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A spot of reverse engineering...

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demanddeepbass View Drop Down
Young Croc
Young Croc


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    Posted: 09 June 2009 at 1:31pm
I have a couple of 2X18 reflex boxes which used to house beyma g-400. These are all blown and I'm looking to make them a bit more ballsey as they'll be driven from a QSC 5050 the does 1800 watts into 4 ohms. The volume for each driver is 183 litres, they have a 100mm port which is 140mm long. I tried modelling Void V18-1200 and beyma 18P1200Nd but the results wern't great: they both want a smaller box. Ideally I don't want to modify the cab. I spose I could fill them with bricks to bring the volume down!!
Anyone got thoughts on a good quality driver with lots of watts that I could try?


Edited by demanddeepbass - 09 June 2009 at 1:36pm
"These amps go up to 11"
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SteveAATW View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SteveAATW Quote  Post ReplyReply Direct Link To This Post Posted: 09 June 2009 at 1:51pm
Unless I'm going mad V18-1200 is quite a hard cone, won't work well in reflex. You thought about a B&C 18" (eg 18TBX1000) or Turbomax 1000?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote adambomb Quote  Post ReplyReply Direct Link To This Post Posted: 09 June 2009 at 3:06pm
Originally posted by SteveAATW SteveAATW wrote:

Unless I'm going mad V18-1200 is quite a hard cone, won't work well in reflex. 
 
Umm.. think the v1200 has a slightly lighter cone than the V1000.. and was actually designed for scoops and reflex designs (unlike the V1000 that has a heavy cone and designed for horn loading).
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Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SteveAATW Quote  Post ReplyReply Direct Link To This Post Posted: 09 June 2009 at 5:11pm
Hmm - mad then. Knew it was one way or the other, wrong way round. No doubt even if it works though the op will have a hard time trying to get hold of them LOL
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Post Options Post Options   Thanks (0) Thanks(0)   Quote opus jody Quote  Post ReplyReply Direct Link To This Post Posted: 09 June 2009 at 5:14pm
Is it an old opus 218?
measurements sound familiar.
Improvised Hardware Music http://vimeo.com/user9389813/videos
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demanddeepbass View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote demanddeepbass Quote  Post ReplyReply Direct Link To This Post Posted: 09 June 2009 at 10:28pm
Don't know but it wouldn't surprise me at all. It is very well built from marine ply and carpet covered in black. Couldn't find a logo on it but it is under a stage in the dark! I found an opus wedge at the back of a cupboard so it may well be. Drivers were made in '96


Edited by demanddeepbass - 09 June 2009 at 10:29pm
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ceharden View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 09 June 2009 at 10:32pm
My personal preference is for the 18Sound 18LW1400.

Any of the B&C 18" sub drivers would work, all of them would sound slightly different.

183 litres is a good volume for most sub drivers.  What did the tuning come out at?  I would want to see it in the 35-40Hz range.

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Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote demanddeepbass Quote  Post ReplyReply Direct Link To This Post Posted: 10 June 2009 at 12:10pm



Actually looking at this again I've had a thought. I was messing with the tuning to get the void and the Beyma to match the port length that's in the cab so I didn't have to get a saw out! If I leave it alone the void tunes to 38Hz, the beyma to 44Hz and the 18sound to 43Hz. The Void wants a port of 17mm so I could just pull the tubes out and use the front panel which is 18mm deep. I've never done a cab with a port this shallow before does it work or do things get odd?
If it's probably ok then the Void looks pretty good!
Interestingly the Bema G400 looks rubbish! I fiddled the tuning till the vents matched (it's tuned to 24.6Hz) and it is not at all impressive. Even if you assume the cab is well made and up the QL to 15 it is still not good. Mind you I never quite trust Win ISD. I'll bass box it when I get home and see how it comes out.


Edited by demanddeepbass - 10 June 2009 at 12:25pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mobiele eenheid Quote  Post ReplyReply Direct Link To This Post Posted: 10 June 2009 at 12:17pm
I'm not really familiar with that version of WinISD but IIRC the vent mach should be in green letters and below 0.05. The newer WinISD Pro a.7 corresponds to the sticky guide in the newby section.
 
For an 18" you should at least use 3 of those ports (~225 cm^2) but area's of 500 cm^2 are also common. This will off course increase the vent length.
 
Best regards Johan


Edited by mobiele eenheid - 10 June 2009 at 12:18pm
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demanddeepbass View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote demanddeepbass Quote  Post ReplyReply Direct Link To This Post Posted: 10 June 2009 at 12:33pm
Yeah, I was surprised by the lack of port area on this cab. I didn't really want to have to get my saw out but I think I might have to with the more powerful drivers or it's going to sound like a steam train! Very little space left on the front panel though. These might be getting top ports!
"These amps go up to 11"
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