stevie

That's interesting, Shrek, thanks. I have to agree with Bill Fitz on this: manufacturers tend to be more interested in how a cab looks than how it performs. Love the crossover!

I could estimate it: 7kg wood. 4.3kg Beyma 12. 1kg Celestion compression driver and horn. 2-3kg crossover, handle, feet, grille, paint. It should be under 15kg anyway. Going neo would take that down to about 12kg. But let's see what John's scales say. The grille works well but I think it needs some piping to finish it off. Perhaps carpet would be an easier finish than paint for the occasional builder. I wonder.

What a great turnout. I was at the last two SW bashes but had to miss this one because of work. Keep the pictures coming!

That template will prove invaluable. I found it really tricky (i.e. messy) to cut the oval shape out on the prototype and wish I'd had it them. I think it needs to be pinned to post #1 so that all the reference documentation is in one place. [Edit - I just tried to pin it, but it looks like no more than 3 PDFs can be pinned to any one post. We'll consolidate all these files when we're done.]

Paint doesn't have any symbols either; I just drew them as lines or rectangles. It would have been nice to have been able to copy and paste them once I'd drawn them once, or to move them if they weren't quite in the right position. Google Draw does look good, but I found that I can do what I want with the Open Office drawing application. But many thanks for the pointer, 6v6.

Here are the corrected versions.

Oops! I knew there would be something. Thanks for spotting this, tauzero. I'll fix it now.

The drawing progam in Open Office is excellent. Thanks for the tip!

I'll give it a go. I've just tried three other highly recommended drawing programs, but they're not as intuitive to use as Paint. I just need a copy-and-past feature so that I don't have to draw everything from scratch, and the ability to save text as text, so that I can edit rather than erasing and re-writing.

Here's the HF section. Can anyone recommend anything better than Microsoft Paint for this kind of stuff? [IMG]http://i64.tinypic.com/n2g16q.jpg[/IMG]

We're a bit under time pressure here, what with the SW bass bash looming. I've wound the coils for John's cab and he will be picking them up tomorrow. All very skin-of-your-teeth. So here is the LF section of the crossover with the board layout. Please shout if you see any silly mistakes. There will be a PDF pinned to message # 1 in due course.

Supporting the section between the port and the horn is a good idea. A simple strut on the baffle would suffice, but a triangular piece is even better. I like the grille too. It's a lot tougher than your usual fabric but a lot lighter than perforated steel. Let's hope we can iron out the assembly snags. Another thing..... I've found that you can apply Tuff Cab to other finishes all right. I think that the distributors are perhaps being a bit over-cautious with their advice. Of course, there's always a first time.

[quote name='sk8' timestamp='1490741199' post='3267658'] Maybe I've spent too much time on TB.......... [/quote]

They fit an MP520.

These are the components that John will be fitting to his cab. A P Audio PH-170: and a Celestion CDX1-1455 compression driver: My prototype version looks something like this: It is worth mentioning that 1" exit compression drivers come in different voice coil sizes. The most expensive versions have 1.75" coils. This one has a 1.4" coil, which offers a good compromise between performance and price as long as you don't try to use it too low. But it works well down to 2kHz. I have always found that compression drivers with 1" coils sound really tizzy and are only useful as supertweeters. Some bass cabs manufacturers use them, however, because to most people a compression driver is a compression driver. Because we are unable to take advantage of the natural rolloffs of the drivers this time, the crossover is more complex. Also, this is a constant directivity horn, which by its very nature requires a more complicated crossover circuit. The design is finished, and I'll post the details of the crossover, the crossover layout, frequency resonse and impedance measurements as soon as I can. Despite the fact that the horn and driver only cost around £50 together, this is probably the most advanced HF unit on any bass cabinet on the market.

Yes, well I noticed. But would you say it to your friends down the pub, or is this an internet thing? I'm not being critical - I am genuinely curious.

My printer packed up leaving me with about 20 cartridges, a few originals but mostly not. They fit the following Canon printers: IP3300, 3500, 4200, 4300,4500,5200, mp500, 510, 530, 600, 610, 800, 810, 960. They are CLI-8s and PG-5BK. They're all brand new, sealed and boxed. I'd prefer pickup from Dorchester at the moment. If there are no locals who can use them, I'd be happy to pack them if you can arrange for them to be collected.

I'm just idly wondering whether people actually say "pull the trigger".

Not really a purchase, as BC member Alyctes generously gave me a Behringer BX4500H head; I just needed to replace the internal fan to get it working properly. Anyway, I took it to a two-hour rehearsal recently and kept switching over from my normal Tonehammer 500 to the Behringer - both set flat into a very transparent cab. I listened very carefully. There was *[i]no discernable difference[/i]*. How is that possible when the TH500 is considered to be the cream of the current amplifier crop and costs about £800 while the Behringer originally cost about £180 and can now be picked up for peanuts? This was a bit of a reality check. Definitely recommended for anyone on a budget.

The speaker used in the F112 certainly woofs very well indeed. Interestingly though, the Beyma SM212 we used in the BC 1x12 DIY cab goes just as low. I have both here and have measured them in the same cab. If I didn't roll my own, Greenboy's creations would definitely be at the top of my wish list.

I believe the Matrix guitar amp has the damping factor artificially lowered to give a "looser" type of sound preferred by guitarists.

This is why I spent the time sorting out the bracing. With a birch cab, a circular brace above the driver, one behind the driver and one on the top panel would be more than enough. If weight isn't an issue, that would be my first choice for performance. 7kg sounds good though.

[quote name='The Shrek' timestamp='1489696507' post='3259092'] Hey guys, I can't stress enough about sourcing good plywood. [/quote] Totally agree with this. If you are going to spend your valuable time building a cab like this, don't dry to save pennies on the wood. You can make this cab from just 1/2 sheet - so it's not that much more to get the good stuff. Cheap plywood will just not do the job properly. If you're going to use normal ply, get Finnish or Russian birch plywood. If you're going to use poplar ply, get the Italian stuff. Unless you're a wood expert, avoid anything from China.

I quite like the idea of using round holes for this. I imagine it would be a lot quicker.