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Old 16th April 2015, 10:21 PM   #1
jhrlrd is offline jhrlrd  Canada
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Default Sub amp question

I have a mordaunt-short ms909w. I believe its powered by a built-in class D amp.
Is there any tweaks or upgrades a guy can do? Not familiar with class D amps, so I'm wondering if there are any opamps , caps or resistors etc that can be upgraded. Not getting bad sound, but any improvements are welcome.
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Old 16th April 2015, 11:24 PM   #2
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Class d amps suffer from bus pumping with long low notes.
Its better to bridge class d amps for a subwoofer.
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Old 17th April 2015, 02:27 PM   #3
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It probably operates in BTL. I'd be very surprised if it was single-ended.

To answer the OP, what exactly are you looking for?
IMHO, its a middle-range consumer subwoofer. You're very unlikely to change the sound noticably/at all by swapping some op-amps and resistors.
Power supply caps, maybe.

If it as mine and I wanted better low end, I'd either sell it and buy parts to build something better, or pull the driver and amp, sell the cabinet and build a tapped horn that'll hit 20Hz.

Chris
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Old 17th April 2015, 03:13 PM   #4
jhrlrd is offline jhrlrd  Canada
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Looking for deeper extension, better clarity and/or tighten up what it does do. So you're saying better components won't do anything, and that I should just go with a better one. Any suggestions? No bigger than 10". I don't have time to build anything.

Last edited by jhrlrd; 17th April 2015 at 03:30 PM.
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Old 17th April 2015, 03:18 PM   #5
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You might try moving it to different locations in your room. That can make a big difference in how it sounds. Room placement makes surprisingly large differences. You could get another sub, and use both... Helps smooth out room response.
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Old 18th April 2015, 09:36 AM   #6
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Quote:
Originally Posted by jhrlrd View Post
Looking for deeper extension, better clarity and/or tighten up what it does do. So you're saying better components won't do anything, and that I should just go with a better one. Any suggestions? No bigger than 10". I don't have time to build anything.
I'm saying that a different op-amp will make the most miniscule of difference, if any. Further down the chain, we're wiggling bits of cardboard around using magnets. I'd try to optimise the worst bits before messing with trying to fix something benign.

Block one of the ports and see how you like that. That'll tune the cabinet lower, and give a more gradual rolloff. Combined with room gain, you'll probably get a "tighter" sound, but there should be more right at the bottom end, too.
Playing with positioning is also good advice.

Chris
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