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Running both channels on an old Bassman 100 head

Discussion in 'Amps and Cabs [BG]' started by Eric Cioe, Jan 23, 2006.


  1. Eric Cioe

    Eric Cioe

    Jun 4, 2001
    Missoula, MT
    Can one run both channels simultaneously on an old Fender Bassman? I know guitarists do it all the time with period Marshalls.

    Basically, the idea is to try and get both the bass boost (which sounds great) and the mid eq (I find not enough mids in the 2 band bass channel) at the same time.

    How would I do this? Is there a cable that is female 1/4 to two male 1/4s that I can purchase, so I could use a decent length instrument cable with it? Has anyone done this with good results? And lastly, does it matter which input I use on each channel? I know on the old Plexi guitar heads, you're supposed to use the top input of one channel and the bottom of another.

    I can't really experiment with this right now, as I'm at college 180 miles from the amp. Thanks for the help.
     
  2. jgsbass

    jgsbass

    May 28, 2003
    Floral Park, NY
    We used to "jump" the channels.Take a cord from the unused input on channel one and run it to channel 2. Plug in and you now have both channels.
     
  3. Eric Cioe

    Eric Cioe

    Jun 4, 2001
    Missoula, MT
    This seems like a good idea. I did a search on channel jumping, and some say it doesn't work with a 100. Anyone?
     
  4. jgsbass

    jgsbass

    May 28, 2003
    Floral Park, NY
    As long as the dual inputs are in parallel, it will work.
     
  5. Passinwind

    Passinwind I Know Nothing Supporting Member Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    It works better on Fenders where the two channels are out of phase with each other. The 100 and 135 have the same number of gain stages for each channel, so they're nominally in phase and you won't get the cool tone stack interaction. You still might like what it does anyway though. The older 50 watters interact quite markedly, because there is an extra (inverting) gain stage in Channel 1. On a lot of the Fender guitar amps, reverb recovery adds an extra stage to Channel 2, so the two channels are out of phase.

    You don't need a Y cord to try this though, just use the second jack on one channel, and try both of the inputs on the second channel. There is a gain difference from jack to jack, check it out for yourself. It would be quite easy to modify your bass channel for more mids too, but that lessens the effectiveness of the other tone controls.