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Thanks for the explanation, but I don't know if I can buy it. First
let me say that I've never fooled around with either unit, and that
I'm not anywhere as sensitive to the differences in sound as most
players. I'm also sure you hear a difference, so please don't take
any offence.
That said, I'm looking at the schematic right now, and as I see it,
the "Dwell" pot is nothing more than the equivalent of a volume pot
on an amp. In and of itself it wouldn't affect the duration of the
sustain of the reverb, except that it's controlling the level of the
signal to the 12AT7 that's driving the 6V6 which drives the reverb
tank. So the harder the reverb tank is hit, the longer the reverb
will sustain or dwell. So what I'm trying to say is that, I would
think that the dwell is totally a function of how much voltage the
driver tube is allowing to flow through the reverb transducer, if
driven just below the point that is too much, the dwell should be the
same whether the driving tube in the circuit is capable of driving it
harder or is at it's limit. BTW, the power rating of a tube is like
it's save upper limit, so replacing a tube that can deliver more
power doesn't mean it necessarily will, it's not like a light bulb.
Maybe the 6K6 itself, having a lower power rating is actually
distorting or compressing causing a different sound.
--- In , "unlunf" <unlunf@y...> wrote:
>
> 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
>
