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Old 25th June 2013, 05:32 AM   #21
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Well, my current amp is running on an unregulated psu consisiting of a 12v 3a radioshack power transformer, a full wave rectifier with .1uf subbing ceramics on it, and 3x4700uF caps, not snubbed. all this runs into a 3300uF smoothing cap. input caps are polarized elecrtolitics, I think either 1 or 10uf. Sounds decent, but I want to rip it apart and go to point 2 point, so this would be an opportune time to upgrade it. As i am already ordering from Mauser, I can use the caps i have right now to make this thing sing better.
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Old 25th June 2013, 05:40 AM   #22
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Well sounds to me then that you could just improve your setup without playing with the active bits at first. I'd recommend building a multistage CLCLC power supply to filter out the ripple , rather than lumping all your caps into one bundle.

Buy some toroidal metal powder cores and wind your own inductors for the L part. Or if you have an aversion to inductors, use low value Rs (say 0.22R).

When I did such a mod on my desktop active speakers (which are powered with TDA7265s) I was surprised how much improvement I got in soundstage depth from this.
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Old 25th June 2013, 06:08 AM   #23
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Well sounds to me then that you could just improve your setup without playing with the active bits at first. I'd recommend building a multistage CLCLC power supply to filter out the ripple , rather than lumping all your caps into one bundle.

Buy some toroidal metal powder cores and wind your own inductors for the L part. Or if you have an aversion to inductors, use low value Rs (say 0.22R).

When I did such a mod on my desktop active speakers (which are powered with TDA7265s) I was surprised how much improvement I got in soundstage depth from this.
I will take a look at your schematic. I think I have enough components to upgrade the system.

when you say .22R you mean .22 ohm right?
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Old 25th June 2013, 06:11 AM   #24
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My schematic doesn't have CLCLC filtering because I'm using an SMPSU. Yes, 220milliohm resistors.
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Old 25th June 2013, 06:37 AM   #25
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sweet, i will try it out.
SMPSU? I might need some help with one of those also, I will PM you.
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Old 25th June 2013, 06:43 AM   #26
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Feel free to send PM to ask more questions. With an SMPSU you need to take fairly stiff measures in filtering both common-mode and differential mode noise to get the best performance.I use my own hand-wound common-mode chokes because I've yet to find an off-the-shelf one which comes up to snuff. On the differential mode noise, ferrite beads are your friend in a CLCLC style filter where the L elements are wires passed through ferrite beads.
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Old 25th June 2013, 09:24 AM   #27
AndrewT is offline AndrewT  Scotland
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220milliohm can be written as
0r22, or 0.22r, or 0e22.

But do not write as .22r, nor r22.
The omitted leading zero makes for ambiguity and thus mistakes.
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Old 25th June 2013, 03:30 PM   #28
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The omitted leading zero makes for ambiguity and thus mistakes.
Thank you Andrew, did you have any suggestions as to what lm3886 schematic i should use for my amp and power supply?
Is this ok?
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Old 25th June 2013, 04:59 PM   #29
AndrewT is offline AndrewT  Scotland
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definately not for beginners and probably not for builders without good knowledge and good test instrumentation.

You must use all the optional components that National give details of.
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Old 25th June 2013, 05:09 PM   #30
sereal is offline sereal  Canada
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Anyone have a mouser or digikey shopping cart/project for a chipamp?

It would be awesome to just grab it all in one go instead of spending hours on digikey looking for the right parts and inevitably ending up buying the wrong part or a smd part by accident.
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