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Bob Brines 8th April 2012 02:01 AM

Driver Total Volume
 
I am contemplating putting an A7.3 in a small sealed box. The volume of the motor and frame become significant. Eyeballing the diagram of the A7.3 suggests that this volume could be as much as 1/4L. Anyone have an exact number for this and the other Alpair drivers?

Bob

markaudio 8th April 2012 04:47 AM

Quote:

Originally Posted by Bob Brines (Post 2976832)
I am contemplating putting an A7.3 in a small sealed box. The volume of the motor and frame become significant. Eyeballing the diagram of the A7.3 suggests that this volume could be as much as 1/4L. Anyone have an exact number for this and the other Alpair drivers?

Bob

Hi Bob,
You might want to consider taking the rear magnet cover off. I haven't done any recent volumetric calcs for the Alp7 Gen.3 but I'd suggest allowing 0.2 litres (rear cover off). How small a sealed box volume do you intent using?

Thanks
Mark.

Bob Brines 8th April 2012 03:37 PM

Mark,

I'm looking at a Qtc=1.0 sealed box. That figures to be a net 1.2L. I plan to high-pass it well above Fc, so back pressure shouldn't be an issue. I like Qtc=1 because it makes over excursion a not issue.

Bob

planet10 8th April 2012 07:51 PM

1 Attachment(s)
Bob,

I have an estimate in one of my drawings. But easier to re-esimate -- and show how. See diagram.

A sealed box is quite non critical of volume and the nature of the damping will alter the effective volume.

I suggest that leaving the extra magnet on the driver to eat up some volume, will help in getting a box this small to have reasonable depth given that the driver bezel will determine the minimum WxL. You might even need to add blocks inside for that purpose.

For this kind of ap i'd be tempted to take the tape measure and calculator down to the dollar store and go looking at appropriately sized dishes or "tupperware", or the garden shop for ceramic pots.

dave

markaudio 8th April 2012 10:57 PM

Quote:

Originally Posted by Bob Brines (Post 2977468)
Mark,

I'm looking at a Qtc=1.0 sealed box. That figures to be a net 1.2L. I plan to high-pass it well above Fc, so back pressure shouldn't be an issue. I like Qtc=1 because it makes over excursion a not issue.

Bob

Hi Bob,
Sounds interesting. Are these are satellites for Home Theatre, or desktop?
Dave's post is very helpful - thanks.

Cheers
Mark.

planet10 9th April 2012 01:12 AM

I also have a couple of A7 that are beyond redemption -- one that the client damaged the cone on and the VC now rubs. I could so an imersion test and get a more accurate number, but the extra decimal place is unlikely to be all that useful when one considers the parameter deltas across multiple units.

dave

planet10 9th April 2012 01:16 AM

Quote:

Originally Posted by markaudio (Post 2977887)
Are these are satellites for Home Theatre, or desktop?

I suspect Bob's continued exploration of FAST,

http://www.diyaudio.com/forums/full-...w-dipoles.html

dave


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