Thought you guys might like this :-)
It's a 2242 mounted in a six meter long 450mm tube
It was built for a composition project with 12 composers. The labour was divided up by frequency band. The band I was allocated/had to kill a few people to get, was 0-25Hz! There wasn't really any suitable equipment available for this band so I built this thing which turned out really well!
Because the band is mostly subsonic the main aim was to generate pressure waves in the venue so I went with a quarter wave pipe design which at six meters is tuned to 13.5 Hz.
The two subs either side of it are Cepia transmission lines with PD 1850s in. They were used down to about 16 Hz but didn't contribute much below that. The main reason for them is to add mass to the main enclosure (hence the ropes and straps). Without them the whole cab moved back and forth about 15mm at 7 Hz which lost me loads of output.
It was great fun to play with! You could feel the pressure waves all round the auditorium and see the doors flapping in the breeze. I also used 4 eminence buttkickers underneath the seats which were very effective in getting my message across. What surprised me most was how well this thing worked with real music which I hadn't really expected. The HF part was done with five Genelec 1038s which are a lovely speaker and have pretty good extension to 30Hz or so but this thing blended in really well with them and gave an incredible solidarity to anything we played. The distortion was extremely low and it just felt like a bass drop would keep on going down for ever. We tried it with films to and it was amazing, Top Gun, Lord of the Rings, Black Hawk Down, U571 and the middle bit of Pearl Harbour where everything blows up (lets face it the rest isn’t worth watching!). I've never experienced anything like it, better than any cinema I've been to, cleaner than any prosound rig I've heard and more powerful than any home theatre.
I've had this 2242 a while and not had the chance to play with it much but now that I have I have to say that this is a brilliant loudspeaker. I don't think the combination of efficiency, extension, power and low distortion is beaten by any other cone loudspeaker. I've used a lot of the big 18 inchers out there and some 21s and 24s but this is the best all rounder. I also have a pair of the sub1500s which are good but don't give as much raw output and control.
It was very interesting to see how different amps performed at really low frequencies. Most amps have some sort of low frequency filter but I'm not sure the differences I was hearing can't be attributed to that alone. I tried a crest CA9 a couple of Carver PM1200s and a Macrotech 2400. The crest was really not that impressive below 20Hz, distortion went up a lot and it just felt weedy and underpowered. This impression was heightened when it puffed a big cloud of smoke out of the front after 20 mins of full power at VLF and did nothing further.
I changed the main power caps in one of my carvers a while back and managed to shoehorn about four times as many farads in. This doesn't make much difference at higher frequencies but it’s much more solid in the low end than the other one now. I ended up using this amp for the 1850s as the macrotech was the clear winner here. Lots of people say bad things about them but it was cleaner and more solid than any of the others right down to 7 Hz.
Unfortunately I’ve had to disassemble it now as it was just too big to stay where it was. There are plans afoot to permanently install it under the seats with a PD 1850 in it but I expect it’ll take a while to sort out.
Sorry the pictures aren’t great, I whish I’d put more effort into getting really good ones now but I was having too much fun listening to stuff to pay much attention to pics!
Olly