touch sensitivity

[daz]

daz, no need for a switch etc, just ground pin 1 screen grid directly and take cathode pin 8 to ground via the 1 ohm resistor. I doubt it makes much difference, I was just reporting the tone lizard's take on this issue. I recommend that site, just read that page if nothing else. Peter.

At this point i doubt it matters really, so i have 1 and 8 together and both grounded thru the 1 ohm R's.

[Bruce / Mission Amps]

Not silly if you value peace of mind. Has nothing to do with whether or not it's necessary. But if 2 people who are both quite knowledgeable like yourself can argue over things like this, who am i to decide there is one definite answer? Consider this..... someone like myself who can build an amp but doesn't understand enough to easily get it sounding fantastic cannot just get a answer to each of the endless questions I have. Throw into the mix the fact that many of them seem debatable between gurus like yourself, so how am i to decide who to listen to on 100 different design details?! I'd be at this for the rest of my like and never get a chance to play the amp !

So while i didn't add a switch, i AM adding a wire from both tubes to ground to bypass them so that i can simply unsolder when i need to use the resistors to check bias, something i will rarely do once the amp goes into it's new home (cab) that will be finished with this weekend. But you haven't gotten rid of me yet.....i'm building another one after this, so lookout !

I agree that most goofs here spend too much time on nonsense and minute details that are close to nonexistance...... if they spent half as much time practicing or playing with others they probably would be light years ahead in tone, skill level and fun factor.
However, are you talking about wiring a switch to bypass the 1 ohm resistor for current measuring or sending the suppressor grid from the one ohm resistor to the bias supply?
I totally defy anyone to tell me they can hear a difference between the 1 ohm resistor bypassed or not bypassed if the G3 is connected to the cathode or grounded.
The difference in DC potential in any condition I can think of is the no signal DC level of 25mv to 45mv to maybe 200mv with the amp roaring.
It just can't make any real world difference and I won't try it because I'll feel like a nut cake...

[daz]

Yes, pins one and eight soldered together with 1 ohm R's between them and ground, then a switch that bypasses the R's so it's straight to ground. but i realized if i do that the bias would change when i switched it straight to ground after biasing it. then i just said WTF does it really matter ! So no switch, no bypass wire, just 1&8 together with a 1 ohm from there to ground. lets face it...as Nigel would say, "this is just nit picking really, innit?"

[Russ]

Pin 1 & 8 w/ cathode bias

Come to think of it, the 1 ohm resotor, I guess, would provide a very small amount of unbypassed cathode biasing.

So what if the el34s are fully cathode biased, in which case pin 1 (if tied to pin 8) will have +40v to +50v on it. What does that do?

It may not do anything for the sound, but maybe it has an effect on tube life?
If it's ok does this mean that pin 1 should always be at pin 8 potential, whatever that may be?

So many questions.....