Post by: nathan Hulse on March 25, 2010, 11:23:19 AM
My question is, will LAB12 drivers work. I quickly worked out the volume to be ~42lts which is lower than the recommended for a ported cab. Also if they would work, the other thing I was concerned with, is the amount the speaker moves. Would the speaker grill restrict it? I think the distance from were the speaker mounts to the cab to the grill is 2cm. I'll probably be running the cabs (2) of one channel of a QSC PLX 2502, which has a 33hz HPF, in addition to a DBX drive rack for band pass processing.
Picture of one speaker.
I look forward to your input and responses. Any more info required I'll be happy to supply. Also note, we normally only use our own PA for smaller venues, most larger venues it's supplied. We play early 60's music and don't need huge amounts of bottom end, just enough to take away from the tops and a little extra bottom end warmth.
Post by: Silas Pradetto on March 25, 2010, 11:30:28 AM
Post by: nathan Hulse on March 25, 2010, 11:40:10 AM
Post by: Mike Smith on March 25, 2010, 12:53:29 PM
You will not end up with a subwoofer in the truest sense of the word but you will have a little thump down to around 45 or 50 Hz (if you have some decent power available) and give your top boxes some relief.
Keep in mind I'm making some very general recommendations! You will definitely want to look at specifics, like matching a particular driver's attributes and parameters to your box volume and port size. Other people on this forum (or dedicated speaker-building forums) can help you with that.
Post by: nathan Hulse on March 25, 2010, 02:01:33 PM
Post by: Mike Smith on March 25, 2010, 02:48:55 PM
Post by: Art Welter on March 25, 2010, 04:17:22 PM
| nathan Hulse wrote on Thu, 25 March 2010 12:01 |
Thats great Mike, thanks for taking the time to reply. I'm better equipped with information now, to have a better idea of what to look for in a replacement for this cab (and other). Just a shame I'm trying to squeeze a pint out of a half pint glass. |
I agree with Mike as far as replacement, but the original speaker works really well in that box.
I would check into reconing it, rather than replacing it.
Post by: Art Welter on March 25, 2010, 04:34:18 PM
| Silas Pradetto wrote on Thu, 25 March 2010 09:30 |
Not even close to the right woofer for that cab. |
Actually, Labs work pretty well in small cabs, tuned low enough.
The very long Xmax would require a grill standoff.
I still would go for a recone or a more similar cone to the original, as the alignment below would require longer ports than the Ramsa cab, but the size is not far off.
42 liters is 1.48 cubic feet.
Art Welter
Post by: Silas Pradetto on March 25, 2010, 04:48:12 PM
Post by: Rory Buszka on March 25, 2010, 06:11:36 PM
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.
Post by: nathan Hulse on March 25, 2010, 06:45:06 PM
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.
Post by: Art Welter on March 25, 2010, 07:47:35 PM
| 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
Post by: Art Welter on March 25, 2010, 08:06:10 PM
| 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...
Post by: Art Welter on March 25, 2010, 08:12:27 PM
| 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.
Post by: nathan Hulse on March 26, 2010, 07:26:53 AM
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)
Post by: Iain_Macdonald on March 26, 2010, 03:31:48 PM
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.
Post by: Art Welter on March 26, 2010, 04:54:50 PM
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
Post by: Craig Hauber on March 28, 2010, 07:45:02 PM
-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
Post by: nathan Hulse on March 29, 2010, 07:03:54 PM