Line6 G70 and PP2+

Discussion in 'Effects, Pedals, Strings & Things' started by Nota, Apr 6, 2015.

  1. Nota

    Nota Member

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    I was perusing the manuals tonight, and found that the *actual* power usage for the G70 receiver is 350mA (even though the power supply is rated at 500). If I understand the PP2+ correctly, you actually have TWO options:

    1) Use a current doubler cable and plug into outputs 5 & 6.

    2) Use a normal, single cable and plug into output 5 or 6, BUT do not exceed 500mA total from both of these outputs. This will work, from what I've read, because it's not 250 + 250 but 500mA total output spread between the two.


    If someone from Voodoo can comment on the above, or someone who knows what they're talking about, that'd be great! I have the adapter in the mail, but would much rather power it normally with one cable!
     
  2. stinkfoot

    stinkfoot Member

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    The two high current outputs have separate secondary transformer windings and separate voltage regulators. In effect, they are two separate power supplies. So I don't see how they could be 500mA total shared across the two, available from a single output. If you use the outputs in normal mode, they are regulated, and the regulators will not hold the voltage steady if you go past their 250mA limit.

    In the alternate mode, though, those two outputs are unregulated. Then the max capacity is limited by the transformer's secondary winding for that output. The voltage will vary with the load, so at zero load, they are putting out close to 18 volts. At 250mA load, you're down to 10-11 volts, so in theory you might get 9 or so volts at 350mA. And not using the second high current output could potentially help, since it makes the overall load (on the transformer primary) lighter. But again, Voodoo Lab themselves note that the capacity of those outputs is 250mA max, and that's probably not without reason. The transformer secondary for that output can only provide so much, before it gets overloaded.

    Unless you can get an official statement from Voodoo Lab stating anything else, I'd use a current doubler cable to combine 5 & 6 (normal mode on both) to power the G70. Do not use the outputs in the alternate mode, since that would raise the voltage (the G70 seems to run at 5 volts internally - if you feed it more than 9 volts, you may overload the internal 5v regulator).
     
  3. Nota

    Nota Member

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    Ok, that (sort of) all makes sense! Thanks!

    I thought I read somewhere that you could actually run something higher current off 5 & 6. Guess it was wishful thinking :)

    I could also use outputs 5 and something else (100 max) for a total of 350mA right?
     
  4. stinkfoot

    stinkfoot Member

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    I see that too from time to time on the forums, but nobody has yet been able to provide a reasonable explanation as to how using just one of those outputs would somehow increase the capacity of its voltage regulator. :)

    Ooh, another hot potato... :D There are two schools of thought here, and I don't know for sure which one is correct. One school says the two will simply add up (100mA + 250mA), while the other says the pedal will try to draw equal amounts from the two outputs (in this case 175mA from each). I tend to lean towards the second line of thinking, since stuff connected in parallel usually wants to share things equally*. But to know exactly what happens if you combine two mismatched (capacity-wise) outputs in parallel, I'd need to hook up a meter in-line with the feed from each output (before they join up in parallel), and I haven't had the opportunity to do that. And even then, if I were to see 100mA from the 100mA output and 250mA from the other, I couldn't be sure it is because they spread the load that way, or simply because the 100mA output has reached its absolute max and will blow any time...

    Now, I tend to want to err on the side of caution, so I'd recommend sticking to the same voltage and current capacity for both outputs - in this case, by using 5 and 6 together.

    * Let's take speakers as an analogy. Say you have a 100w 2x12" combo that you need speakers for. Rooting around in your parts bin, you find two with the same impedance. They're not ideal, as one is 25w and the other 75w, but it should be ok as that makes 100w total, right? So what happens when you run the amp at 100w power? Assuming they're the same impedance, they'll see 50w each. So the 25w one will be overloaded (possibly blown), while the 75w one will be running cool and working just fine. While this analogy may not translate directly to the power situation discussed above, it does make a case for keeping things balanced.
     
    Last edited: Apr 6, 2015

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