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mesa 400 and 400+ trannies

Discussion in 'Amps and Cabs [BG]' started by K-Funk, Jun 27, 2008.

  1. Jun 27, 2008 #1
    K-Funk

    K-Funk

    Sep 24, 2007
    Auburn Hills, MI
    Do the Mesa Bass 400 and 400+ have the same transformers? Back when I briefly owned both for the same time, I never got a chance to compare size, etc. Forgive my lack of tube amp knowledge, I'm just curious as to the differences between the two amps :meh:
     
  2. Jun 27, 2008 #2
    Vin_MM_Sabre_79

    Vin_MM_Sabre_79

    Apr 14, 2007
    Ballaarat Australia
    Power or output transformer?
     
  3. Jun 27, 2008 #3
    timv

    timv

    Jun 7, 2000
    Chandler, AZ
    Both transformers are different. The 400 has around 540VDC B+ and the 400+ only around 500. I believe the size is a bit bigger also. The output in the 400 is the same one used in the d-180, m-190 etc.... Only meant for 6 output tubes, the 400+ is larger and for 12 output tubs so the turns ratios are different for the change in impedance.
    The chokes are the same though.......
     
  4. Jun 27, 2008 #4
    K-Funk

    K-Funk

    Sep 24, 2007
    Auburn Hills, MI
    Did they use the hotter voltage in the earlier amps to get more power out of fewer tubes? Also, isn't 540V a little spicy for 6L6GC tubes (in the case of the D-180 and late Bass 400's)?
     
  5. Jun 29, 2008 #5
    timv

    timv

    Jun 7, 2000
    Chandler, AZ
    I believe the higher voltages were to get alittle more power but still the max I have bench tested one at was 180 watts with 6550's and 170 watts with 6L6's.
    540 is on the high side but they were originally shipped with sylvania STR-415's which were very robust 6L6's.....

    I've bench tested a m-190, d180 and bass 400 with both types of tubes with the same results clean......