stevie

If you were to fit more powerful drivers such as the Beyma, another port of the same diameter would certainly help and is perfectly feasible technically. 18mm birch ply cab, properly built, braced (no need to go mad), internally damped, a pair of good quality Beyma drivers - not many commercial 2 x 10s will keep up with that. And it will cost you £100 plus the damping, bracing and plastic port. There is no other way of getting such a big bang for your buck - especially as you will certainly get a few bob for your cheapo Eminence 10s. I'd also suggest you fit Speakons if you have XLR inputs, as they're an easy swap. If you decide to go ahead, get back to me and I'll work out the length of the ports for you (or you can do it yourself in WinISD). One last thing, not all tens are the same size. Check with the manufacturer's spec sheet to make sure your driver will fit.

I agree with JPJ. The only thing I would mention is that the cabinet seems to be tuned to 40Hz, which is on the low side. You will increase power handling a bit and maybe get a slightly punchier sound if you take the port out. A port length of 18mm should tune the cab to around 50Hz. My modeling program tells me you are exceeding xmax at around 100/150W.

What a great website you have!

Just to add to my previous post, there are a number of ways of minimising the pipe mode resonances produced by ports. The first one is to shorten the port, which increases the frequency and reduces the amplitude of the resonance. If you halve the port length you double the frequency of the pipe mode resonance, which will generally put it out of harm’s way on a bass guitar cab. The downside is that you have to reduce the diameter of the port at the same time, which may reduce the power handling of the port more than you would like. This is just one of the balancing acts you are faced with when designing a speaker cab. The problem is more difficult with smaller cabs. If you don’t want to, or can’t, make the port any smaller, a good solution is to put the port on the back of the cabinet, preferably near the centre of the cab. If you don’t want to do that, you can put a notch filter in the crossover to take out the offending frequency (you need to be a bit anal to do this, but I've seen it done). The final solution would be to use a midrange driver that covers the frequency where the port resonance would be.

Luke, it's the natural resonance of the port. I specified 4 x 70mm ports, as that's what Phil has fitted to the prototype. Unfortunately, that requires a port of around 10/11 inches in length which gives a low resonant frequency. It would be problematic leaving it like that because it would be audible, but there are ways of fixing it (in the mix!).

OK, here is a quartet of neo drivers. The Faital is used in the Bergantino CN series as far as I am aware, and the others are also found in commercial cabs. [IMG]http://i61.tinypic.com/j7usyv.jpg[/IMG] Pink is the Eminence Kappalite 3012LF Red is the Eminence Kappalite 3012HO Yellow is the Faital PR300 Green is the Celestion BN120300X

And here are another two popular 12" drivers in our box. All ceramic magnets so far. Blue is the Fane Sovereign 12-300 White is the Eminence Delta 12LF

Here are the simulations of the first three 12" drivers in our prototype box. I've tuned the cabinet to 50Hz in all cases. I'll post some more later, but I'm restricting this to three at a time for the sake of clarity. [IMG]http://i60.tinypic.com/2r4oow8.jpg[/IMG] Yellow is the Beyma SM212 Green is the Eminence Beta 12 Pink is the Celestion BL 12-200X

You can make quite a good case for the superiority of round ports, but I know Phil is using them in the prototype because they are easier to swap out.

[quote name='redstriper' timestamp='1398349853' post='2433268'] Looking good Phil and well done for keeping the weight down. Do you have an Eminence kappalite 3012LF driver to try in there? I am particularly interested in it's low end capacity for dub reggae. Steve. [/quote] I know weight of gear has been a hot topic with bassists for some time. My personal view is that a cabinet of this size should be made out of 18mm birch because it will be substantially more rigid yet will only to add 3.5kg to the total weight (even less when you consider the extra bracing needed for a 12mm ply cab). Everybody's needs are different though, and light weight remains a 'must' for many. Phil's choice of the Beyma is quite interesting, as it is relatively lightweight for a ceramic driver of this quality. I have a couple of 3012LFs, one of which will no doubt find its way into one of these boxes eventually. I know it probably doesn't bother you too much, Steve, but that chassis really needs a midrange unit to function properly (as Phil suggested). Now that we finally have a box, Phil has asked me to post some simulations of some of the more popular drivers on the market, including some we do actually physically possess, and I'll try to do that before the weekend. I think these might surprise a few of you......

I have a Carvin 1000W power amp (non-lightweight). It's got some intelligent features and build quality is very good. I have my doubts about support though: I sent them a straightforward query by email and it was ignored.

For most people that's true, JTUK, although I'm firmly of the opinion that swapping out an OEM driver for a top quality one is one of the most cost-effective upgrades you can make to your sound. You do need some background knowledge to do it properly though, as some swaps will work and others won't. Also, the cabinet often requires some modification to suit. You could easily improve on the OEM Eminences inside the TC 212 but you'd probably have to forget about having a coaxial driver.

The answer to your question is yes, the power (handling) of your cabinet will increase if you put more powerful speakers in it. As others have suggested, it's not necessarily as simple a job as it might appear.

I had one of these - for about two weeks. It was one of the Chinese-built ones. It was nicely finished and had a useful feature set. Even the piezo tweeter didn't sound that bad and I rather liked the GK 'growl'. The bad news started when I took a look inside. The driver had the smallest magnet I've ever seen on a speaker (well nearly!). It was really cheap and nasty. The cab itself was made from half-inch poplar or some other lightweight ply and constructed using staples and heat glue. The ply had obvious voids in it. The staples had missed the bracing in a couple of places and the brace rattled when you tapped it. It sounded quite good at low volumes but as soon as I turned the volume control up the cabinet vibrated in sympathy and it just sounded annoying. It was light, but that's because it was build like a packing crate - although it's not alone in that respect and there are lots of bassists out there using boxes like this and loving them. I didn't waste any time getting rid of it.

It would be interesting to know what the crossover is supposed to be. The picture of the x-over earlier in the thread shows four 100uF 40V *polarized* electrolytics and two diodes. That's a weird configuration. I wonder if somebody has changed the caps at some time (from bipolar).

Yes, thanks Keith for all your efforts. I do hope this has now developed into an annual bash.

I've upgraded most of the parts on my BB1100S over the years. Its main problem was being neck heavy, which I fixed with a set of Hipshot lightweight tuners. I've never looked back. It's also got a Schaller bridge, a Duncan Vintage P-Bass and a Duncan Musicman pickup. I've never felt the need to change the preamp. Your mileage may vary on the pickups. The Schaller bridge looks a lot better and is nice to adjust but probably doesn't change the sound one iota. However, if your bass is a bit neck-heavy, I strongly recommend lightweight tuners, as they will make your bass so much more comfortable to play.

I remember the original Brightbox speakers having rubber, not foam, surrounds. They were purely midrange drivers with a phase plug in the middle. They stopped making them last century. I expect any decent quality 5" PA midrange would do a similar job. Bass/midrange or hi-fi drivers are unlikely to be sensitive enough. Edit: I obviously missed the photo of the original drivers on the previous page.

Don't forget the Major's amazing contribution to this site: <http://basschat.co.uk/topic/74284-the-majors-bass-boot-camp-session-index-1-36/>

I'd like to thank all of who who brought and set up their rigs for us to try. They all sounded great in their own ways - not a dud amongst them. I certainly learned a lot.

We did, thank you. Just arrived back in Dorchester.

I think it's a Stingray. If my memory serves, it featured strongly in a thread on here about "The worst bass amp you've ever played" - or something like that. Found it for you: <http://basschat.co.uk/topic/198205-worst-amp-you-have-owned-or-had-the-luck-to-use/> Described by one experienced contributor as ".... the most toneless, lifeless waste of components I have ever had the misery of hearing. I hated the bloody thing." I suspect this wasn't the answer you were looking for.

Looks like I'll be able to make it too. I'd be interested in having a look at the Fearful, Jim. I'm not sure what to bring though - all my gear is heavily customized. Anyone interested in trying out a Seymour Duncan Double Back compressor?

[quote name='dannybuoy' timestamp='1392397618' post='2368257'] Must be a good amp if Gandalf uses it. [/quote] Yeah. Dolly Parton appears on their Artists web page. Must be good.....