stevie

I suspect that if Al were interested in all that geeky, nerdy stuff, he'd have read it already. Allow me to summarise. The original thread, which is probably another 28 pages, was Phil Starr's original idea. He suggested that a few of us should get together to design a bass cab that would perform well, be relatively cheap, and be easy for DIYers to assemble. Phil's background is in hi-fi while mine is more in PA, but neither of us had designed a bass guitar cab before. So it was a bit of a learning process for us, and we shared the lessons we learned with the Basschat community in the Diary thread. We came up with a cabinet equipped with a single, high-performance driver. Phil also made a more compact version, which he assembled in about 20 minutes in front of an admiring audience at the last South West Bass Bash. The video is online and well worth a watch. The next stage in this project (where the Continued thread begins) was an attempt to design a compact DIY bass cab that would compete with high-end commercial products. It wasn't an all-out, cost-no-object design, as we did keep a eye on costs, but there was no skimping on either components or materials. One of the goals was that the cab should be able to handle the output of the many lightweight 500W (into 4 ohms) amps on the market. By this time, I had come to the conclusion that an FRFR design was by far the best design approach for bass guitar (and not just with modellers). So I published a design based on the Beyma 12" driver we had been using very successfully up until then - but with a compression driver and horn. Surprisingly, I thought, didn't attract much attention. The next step was to work on the weight factor. So I chose a couple of very high quality neo drivers and designed a system around them. The first one I built was demoed at the South West Bass Bash and went head-to-head against several expensive branded cabs. The latest version, which will be available as a kit (soon, honest!), took into account some of the comments made at the Bash. It is slightly larger, which extends the bottom end response a tad (it should now be similar to the Fearless in this respect) and I've modified the crossover to reduce a slight excess in the midrange. Basic specs just for Al - power handling: 300W AES, weight with metal grille: 14kg approx., frequency response: +/- 1dB from 80 to 18kHz, 8 ohms. The major design feature as far as I'm concerned is that you can hear your bass very clearly even when you're directly in front of and above the cab. Not only that, but the sound you hear in front of the cab is the same as your audience hears when they're 20 feet away; it doesn't change. It's all about dispersion and power response (but let's not go there now). It plays music like a monitor. So your bass sounds like your bass, or like it would through a console and monitors in the studio. It also has the ability to kick like a mule. During the demo at the SW Bash, Phil turned the volume up and it did that physical chest-hammering thing that you get from big systems with subs. You should be able to build one for about £300, thanks to some canny purchasing input, although experience has shown that the costs of DIY projects can easily escalate if you're not careful. No pics of the final cab until Blue Aran deliver my paint - but it'll look good.

pm'd

Send a pm to John, who is Chienmortbb. He's been looking into sources for the B&O modules recently and might be able to help.

On the matter of finishing, one of the beauties of rolling your own is that you can choose the finish and colour you prefer. If you're using paint, which I think most people will, you can easily change the colour to suit your mood, or if you see something you like better - not something you would want to do to your expensive Bergantino. I notice, for example, that Tuffcab is available in orange. So that's an easy way to match the cab to your Orange amp. I've been waiting for Blue Aran to get some light grey Tuff Cab back into stock, but it's not happening. So I'm going to order some of the new matt black Tuff Cab and use some pigment to make it the colour I want. I want a Marshall-ish tolex kind of finish. I'll post the results, as I think that could be a useful option for some.

The waiting list is starting to build for the second batch. So, JohnA, just send me a pm and I'll put you on the list. If we do get to 20, I think I'll have to call a halt there. I've been taking a crash course in CNC routing. Luckily, Chimike has kindly agreed to sort out the CNC files for me, which should ensure a more reliable and cheaper result. This is definitely becoming a group project, and it's very good to see Basschatters chipping in to help where they can. Please keep your woodglue warm and your clamps at the ready. This will happen. And it'll be worth the wait.

My goodness, that deal was three-and-a-half years ago. Oops. Better late than never, eh, Colin?

Just catching up on my feedback and I noticed Colin says he bought "some kit" from me a while back. I can't remember what the kit was, but if the sale had been anything other than perfect, I would definitely remember. Glad to add to his feedback thread.

Bought my Ibanez SR500 bass - a while ago actually, I'm only just catching up. Everything went well and I'm happy to start a feedback thread for him.

Catching up on my feedback - sorry for the delay. Dave sold me a set of very nice Gotoh tuners. They were new and I got a nice discount. So I have nothing but good things to say. Recommended.

Rechargeable batteries. Now there's a subject. There isn't a voltage problem with the 9-volt ones. They all measure 9 volts. In fact, most measure just over 10 volts when fully charged. The problem ones are the 1.5V ones, which only produce 1.2V. It's not normally a problem, but it can be for some devices that really need 1.5V - like my Canon camera, for example. The only exception to the 9-volt rule are the Li-Ion ones just mentioned. I can only speak for the ones I have, of course, but both of them are max. 7.2V or so. If your device is OK with that, they do last for ages. But unless they've changed them recently, they won't produce 9 volts. A handy tip from someone who's been using rechargeables for over a decade. The best rechargeables by a country mile are made by Eneloop (Panasonic). I'd certainly not buy any more Energizers - most of mine failed after a year - I have pre-Eneloop Panasonics that are still going after ten years. Another tip: Ikea sell Eneloops under their own brand for a fraction of the normal price. Google it. For some weird reason, Eneloop don't make 9V batteries though - which is a shame.

Would any of you CNC specialists consider contributing to the Basschat cabinet project by casting your expert eye over a dxf file and making a few tweaks?

The U-shaped piece is the largest piece but I'm sure you'll be fine if you cut it to the right size first.

It's all good. Now everyone knows to treat the felt with care - something I should have mentioned.

I did quite a bit of work to arrive at the damping for this cab. I tried polyester wadding, acoustic foam and different types of felt. The one that was most effective at damping the main standing wave was the 'fluffy' felt that I used in my first cab. However, I decided to recommend the firmer, needled felt because it's more practical - it stays in place better. It may well be that some combination of the two is the answer, but that will have to wait until I have more time to experiment. The point of internal damping is to minimise internal standing waves and the reflections at higher frequencies that travel through the cone. The damping efficiency of the different materials available varies by frequency, but here we need something that works down to a relatively low frequency, as the main standing wave is about 250Hz. As you can imagine, the more damping material you use, the more effectively you damp internal reflections. On the other hand, use too much and you'll kill the output from the port. What I did originally was to measure the output from the port with no damping in the cab. Then I used different quantities of the various damping materials whilst observing 1. the output from the port and 2. the behaviour of the main standing wave. The balancing act involved is in minimising the standing wave whilst maximising the port output. I'm afraid the only way you can do this scientifically is by measurement. As Sharkfinger says, the needled felt is fragile - so you need to handle it carefully. If you grab it and pull it, it will come apart. But if you cut it to size before fitting it to the cab you won't have any problem, especially as each piece you fit is fairly small anyway. Take a look at the photos on the previous page.

Oh, and I've added tweeter protection to the crossover. Bass guitar is never going to stress the compression driver in this system, but better safe than sorry.

Thanks to the stupendous work of RichardH, I am pleased to announce that we have the final drawings for the complete design of this latest version. On page 1 of this thread you'll now find a PDF containing the technical drawing, exploded assembly view, wood cutting list, crossover circuit and crossover layout - everything, in fact, that you need to build one of these from scratch. LukeFRC, who's about to go on holiday for two weeks, has done a great job with the design for the logo and name, and has sourced and ordered badges for the grille, and stickers for the handle and input panel at a price that is difficult to believe. They'll be available when he gets back, and I think I should let him do the reveal. The CNC cabinet kits are progressing at a pace that is causing me to pull my hair out, but we should have one or two pre-production prototypes soon. I expect these to be perfect, but it would be foolish to order an entire batch without making sure. The first two will go to those in the queue who are close enough to the supplier to collect. Failing that, I'll offer them to those who placed their orders first.

Decisions, decisions... The good thing about that driver is that it works well in a relatively small cab.

I know how good it sounds, Shark - I've got one myself. I did a very similar project to this a few years ago, but with an Ashdown Mini 15 cab. Yours should have a bit more lower-end oomph. The midrange tone from that driver is just fantastic, and I've now got it in a larger cab. Unfortunately, not many people are prepared to spend £200 on a 15" chassis. But we know better.😀

It's a genuine 500-watt driver. Don't worry about it.

Not a bodge job at all - that looks fine. I should have warned you about the difference in driver sizes. You almost always have to open the driver hole up when switching from a pressed steel to a cast chassis. My tool of choice for that is the jigsaw. When were you thinking of connecting your amp?😀

Fixed! Thanks tauzero. 🙂

If there are any other queries about the parts list, please post them. I've included supplier information whenever possible because some of these bits are not easy to source, but if you know of a better/cheaper supplier, do let us know.