mejoshee
Well-known member
hey all. just wanted to get something set up once and for all about compatible tubes for the mark v. hopefully, this can be stickied or something, depending on the reliability of postings from "legit" sources (esp mesa themselves). exact brands should not be necessary, though maybe that can be commented as "works good so far" (ex: jj/tesla). this is not to say i don't trust the prior postings in the "mark v tube thread" and the like, but i just wanted to help out the new mark v users and tube n00bs who don't want to have to sift through the opinion-laden portions of the forum (i confess to being opinionated 
). just try to be straight-forward with what works or not, not why you like brand "a" better than brand "b". if you must post an example brand, try to give a website link or something of someone who may sell it.
this will mostly comprise of power tubes, but preamp or rectifier tubes should be indicated in here as well for the more basically available options. for example 12ax7, 12at7, and other 9-pin (noval) tubes; 5u4, 5ar4, etc.
my expectations for this thread are a list of:
1) 100% electrically compatible tubes for the mark v requiring no mods or anything special that isn't already available on the amp as a "standard" feature
2) tube combinations that may be "iffy" for some reason because of their high heater (filament) current draw, non-mixable with certain types (e.g. kt66+el34) for a single bias setting, oversized bases (too big for bear trap socket retainers)/envelope heights (i.e. physically does not fit in a head format), etc. but still generally available from a tube supplier (e.g. mesa, eurotubes, doug's, etc.)
3) tubes that 100% absolutely do not work without some major mod to the circuit as of the writing of this thread
when you post a tube model, try to give some general specs like a typical max power rating, the bias setting required (6l6 vs. el34 switch), heater current draw. if it's incompatible for whatever reason, indicate why.
i'll start it off with the easy and obvious examples:
6l6gc (power):
default tubes. work on both power settings & all wattage modes with bias select on "6l6".
el34/6ca7 (power):
option. work on both power settings & all wattage modes with bias select on "el34". do not mix w/ 6l6 type tubes! biasing system on mark v is different from iv.
6v6 (power):
works on variac setting (low b+) only & all wattage modes with bias select on "6l6".
12ax7 (pre):
default tubes.
5u4gb (rect):
default tubes.
6v6 & 6l6 (power):
in variac only, in 90w or 45w only. do not use in 10w mode!!! match tubes in xyyx layout, i.e. 6l6/6v6/6v6/6l6 or vice versa as mentioned by phyrexia.
). just try to be straight-forward with what works or not, not why you like brand "a" better than brand "b". if you must post an example brand, try to give a website link or something of someone who may sell it.this will mostly comprise of power tubes, but preamp or rectifier tubes should be indicated in here as well for the more basically available options. for example 12ax7, 12at7, and other 9-pin (noval) tubes; 5u4, 5ar4, etc.
my expectations for this thread are a list of:
1) 100% electrically compatible tubes for the mark v requiring no mods or anything special that isn't already available on the amp as a "standard" feature
2) tube combinations that may be "iffy" for some reason because of their high heater (filament) current draw, non-mixable with certain types (e.g. kt66+el34) for a single bias setting, oversized bases (too big for bear trap socket retainers)/envelope heights (i.e. physically does not fit in a head format), etc. but still generally available from a tube supplier (e.g. mesa, eurotubes, doug's, etc.)
3) tubes that 100% absolutely do not work without some major mod to the circuit as of the writing of this thread
when you post a tube model, try to give some general specs like a typical max power rating, the bias setting required (6l6 vs. el34 switch), heater current draw. if it's incompatible for whatever reason, indicate why.
i'll start it off with the easy and obvious examples:
6l6gc (power):
default tubes. work on both power settings & all wattage modes with bias select on "6l6".
el34/6ca7 (power):
option. work on both power settings & all wattage modes with bias select on "el34". do not mix w/ 6l6 type tubes! biasing system on mark v is different from iv.
6v6 (power):
works on variac setting (low b+) only & all wattage modes with bias select on "6l6".
12ax7 (pre):
default tubes.
5u4gb (rect):
default tubes.
6v6 & 6l6 (power):
in variac only, in 90w or 45w only. do not use in 10w mode!!! match tubes in xyyx layout, i.e. 6l6/6v6/6v6/6l6 or vice versa as mentioned by phyrexia.
