REISSUE Rumor: Mark IIC+ and 2ch Recto

[Appleridge]

Probably should start a thread just with links to the videos about this nice, new amp. Here is a nice one (I presume, I’ve only watched the first 10 seconds) of Dinesh and Tone Boy Mr. West doing a deep dive on the Mark IIC+ reissue. 52 minutes of goodness!!

Great video! It’s great to see them spending the time getting the unbaptized up to speed. I remember playing a mark iv in a local music shop when I was young. The amp was so intimidating, and sounded terrible to my ears. I walked away thinking Mesa was not for me. Years later I bought one and spent months learning. Hopefully people watch these vids to save some time learning how to shape!

Where did they find that patch cord though…looks like something from a Commodore 64 lol.

 

[Vinzenz]

Mesa did state the IIC+ reissue was suitable for EL34 in the Class A sockets. Even Mike West stated it is best to use the older NOS EL34 tubes. This is more of a quality issue regarding current production EL34 tubes not holding up under certain conditions. STR450, STR442, STR416 would be suitable. The STR447 or others may be questionable. Bottom line, Mesa/Gibson decided not to include any mention of the EL34 as alternative use in the Class A sockets as this could be an issue as most NOS tubes with Mesa branding (yeah it has to have the Mesa logo printed on them to be acceptable to meet warranty requirements) may lend to issues as the STR447 or the STR446 may not do well in the reissue. Whatever the case may be. I do not have the reissue yet. Still waiting and waiting, and well not sure it will come this year. Perhaps by April, I may see it. That did get upgraded to March then to February. If everyone drops off the list I may see it sooner. This has nothing to do with supporting the heater current. This is not 1960. I doubt they skimped on the windings to support the heaters. Perhaps KT88 or 6550 tubes may pose some issues. It is more of the bias voltage at the control grid of the class A sockets. Is it low enough to support EL34 effectively or is it too high (in magnitude) that ends up with cold tubes?

If you want that 6CA7 effect with 6L6 tubes, just leave the STR445 in the Class A sockets and change what you place in the Class AB sockets. The STR445 do have some 6CA7 characteristic sound to them. Actually, I am curious to find out how the reissue will sound with the stash of Mesa tubes I have. NOS STR415, NOS STR454, NOS STR440 (they became NOS when the company closed shop due to fire), current STR441, STR443, STR448. Since it is Simul-Class, you do not have to run the same tubes in the amp. Blending STR415 in Class AB with the STR445 in Class A may be interesting. I actually like the blend of the STR448 with the STR445 in the Mark VII but that runs full pentode at 90W. the triode/pentode thing may be different with the EL34 in the Class A. At this point, I no longer care. Mark III DRG sort of lost its flavor with all 6L6GC tubes. The EL34 were ok but not as nice as the 6CA7 STR416 tubes. I am sure some remember the 90's when you could not find any Mesa power tubes. Nothing but Groove Tubes or Sovtek tubes of unknown origins back then. At least in PA/NJ the tube availability was rather scarce in most shops that carried Mesa amps.

 

[Vinzenz]

I suspekt Mesa to be rekuctant wrt warranty as modern el34s are so many different flavors that its impossible to warrant every Kind of el34 especially when driven hard to their limit. Its not a quality issue but rather the fact that not every el34 although being in Spec can stand the circuit demands.

 

[Vinzenz]

I suspekt Mesa to be rekuctant wrt warranty as modern el34s are so many different flavors that its impossible to warrant every Kind of el34 especially when driven hard to their limit. Its not a quality issue but rather the fact that not every el34 although being in Spec can stand the circuit demands.

Especially the Mk2c circuit is not built to run el34s safely. the screen grid resistors are much too low to keep the el34 in a safe state. In later mk3s they were like 2k7 which is roughly 6 times as high. So from a reliability PoV it is mandatory to NOT warrant any el34 usage.

 

[Theresa]

Especially the Mk2c circuit is not built to run el34s safely. the screen grid resistors are much too low to keep the el34 in a safe state. In later mk3s they were like 2k7 which is roughly 6 times as high. So from a reliability PoV it is mandatory to NOT warrant any el34 usage.

Interest POV, whereas the manufacturers have stated for years a limited warranty or no warranty depending on covering tubes, but OG owners have populated the class A side with EL34's for as long as I can remember and not heard of issues. Maybe it's because of the robust EL34's we use in that application. I suspect this is the case. Just as I favor NOS Tesla or NOS =C= Svetlana's. I have not heard HRG users co-mingling tubes. I don't believe the 100/60 watt variants accommodate this in the design.

 

[Vinzenz]

Interest POV, whereas the manufacturers have stated for years a limited warranty or no warranty depending on covering tubes, but OG owners have populated the class A side with EL34's for as long as I can remember and not heard of issues. Maybe it's because of the robust EL34's we use in that application. I suspect this is the case. Just as I favor NOS Tesla or NOS =C= Svetlana's. I have not heard HRG users co-mingling tubes. I don't believe the 100/60 watt variants accommodate this in the design.

I strongly believe that a typical el34 (be it NOS or not) ist abused because of much too small grid resistors. There is a reason why mk3 grad resistors are 6 times as high. These are current limiting resistors to protect the tubes.

 

[Vinzenz]

I strongly believe that a typical el34 (be it NOS or not) ist abused because of much too small grid resistors. There is a reason why mk3 grad resistors are 6 times as high. These are current limiting resistors to protect the tubes.

Of course there are different was to handle this: 1) put 1,5k/5W or higher resistors in the class A Socket 2) leave them as they are and take the risk ( which might be Boogie but not Gibson)
3) Leverkusen them and no warranty if el34

 

[bandit2013]

Great video! It’s great to see them spending the time getting the unbaptized up to speed. I remember playing a mark iv in a local music shop when I was young. The amp was so intimidating, and sounded terrible to my ears. I walked away thinking Mesa was not for me. Years later I bought one and spent months learning. Hopefully people watch these vids to save some time learning how to shape!

Where did they find that patch cord though…looks like something from a Commodore 64 lol.

It was a radio shack special.

 

[bandit2013]

Interest POV, whereas the manufacturers have stated for years a limited warranty or no warranty depending on covering tubes, but OG owners have populated the class A side with EL34's for as long as I can remember and not heard of issues. Maybe it's because of the robust EL34's we use in that application. I suspect this is the case. Just as I favor NOS Tesla or NOS =C= Svetlana's. I have not heard HRG users co-mingling tubes. I don't believe the 100/60 watt variants accommodate this in the design.

HRG versions do not support it. I would not recommend it either as some tubes even if Mesa branded of the same color code but different makes may not have a balanced current as a full quad of the same tube. I tried running two different pairs of 6L6 tubes in the JP2C just to hear how it may sound, terrible.

 

[Joey1970]

Mesa did state the IIC+ reissue was suitable for EL34 in the Class A sockets. Even Mike West stated it is best to use the older NOS EL34 tubes. This is more of a quality issue regarding current production EL34 tubes not holding up under certain conditions. STR450, STR442, STR416 would be suitable. The STR447 or others may be questionable. Bottom line, Mesa/Gibson decided not to include any mention of the EL34 as alternative use in the Class A sockets as this could be an issue as most NOS tubes with Mesa branding (yeah it has to have the Mesa logo printed on them to be acceptable to meet warranty requirements) may lend to issues as the STR447 or the STR446 may not do well in the reissue. Whatever the case may be. I do not have the reissue yet. Still waiting and waiting, and well not sure it will come this year. Perhaps by April, I may see it. That did get upgraded to March then to February. If everyone drops off the list I may see it sooner. This has nothing to do with supporting the heater current. This is not 1960. I doubt they skimped on the windings to support the heaters. Perhaps KT88 or 6550 tubes may pose some issues. It is more of the bias voltage at the control grid of the class A sockets. Is it low enough to support EL34 effectively or is it too high (in magnitude) that ends up with cold tubes?

If you want that 6CA7 effect with 6L6 tubes, just leave the STR445 in the Class A sockets and change what you place in the Class AB sockets. The STR445 do have some 6CA7 characteristic sound to them. Actually, I am curious to find out how the reissue will sound with the stash of Mesa tubes I have. NOS STR415, NOS STR454, NOS STR440 (they became NOS when the company closed shop due to fire), current STR441, STR443, STR448. Since it is Simul-Class, you do not have to run the same tubes in the amp. Blending STR415 in Class AB with the STR445 in Class A may be interesting. I actually like the blend of the STR448 with the STR445 in the Mark VII but that runs full pentode at 90W. the triode/pentode thing may be different with the EL34 in the Class A. At this point, I no longer care. Mark III DRG sort of lost its flavor with all 6L6GC tubes. The EL34 were ok but not as nice as the 6CA7 STR416 tubes. I am sure some remember the 90's when you could not find any Mesa power tubes. Nothing but Groove Tubes or Sovtek tubes of unknown origins back then. At least in PA/NJ the tube availability was rather scarce in most shops that carried Mesa amps.

So they are calling "Class-A" mode in the re-Issue 25 Watts, which is what the Green Stripe Mark 3 is rated (Triode). Hmmmm....

 

[bandit2013]

There have been many documentaries on the subject. Green stripes Simul-class Class A is wired pentode. All of the previous versions including the IIC+ were 15W triode. The Green Stripe was closer to the Mark IV as they both had the same max power rating of 85W.

Green stripe would be Class A 25W in pentode. The reissue is 25W triode. Comparing that to say the Mark VII, the Class A is 45W pentode or 25W triode. That is what seemed to stick out. Uncertain but would be interesting to find out if the Mark VII and reissue are using the same transformers.

 

[bandit2013]

This is not bad for a demo. No Gibson influence involved here.