Picked up a Mark IV yesterday!! tubes/serial number question

[Terje79]

Hey everyone. Last night I picked up another Mark IV to add to my collection (this makes 3 now). This one is the 'A' version instead of the other 2 i have are the newer 'B' versions. I checked and it is serial number 787 i believe. The serial number goes something like 'IV00787'. I must say that I think it sounds superior to my other head and combo. Is there something to do with lower serial numbers on these, I have heard these amp is voiced a little differently than the newer ones.

Do I have one of the fabled "Pre-1000 Mark IV's"??? hahaha

also, the tubes in it sound beautiful in the cleans but seem to be lacking some punch in the lead channels I believe there are sovtek 6l6's in there. I am going to be using this in a metal band I need something punchy and heavy. What tubes do you guys use that are using it for the same type of music?

 

[boogietone]

I love STR454's in mine. Although at the moment I have SED EL34's in the outside sockets and it sounds really good.

 

[Russ]

3 Mark IV's.... That'd be nice. I envy you for that.

My Mark IV is an A with a lower serial than yours (IIRC 560's?) and sounds really "grrreat!" <--- as Tony the Tiger would say.

You are right, with the change to the B came a slight change in R2 and Lead. This makes the amp slightly different than it's older A brethren. I cannot say that I know of any special things about the early A's v. the later A's.

You might ask Boogiebabies if he is aware of any changes that may have been made during the A's. I did see that some IC's had sockets for easier changes but other than that I wouldn't know. The IC chip socket really wouldn't change the tone noticeably either if you were wondering.

You might try running 5881's like the Mesa 420 6L6. Those can still be had even though Mesa is no longer grading them. There is a link in one of the posts concerning the 420's. Another tube you might like is the Mesa 415 if you can find them. Those are out of production. You might find NOS non-Mesa branded examples if you cannot get Mesa ones. I have some JAN Phillips 7581's in my 2 ch DR that I would love to try in my Mark IV but I just haven't had a chance too. I probably won't get a chance to until next year either. Those tubes sound really good in the DR and keep it pretty tight. I can only imagine how they might sound in the Mark IV because the Mark IV is so much tighter already.