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Mesa 400+ impedance question

Discussion in 'Amps [BG]' started by ariff, Dec 10, 2012.

  1. ariff

    ariff Supporting Member

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    So the 400+ has two output taps on the back marked 2 ohm, two marked 4 ohm and two marked 8 ohm the idea here is it you are running 2- 4 ohm cabs you hook them to the 2 ohm taps to present the amp with a 2 ohm load likewise with two 8 ohm cabs run hook them to the 4 ohm taps. What should I use if I am running a 8 ohm and 4 ohm cab together which total around 2.6 ohms?
    Thanks!
  2. MAMMOTHvolume

    MAMMOTHvolume

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    What are the cabs? I wouldn't recommend running different impedance cabs in most cases
  3. ariff

    ariff Supporting Member

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    2x10 avatar and 1x15 avatar.. 2x10 is 8 ohms and the 1x15 is 4 ohm. Been running these cabs with several different heads (Peavey and Carvin) without any issues ever. Just picked up the 400+ on CL a few weeks ago which will mainly be used with my Power House 8x10.. But for smaller gigs which require us to lug gear up stairs I like to use the 2x10 and 1x15..
  4. Downunderwonder

    Downunderwonder

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    You're onto it.
    With tubes it's generally better to run under the rated tap impedance than over it. In this case 2.6 is so close to 2 it probably wouldn't stress things too much but tough call to make.
  5. Bassmec

    Bassmec

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    Disclosures:
    Proprietor Springvale Studios
    If the 400+ is not fixed variable bias modded?, its such a cold running amp on its tube set, it would do no harm to run it at 2.6 ohms on the two ohm tap and I am usually a bit of a stickler for not messing with tube amp output tap/speaker matching impedances.:bassist:
  6. ariff

    ariff Supporting Member

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    OK good to know.. This is my first tube amp so I am still learning about them. I actually think I have a 8 ohm 15" speaker in another cab I might just switch them out to be safe. And no the amp has no bias mods done to it. It is stock fixed bias..
  7. NecroticImbecil

    NecroticImbecil

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    IIRC There was mention of your situation in the manual, which the last I knew was still available for download on Mesa's web site.
  8. Brookdalebass

    Brookdalebass

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    Yikes. Now I'm confused. I've been running my 400+ with two 8 ohm MarkBass cabs (4x10 and 2x10). I plug one cab into the 4 ohm output of the Mesa and take a Speakon from that cab to the other...two 8-ohm cabs in parallel...isn't that presenting the amp with 4 ohms?
  9. nicoli

    nicoli

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    Yes... so why the confusion?
  10. Brookdalebass

    Brookdalebass

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    Thanks, Nicoli...ariff's original post kind of made me think I was doing something wrong...my 400+ sounds great and is actually louder and much meatier than my MarkBass Tube 800 head through the same cabs.

    I started my bass playing career with tube amps but switched to solid state...then hybrids: Hartke, Ampeg, Eden, Aguilar, Mesa...always felt something was missing. Got the Mesa 400+ a few months ago and found out what that missing link was.

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