Can you use parallel ext. speaker out as a speaker input?

Discussion in 'Amp Input - Normal or Bright' started by wayfaerer, Jul 21, 2021.

  1. wayfaerer

    wayfaerer Strat-Talk Member

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    Hello! Quick question: If you have a combo amp with a parallel speaker out jack (for adding a second cabinet/speaker in parallel with the internal speaker), can you use it as an *input* by sending it a signal from an external power amp, instead of the internal one?

    The scenario is simple: I have a combo amp that I want to temporarily use as a cab only, unplugged from the wall, with a separate preamp and power amp. The combo amp has a parallel speaker output jack that I am hoping I can use for this purpose.

    I know that if I do this, the powered signal will reach the speaker just fine, but I want to make sure I don't damage the combo's (turned off) power amp, as well as the external power amp, since their outputs would be in parallel with one another. To reiterate, the combo amp would not be plugged into the wall.

    In case it's relevant, the amp in question is an old Peavey Bandit Silver Stripe... solid state.
     
  2. AxemanVR

    AxemanVR I appreciate, therefore I am... Silver Member

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    It *might* work, BUT, if both of the first amp's external speaker outputs are directly connected to that amp's power section, then I'd have to seriously advise against it.

    Only if there is a direct path to the first amp's internal speaker with no chance of it being connected to that amp's output transistor(s) can you consider this to be a safe connection. Otherwise there could be a disaster of biblical proportions (as amps go) if you try hooking it up the way you described - something you won't know until you try it, and then it'll probably be too late if you change your mind.

    Let us know how it goes should you decide to move forward on this venture (with picts)... after you put out the fire of course...


    `
     
    Last edited: Jul 21, 2021
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  3. rocknrollrich

    rocknrollrich Most Honored Senior Member

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    Your output transformer from the combo amp (not plugged in to the wall socket) would still be in the circuit.
    At the very least, I imagine this would cause an impedance issue.

    Just connect a speaker cable directly to the speaker (spade connectors on the speaker tabs).

    And yes, I know it's solid state, but I am pretty sure that old peavey solid state amps still employed an output transformer.
    I know my solid state peavey renown certainly does.
     
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  4. Uncle Jimmy

    Uncle Jimmy Senior Stratmaster

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    Do you have an effects loop?
     
  5. misterwogan

    misterwogan Senior Stratmaster

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    First up, I'm not picking on the OP - at all. But I am curious as to why people use the term 'Quick Question'. What makes the question quick as opposed to not quick or maybe even slow? I've had many PMs from ST members over the years where the subject line was: 'Quick Question'. Does it really mean that they don't expect an in-depth answer? When would you ask a question and NOT stipulate that it was QUICK?
     
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  6. wayfaerer

    wayfaerer Strat-Talk Member

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    Thanks for the responses... I think I'll play it safe and wire a switch for this, so that I can disconnect the internal power amp from the speaker as needed. If it were an amp I liked less, I'd just try it and report back, but the Bandit is such a great backup amp, I'd hate to mess it up.

    Yes I do have an effects loop but I have a separate power amp I love so I'd rather use that.
     
  7. Guitarmageddon

    Guitarmageddon Dr. Stratster

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    This reminds me of my friend's 6 year old son, he plays Minecraft, and he wanted to show me his inventory of items. He said to me "don't worry, this is going to take a long time"
     
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  8. wayfaerer

    wayfaerer Strat-Talk Member

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    No offense taken.

    However to answer your question "Does it really mean that they don't expect an in-depth answer?", yes that was my intention. I suppose it's a poorly worded idiom in that regard.

    I would not say "Quick question" when the expected answer is opinion-based or would require a long explanation, e.g., "Quick question: What's the best pickup position on a Strat?" doesn't work, "Quick question: How do pickups work?" doesn't work, but "Quick question: Which pickup position did Hendrix use most often?" does. At least that's how I use it. It kinda sounds dumb though, now that I think about it.
     
  9. misterwogan

    misterwogan Senior Stratmaster

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    That makes perfect sense, thank you. So. Quick question: How old are you? That works. Whereas - Quick Question: Tell me about the Roman Empire...
    So after all that, it's not about the pace of the question but rather it's about the precision of the question.
     
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  10. AxemanVR

    AxemanVR I appreciate, therefore I am... Silver Member

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    How about this: "Quick Question: Tell me about the Roman Empire in 30 seconds or less... and be precise!"



    `
     
  11. CB91710

    CB91710 No GAS shortage here Double Platinum Supporting Member

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    Quick answer, no, you can't.

    Longer answer, the output transformer and output transistors will still be connected and could be damaged. The transformer will back-feed into the amp's outputs and power supply. It was not designed to run that direction, it is similar to hooking up your jumper cables backwards.

    Unplug the speaker, or if the Bandit does not have a jack for the internal speaker, make one.

    A tube amp might be a little more tolerant, but you'll still be hammering the plates with full induced voltage.
     
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  12. misterwogan

    misterwogan Senior Stratmaster

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    It came, it saw, it conquered - and then it died.
     
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  13. cranky

    cranky Senior Stratmaster

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    Wouldn't this be a no-no due to the ohm factor?
     
  14. Robins

    Robins Dr. von Loudster

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    Quick answer, bad idea.
    Even the switch will do bad things.

    All the best,
    Robin
     
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  15. AxemanVR

    AxemanVR I appreciate, therefore I am... Silver Member

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    Some more "Quick Questions": When did it come? What did it see? Whom did it conquer? And how did it die? You have 27 seconds left... nowww... GO!!!




    `
     
    Last edited: Jul 21, 2021
  16. rocknrollrich

    rocknrollrich Most Honored Senior Member

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    I'm saying use a cable (speaker cable) one end has a normal 1/4" jack, the other has spade connectors to put right onto the speaker terminals.
    This , so as not to be electrically connected to the Peavy amp at all.
    Just the Peavy speaker.
    Whatever the ohms of his Peavy speaker, would be the ohms he should select on the amp doing the driving.
     
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  17. cranky

    cranky Senior Stratmaster

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    Gotcha.

    Didn't know they made cables like that. I wouldn't trust myself to rig my own. I'd rather just get another amp :)
     
  18. wayfaerer

    wayfaerer Strat-Talk Member

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    Thank you for this. Good thing I asked because I plugged it in last night and was just about to flip the switch on the external power amp before I thought "Eh, I doubt it matters, but I guess I should check just to be sure."