I knew this was going to come out sooner or later. The tone of the TC-100 does seem to be brighter than the TC-50. It could be related to the power tubes or the preamp tubes. I did change the two 12AX7 tubes V3 and V4 as I started hearing a ping when channel changing. I think it was V3 as it was noisy on the tap and caused some noise if I touched it. Had to pull the chassis out so I could confirm if it was V3 or related to the clean channel V1 and V2. I had similar thoughts on the TC-50 when I first got it, seemed too bright. Now the TC-100 is getting brighter on the gain channels. I isolated the two tubes I pulled so I can put them back in. I do have 10 new Mesa tubes available so I may end up replacing all of the preamp tubes anyways. I had a similar issue with the JP-2C when I got it too. When amps end up on the back of a truck, bouncing around and what ever jarring it may endure when shipped ground could be one issue (more so a problem with power tubes than preamp tubes). At least the box the amp came in is in perfect shape so it was not dropped. At the moment, I think I like the TC-50 more than the TC-100. One thing to note, I have used it with the power soak for a while and when I went back to the 100W it sounded really good. Now it seems to be on the bright side. Not brittle though. Think of a Fender tone with 6L6 on how much brilliance and chime you can get with it on the cleanest channel. That is what the Lo gain is sounding like but with way more distortion. Presence and Treble cut did not seem to tame the brilliance of the top end. Reduction in gain helped a bit. If I cannot compensate the treble on the lo gain channel with some Mesa tubes (I do have two SPAX7 tubes to try) I may roll in a long plate Mullard as that has better roll off on the higher frequencies. While I am at it, may stuff in a quad of Mesa STR440 6L6GC (yellows) that I got for the Roadster. The quad of greens ended up in my Mark V, I can also take those out and swap something else like the SED =C= 6L6 or the Preferred series (thetubestore brand which is the same as Doug's tubes Ruby 6L6GCBSTR)
I also have a 6 of the gray color coded EL34s. Two of which were originals that came in the TC-50 and the other 4 have not been used. Most of all I will be patient with the TC-100. I jumped on the TC-50 a bit prematurely for the same reasons and did not like it much at first. Now I love it. Time to change preamp tubes in V3 and V4. The clean channel will remain unchanged as that sounds awesome. I am glad that Mesa stayed with the two isolated preamps, having the clean separate from the high gain channels. Difference between the Hi gain and Lo gain is one preamp gain stage. very much the same as the Royal Atlantic and the Electra Dyne. Unlike a Mark series amp, where all the tubes are cascaded and harder to isolate one tube without affecting some other feature. the TC series is laid out with two primary preamps that each use a pair of tubes. reverb uses one tube and does not share a triode with a gain stage, FXloop is one tube and obviously the PI is one tube. Say you did not like the clean channel for some reason, you can change preamp tubes in V1 and V2 and not effect the hi/lo gain channels. In essence, V1 is the primary stage for the clean, V3 is the primary for the gain channels. In another perspective, the amp has two V1 tubes if you think DR, Roadster, Mark or other amp where V1 has the first gain stage for all channels. If someone says change V1 for a better tone on the Hi /Lo channels they actually mean V3 since this amp is quite different than the ladder style cascaded gain structure of most amps.
I also have a 6 of the gray color coded EL34s. Two of which were originals that came in the TC-50 and the other 4 have not been used. Most of all I will be patient with the TC-100. I jumped on the TC-50 a bit prematurely for the same reasons and did not like it much at first. Now I love it. Time to change preamp tubes in V3 and V4. The clean channel will remain unchanged as that sounds awesome. I am glad that Mesa stayed with the two isolated preamps, having the clean separate from the high gain channels. Difference between the Hi gain and Lo gain is one preamp gain stage. very much the same as the Royal Atlantic and the Electra Dyne. Unlike a Mark series amp, where all the tubes are cascaded and harder to isolate one tube without affecting some other feature. the TC series is laid out with two primary preamps that each use a pair of tubes. reverb uses one tube and does not share a triode with a gain stage, FXloop is one tube and obviously the PI is one tube. Say you did not like the clean channel for some reason, you can change preamp tubes in V1 and V2 and not effect the hi/lo gain channels. In essence, V1 is the primary stage for the clean, V3 is the primary for the gain channels. In another perspective, the amp has two V1 tubes if you think DR, Roadster, Mark or other amp where V1 has the first gain stage for all channels. If someone says change V1 for a better tone on the Hi /Lo channels they actually mean V3 since this amp is quite different than the ladder style cascaded gain structure of most amps.