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Switch transfromers?

Discussion in 'Shock Brother's DIY Amps' started by iansmitchell, Aug 13, 2009.

  1. iansmitchell

    iansmitchell Tele-Afflicted

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    Okay. So i want to know more about these, and where to get ones for future builds. I have one in my crate V-18, and I know three things about them:
    They're VERY lightweight. I love that.
    They work for euro and US power sources with the flip of a switch and different cord. Neat!
    They're cheaper(well, at mfg. quantities) than traditional transformers.

    Where can I get some?
     
  2. celeste

    celeste Friend of Leo's

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    SMPS, Switch Mode Power Supply. The lack of transformer ( they usually do have a small transformer to run the control circuitry) means no galvanic isolation between input and output. That makes them unsafe for guitar unless you like to chance having mains voltage on your strings and any earth will complete the circuit.

    If you were to use an input transformer to isolate the guitar from the amp you could get away with it, but a good input transformer costs as much as a PT and all you would gain is less weight.
     
  3. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    I would just use normal PT's with multiple taps for primary/mains.
     
  4. iansmitchell

    iansmitchell Tele-Afflicted

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    I'm mainly looking for the lighter weight. I'm not sure about the strings carrying current thing when the amp's properly grounded. I may have to look up a shematic.
     
  5. celeste

    celeste Friend of Leo's

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    If you are using it live, can you be sure it is properly grounded? Is it legal to use outside your own home?
     
  6. iansmitchell

    iansmitchell Tele-Afflicted

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    My own home isn't properly grounded.
    Could I ground it to neutral as in usual 2 slot wiring, without having strings live?
     
  7. celeste

    celeste Friend of Leo's

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    That would require the polarity of the two prongs to be correct, about the same chance that the ground is correct. Not really safe, to much chance for an accident.

    to be safe, you have to have complete isolation between the guitar and the mains. A transformer usually provides this
     
  8. iansmitchell

    iansmitchell Tele-Afflicted

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    Couldn't i just carry one of those plug-ins that tells you if everything's on the up and up and when it says there's a problem use the PA?
     
  9. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    You want to flip a coin 50/50 just for 1 or 2 less pounds? If the test plug says its a no-no, then you'll use something that sounds not-so-good?

    Save weight on speakers (use neo's), but be safe. I've had a few cracks from poor electrical at some clubs - and this was in a major metropolitan area. Mic to bottom lip and it kinda hurt.
     
  10. celeste

    celeste Friend of Leo's

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    It weight is the whole issue, then an input transformer may be the way to go, but a transparent one is likely to run $60 or more. A lesser one may be fine, it could be part or the amps tone.

    Now, implementation. You need an up converting supply for your B+ and a down converting one for the heaters. If yoiu are not able to build your own, then it means prepackaged off the shelf units and you just lost a lot of your weight advantage.
     
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