Call VTL and as for a confirmation as to what is correct.
VTL Deluxe 300 Biasing
On the VTL website is says the following-
Therefore, to get a result of the required 27 – 30 milliamps the voltage reading should be 270 – 300 millivolts for the 10 Ohm resistance readings, and 125 – 150 millivolts for the 5 Ohms resistance measurements.
However, I found a copy of the VTL Book which was published around the same time the amp was manufactured and it states-
BIAS: Conservatively set at factory for 6550 to approximately 30/35mA, bias current can be increased to double and triple those figures (moving nearer to Class A operation) but to no sonic benefit; and shortening tube life thereby.
Can anyone advise me as to which one I should follow?
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