[raindance]

It doesn't matter. If you are measuring the voltage across a resistor it will increase when more current is flowing. More current is more bias. The resistor you are measuring is in the cathode of the power tube. You don't measure grid voltage on any commercially made amp I am aware of. It would be pointless because different tubes require differing amounts of bias voltage at the grid to produce the right bias current anode to cathode.

[Captainhemo]

It doesn't matter. If you are measuring the voltage across a resistor it will increase when more current is flowing. More current is more bias. The resistor you are measuring is in the cathode of the power tube. You don't measure grid voltage on any commercially made amp I am aware of. It would be pointless because different tubes require differing amounts of bias voltage at the grid to produce the right bias current anode to cathode.

Yeup,  I hear you..  I guess where the conbfusion  comes in  is  that it would appear  most amp manactuers are calling the measurement of  plate V @ ilw with no  input signal the bias  And yes,  I understand  that this  measurement does  corrolate directly to the  current between teh cathode  and the plaste (which is what we should be concerned about).  From  what  I've been reading today,  the  actual bias voltage is  the - V  applied to the   control grid  which is why  Eric was saying    increasing the bias V  would actually decrease the    current to the plaste

I see your point   in saying  monitoring the  grid V is kind of pointless as    the plaste  V/I could differ greatly from  tube to tube using the same bias V.

I think   I've got it...  someone slap me if  I'm   way off  here   

[raindance]

Yes, you got it.

So: the bias voltage that you are adjusting is a negative voltage that you do not measure. The voltage you do measure is across a low value cathode resistor, conveniently added by the manufacturer, which allows you to "see" the current through the tube using ohms law.

If the amp did not have this resistor, you would need to insert a current measuring device in the circuit where the resistor goes at the cathode, either way you would have to break the circuit to do this or use a bias socket adapter.

So to some degree there were elements of truth in most statements.