Max wattage for a JTM 45 style amp?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by centsmin, Feb 22, 2008.

  1. centsmin

    centsmin Member

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    I've heard that a 50 watt RMS 4 hole Marshall with solid state rectification actually has max ouput around 90 watts with the volumes dimed.

    I have a Germino Classic 45 which is 35 watts RMS with a tube rectifier. If I dime the volumes, will the max output be 60 to 70 watts, or significanlty less becuase of the tube rectification?
     
  2. killer blues

    killer blues Member

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    short answer is no. Some of the 50 and 100 watt 4 holers had PT's that could produce up to and over 600 VDC on the power tube plates. These amps were the ones that produced over the rated watts. A JTM45 has a PT that only spits out 180mA, and an OT that puts out 30-35 watts. Even with SS rectification and EL34's you may squeak out 40-45 watts tops
     
  3. DGDGBD

    DGDGBD Member

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    I've read that in a Marshall reference book - 50 watts at onset of clipping, 90 watts at a higher level of distortion.

    Don't remember exactly, but my impression was that this wasn't for the older models, but rather the later JCM era models.

    Not sure about the JTM45.
     
  4. phsyconoodler

    phsyconoodler Member

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    The output transformer impedance is key to getting the most power from an amp.
    A properly designed JTM45 has a 6.6k primary which at the plate voltage available,is lucky to put out 35 watts at full song.
    A JCM800 can put out about 65 watts if the plate voltage is about 475v.There are other factors as well like current and losses,but you get the idea.Distortion ideed does wierd things to the output.
     

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