2 Amps 1 Cab & Channel Switcher

Discussion in 'Amps [BG]' started by nlabat, Mar 25, 2014.


  1. nlabat

    nlabat

    Joined:
    Jul 10, 2013
    Location:
    Miami Beach FL
    Hi Guys I got my GK MB500 and The Little Bastard Ashdown.

    and only one Cab the Fender Rumble 4x10 (4 ohms 2013)...

    My question is, Can I have in the parallel input one jack per amp and running with a Channel Selector (no intention to run both same time), Is it possible ????

    Is there any risk ??

    and Why ???
     
  2. Downunderwonder

    Downunderwonder

    Joined:
    Aug 26, 2009
    Location:
    New Zealand
    The LB tube amp won't like having no cab attached so it's a no go.
     
  3. Bass_Pounder

    Bass_Pounder

    Joined:
    Jan 19, 2002
    Location:
    Palm Coast, Florida
    Risk is blowing both amps.

    Unless you use a splitter specifically designed for switching your output load, you will be running one amps output into the power section of the other one.
     
  4. nlabat

    nlabat

    Joined:
    Jul 10, 2013
    Location:
    Miami Beach FL
    ok so no way to do it ?
     
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  6. middy

    middy

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    Mar 14, 2007
    Location:
    Texas
  7. RickenBoogie

    RickenBoogie

    Joined:
    Jul 22, 2007
    Location:
    Dallas, TX
    Not worth the risk. Get another cab.
     
  8. nlabat

    nlabat

    Joined:
    Jul 10, 2013
    Location:
    Miami Beach FL
    Its mandatory to connect a Cab on the LB ???

    what if i would like to use it as a DI output sound head and no cab on them ???
     
  9. Bass_Pounder

    Bass_Pounder

    Joined:
    Jan 19, 2002
    Location:
    Palm Coast, Florida
    Can't run a tube head without a load connected
     
  10. nlabat

    nlabat

    Joined:
    Jul 10, 2013
    Location:
    Miami Beach FL
    OH good info ... I did not knew it ....

    what can cause that ??

    so no way to run it as a Pre from the DI output??
     
  11. middy

    middy

    Joined:
    Mar 14, 2007
    Location:
    Texas
    You can put a dummy load on it... like an attenuator.
     
  12. nlabat

    nlabat

    Joined:
    Jul 10, 2013
    Location:
    Miami Beach FL
    any idea where to get that dummy load ??? because im not finding it ...
     
  13. SteveV74

    SteveV74

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    Jul 24, 2012
    Location:
    Newton,KS
    What about a Morley ABY pedal?
     
  14. Bass_Pounder

    Bass_Pounder

    Joined:
    Jan 19, 2002
    Location:
    Palm Coast, Florida
    Nope............

    Not made for output wattage, and would not present a load to the tube amp.
     
  15. nlabat

    nlabat

    Joined:
    Jul 10, 2013
    Location:
    Miami Beach FL
    Where I can get a dummy load???.?
     
  16. nashvillebill

    nashvillebill

    Joined:
    Oct 13, 2002
    Location:
    Nashville TN
    You're not going to find a pre-manufactured dummy load "off the shelf" to meet your needs. The actual dummy load resistor is readily available at Parts Express but you would have to finish making it into something useful.

    Your Ashdown is rated 30 watts, right? So the Parts Express 100 watt dummy load would likely suffice, although it would need either a heat sink or fan cooling if you are going to be using it for long periods of time.

    The real answer, though, is to simplify the rig down to one amp and forget the switching and dummy load and all that.
     
  17. RickenBoogie

    RickenBoogie

    Joined:
    Jul 22, 2007
    Location:
    Dallas, TX
    I'd forget about a dummy load as well. A tube amp is best used with a cab attached, and enjoy the sweet tone. Too much risk to the amp any other way.
     
  18. Steve Dallman

    Steve Dallman Supporting Member

    Joined:
    Mar 5, 2006
    Location:
    East Central Wisconsin
    I would build a switcher that would not only switch the amps to the cab (with a dummy load on the Ashdown, but simultaneously switch the inputs as well. The tube amp into the dummy load wouldn't heat it up if it didn't have any signal running through it.
     
  19. nashvillebill

    nashvillebill

    Joined:
    Oct 13, 2002
    Location:
    Nashville TN
    Which would be my approach if I absolutely had to do amp output switching. The technical aspects that must be overcome:
    -the switching of the input signal, which is low voltage and low current, and requires shielding
    -the switching of the high current amplifier output. This must be "break before make"
    -the switching to the dummy load for the tube amp
    Looks to me like a 3PDT switch which is rated for switching something like 15A...under load. A relay 2PDT motor contactor could be used here if a separate relay was used for the input switching.

    There's also the gig hassles of setting all this stuff up, as well as tearing it down. The more complicated the setup, the more chances there are for things to malfunction.

    And one final thought related to the gig. The big amp is 500 watts. Suddenly it's switched to a little 30 watt amp. The audience is going to wonder "what happened to the bass?" That 30W tube amp grind which sounds so good at home isn't going to cut through on stage. I suspect that at best the audience might think that the guitar player suddenly got a little muddier.

    If the OP really must have that 30W amp, why not just buy a separate cab for it? Then a simple AB input switcher could be used and be done with it. It'd be far cheaper and more dependable, a used single 10 inch bass cab would be cheap.
     
  20. sxaxsx

    sxaxsx

    Joined:
    May 23, 2012
    Location:
    Harrisburg PA
    What is that quote from Jurassic Park where Ian Malcolm says, "Yeah, yeah, but your scientists were so preoccupied with whether or not they could that they didn't stop to think if they should."

    I'm having trouble figuring out why you would want to do this? :meh::confused:
     

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