Mark IIA - a few questions

[Chachi]

I just got a Mark IIA head. I'm pretty sure it's A vs. B as sharpie date on chassis is 12/78. I've only had limited time to start getting it dialed in, but I have this initial question... the manual I downloaded says that Lead Master overrides Master 1 in Lead Drive mode (where I'll be playing most of the time). But mine does not, or at least it doesn't in the way I interpret the manual.

My Master 1 is still effective in Lead Drive mode. With Lead Drive pulled out, the Lead Drive adds 'gain' and the Lead Master increases the signal, but not like a master volume. And again, Master 1 is still effective and acts like a master volume the way it does in non-Lead Drive mode. Does this make sense? Is it correct that it still functions in Lead Drive mode? I took the manual to mean that the Lead Master overrides the Master 1 entirely. Maybe I am misinterpreting that.

As I think about it more... is it set your Master 1 volume in conjunction with Volume 1 for clean; and amount of gain in Lead Drive with Lead Drive knob and 'volume' of Lead Drive with Lead Master... but the Lead Master uses Master 1 as it's baseline? And I know that Volume 1 still impacts signal strength in Lead Drive mode.

I took manual to mean that for clean, use Volume 1 and Master 1; and for dirty use Lead Drive and Lead Master. Which is true, but Volume 1 and Master 1 are still active in Lead Drive mode.

I haven't had time to search this forum as I'm new here, so feel free to point me to some threads. This is my second Boogie. I had a Mark III about 20 years ago. Just got this Mark II today!

 

[Chachi]

FYI Just read serial... 3272.

 

[woodbutcher65]

I used to own Mark IIA serial number 3116.

Yes, the clean master (master 1) functions as a volume limiter when in the lead mode. To get louder by turning up the lead master, master 1 has to be high enough to allow it.

It is best to think of master 1 as a limiter. Or as the TRUE master volume on the amp. It determines the ultimate maximum available volume.

With master 1 at 3, you can turn the lead master to 10 and the lead channel's volume won't get any louder until you turn the clean master up higher.

That is normal behavior for a Mark II or Mark III. My Mark III operated in the same manner.

 

[Chachi]

Ah OK. Cool. Thanks. That is how it is working, just got confused by manual.

 

[Chachi]

I'm sure there are a ton of threads on here... but what tone change would I see from swapping the Fetron to a 12AX7? I know my Fetron switch is to that position, but I haven't pulled any of the tubes yet. All I know for sure is I have Ruby power tubes. And also, to make sure... I have a 4x10 140 watt 8 ohm cab (Celestion G10L-35 x 4); it's safe to use 100 watt mode connecting that cab to 8 ohm speaker out, right?