From a Mesa Junkie perspective, I found the Mark IIC+ Reissue to be a very close match to Mesa's first reissue of the IIC+; The JP2C. Now that surprised me more than I expected since the JP2C is based on the 100W Class AB (HRG) the IIC+ reissue is based on the Simul-Class (DRG). Before I got my hands on the IIC+ reissue, my only comparison of the JP2C to another Mark was the Mark V90, then followed by the Badlander100 and then the Mark VII. Why the Badlander in this list of amps? It sounds very close to the JP2C in many ways, just slightly different. Besides that, the BAD is based on the lead drive circuit common to all Mark amps, just placed in a different location.
Reissue IIC+ is a dead on ringer for the JP2C which I did not expect. Figured the JP2C would have a darker tone. Nope, they practically sound identical. I was even surprised the 75W was holding its own against the 100W JP2C. Sure, not the comparison you asked about.
Mark VII is just different. More related to some of the changes made since the Mark IV came out. I would assume it is closer to the Mark IVA than the IVB. I had the IVB as that amp had a slight nasal tone shift with the midrange that was hard to avoid and made the EV less desirable speaker to use with it. Too Sterile. Mark V90 carried that similar tone but modified the circuits with added tubes in attempt to replicate some sounds but not really using the same circuits to do it. Not a bad amp, just missed the mark in my opinion (at least the one I have). First time I heard the Mark VII, it was love at first sound. This amp has the same characteristic of the Mark III as I recall it sounding. More open and airy on CH3 with the same grind and gain structure that made me a follower of the Mark amp in the first place. Yes, the JP2C has that too but not as much fire as it only gets close on CH3 with the gain pulled out. Mark IV mode has more of that tube saturated sound that may be on the same level but seems to have more gain to it. The crunch and VII modes are similar but different, VII has much more compression and the tone stack is post gain. IIB is just a bypass on the overdrive stage and punches through with the boosting stage. At least Mesa did it right since the amp with its modes are using the original circuits to get there. Having the pentode/triode based on 45W or 25W provides that feature. It could have been a switch like the IV or V which would have provided 4 different power modes: 90W pentode, 75W pentode/triode, 45W pentode, 25W triode. The Mark IV had this as a universal function, Mark V it was only associated with CH3. I do not mind the 3 power modes of the Mark VII, having them on the front panel for each channel is nice. Too bad it does not have a variac/tweed power option.
Since I have two Mark VII, I compared one loaded with stock 6L6 tubes and the other with the STR447 EL34. I could not tell them apart, they sounded much the same. No drop in voltage or shift in tone. The STR445 tube are fine with the Mark VII. Seem to be a good fit for the amp. Not exactly a full 6L6GC tone as it does have some other characteristics to them. The STR445 (JJ 6L6GC) based on Mesa's description from their website:
The MESA® STR-445 is a 6L6 that shares some qualities of a 6CA7 in that it has tight, articulate low-end for excellent bass definition along with beautifully balanced mids and a chiming top-end that cuts without harshness. It’s a great choice for our Rectifier Series to tighten low-end, add top-end cut in a perfect “Rock/Claw” frequency, while avoiding “buzz” or “sizzle” in the upper octave.
I can hear that 6CA7 sound as I did try the JJ 6CA7 tubes in the Mark V90, they did not last very long but had a unique sound to them. Not even close to the STR416 6CA7 tubes from 1989.
The odd thing I noticed with the STR445 tubes stuffed in the Reissue IIC+ are much longer than the STR445 tubes that were stuffed into the Mark VII amps. Practically the same length as the STR448 tubes (not the same manufacturer and the tubes are different in internal structure). When my hearing comes back I do plan on trying different power tubes out of curiosity. Interested to hear the amp with STR440, STR454, STR441, STR443, STR415, STR448, either full set or mixed pairs. Sort of liked the mixed pair of the STR448 with the STR445 with the Mark VII. The 448 were in the Class AB sockets. Added a bit more depth to the 90W sound. Curious on the Reissue as it is a blend of pentode Class AB, and triode Class A.
