Turbomax Reflex - It begins... |
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Tony Wilkes
Old Croc Joined: 02 August 2004 Location: West Midlands Status: Offline Points: 4840 |
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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 |
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SteveAATW
Young Croc Joined: 04 September 2007 Status: Offline Points: 1173 |
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If anyone has a PLX near Bradford/Leeds I will happily oblige but not got one handy myself |
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5175 |
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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, |
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Elliot Thompson
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Hugo Biermann
Young Croc Joined: 05 February 2005 Location: South Africa Status: Offline Points: 809 |
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Seen that a lot Elliot!
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www.aggressiveaudio.co.za
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levyte357
The 10,000 Points Club Joined: 10 May 2004 Location: UK, London Status: Offline Points: 11743 |
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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. |
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"Who am I? I'm the guy who does his job.. You must be the other guy".
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nickyburnell
Old Croc Joined: 06 February 2005 Status: Offline Points: 4410 |
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It's everything, not everythink!
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Tony Wilkes
Old Croc Joined: 02 August 2004 Location: West Midlands Status: Offline Points: 4840 |
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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 |
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hmaudio
Old Croc Joined: 03 April 2009 Location: Nottingham Status: Offline Points: 3844 |
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lookin awsome mate., buidin 2 of these (b&c desighn) in two days
good luck with the finnish
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Nottingham based cab builder. https://www.facebook.com/HMAudio-154352667920145/?ref=bookmarks
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Tony Wilkes
Old Croc Joined: 02 August 2004 Location: West Midlands Status: Offline Points: 4840 |
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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 |
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5175 |
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The vibration comes from the woofer, which in turn will cause the box to move if the cabinet is too light. The only way to reduce box vibration is to brace the essential parts of the cabinet where the root of the vibration resides. Since the baffle board is the weakest link in the box, it would help if the wood were either thicker and/or braced to combat vibration caused by the speaker. If the box is not properly braced when the driver is moving like a jackhammer, it will cause the whole enclosure to move forward, backwards, left or right. I’ve experienced this throughout the years owning Scoops, Folded Horns and, Double Fifteens playing bass. All of the boxes were rather light (63 kg total with speakers) and found no alternative but to use multiple straps or C-clamps to keep the cabinets uniform. There is nothing sweeter than hearing 3 C-Clamps per side adding it’s own characteristics to the bass. Learning from those cabinets, I braced my Double Eighteens heavily (36 mm baffle board with a two-by-four skeleton braced frame) in which, all movement of the cabinet ceased while using twice the piston power per box. I prefer having my cabinets remaining where I set them once the show is over than finding each cabinet facing in all the wrong directions. I's great to view things from technical standpoint. I may even come across that way with my replies. However, I use a combination of book knowledge and real world experience on every aspect of audio. Best Regards, |
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Elliot Thompson
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Tony Wilkes
Old Croc Joined: 02 August 2004 Location: West Midlands Status: Offline Points: 4840 |
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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 |
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Contour
Young Croc Joined: 03 March 2004 Status: Offline Points: 624 |
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I have to agree with Elliot. A thick baffle is very effective, even if the total baffle is only slighty larger then the driver. In that case using 36mm instead of 18mm will also not cost you many internal litres. Because of the cut-out for the driver, almost no wood remains.
Best regards,
Walt
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