The X-Mod Story!
History: Originally the X-Mod was developed in response to the requests of a relatively small, yet significant group of Guytron customers which all seemed to be asking for pretty much the same thing. After a couple years in production, the people who used the Guytron GT-100 were beginning to fall into two distinct camps. Although most customers loved the amp in the original configuration, the 'camp' in question did comprise about 20-30% of the user base, and their requests were consistent, so experimentation on a solution began in mid-1999.
Group-1, seems to absolutely love the GT-100 as is, and wouldn't change a thing about it. Except possibly the weight! End of story.
Group-2, were mostly satisfied with the GT-100, especially Channel A, but just felt that Channel B was a bit too dark and smooth, not modern enough. They usually requested a more aggressive, brighter and tighter, more contemporary tone with CH-B while leaving CH-A as is.
Note: This perception was at least partially brought on by a change in Chinese 12AX7 tube availability. The new JJ and Russian 12AX7's tended to make the amp even smoother, which was fine for CH-A, while a bit too much for the already smooth CH-B.
First Solution: The challenge was to create a more aggressive and midrange focused CH-B while leaving CH-A alone. This was especially difficult to fine tune, because the channels share a master tone section. Therefore, the amp would become useless if you had to adjust the tone controls each time you switched channels. These are the kind of details that always give engineers gray hair. Because of the 3 year long 'fine tuning' process not all X-Mods are the same, so these are the only GT100 examples that were less consistent in tone. With the exception of changing tube supplies (which can range from subtle to significant) Guytron amps are otherwise very consistent in tone.
Public Response: Interestingly, after people got the amps modded, they most often missed the original tones, and wanted both. This scenario played out so many times, that the X-Mod was ultimately dropped. The seed for the FV was planted.
Switchable X-Mod Solution: Work soon started on a new X-Mod PCB card to add to any GT-100 amp. This would make the X-Mod a switchable solution. Thus, it would expand the tonal capabilities of the amp, without commitment to either the X-Mod or the original GT-100 configuration. As it turned out, this switchable X-Mod was so involved, that before it was finished, it became possible to add a total of 16 combinations of former X-Mod's. This ultimately turned into the GT100-FV amplifier now in production.
Summary: The following quote from Fall-2003 pretty much sums it up...
THIS JUST IN!, Forget the X-Mod, and check out the new GT100-FVamp.
It does the X-Mod and way more! Mod your amp "On The Fly" and you can always switch it back to the original voicings.