HOG SCOOP PLANS ANYONE??

 

The main problem will be the cone lossing control at and around the low cutoff point (Fc). A driver with a more powerful motor can help here, but you don't want really tight either as some amount of lack of control must be present too. So the V18-1000 is probably too tight for a long scoop and mush motors like the Kilomax 18 pro are too lose. In between the two and towards tighter seems to be the way.

 

The surround will also play a big part in control too. Some surrounds are too lose and cannot control the excursion at low frequencies. These drivers will have a very high Vas and are to be avoided in scoops. Its not all motor control. You can have a very powerful motor system with a BL of over 36, but have a weak surround that will give the driver a high compliance. This means the driver will function quite well when the coil is still in the gap, but lose it very quickly after this. This is a no no for scoops as they do little to help with the damping below Fc. And even above Fc the fact that its a none symetrical design means damping can be quite bad. The other extreme is a driver with a strong surround but weak motor. This driver would have a high Qts and low BL. The Vas would also be low. Depending on the rear chamber size of the scoop this kind of driver is better suited to scoops. Many car woofers are like this. They have to have good control of the cone after the coil is out of the gap as they mostly get used in sealed boxes which increases the excursion of the cone, and need a weakish motor system to unload enough to get low bass.

 

Designing any driver is a balance of the compliance and the motor system strength. I would rather go for a slightly weaker motor and stronger suspension system with scoops. But that would require a smaller rear chamber. Trouble is that most strong motor system drivers also have a tight suspension. This can give a very high output in scoops with a small rear chamber as Lev's sims are showing, but the low end performance is compromised a bit. Enter the V18-1200. This is why I'm saying its the first driver designed for scoops, as it can control the excursion when the coil comes out of the gap well and can also give low bass due to the motor system not being the srtongest around. When most drivers are designed its not a prerequest that the surround has to try to control a cone that has decoupled because of the nature of a scoop. I know what happens below tuning in a scoop and tried to make the best compromise between control and low frequency output. Funny thing is, by doing that I also ended up with one of the best sounding large woofers I've ever heard.

 

Rog.

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