What to do with your 2242s

[demanddeepbass]

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

[Steve Schell]

Hi Olly,

Wow, I wish I could have been there to hear your system! Yours was a noble and apparently successful effort, such as has been attempted by few. Congratulations.

I have found with my front loaded horn designs that low distortion extension to 20Hz. adds much to the believability of most any recording. I can only imagine what extension to 7Hz. or below in a large space must be like.

I have ventured into the room of Hsu Research at several CES shows. Dr. Hsu markets compact subwoofers using small drivers in relatively short cardboard tubes. Often he would place one behind the listening sofa, and even that small device could really rattle your giblets. A similar device scaled up to six meters in length must really be something.

Perhaps the long pipe functions similar to a horn in that it loads and damps the driver to well below its resonant frequency. In this case the driver functions as a simple air pump, with impressive results.

[JBL 4645]

Impressive most impressive I must have read this a few times over. The concept of this sounds too incredibly easy. I have two 15” JBL that I could use for a tube like sub system, but, where do I get hold of tubes that wide!? Most carpet tubes are too narrow? What to use?

[boputnam]

I've had this 2242 a while and ... 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.

Yea, I like them a great deal.

In my application - SR subs - they have a smooth FR and create less resonance(s) than other top-quality drivers used previously in the same cabinet. The result is more tonality and less muffled LF than previous = less filtering needed and almost no problematic house resonance. Bingo...

[pos]

Impressive most impressive I must have read this a few times over. The concept of this sounds too incredibly easy. I have two 15” JBL that I could use for a tube like sub system, but, where do I get hold of tubes that wide!? Most carpet tubes are too narrow? What to use?

Sonotube produce such cardboard tubes for cast-in-place concrete.

This could be of some interest for you:
http://www.passdiy.com/pdf/el-pipe-o.pdf

[demanddeepbass]

It's really hard to get hold of the sonotube brand stuff in the UK - I spent quite a long time searching. Eventually I came across Essex Tube Windings who make basically the same stuff:
http://www.essextubes.co.uk/
They were very helpful and can make custom make whatever size you need but this gets expensive. The 450 mm stuff that I used is one of their stock sizes and from memory it cost £117 for 6 meters of it. They looked like some kind of crazy rocket launchers when they were strapped to the top of the car!


Olly

[pos]

Olly,

Your JBL 2242 Cannon makes Bose's Acoustical Wave Cannon look like a toy !


Did you use eq of some sort?
How high in frequency do you think your sub could go?

[JBL 4645]

Thank you for the link. I was looking at the (concrete tube) coverings about 30 minutes ago before you posted, I noticed the name on the tube in one of the DIY threads on this site and decided to investigate.

I’m reading a PDF file at the moment on loudspeaker positions and there affects on room modes. http://world.std.com/~griesngr/asa05.pdf

[JBL 4645]

It's really hard to get hold of the sonotube brand stuff in the UK - I spent quite a long time searching. Eventually I came across Essex Tube Windings who make basically the same stuff:
http://www.essextubes.co.uk/
They were very helpful and can make custom make whatever size you need but this gets expensive. The 450 mm stuff that I used is one of their stock sizes and from memory it cost £117 for 6 meters of it. They looked like some kind of crazy rocket launchers when they were strapped to the top of the car!


Olly

Olly

I’ll give them a call in the morning do you think they’ll have some near to 15”? I saw how the bottom part is fixed with a piece of MDF cut to size and the sub bass driver securely attached to it. all I need is a lengthy tube not to long otherwise I’d never get the bugger though the door.

Unless I order two lengths and then attach them together in the room, I’ll see how I feel about this in the morning.

[pos]

Unless I order two lengths and then attach them together in the room, I’ll see how I feel about this in the morning.

If you decide to go that way then you should order two different lengths, one being less than 1/2 of the other, and install the driver in between.
This is what Bose did in its cannon as you can see on the picture I attached in my previous post, and it is supposed to smoother the response in the LF (say between 50 and 100hz) without affecting the VLF.

[A9X]

May I suggest you spend $25 on Martin King's TL software and model it before you start spending money of the tubes themselves. It's quite easy to use, well supported and the results match quite well against the sims.

[Michael Smith]

well the yanks won't know what we are talking about A9X,do you have one?
Regards
L34

[A9X]

well the yanks won't know what we are talking about A9X,do you have one?
Regards
L34

An A9X? No, I wish though. I use the moniker in honour of Brockie. I'll never forget the final lap at Bathurst in 79.

[Michael Smith]

Me neither, nearly a year ago it's all coming around too quick for my liking.Fond memories.
Fantastic day down here so the L34 has made it's spring appearance