Hello/Mark III non-simulclass with all el34's!?!

[70sstrat]

Hello all,
I didn't see an introduction section so I'll take some time to do that here. If you could care less please skip ahead to read about my questionable mark iii . I've been through a bit of a journey with my gear. Growing up my dad played guitar and I always said "I don't want to sound anything like that". Well his main set up was a 73 SG and a Mark IIC+. It wouldn't be till years later that I would understand what a epic set up that was. Now that era SG may be hit or miss depending who you talk to but starting playing with the benchmark Mark as your point of reference is crazy. So being a teenager and wanting to be different I went after the blackface sound (which I thought was more divergent from a Boogie then it actually was) and played with very mild gain usually from a pedal with a strat. Over the years I gravitated to heaver music and increased my gain. Fast forward ten years and what am I playing?... a mid 90s Les Paul Studio and a Mark III blue stripe. It's funny how things work out.

The story:
So after looking for a mark iii for a while I finally found a mark iii long head locally and jumped on it. Now the tolex was a little beat up and one of the knobs had been replaced, so it had seen some fair use. What really worried me was that it was running 4 el34's and it is non-simulclass. It had been sitting in storage at a local music college. Supposably the studio coordinator at the time was a former mesa tech and pressured the college into using mesa amps for the studio. How good a 60/100 watt long head mark iii was for recording I'm not sure but that's how the amp came to be. Now I would think a mesa tech would not just let the school throw in el34's on a fixed bias amp and just let them run super cold. Maybe someone else confused mesa's use of el34's? Perhaps, but this amp actually was serviced by authorized mesa tech recently because of a bad power tube. Now I don't know how may of you know about Savage amps but savage audio is a big deal out here (twin-cities) and they're the ones that worked on the amp. I can't imagine a company with this kind of reputation would overlook the correct power tubes.

The Issue
From what I've read here only simul-class amps can run the 34's in the outside positions and non-simulclass amps used 6l6's only. I'm wondering if you guys could help me spot any anomalies in my amp and if it's been modified for el34's. The only mod I know it has it the R2 vol mod. Here are some photos:

20130411_000947 by 70sstrat08, on Flickr
Transformer pics (definitely not Simul-class right?):

20130410_232637 by 70sstrat08, on Flickr

20130410_232627 by 70sstrat08, on Flickr
Inside chassis:

20130410_232246 by 70sstrat08, on Flickr

20130410_232241 by 70sstrat08, on Flickr

20130410_232226 by 70sstrat08, on Flickr

20130410_232220 by 70sstrat08, on Flickr
Bonus date stamp

20130410_232407 by 70sstrat08, on Flickr

Any help is greatly appreciated and thanks stoping by!

 

[MrMarkIII]

Images aren't appearing. Upload photos to a hosting site like Photo Bucket, get codes, then download to your post.
It's possible the tech modded the amp to accept 4 x EL-34s.

 

[70sstrat]

Ok moved all the pics to flicker let me know if there still not showing up.

 

[70sstrat]

Would this have been more appropriate for the tubes section? I figured you mark guys n' gals would know the most about what would have been changed to accomodate el34's. I'm avoiding playing the amp like this till I know whats going on any help is greatly appreciated .

 

[ncdb07]

Hi - sort of hesitant to reply. I have a limited bit of knowledge compared to most of the guys here. Some may be on vacation right now as its spring break for some. You may want to send these pics to Mesa along with the serial number for their advice.

Now on to what little help I can give.

I have never seen a mark series mesa run on all el34's so I would be very cautious! I also see what I believe are several mods or updates to your mesa.

In picture 4 those 2 big Illinois caps should have mesa heat shrink labels unless replaced by someone other than mesa. In pictures 5 and 7 the big blue caps? I have never seen a mark 3 with 4 caps there not to mention with resistors across them like that. Could be a mod. Also in pics 5 and 7 the radial electrolytic cap with the heat shrink coming off either indicates a swollen cap or a repair. Also in pic 7 there are 4 resistors in a row between the radial electro cap and the 4 big blue axial caps. There is obvious signs of those resistors being burnt and replaced. In the same picture at the bottom are some Xicon resistors (white square boxes) that I do not think are factory at least I do not remember seeing them in mine. I see enough red flags that I would get more advice on before I fired it up also.

To answer your original question it should be all 6l6's in your amp only. I think the guys here would need better pics of your power tube sockets for really accurate diagnosis.

Hope I helped at least a little!

Also welcome to the board!

 

[70sstrat]

Thank You! You certainly know more than I. Here are some close up pics and I'll see if I can get in contact with mesa. Stay tuned for the exciting conclusion of what happened to my mark III :lol:

 

[ncdb07]

No problem! Definitely keep us updated here! I only know what I know because I replaced all the capacitors in my mark III myself, so I spent a fair amount of time inside it. It would be rare to buy a 20+ year old amp without somebody modding or replacing something inside it. The 4 resistors on yours with the smoke damage seems to be a common repair, they had been replaced on mine as well. The capacitor replacement on your power tube sockets most likely is an upgrade. but the 4th big blue capacitor with the resistors across them is a puzzler.

Hopefully some of the other guys here will come along in the next couple of days!

 

[70sstrat]

O.K. I got in touch with Savage and they have on record they "went through the amp, replaced a volume control, re-tubed both power and preamp tubes, re-biased and cleaned it". Now I don't see a bias pot in my amp. From what I've read here I believe the bias mod is R117 correct? Here is a cose up of what I think is R117 based on a photo of another mark iii (as you can see the label is soldered over:


r117closeup by 70sstrat08, on Flickr

If you look at the first picture in the second batch I posted you can see the colors better. It looks to be brown black orange gold, so that should be 10K. Does this help anything? Also when they say they adjusted the bias does that mean that just changed the resistor? or does the fact that there is a resistor and not a pot mean they didn't actually adjust anything?

I also head back from mesa. They said the only service records they have were that the amp was in in 91 and converted to 100W. I'm not sure if this means it was once a 60Watt model (did they even make a 60W long head?) or it was converted from simul-class.

 

[kc_ksom]

Hi

I have a mark III, blue stripe, NON-simulclass, with EQ & REVERB, and it is a 60w, but it runs EL34's, I have had a tech check mine out before I powered it up, but he said it was modded to suit the EL34's and said I should just leave it that way as unmodding could bring other problems.

Good luck, & good score

regards

Casey Hilton

 

[70sstrat]

So I've been away for a bit but I wanted to thank everyone for their help. To update I was able to get some pictures to mesa and was told it looked like could have been modded for el34's. I also had a tech take a look at it and made sure everything was checking out. So far so good! The longer I spend with this amp the happier I am with it, although I think you need to be a tinkerer or a tone tweaker to really dig these amps.