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Jeff,
> I have a silly question... If the 6V6 distorts because it is
> overdriving the tank, why can't you just back down the level
> a little so it doesn't overdrive the tank? Wouldn't you then
> still be hitting it hard enough for surf? Seems to me, you'd
> be hitting it as hard as you can without overdriving it.
Well, the theory goes like this.....
In essence, the dwell time of a tank's springs is dependent
on the incoming voltage level - reduce one, you also reduce
the other. (As seen in the schematic, the dwell control.)
Where the problem arises is in that the same voltage level
also drives the tube to some particular rated wattage.
For a 6V6, it's about 8 or 8.5 watts, for a 6K6, it's
about half that.
So if you're driving, say 1.0 volts into a tank at 4 watts,
and everything sounds good, what happens when you switch to
the higher wattage tube? The dwell time is the same length,
but the springs are now distorting the signal - they're being
overdriven with more wattage than they were designed to handle.
Reducing the incoming voltage level (turning down the dwell)
to reduce the distortion works, but it also has the undesired
side effect of reducing the dwell time. (Well, duh!)
OK, yeah, I can hear some of you now. "The dwell time is too
longer with 6V6", you say. Ever hear of a distortion box that
also sustains? Same principle here - the lower signal levels
were increased to higher levels (the paramount operation of a
sustainer), so that added a slight bit to the overall dwell
time (more signal of a higher level present before total decay).
But the signal is very distorted, and to my ears, unpleasant.
Jeff, I hope that helped. There's lots more theory behind
this, but I tried to keep it short and sweet. <g>
unlunf
