Thanks Tony.Are you trying to say changing tubes may not be the solution. I read somewhere that A70-t has better output transformers than A80-t.
Or are you saying cayins have a week bass out put from using a smaller transformer? To be honest I am the only one having this issue.
About red plating is it increasing or decreasing bias voltage that causes red plating?
qguy basing manually is fun.its like tuning your engine yourself. auto bias version can take 6555. But do you know it is the same for manual biased version?
red plating can be caused by several reasons, one if the plate dissipation specs of the tube is exceeded, i.e. the EL34 is rated for 24 watts and you biased the tube for 30 watts, another is when your output stage oscillates at RF, you will not hear that but it can happen.....
decreasing the grid voltage increases plate current and vice versa....this is what happens when you turn the bias controls....
i would not give you false hopes, one man's experience may not hold true to you.....if you can borrow a preamp with tone control, then i think that is your best option to try.....
you see here how many tried changing tubes, changing caps, etc, then later on sold their amps....
besides, the enjoyment of music can not hinge on just the tubes, nor the amplifier alone, you have to look at the whole chain from source to speakers and the listening environment......if you focus on just the amp, you may never get there......
since your amp is 5 years old, go ahead and change tubes....
