Misc. Mark III issues

[lesdavaz]

Please jump in:

I recently bought a short Mark III in ostensibly good shape, but with several issues, plus I am having trouble dialing in good clear sound, especially with my stock G&L ASAT and S500. Here is a list of my concerns:


1)Came with a 4X12 Traynor cab with their speakers in it from the early 80's. Since replaced theirs with a Celestion and some Fender open-back speakers I had. Question: would this amp sound a lot different with some good speakers, and what should I get?

2) It is a blue stripe, simulclass, the switch is labled "simulclass" and "class A". Question: What is the Power of each position? Manual is unclear.

3) I have four 6L6 Mesa tubes. Question: Would it sound a lot better with the EL34's where they belong, and could I use the 6l6's as backup even though they are different stock numbers?

4) Reverb does not work. Spliced cables and it did work, but did not sound good. When I re-mounted it and plugged it up, the amp started distorting and the powert tube closest to the simulclass switch got red hot. What is up with this?

5) No fan; see the mounting screws and have the part located, but the prior owner said it hasn't had one since '87. Question: is this necessary, and where does the power cord go?

6) After awhile on "class A" I get static. What is this indicative of? Sometimes goes away, sometimes not. Always disappears when back on Simulclass.

All in all, I am a little disappointed with this amp, because I play single coil in clear ranges most of the time. I guess you could say I'm a bit of a twanger/quacker on rhythm, and I am missing that. Only would use the reverb on 3 on rhythm, I cut it for lead. Can't accept that the distortion sounds so good, and clear sounds so ordinary, so I think it's me. Please comment, especially if you think I just have the wrong amp. I have been playing through low-watt Fenders and using a pedal or two, but owned HIWATT's in the early '70's that I bought in London. They didn't work in the US, and I have always heard that MESA was a great alternative to those...Thx...LPD

 

[zodiac272]

Nice amp... you should be able to dial in some sweet cleans. Simul-class should be 75 watts, and class A is 15 watts. I think anyway. Did you check the tubes to see if they are ok? Maybe you might like a pair EL 34's in the outer sockets. If an inner 6L6 goes out switch the pair with your soon to be spares. I'm sure you want a fan installed... the cord should plug into the power tranny... the socket is kind of hidden inside. The class A static could be tubes, or a resistor gong bad in the SC circuit. When you spliced the cables, do you mean you did the reverb mod? I'm totally talking out my rear end, I'm not a tech by any means, but usually most issues are tube related, or something else simple. Mark series amps love the old half back style cabinets... open top closed bottom. EV 12L speakers on the bottom with MC-90's on top. or Thiele 1x12 with EV12L and an open back 1x12. but that's how I feel.
When was it last serviced? You might be well served by sending it to Mike B. at Mesa and have him go over it. Might cost $150 plus shipping, but you will have a brand new amp after. and I'm almost certain, you would be happy with it. If not you can flip it and get a lonestar or something.

scott

 

[lesdavaz]

Thanks. No, by splicing, I mean i cut off the old jack ends and bought some new solderless angle-ends and reconnected. Like I say, it worked until it didn't. I have replaced half a dozen tanks in my day, so I thought it strange that this did not work. Thanks for all the other info. I will buy the EL34's today. LPD

 

[MrMarkIII]

Looking at the rear of the amp, the A/C socket for the fan is on the far left side of the chassis between the large transformer and the cabinet.
To the best of my knowledge, the white wire for the reverb is not grounded or shielded, while the grey wire is.
In Simul-Class, all four power tubes are used, giving you 75 watts.
Class A uses only the outer pair of power tubes and is 15 watts. The tubes in the outer pair ONLY may be either EL-34 or 6L6.
Not sure what you mean by "stock numbers" on the 6L6s. If they are Mesa tubes, they will have a "color" designation, such as BLU, GRY, GRN, RED, YEL. Each pair, outer or inner, should have matching colors.
It won't kill the amp if they don't, but it might not sound as good.