Testing my A15MK2

    Hello,

    I just finished assembling my amp, and all seems ok :cool:.

    However, some voltages at V1 are a bit far from the expected voltages :

    At V1 : 136V(Pin1) and 128.5V(Pin6) where it should be
    154V(Pin1) and 145V(Pin6).

    Also the heater voltage is 7V instead of
    6.3V.

    All other voltages are ok.

    I'd just like to know if these differences can be explained (they are a little bit bigger than the 10% window) and if some people had the same differences.

    oksuper

    Thanks.
    The ingoing AC voltage I use is a little bit high, you're right, it's 235V.

    Can it be the reason why my heater voltage is a little too high ?

    However, the Pin1 and Pin6 voltages at V1 are not too high, they are 12% too low. ???

    Regarding the heater voltage, +10%/-5% is acceptable, so 7V is at the upper limit, but still OK. As 235V is not too high, you can lower the heater voltage a bit by inserting two resistors in the heater path. Just calculate the values with Ohm's law to lower the voltage to about 6,5V.
    Regarding the voltages at the tube, this is still OK when all connected resistor values are correct! The deviation might result from tube 's spread in values, but as said the voltage values are still OK.
    Regards,
    Martin

    Thanks MAD.
    I've double check and all the resistors are ok around V1.
    Anyway if those voltages are normal, it's ok for me. I'll try to change the order of the tubes to see if it's the spread of the tube's caracteristics that causes the deviation.

    FYI, here are a couple of pics from my amp. You can see the Tube Town cab (4*10) that I bought for my A15MK2, loaded with 4 Celestion G10 vintage 10''/60W/8ohm.

    In the second pic is my amp assembled, with the footswitch option.

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