There's two Mark II heads on eBay. Yup, same auction:
http://cgi.ebay.com/2-Vintage-Mesa-Boogie-Mark-III-heads-tc-electronics_W0QQitemZ270473361563QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3ef977f89b#ht_556wt_675
Anyway, the pic of the 60/100 hard shows EL-34s in the outer sockets, so being the helpful dood I am, I shoot him an email:
My helpful hint:
Dude, you'll blow the amp if you run EL-34s in the outer sockets
of your 60/100 (#15305). They're not made for that - only the
Simul-Class amps. Jus' tryin' ta help. Good luck!
His answer:
(sic) "Simul Class doesn't means combination of el34/6l6, normally in most amps power tubes are wired in class AB, on other brands like Vox AC30, the power tubes are wired in class A, which gives you a little bit less power but more compressed sound, all mark 3 amps have fixed bias resistors and special transformer with extra windings for been able to run el34's on the outer sockets, but not all amps are simul class, in the case of my simul class head, el34's are factory wired in class A, while 6l6's are factory wired in class AB, on the other hand my other head, all tubes on 60/100 head are factory wired in class AB, other piece of information can be that most boogies prior to the mark 3 red stripe are wired tetra mode (4 wire) while after this red stripe tubes come in penthode mode (five wire), boogie simply is adding an extra negative voltage grid to control electrons returning from plates to cathodes, hope all this info help you in your understanding of power amps."
(WTF?) :roll:
My response:
Your statement "...all mark 3 amps have fixed bias resistors and special transformer with extra windings for been able to run el34's on the outer sockets..." is incorrect. Not "all", but only Simul-Class amps are capable of running EL-34s (or 6L6s) in the outer sockets. You are indeed correct that "...all tubes on 60/100 head are factory wired in class AB...". However, this does not mean they can run EL-34s in the outer sockets, as shown in your photos. Only the Simul-Class amps may safely run EL-34s in the outer, Class A sockets. The 60/100 amps are designed for all 6L6 operation. No EL-34s. Lastly, all Mark III Simul-Class amps up to the green stripe are wired triode (outer sockets) and pentode (inner). The green stripe Simul-Class amps are wired pentode in all sockets. All 60/100 amps are also pentode in all sockets. Hope this helps.
http://cgi.ebay.com/2-Vintage-Mesa-Boogie-Mark-III-heads-tc-electronics_W0QQitemZ270473361563QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3ef977f89b#ht_556wt_675
Anyway, the pic of the 60/100 hard shows EL-34s in the outer sockets, so being the helpful dood I am, I shoot him an email:
My helpful hint:
Dude, you'll blow the amp if you run EL-34s in the outer sockets
of your 60/100 (#15305). They're not made for that - only the
Simul-Class amps. Jus' tryin' ta help. Good luck!
His answer:
(sic) "Simul Class doesn't means combination of el34/6l6, normally in most amps power tubes are wired in class AB, on other brands like Vox AC30, the power tubes are wired in class A, which gives you a little bit less power but more compressed sound, all mark 3 amps have fixed bias resistors and special transformer with extra windings for been able to run el34's on the outer sockets, but not all amps are simul class, in the case of my simul class head, el34's are factory wired in class A, while 6l6's are factory wired in class AB, on the other hand my other head, all tubes on 60/100 head are factory wired in class AB, other piece of information can be that most boogies prior to the mark 3 red stripe are wired tetra mode (4 wire) while after this red stripe tubes come in penthode mode (five wire), boogie simply is adding an extra negative voltage grid to control electrons returning from plates to cathodes, hope all this info help you in your understanding of power amps."
(WTF?) :roll:
My response:
Your statement "...all mark 3 amps have fixed bias resistors and special transformer with extra windings for been able to run el34's on the outer sockets..." is incorrect. Not "all", but only Simul-Class amps are capable of running EL-34s (or 6L6s) in the outer sockets. You are indeed correct that "...all tubes on 60/100 head are factory wired in class AB...". However, this does not mean they can run EL-34s in the outer sockets, as shown in your photos. Only the Simul-Class amps may safely run EL-34s in the outer, Class A sockets. The 60/100 amps are designed for all 6L6 operation. No EL-34s. Lastly, all Mark III Simul-Class amps up to the green stripe are wired triode (outer sockets) and pentode (inner). The green stripe Simul-Class amps are wired pentode in all sockets. All 60/100 amps are also pentode in all sockets. Hope this helps.
