stevie

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.

Thanks for the corrections, chaps - much appreciated. I've posted an updated parts list in response to your comments and to include an additional few items. Next week, I'll post the final drawings and cutting list (thanks RichardH) with the crossover circuit and layout for the Faital PR320/Celestion CDX-1425 system. Anyone wishing to cut their own wood and build their own crossover will then have all the information they need. All the quotes are now in for the CNC kit cab. I'll be choosing a supplier early next week and progressing the matter so that we can get moving on the kits again.

PVC pipe is not the easiest material to glue but silicon sealant does a reasonable job. Wood glue won't stick to PVC at all.

Standing waves certainly exist in loudspeaker cabs and most good designers spend time trying to minimise them. Some go to extreme lengths trying to try to get rid of them. They are particularly problematic in tall, hi-fi cabs, where standing waves occur at frequencies around 200 to 300Hz. There are a number of different ways that a designer can measure them. Dealing with them is more tricky. A typical bass cab isn't exactly small, and they tend to suffer from standing waves between 170 and 300Hz. These are critical frequencies for bass guitar and will colour the sound unless some steps are taken to keep them under control. I've found that felt is quite good at taming standing waves and flutter echos inside cabinets. It's also fairly cheap. Place more damping material at the end of the longest dimension of the cabinet because that's where the biggest problem is.

I thought it was great. Very professional but relaxed and informal. The teacher's personality came across well. He wasn't annoying (important!) and can clearly play a bit. Looking forward to your bass efforts. Well done!

Sorry, Stew, I should have been clearer. It's bitumen damping material used for sound deadening. Dynamat is a well-known brand. I happened to have some bitumen roof flashing in my garage and used that. It's not a critical component but the more fastidious amongst us will want to damp the thin plastic of the handle. By the way, the cab I now have is as dead as a doornail when you knuckle-rap it - a noticeable improvement on the previous one. The only difference between the two is that the braces are now inset into the panels whereas previously they just used butt joints. I've tuned the port and finished the crossover. I won't bore anyone with more frequency response curves - but draw a line with a ruler and that's what we've got. Off axis response is also exemplary.

That's a shame. It's such a great body of work. A pity it's not complete, but there's still plenty to be getting on with.

You're right, Ricky. I've just checked my hard disk and I don't have them. I'll check my laptop later today, but I think they might be lost for all time - unless someone else has saved them. The Major hasn't posted on here for years. I often wonder what happened to him. Retired maybe?

I've added a parts list to the very first post in this thread - and have taken the opportunity to delete the old drawings, which are now out of date. I'll post drawings of the latest version shortly.

This is a great way to get a great sound at minimum cost. This is going to sound fantastic! I'm intrigued to find out how you solve the port problem.

The cab is now connected up to my measurement system and I'll finalise the crossover at the weekend. The preliminary design I did last week is pretty close - so that shouldn't take too long at all. I'm also contacting CNC companies to see who can produce these kits for us at a reasonable cost. I'll report back when I have some news.

And this is how it's wired up. All the terminals are pre-fitted - you just need to push them on to the appropriate tags.

Here is the crossover with the cables connected. There is a terminal block on the crossover board with a label that shows exactly where each wire goes (it's a bit difficult to see from the photo, but trust me). Just insert the fork terminals into the appropriate connector on the terminal block and tighten the screws, as I've done here.

The final thing you need to do is to even out imperfections at the joints. I discovered a really useful, water-based wood filler from Everbuild that I used for this. It's not as tough as a two-part filler - so don't use it to fill chips in corners - but it's ideal for this kind of job. It dries in half an hour and sands really easily. Then hardens over time. Now you can paint the cab. I haven't shown the batten used for fixing the grille because I haven't got any at the moment. But it's not rocket science, and I will probably mention it when I get the grilles sorted out. I'm leaving my cab unpainted for the moment because I have to tune the port and tweak the crossover. But your next job when the paint has dried is to wire the drive units up. Ooooooh!

You now need to round off the corners. To prevent sawdust getting into the cabinet, it would be best to do this before painting the baffle and installing the wadding. But we wanted to keep the top of the cab open - so we're going to have to do it now. It would be a good idea to cut a piece of cardboard to place over the baffle. Because poplar plywood is relatively soft, you don't need a router for this job. An orbital sander is fine, finishing off by hand. You could even do it all by hand if you don't have a sander. The trick is to get the round edge of the cabinet to match your metal corners. It doesn't need to be perfect - it will look fine when it's painted, honestly. Remember to sand off each corner so that your metal corners fit.

This is where we are now. It didn't take long, did it?

You can give the front baffle a coat of blackboard paint now. You could, of course use Tuffcab paint, but I prefer to have a baffle that's matt black. You don't need to paint right to the edge, as you will be fitting some batten all round the outside of the baffle later. While the paint's drying, fit the top handle. It will have to come off later for painting, but it'll make it easier to carry the cab around for the time being. I stuck some bitumen damping material on the back of mine. If you have something suitable, you could do the same. This isn't the kind of touch you see in commercial cabs, but that's one of the reasons why we're building our own (isn't it?). By the way, the handle will need foam strip. You don't need to do it now but don't forget to do it later. I'm using woodscrews on mine, because six woodscrews into 30mm of plywood are not going anywhere - especially given the weight of the cab. You can, if you prefer, use t-nuts and machine screws. Up to you.