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  1. #1

    PC Power supply?

    I have a spare PC power supply with various 5v outputs, would this be better than the standard one provided with SB2?

    Regards
    Simon

  2. #2
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    Quote Originally Posted by Simon
    I have a spare PC power supply with various 5v outputs, would this be better than the standard one provided with SB2?
    PC power supplies are switched mode, which are not generally thought of as the greatest type for powering audio equipment. But then again, from the size of the thing, I suspect that so is the SB2 wall-wart. So whether the quality of the power coming from the PC supply would be any better is anyone's guess.

    But one thing's for sure: unless it's one of those expensive fanless power supplies, it'll be a heck of a lot more noisy than the (silent) SB2 wall-wart. One might argue that the additional background noise of the PC supply's fan could be enough to mask any improvement you might get if it gave a cleaner feed.

    There's only one way to find out, of course: try it and see if they sound different, and if so which one's better. But before you do, double check with Slim Devices that you won't do any damage. I'd assume that since a PC power supply is regulated, you'll be OK, but don't take my word for it. And whatever you do, don't get the 12V and 5V supplies confused!

  3. #3
    Senior Member max.spicer's Avatar
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    Quote Originally Posted by cliveb
    PC power supplies are switched mode, which are not generally thought of as the greatest type for powering audio equipment. But then again, from the size of the thing, I suspect that so is the SB2 wall-wart.
    What's a wall-wart?

    Max
    Some people think the title of this song is irrelevant,
    but it's not irrelevant - it's a hippopotamus.

  4. #4
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    Quote Originally Posted by max.spicer
    What's a wall-wart?
    Sorry, that's an Americanism. Although I'm British, I sort of assumed it was the most widely understood terminology.

    A "wall-wart" is a power supply with built-in mains plug, the sort of thing we tend to call a "power brick" here in the UK.

  5. #5
    Christian Pernegger
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    Re: PC Power supply?

    Are there battery based power supplies? I should think something that
    runs its output off battery and keeps recharging that should be pretty
    much perfect for audio equipment. Something like a online-type UPS
    with DC output.

    C.

  6. #6
    Senior Member Mike Hanson's Avatar
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    Quote Originally Posted by Christian Pernegger
    I should think something that runs its output off battery and keeps recharging that should be pretty much perfect for audio equipment. Something like a online-type UPS with DC output.
    Actually, batteries don't provide their exact voltage. It usually starts out a bit high, and then fades over time. Also, the chemical reaction that occurs in the batteries creates noise, analogous to "bubbles". At least that was what Naim determined, when they researched using batteries instead of regulated supplies.

    I'm build a pre-regulated, linear supply for my SB1 and SB2. We'll see how that helps out.

    -=> Mike Hanson <=-

  7. #7
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    Linear PSU Questions

    Mike - I'd be keen to know how you get on with your home brew SB linear PSU - are you planning on including any mains filtration or will it be straight x-former/bridge/smoothing caps job? Any exotic parts planned?
    Regards and best of luck,
    Phil

  8. #8
    Quote Originally Posted by Simon
    I have a spare PC power supply with various 5v outputs, would this be better than the standard one provided with SB2?
    One thing to bear in mind is that switch mode PSUs have a minimum power rating which means that they won't work unless you draw the minimum current. From my bad memory I think this is 0.5A but it may be more.

    Neil

  9. #9
    Senior Member Mike Hanson's Avatar
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    Quote Originally Posted by Phil Leigh
    Mike - I'd be keen to know how you get on with your home brew SB linear PSU - are you planning on including any mains filtration or will it be straight x-former/bridge/smoothing caps job? Any exotic parts planned?
    I'm actually concentrating my efforts on the regulation stage. The initial prototypes are leaving the transfomer, rectifier and initial smoothing to an unregulated, linear wall wart. I've purchased a couple of these from a local surplus store, rated at 12VDC and 2A. Once I get done with the regulation stage, I may replace the wall wart with my own raw supply.

    I'm taking this approach to keep the transformer away from the audio gear, while the supply regulation is very close to the load. Even if I do my own raw supply, it will still be positioned away from the regulation stage.

    I'm using a tracking pre-regulator arrangement, in which one regulator sits on top of another. IOW, the first regulator's "ground" is the output of the second regulator. The first then feeds its output into the intput of the second regulator. This enables the first regulator to have a quiet ground (because it's really the regulated output of the second regulator). The second regulator has a smoother input supply (the output from the first regulator). I know it seems almost like pulling yourself up by your own bootstraps, but it really does work!

    For regulators, my initial testing has been with basic Fairchild LM317T adjustable regulators. However, I'll probably end up using a low dropout-voltage LD1085V. I'll use a scope to see which configuration "looks" quieter, as well as do listening tests (because if it doesn't sound better, then what's the point?).

    For capacitors, I'm just using a bunch of 10uF electrolytics, although I'm probably going to add/replace some of them with 1uF and/or 100nF tants.

    You can read the ongoing saga (quite a learning experience for me) at http://www.pinkfishmedia.net/forum/s...threadid=10540.

    -=> Mike Hanson <=-

  10. #10
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    Quote Originally Posted by Mike Hanson
    You can read the ongoing saga (quite a learning experience for me) at http://www.pinkfishmedia.net/forum/s...threadid=10540.

    -=> Mike Hanson <=-
    Mike,
    Great thread!

    I'd like to try your dual reg circuit once you've perfected it.
    Any chance you could draw a circuit diagram and post it when tested & working - I'm sure other SB owners would be interested...
    Regards
    Phil

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