I have a question relating to line stage with tall bias, such as a 6V6 preamp with a bias of -10V or so.
I understand one rationale behind putting the volume control in front of the line stage is that the stage will then never see anything close to an overload condition, so distortion will be minimized. In the typical preamp using something like a 6SN7 or 5687 tube with a bias of maybe -4V, a 2Vrms signal applied at its input can come close to overloading the stage, causing distortion to increase.
However, if I have a 6V6 line stage (like Salas') with a grid bias of around -10V or more, even that 2Vrms signal shouldn't come close to overloading it. Does it now make sense to consider putting the volume pot (or stepped attenuator) on the output of the preamp, instead of at the input? Or does that cause frequency response errors due to a changing resistance on the output of the preamp stage?
What if the tube used for that preamp has a plate resistance of well less than 1000 ohms (and a mu below 10), and I use a 50k ohm pot on its output?
I don't know enough to identify all the issues that might be involved, and I'm hoping to gain a better understanding. Thanks for any advice you can send this way.
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I understand one rationale behind putting the volume control in front of the line stage is that the stage will then never see anything close to an overload condition, so distortion will be minimized. In the typical preamp using something like a 6SN7 or 5687 tube with a bias of maybe -4V, a 2Vrms signal applied at its input can come close to overloading the stage, causing distortion to increase.
However, if I have a 6V6 line stage (like Salas') with a grid bias of around -10V or more, even that 2Vrms signal shouldn't come close to overloading it. Does it now make sense to consider putting the volume pot (or stepped attenuator) on the output of the preamp, instead of at the input? Or does that cause frequency response errors due to a changing resistance on the output of the preamp stage?
What if the tube used for that preamp has a plate resistance of well less than 1000 ohms (and a mu below 10), and I use a 50k ohm pot on its output?
I don't know enough to identify all the issues that might be involved, and I'm hoping to gain a better understanding. Thanks for any advice you can send this way.
-=|=-