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Thread: Subwoofer Theory |
    
Bronze Member Username: Leonski
Post Number: 40
Registered: Jan-07
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| Posted on Friday, March 02, 2007 - 08:25 pm: |
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http://www.analog.com/en/content/0,2886,759__7004,00.html#con
Above, please find a link to an interesting theory article about using an acclerometer to help control subwoofer distortion. I seems they got a positive result, but since the project had a short timeframe, much more research and experiment is needed.
While this can be considered 'negative feedback', and is a no-no so some, this may point the way to future developments in this class of speaker. |
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Gold Member Username: Jan_b_vigne
Dallas,
TX
Post Number: 9902
Registered: May-04
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| Posted on Friday, March 02, 2007 - 08:46 pm: |
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The basic circuit and its applications are already in place. |
Gold Member Username: Nuck
Post Number: 6104
Registered: Dec-04
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| Posted on Friday, March 02, 2007 - 10:19 pm: |
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leo, you are familiar with servo drive subs?
I like the idea of servo drive subs, but thr term 'servo' is a bit misplaced.
A 'servo' is a motor which receives command from a controller and heeeds these commands. The Resolver part of the motor reports transitional responses back to the controller of the results.
The controller then modifies commands depending on the feedback from the resolver.
In a sub, the feedback is usually a simple positional transducer, used as a positional feedback to the controller, which is , in fact, no more than a stepping controller, in most cases. |
Bronze Member Username: Leonski
Post Number: 41
Registered: Jan-07
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| Posted on Friday, March 02, 2007 - 10:51 pm: |
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Yep, the old Velodyne servo static comes to mind.
Is this related or are these guys ahead or behind?
If late, what are these guys crowing about?
As for 'servo', you are correct. We have 2 different types at work. One type is simple...it has a tachometer (optical or from a separate coil)output back to the controller. It can control acceleration ramp as well as peak speed. The other type is a 'stepper' motor of which I am less conversant. I know, though, that they are used where precision positioning and repeatability are important.
One thing this article mentions, though, that was interesting, was the huge accelerations of the cone. On the order of 50g seems bigtime, since if a person were subjected to that, they'd be squashed like a bug!
It seems like a neat idea, no? Or is this a non-starter? |
Gold Member Username: Nuck
Post Number: 6122
Registered: Dec-04
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| Posted on Saturday, March 03, 2007 - 09:21 am: |
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The application is more for damage prevention than acoustic ability, IMHO.
The music is the signal, the amp and it's properties control the ramp of the signal delivery via attack and decay abilities, the servo decides how much is too much, via positional sensing. |
Gold Member Username: Jan_b_vigne
Dallas,
TX
Post Number: 9909
Registered: May-04
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| Posted on Saturday, March 03, 2007 - 12:36 pm: |
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As the article points out, servos are considered bad JooJoo in audio. Why? Because for a servo to make a correction, something has to go wrong first. |
Gold Member Username: Nuck
Post Number: 6131
Registered: Dec-04
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| Posted on Saturday, March 03, 2007 - 03:08 pm: |
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A servo ain't never played guitar.
Steve Vai has...and does.
Servo's are useful for avoiding banging the physical stops.
Thats all.
Not that I ever hit the stops. |
Gold Member Username: Arande2
Extreme SQ FTW
Post Number: 1759
Registered: Dec-06
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| Posted on Saturday, March 03, 2007 - 03:11 pm: |
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I have a Steve Vai CD and DVD in my hand! |
Gold Member Username: Nuck
Post Number: 6142
Registered: Dec-04
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| Posted on Saturday, March 03, 2007 - 04:10 pm: |
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Good to know that you have music in hand Andre.
As opposed to the usual high school guy thing in hand. |
Gold Member Username: Nuck
Post Number: 6143
Registered: Dec-04
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| Posted on Saturday, March 03, 2007 - 04:12 pm: |
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Try 'the hell oughtta here'.
Loud |
Gold Member Username: Arande2
Extreme SQ FTW
Post Number: 1766
Registered: Dec-06
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| Posted on Saturday, March 03, 2007 - 04:14 pm: |
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Lol... |
