Access link in "re: 12AX7 parallel triode question"?

[TubeRube]

While searching for info, found sluckey's Reply #27 (26Feb2010)... something like, IIRC "Look at the V1 circuit on this Marshall 18 Watt(link) amp. Switching jacks allow single triode mode (LO input) or parallel triode mode (HI input)"...  but the link is past its expiration date? Failed to find schemo of said circuit in the archives (ineffective search dog?). Is it just 2 switching jacks (wired as either/or, but not both input) so that one jack disconnects a triode's
cathode resistor/bypass cap. from ground? Seems I've read that this is one way to "turn off" a tube, but don't know if it's safe to use on one triode of a standard parallel triode input circuit. Not sure why not... unloaded grid? run-away condition? cathode poisoning? S.Luckey said this was a widespread popular circuit-- I just have a "blind-spot" ignorance of it.  Can anyone re-direct my search or re-post this info? Any help muh appreciated.

[jeff]

My guess. Single, parallel, or two singles.

[sluckey]

I fixed the broken link in the original message. Just in case you don't see it, here it is again...

http://home.comcast.net/~seluckey/amps/18w/18w.pdf

BTW, Jeff nailed the circuit for you.

[TubeRube]

Hey, Jeff & Sluckey! Thanks a bunch for the circuitry posts! That's exactly what I was looking for...  I'd never figured out how to make it work like that!
This circuit approach is so cool! Everything stays connected except the grid sides of the triodes switched for the chosen mode of operation...  no signal to one grid, no triode-- but still has grid reference and input shunt to ground? You guys make the "seek and ye shall find" axiom come true! Thanks!