11
An example is as follows:
25
𝑊
430
𝑉𝐷𝐶
×
65%
×
1000
=
𝑎𝑏𝑜𝑢𝑡
35
−
37
𝑚𝐴
You might wonder why your DMM is set to millivolts and not milliamps – simply, we have a 1 Ohm resistor placed between your
probe jacks and ground to convert a current reading to a voltage reading. That way, a bias current of 36mA measures as 36mV
on your DMM.
NOTE
– Only set your DMM to mV for measuring bias on the amplifier. Not doing so may damage your DMM.
A FEW COMMENTS ON BIASING
Due to the nature of vacuum tube amplification, there are inherent risks when biasing your amplifier. Extremely high-voltages
are present, and vacuum tubes reach high temperatures during use.
The risk of electrical shock and/or skin burns should ALWAYS be kept in mind. Therefore, bias at your own risk, and only while
paying attention and taking all precautionary measures.
Biasing should only be done on a clean workbench with no distractions. Do not wear loose clothing or any jewelry. Take your
time, and think carefully before each step.
Even though the bias test points and adjustment is external to reduce risk of electrical shock, all precautions must be taken
while biasing.
Again, bias at your own risk. Ceriatone Amplification is not responsible for any damages or injuries resulting from user biasing.
