FirstWatt F5 Turbo V3, Инструкция по сборке, Страница: 7 / 15

F5 Turbo Assembly Instruction Version 2 Page 7
mosfet is matched within a reasonable limit and share an almost equal load on the total
bias.
i. Note that the DC offset will drift from cold to hot and it is normal. The target is that when
hot, the dc offset should be /-10mV relative to ground.
j. Thus adjust the bias value according to the heat sink size used. Target temperature of the
heat sink should be below 50 degC.
k. If you do not have 3 meters, then check the output DC offset and voltage across R20. I think
two meters is a minimum.
l. For P3 pot adjustment, refer to Pass’s article for details.
m. Picture of a complete set F5 Turbo:
This set use Airlink 625VA 25Vx2 transformer, Bridge rectifier, 70000uF 50V Mallory, 1mH solen coil,
30000uF 100V Rifa long life. The ripple at the Rifa cap is below 5mV. Bias is set to 1.7A to 1.8A per
channel and heat sink temperature is 52 deg C, room temp is 20 deg C. The idle noise level is around
75uV which is very low in the AP measurement. FFT and Distortion vs Power charts are attached in this
document for reference. Distortion at 1W 8.2 ohm load is 0.004%.
Attachment follows:-
www.FETAudio.com