Twin Triode
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2AU7 = ECC82, 5963, 5814, 6189
ECC81 (which will be somewhere between the '82 and the '83 in gain terms).
The ECC82 is a 12AU7 medium gain pre-amplifying double triode. Provides a very smooth sound with well-defined tones suitable for audio and guitar amplifiers.
ou can run a valve at any voltage below the recommended voltage .. the question is maximum performance in terms of gain factor.
The 2AU7 = ECC82, 5963, 5814, 6189 all give you a gain
GAIN
ECC82=12AT7=Gain of 70
ECC83=12AX7=Gain of 100.
ECC81 (which will be somewhere between the '82 and the '83 in gain terms).
GRID BIAS
ECC82 - recommended grid bias -8.5V
ECC83 - recommended grid bias - 2V .
The see how Anode voltage and types of tubes used impacts gain factor?
The current that flows through the 1k resistor in cathode, the tube and 100k resistor in anode causes voltage drop on 1k cathode resistor that is applied between cathode and the control grid that is at the zero volt potential through 47k grid stopper and 470k grid leak resistors.
From plate curves (anode curves) you can estimate the bias voltage, anode voltage, and current through the tube. Self bias works because the higher is the current, the higher is bias voltage (voltage drop on 1k resistor), and vice verse.
10K + 100K + 1K = 111K
I=v/r = 200/111K = 1.8miliamp
The current that flows through the 1k resistor in cathode, the tube and 100k resistor in anode causes voltage drop on 1k cathode resistor that is applied between cathode.
The control grid that is at the zero volt potential through 47k grid stopper and 470k grid leak resistors. From plate curves (anode curves) you can estimate the bias voltage, anode voltage, and current through the tube.
Self bias works because the higher is the current, the higher is bias voltage (voltage drop on 1k resistor), and vice verse
