Nope! The circuit doesn't work that way.
The whole 18 watter trip grew out of a hobby group of tubeheads called the
project. These guys were trying to develop a lower powered amp with the classic Plexi sound. Overall, most folks think they succeeded quite well.
They stuck to the classic preamp and substituted EL84's or less often 6V6's. For the most part they used cathode bias, although some went for fixed or a dual-mode switch to give players something to diddle with.
From a technical standpoint, once the circuit was developed anyone could see that it was pretty straight forward and you can't mess with it beyond a few simple tweaks or you'll lose that Plexi tone.
Things have moved along and now there are a raft of guys offering 18 watt amps that are essentially knockoffs of the AX84 design. Not to mean that they may not be good quality. Most of them are well built, although the odd crappy one has come in to my service bench. They're just not really unique or original.
As for the AC15 and/or the Vox "chime", I've played a bit with those circuits. The output stages never seemed that different to me from anybody else's. What WAS very different was the use of a pentode tube for the 1st preamp stage, instead of the usual triodes of a 12AX7! It has quite a different flavour than most other amps. Some boutique guys are now offering a pentode channel. I just fixed a Divided By Thirteen amp and one of the two channels was that way.
So many amps, so many tones, so little time...:rockon: