Quinnamp SDQ1b Owner's Manual - page 10
Warning – No user serviceable parts inside. Refer to a qualified technician for servicing.
BIAS PROCEDURE:
1. When new output tubes are installed it is important to re-bias the amp for optimal
performance.
2. ALWAYS HAVE A SPEAKER CONNECTED.
3. Use a digital volt meter set to DC volts at lowest scale (MV). Makes sure the black lead is the
common terminal of the meter and the red lead is the DC voltage terminal of the meter.
4. Place the Amplifier in operate mode with the Master Volume and Reverb controls set to
zero.
5. Set the 100 Watt/50 Watt switch to the 100 Watt position.
6. Place the red meter lead in the test point hole (red tip jack) And touch (or clip) the black
meter lead on one of the metal output tube retainer clips.
7. Use a small flat blade screwdriver to adjust the bias pot.
For 6L6GC's a reading of 160mV +/-5 mV maximum is recommended.
For EL34's a reading of 135mV +/-5 mV maximum is recommended.
The reading is the sum of the idle current for all four tubes.
(The plate voltage is approximately 475 volts).
8. Recheck the reading after 10 minutes of operation, and again after a week or two of
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