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105.2 cabinet damping
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speakerguru
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PostPosted: Tue Mar 17, 2009 6:45 pm    Post subject: Reply with quote

audiolabtower wrote:
proffski wrote:
Lead lining sounds fine, but what happens once the panel starts moving, it will take longer to stop...

High mass can have high Q resonances which are much more deadly to sound quality.


Not lead. Have you ever hit a lead sheet and heard it ring like a bell? I think not. More like a soggy Yorkshire pudding. Lead is almost perfect for lining speaker boxes (apart from the cost, labour and subsequent weight of the box, of course).
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proffski
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PostPosted: Tue Mar 17, 2009 6:52 pm    Post subject: Reply with quote

speakerguru wrote:
audiolabtower wrote:
proffski wrote:
Lead lining sounds fine, but what happens once the panel starts moving, it will take longer to stop...

High mass can have high Q resonances which are much more deadly to sound quality.


Not lead. Have you ever hit a lead sheet and heard it ring like a bell? I think not. More like a soggy Yorkshire pudding. Lead is almost perfect for lining speaker boxes (apart from the cost, labour and subsequent weight of the box, of course).


I agree that it is good at damping but a heavy panel if not well braced will still have more inertia than a thin damped one... Confused
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T.O. Chef
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PostPosted: Wed Mar 18, 2009 12:55 am    Post subject: Reply with quote

[a VERY good point from proffski. Cost would have been a consideration but not the main one in their (at that time) top speaker because they put all the research into the mounts which were carefully designed not to transmit to the cabinet if torqued exactly right. ]

Ah. Interesting. Does anyone know exactly what the correct torque factor is (was) for the B-300 in the Ref 105 II? As I've found that periodic rotation of the driver is now essential this would be good information to have. But, would it even be relevant after 30 odd years considering the likely changes to the structure of the rubber used? [/quote]
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audiolabtower
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PostPosted: Wed Mar 18, 2009 1:54 pm    Post subject: Reply with quote

speakerguru wrote:
Not lead.


yes, I was not thinking about lead, more about normal methods of thick chipboard etc. The BBC showed that even bracing can push resonances higher in frequency and Q into the more objectionable mid band if not done very carefully and results measured etc.
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