Mesa boogie 400+ ohms question

Discussion in 'Amps and Cabs [BG]' started by Flounderkeg, Feb 9, 2022.

  1. Flounderkeg

    Flounderkeg

    Jan 5, 2022
    I'm looking to buy a mesa boogie 400+ sometime soon. The cabinets I have are all mesa boogie diesel with pro line drivers; a 4x10 600 watt(8 ohms), a 1x15 400watt(8 ohms), and a 2x15 400watt (4 ohms, but each 1x15 is 200 watts rated at 8 ohms.) So my question is: could I plug each 8ohm cab into the 8 ohm speaker jacks on the head while running the 2x15 to one of the 4 ohm jacks? Would this be the correct way to set it up? Is there any reason not to do it this way? Let me know if there is a better way to set up all three cabs, and if you recommend against using that many cabs with the 400+, which two cabs do you think would work best together? Thank you for you time
     
  2. Wasnex

    Wasnex

    Dec 25, 2011

    Combining 8 ohms, 8 ohms, and 4 ohms in parallel gives you 2 ohms. AFAIK the 400+ has a 2 ohm output with two jacks. The 2 ohm label is in a weird place along the top back edge of the chassis.

    mesa_bass400_back-jpg.jpg
    The top two outputs jacks are 2 ohms total load, and the label is just above them on top of the chassis. The jacks are connected in parallel, so you would hook up two 4 ohm loads to present a total load of 2 ohms to the amp. Or you could hook up a 2 ohm load to one of the jacks.

    Mesa's suggested impedance mismatch is to present a load that is up to one order higher than the amp expects. For example, you could do one of the following: 1). 4 ohm load on the 2 ohm output, 2). 8 ohm load on the 4 ohm output, 3). 16 ohm load on the 8 ohm output.

    If you want to run just the 115 and 215, 8 ohms and 4 ohms in parallel is 2.6 ohms. Since Mesa recommends running the load higher than the amp expects, use the 2 ohm output.

    IMHO it's better to run the expected load, unless you have some sort of weird emergency. Running an impedance mismatch will reduce power and it's harder on the amp and tubes.

    Most amps are not designed to run two output taps simultaneously. Mesa's may be an exception, but I suggest you call Mesa Tech Support to confirm the 400+ will support this. If the answer is yes, I believe it will be best to run 4 ohms on the 2 ohm tap and 8 ohms on the 4 ohm tap. This presents a 2:1 impedance mismatch to each tap, but since you are doing it twice, I believe it actually works out to matching impedance.

    I suggest asking specifically what is best: 1). 2.6 ohms on the 2 ohm tap, or 2). 4 ohms on the 2 ohm tap and 8 ohms on the 4 ohm tap.


    Good Luck!
     
    Last edited: Feb 9, 2022
    Flounderkeg likes this.
  3. mikeswals

    mikeswals Supporting Member

    Nov 18, 2002
    Seattle / Tacoma
    If you're going to run all three cabs at the same time, then it will be a 2 ohm load, so use the 2 ohm jacks:
    Plug the 215 into one of the 2 ohm jack.
    Daisy chain the 115 into the 410 cab (this now makes that combo 4ohm) and plug it into the other 2 ohm jack.

    If you're going to play the stacks separately then use the 4 ohm jack: like if you're only going to use the 215.
    Same if you use the 115 & 410, goes in the 4 ohm jack.
     
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  4. Flounderkeg

    Flounderkeg

    Jan 5, 2022
    Just to clear up my own confusion, are the cabs still considered parallel when they aren't daisy chained to eachother? I should've mentioned that only the 1x15 has a parallel jack so I was wondering if I could safely run 3 different chords individually to 3 of the jacks on the amp? If I can do that, do all of the ohm loads on the cabs match the ohm load on the output jacks on the head? Or do you still plug each cab into a lower ohm load (4ohm cab into 2 ohm output jacks, 8 ohm cabs into 4 ohm output jacks)? Or is it a bad idea Lastlyth
    Thank you that is very useful information. I forgot to mention it but my 1x15 is the only cab with the parallel out so the cab scenario you suggested would work fine for me. I wonder if there's any disadvantages or reasons not to use all 3 cabs at once?
     
  5. Wasnex

    Wasnex

    Dec 25, 2011
    The jacks on the cab should be parallel.

    The panel should look like this:
    q8yocvf0qdzbrmqinigf.jpg

    AFAIK this your cabs:
    8 ohm 115 with parallel In and Out jacks
    8 ohm 410
    4 ohm 215​

    Use the two 2 ohm outputs on the amp. Plug the 215 into one output. Plug the 115 into the second output. Plug the 410 into the 115.


    Rock On! :bassist:
     
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