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In Reply to: RE: Hi Jim..... posted by Winston Smith on December 01, 2014 at 11:59:23
As usual Winston great detail and good follow up in your post. You wrote:" The BlackPods weakness is their HF extension and details, when compared to the Stillpoints."
How compliant or soft is the bottom and top of the footer? I find the softer and more compliant they are they lessen and/or soften HF more. This can be good in some systems and say for digital sources where analog sources might work better with a stiffer footer bottom and/or top. Like most things they are tunable with different composition. Think room treatment types and locations for instance.
E
T
Follow Ups:
Awe-d : you asked about compliance, so I thought I'd give a short explanation. (Yes, I agree that soft footers eat treble. And rubbery/springy footers smear by storing energy and releasing in the future. But also hard footers have their own problems, for instance a bunch of resonances, which can make them shrill.)
The overall design goals were to make them hard-coupled in the vertical (up down) direction, with no compliance; but in the other two planes, laterally, there is a small amount of movement allowed which is damped with constrained layer damping.
This is realized using two variable-density top and bottom plates, kept apart by separators that allow some lateral sliding. This is also bound with a lossy elastomer to form a constrained layer damping system.
They are topped with a lead ball. Why lead? Well I tried other materials and lead sounded the most musical. Lead normally does not have a great sound when used (randomly) on audio systems - it can make things seem slow of muffled. But in this application it just works. It's coated with a thin layer of spray-on rubber which is removable. The rubber is so thin that it has virtually no effect on SQ
Thanks for the detailed post!
E
T
Good posts. Thanks.
Okay, about the make up of the footers, Bob is Mr Zippo Lippo, i.e., he won't say much about their construction.
But just by physically looking at them, it seems obvious to me it is a multi-material approach involving layering, damping and rigidity. He did say that the rubberized covering on the lead ball helped in many ways. And the center material looks like a form of silicon, so it would seem (like Marigo and Stillpoints) that a combination of compliance and rigid tuning is employed.
Compliance usually does affect HF response in a reductive manner, I could not agree more. The Stillpoints avoids this by using very hard materials, even the Delrin damper (internally) is pretty darned hard stuff. And that probably explains the Stillpoints incredible details and HF extension.
It's all about balance, as you aptly described in your post. Again, I could not agree more.
I hope this helps you, and others, in some small way.
Cheers,
WS
Yes Delrin is quite hard. They use it on the side of cafe racer motorcycles as a first point of contact to protect the bikes bodywork in the event of a crash. Thanks for the reply!
ET
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