Turbomax Reflex - It begins...

Elliot Thompson wrote: That would make matters worse considering how small the box is. Inefficiency only plays a factor if the designer did not take in account how much room is lost in the internal chamber. The weakest link is always the panel in which the driver sits on and, the rear wall of the enclosure. Having an 18-inch driver placed on an 18 mm board with no means reinforcement will have the entire box dancing around the venue. Best Regards,

How on earth do you work that out, even if you just braced across the chamber space with 25 dia dowel the sides would be more rigid than with the corner braces.

Because of the size of this box baffle bracing is irrelevant, to get the baffle to vibrate (distort ) the driver frame would have to bend er. I don't think so.

Tony

Tony Wilkes wrote: Elliot Thompson wrote: That would make matters worse considering how small the box is. Inefficiency only plays a factor if the designer did not take in account how much room is lost in the internal chamber. The weakest link is always the panel in which the driver sits on and, the rear wall of the enclosure. Having an 18-inch driver placed on an 18 mm board with no means reinforcement will have the entire box dancing around the venue. Best Regards, How on earth do you work that out, even if you just braced across the chamber space with 25 dia dowel the sides would be more rigid than with the corner braces. Because of the size of this box baffle bracing is irrelevant, to get the baffle to vibrate (distort ) the driver frame would have to bend er. I don't think so. Tony

What are you basing that on?

Have you ever experienced 18-inch drivers shaking the enclosure to the point it begins to move?

I have yet to see an 18 mm panel maintain it's strength holding a 13.6 kg 18-inch driver while it is moving as a piston without the aid of bracing under long-term conditions. Having to fasten your bass cabinets together with straps to prevent movement @ high SPLs means the box is too light to manage the air pressure build up caused by the woofer. Finding yourself tightening the T-Nuts from time to time is another sign of the box not braced enough to prevent the driver from flexing the baffle board.

There is a huge difference generating 40 – 30 Hertz when the air pressure increases in the cabinet substantially oppose 60 – 50 Hertz in a reflex bin.

Best Regards,

Elliot Thompson wrote: What are you basing that on? Have you ever experienced 18-inch drivers shaking the enclosure to the point it begins to move? I have yet to see an 18 mm panel maintain it's strength holding a 13.6 kg 18-inch driver while it is moving as a piston without the aid of bracing under long-term conditions. Having to fasten your bass cabinets together with straps to prevent movement @ high SPLs means the box is too light to manage the air pressure build up caused by the woofer.

Normally true...

I would say best assembled/constructed/most braced cabs I have ever owned are ASS 18" scoops.

However, Paulus has got these to move around with enough power, and Turbomax drivers.

Elliot Thompson wrote:

How on earth do you work that out, even if you just braced across the chamber space with 25 dia dowel the sides would be more rigid than with the corner braces.

Because of the size of this box baffle bracing is irrelevant, to get the baffle to vibrate (distort ) the driver frame would have to bend er. I don't think so.

Tony


[/QUOTE]


What are you basing that on?

Have you ever experienced 18-inch drivers shaking the enclosure to the point it begins to move?

I have yet to see an 18 mm panel maintain it's strength holding a 13.6 kg 18-inch driver while it is moving as a piston without the aid of bracing under long-term conditions. Having to fasten your bass cabinets together with straps to prevent movement @ high SPLs means the box is too light to manage the air pressure build up caused by the woofer. Finding yourself tightening the T-Nuts from time to time is another sign of the box not braced enough to prevent the driver from flexing the baffle board.

There is a huge difference generating 40 – 30 Hertz when the air pressure increases in the cabinet substantially oppose 60 – 50 Hertz in a reflex bin.

Best Regards,


[/QUOTE]

I am basing that on experience and oh yes a degree in structural engineering!!

As I sell BMS products in the UK and personally use 18N850's in my own boxes I might have some idea.

For your information the pressure in a 18" reflex box even with a very high Xmax driver is in fact actually very low. Do the maths!!! If your bolts come loose simply put a low strength thread locking agent on them.  Trust me small baffles like the one above do not flex.

Tony


Edited by Tony Wilkes - 06 July 2009 at 8:27pm

Forgot to add the movement of whole cab is caused by vibration. Google "vibratory conveyors" if you want to see how effective this can be.

Tony


Edited by Tony Wilkes - 07 July 2009 at 8:39am

Elliot,

I think you will find it is added mass that is stopping your cabs from moving!!!

I will say one more time on the box as shown in the original photo the thickness of the baffle is almost immaterial as the driver frame will be taking most of the load. Where it is transferring this load back to the wood it is already more than stiff enough due to the close proximity of the side walls acting as a brace.

You could probably get away with 10mm (3/8") without it flexing in the slightest.

Now if it was in the middle of a 4 foot square baffle, that is an entirely different matter and would need either a thicker component or bracing (or even a stronger material).


Now the inside part of the port on the above box that's a different story and wants bracing to stop it flexing.

Best Regards

Tony