wasn't playing at an outrageous volume. I can think of two possibilities, which are not mutually exclusive. The first is that sub-E-string frequencies were being sent to the cab. This is what Phil has suggested and it makes a lot of sense. The port has been designed to support the frequencies 40 to 80Hz, which is the bottom octave of the bass guitar. Below that, power handling reduces quickly, causing quite severe movement of the cone. The second possibility is that the amp's frequency response wasn't flat during the test. The specs on the GK amp review Pete posted mentioned +/-7bB. So I decided to take a look at the original review, which is here: <https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=2ahUKEwj1n8-e-dTkAhWoRhUIHe0eCYMQFjAAegQIARAC&url=https%3A%2F%2Fbassgearmag.com%2Fwp-content%2Fuploads%2F2017%2F07%2FIssue8.pdf&usg=AOvVaw03uQIy_EsBJQP-iYWC1vxL> Go to p. 74. Unfortunately, the graphs are a bit pixellated, but I'd say that, with its controls at noon, the amp has a baked-in bass boost of about 4dB at 50Hz and a strongly rising treble (+7dB at 10kHz). That could also account for the excess treble Pete noticed. It looks suspiciously like a Trace Elliot "smile" in fact. Optimally flat settings for the amp are Contour off, Treble 10 o'clock, Bass 10 o'clock, Hi-mid one o'clock and Lo-mid one o'clock. Back to the grille. I found some 3mm foam strip in my workshop and have decided to use that instead of adding batten. As long as I don't fully compress the foam, it doesn't poke through the grille. That gives me an additional 3mm of clearance. If the cone hits the grille now, it will be doing so at twice xmax, which is plenty - and just 4mm short of xlim. Perhaps a warning that you're about to reach xlim isn't a bad idea. I'll alter the Parts List for the batten accordingly.

It's not just the orientation of the horn, although that helps. It's also the fact that the HF driver extends quite low and compensates for the lack of mids coming out of the main driver when you're off axis (above or to the side of the cab). It's the "beaming" at midrange frequencies that causes lack of clarity when you're standing in front of the cab. Even if you do tilt your cab so that you can hear the mids and highs that are vital for tone definition, the audience will still hear the muffled sound that you are trying to fix. Unless your bass is going through a PA, of course, which is unlikely to suffer from this midrange dispersion problem. If you don't want to build your own, the only commercial cab AFAIK that deals with this problem properly is the Fearless F112 3-way cab - which also that also has a tilt facility for good measure.

Right, I'll see if I can get hold of some of that too.

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.