Cubo 18

This is my first post here.I have 4 of this in an old keele's W-bin,can i use this in the CUBO 18?Thanks you!

www.jblpro.com/pub/obsolete/2240gh.pdf

Hi Cubo, is there much difference in SPL with the MAGNET inside the chamber as opposed to outside? I think you have mentioned that the SPL increased with the Magnet Out?

From a basreflex perspective: The magnet inside the chamber means the chamber is smaller, whcih means a higher tuning. The port on average has a larger surface area and thus a higher tuning.
With the magnet outside the chamber it means a larger chamber with thus a lower tuning. The port looses surface area which results in lower tuning.

From a horn prespective: The magnet inside the horn means a smaller horn volume, thus less effciency but a lower Fc. The chamber is increased which means better low frequency reproduction.
The magnet inside the chamber increases the horn volume (and area in front of the driver), it lowers the chamber volume and thus the low frequency reproduction.

Both the effect on the chamber volume and the port/horn volume are small, together they can just be noticed. With the magnet inside the chamber for maximum output between 50-90 Hz (up to a 1 dB). With the magnet inside the horn the Fc is lowered a full 3 Hz. Some drivers might give a bit more output around the 50 -63 Hz mark 8with the magnet outside the chamber), at the cost of 70 - 100 Hz, suggesting higher output, as usually a lot of output is centered at 63 Hz in most populair music.

I am guessing that if the cabinet was bigger then the cab could play higher freq's but the output would be lower?

If you mean lower frequencies in stead of higher frequencies you're correct. Cubo Sub has equal sensitivty (on average) in comparison with Cubo 15. The Fc is lowered up to 8 - 10 Hz compared to Cubo 15. Excursion is increased on average, to keep the volume of the cabinet to a minimum. Therefore 15" would work but as a rule of thumb an 18" would handle more power mechanically.

Hi Cubo, what about using p-audio c18-650el.will it work?

There is a very big chance that it will, however: It has many different T/S-parameter sheets floating on the web, some with inconsistant parameters. So it's very hard to do a simulation on it. Luckily Cubo 18 will work with a wide variéty of drivers (from V18-1000 through the 18LW1400 upwards the infamous 18" Kilomax). So there is a goof chance it will do just fine.

This is my first post here.I have 4 of this in an old keele's W-bin,can i use this in the CUBO 18?Thanks you!

Those are not the average loudspeakers T/S-parameters but they should work nicely (Cubo 18 Extended). Very efficient so 600 Watts should get you a long way.

Best regards

Cubo

Thanks Cubo. As usual your answers are brilliant. You are a true credit to this forum.

regards, smiley32

Do i need to damp the inside?Thank you very much!

Dampening materials should only be used in the rear chamber, without restricting the air flow to the horn throat. Differences between with, or without dampening materials are usually small in bass cabinets. In the next line of cabinets I will do some subjective testing. usage largely depends on personal preferences imo. Some dampening materials might extend the virtual volume of the chamber (10-15%), lowering overal efficiency a bit in exchange for a bit more low frequency extension.

@Jim: Thanks.

Best regards

Cubo

Thank you very much for the reply!

How should it be wired?Magnet in the box = normal phase?Magnet outside the box = reverse phase?

I use normal wiring for the magnet in the horn. Reversed for the magnet inside the chamber. However I test what sounds best to me for every new model.

Best regards

Cubo

Hey Cubo

Great plans. I gotta say I love the design of the cubo 12, 15 & 18.
Is it possible that you can sim the 18 with the RCF L18P300. I have 4 of them waiting for new homes. I am tired of lugging around double 18s.
Let me know if you think it would be a good fit and if it would sound better in these than in some empty SRX4718 cabs
Thanks a mil

No need to simulate the RCF L18P300, I've no doubt that it will perform well.

The SRX4718 will likely be able to be crossed higher, the Cubo 18 will be louder and looking at the specifications of the SRX4718 it will go just as deep.
I think wether you'll put it in a SRX4718 or Cubo 18 it will sound well.

Best regards

Cubo