Hello. New guy, MKIII owner.

[boogietone]

Hey all,
First off, great forum. Very informative. I just bought a MKIII blue stripe a while back. It's a 60 watt short head with EQ, no simulclass and reverb. It sounds great. I love it! I've never owned a Mesa before and now I'm sold. Anyway, reading some of the posts in these forums it sounds like MKIII's, or at least some MKIIIs have 5 preamp tubes. Is this true? Mine only has 4. Is this normal for a 60 watt MKIII? There have been some mods done to this amp I've discovered after receiving it. I'm wondering if someone removed the fifth tube for whatever reason if my amp did originally have 5 preamp tubes. There is a spot for one in the chassis for another preamp tube but nothing to plug into. Please excuse the noobie question and long post, just trying to figure out what all has been changed in this amp. In the chassis it has "wiring by Kaybe 04/18/89" and another date of 06/24/89 written in pen if this helps.
Thanks!

 

[Paul Secondino]

I've read some schematics for Mark 3 heads and havne't come across anything where there are only 4 preamp tubes. That sounds like it has been removed to me but I can't be 100% sure about that.

 

[boogietone]

Thanks for the help!
This amp has all kinds of things done to it that I wish were disclosed before I bought it. I bought it off ebay a while back and couldn't tell from the pics or description some of the mods. Actually any of the mods. All that was disclosed was the bias test point. Seller didn't know about the rest of the changes as he explained. As far as I can tell so far- the reverb has been removed, the R2 volume mod has been done taking the place of the reverb control, a bias test point was installed in place of the direct out control, the input jack for the lead channel in the back of the chassis was removed and there is about a 9 pin jack like you find on the back of a computer installed in the back of the chassis that isn't wired into anything. After a good cleaning and tube change it sounds really good. Haven't had a chance to really krank at all to hear how it really sounds. But at really low volume it's pretty good. Maybe when I get back to the lower 48 I'll send it in to Mesa and have it gone through.

 

[Boogiebabies]

 

[boogietone]

I won't be home till Friday. I'll get some pics up then.
Thanks!