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[nathan Hulse]

Cheers for your replies once again.

the dimensions are 21.15/16" (557) x 10.3/4" (272.5) x 15.3/8" (390)

I'll get the port measurements tomorrow, as it curls round inside the cab.

Your correct, we don't normally play large auditorium with our own system. However, we have on occasions had to use our own sound system in small theatres (200-400 people). How we got away with it I don't know, but that's another thing.

[Art Welter]

Silas Pradetto wrote on Thu, 25 March 2010 14:48

If it's limited to 113dB acoustic power, then I think he's going to need a bit more sensitivity to hear the sub at all. Even with a pair, 119dB is pretty much not even going to be heard when run with any decent mains plus guitar amps, drums, etc.

The McJerry chart seems confusing, I read the single Lab 12 Amplitude Response as 119 dB at 60 Hz, which seems to conflict with the solid line level below in the Acoustic Power chart. 119 dB at 400 watts corresponds to my ground plane SPL measurements.
At any rate, my real world findings are that the Lab 12 in a small ported cabinet can make some bass.  With an amp capable of 800 watts per cone, 122 dB peaks, 128 dB for a pair at one meter in the 60 Hz range can be had. Whether that is “enough” is subjective.
Regardless of cone type, a pair of 1.5 cubic foot boxes are not going to cave your chest in unless dropped from a sufficient distance.
That said, the single 4015LF below has satisfied a lot of drummers as a drum sub, and a pair of Lab 12 in a cabinet of the same gross volume would be capable of more output below 100 Hz.
In a small club, where the sub is basically just bringing the kick drum up to the level of a stage bass amp, that kind of output works.

The chart below shows three cabinets using the same drive level (voltage) shows a 2.58 gross cubic foot  Lab 12 (Lab Tiny) compared to a 4015LF in a 5.17 gross cubic foot box. The Lab 2x12 is 7.76 cubic foot gross.



Art Welter

[Art Welter]

Rory Buszka wrote on Thu, 25 March 2010 16:11

Actually, given the fact that the cab is essentially tupperware, I'd advise pairing it with a lightweight driver with a neodymium motor structure, like the Eminence Kappalite 3012LF. While it's unlikely that the OP will be filling auditoria with the sound from this box, pairing it with a lightweight driver would make it a convenient little thumper for bar band applications. The Kappalite has 9mm of linear Xmax, so it'll most likely have more grunt than the original driver. Of course, loading both enclosures with the new drivers is strongly advised so that the benefits of the better driver aren't negated by the distortion emitted by the overworked original driver. Nathan, can you also give us an estimate on the diameter and length of the ports? If so, we can get an idea of which drivers will work best in the box.

Kind of depends on what you think of as “thump”.

As you can see, the Lab 12 can do around 3 dB more at 50 Hz, but  4 dB less at 80 Hz..


Art Welter

I agree the Kappalite for the weight and the upper bass output would probably be a better choice.

The other question is bolt hole alignment and hole size...

[Art Welter]

nathan Hulse wrote on Thu, 25 March 2010 16:45

Cheers for your replies once again. the dimensions are 21.15/16" (557) x 10.3/4" (272.5) x 15.3/8" (390) I'll get the port measurements tomorrow, as it curls round inside the cab. Your correct, we don't normally play large auditorium with our own system. However, we have on occasions had to use our own sound system in small theatres (200-400 people). How we got away with it I don't know, but that's another thing.

Some people forget that music does not require sledgehammer levels to be enjoyed.

It has been over 18 years since I heard these cabinets in a demo, I did not remember the curved port. I was impressed at the time with how well the cabinet kicked for being such a little bugger.

The extra port length is encouraging, longer ports tune lower.

[nathan Hulse]

For extra info on our band. We'll were not a loud band. We can fart on stage and hear it. Most sound guys say we're great to work with for that reason. We don't need huge amounts of Kick (with some venues we unplugged the kick mic to stop the sound guy pumping it through, (despite being told easy on the kick) it's just not how we should sound. We use vox AC30 amps and a old jazz kit for our sound. I aim for a 90db sound level at most venues, UK law says an average of 80db over whole performance including speech and breaks. We do have CD available on amazon, HMV and track for download on itunes, we're not famous. We're known as having a very authentic early 60's british sound. Huge bottom end isn't needed in the same way todays acts need, Although I would prefer 15 or 18" cabs. We just need a slightly fuller sound at the bottom.

I have the port dimensions 13" long; they curve round in a J shape. Longest side 11" shortest 15" diameter 3 3/8"

cab dimensions again
the dimensions are 21.15/16" (557) x 10.3/4" (272.5) x 15.3/8" (390)

[Iain_Macdonald]

Nathan,

If you are getting nowhere with finding a replacement driver. Try calling Paul McCallum at Wembley Loudspeakers (Hammersmith). I am sure that he will find you a recone kit or a replacement driver. He has competitive pricing on Eminence and Fane.

http://www.wembleyloudspeaker.com/

Iain.

ps Paul plays/played bass with Zoot Money and Georgie Fame etc so you will like the 60's/70's vibe.

[Art Welter]

The tuning (fB) is probably 45-50 Hz.A KappaLite 3012LF would work well in the cabinet if the bolt holes and cutout are the same. On paper it is around 96 dB sensitivity and goes lower than the stock cone which is 91-92 dB sensitivity.

That said, considering you don’t have a huge amount of power, your requirements are not extreme, and improvements don’t look to be huge, I’d still recommend reconing the bad cone if you can.


Art Welter

[Craig Hauber]

I have a bunch of those I've been playing with for years trying to find a good replacement cone.

-Anything Eminence won't fit the circle cutout,  Ramsa used an odd size hole that i'm sure a little carving larger could be done.

-The magnet on any normal deeper pro 12 hits the ports.  (they have a right-angle bend and go partway down the back wall of the cabinet.  Lab-12 definitely doesn't fit.  circle too small and magnet too big.

There's a little TOA 12" sub cube that looks to use a very similar (if not a copy) of the ramsa driver.  I haven't tried any but it looked so similar that I found it worth a look. -you might try their parts dept,  (I've installed every one I had my hands on)

The neo idea mentioned a few comments up would probably work because the magnet is so small.
I was also going to try those thin car audio type subs such as:
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295- 136

[nathan Hulse]

Based on the last post, it would seem that the best option is to get them re-coned. I had previously read somewhere that RAMSA speakers sizes are unique to them. Thanks to Iain Macdonald for the link. I have contacted the person I purchased these from, as they claimed they both worked. They will be getting them re-coned (or replaced if they can find another) for me.