Mark III questions.

[kwirk]

Alright, so I bought a Mark III blue stripe head on another forum and it arrived today. I'm a bit disappointed by the tone, although I'll attribute that to old tubes and a ton of tweaking ahead of me. Anyway, somewhere down the line, it had some mods done to it and I'm not 100% on what they do or if they even do anything. Here's some pictures:

None of the switches on the back seem to effect the tone or anything at all. The reverb knob also seems to add a TON of gain/compression and midrange all at once when it move it slightly, but it's not very pleasant sounding.

Can anyone help me out?

Also, sorry if the pictures are too big.

 

[davidrg1550]

Congrats on your purchase! Sounds like the reverb knob has been changed to some sort of a boost or something! The MKIIIs are great sounding amps and hopefully so will yours! I'd enquire with the seller as to what all the mods are (if he even knows?).

Personally I don't see why somesone would deface such a great amp, but hey that's just me. Again if it were me I'd be looking at restoring this amp to its former glory, ask Mesa for the name of an authorised repair centre and get the amp looked at by a professional mate.

 

[kwirk]

Yeah the guy I bought it from didn't really know too much about the mods either. The guy before him modded it, apparently. And yeah, I'm looking into getting an authorized Mesa tech look at it at some point.

 

[kwirk]

Some other oddities are that the mid controls (both the slider and the knob) only work half of the time? Seems like when the mid controls work, my high end and gain are totally off but when it doesn't work, I get a lot more gain and high end. I'm still betting it's bad tubes but thought I'd mention anyway.

 

[zodiac272]

nice looking amp... should be killer... Send it to mesa, they will make it perfect.

scott

 

[kdorsey]

Yeah, I agree with the others...send this to Mesa and have them give you a professional assessment. Then if you want to return it to original, they will do the best job for a reasonable price. A MkIII coli is a beast and would be a hell of a great amp for anyone if it's working properly. Add a preamp NOS tube cocktail and you'll have a very versatile amp that will last for years.

 

[kwirk]

Yeah, I'll most likely do that. I'd rather not ship it out again but if that's the best option, that's something I'll look into. Anyone have a total cost of sending it out to Mesa and getting it checked up on? Probably just want to restore it to factory specs and put a new set of tubes in it. I'm assuming they can supply a set of tubes and include that in the price.

 

[DarkCloud]

New to the board, so please excuse any faux pas: my guess is the mods would be as follows:

-Reverb has probably been bypassed to add a control for the R2(crunchy rhythm voice)mode. Taking out the reverb also increases the gain within the amp, and reverb is generally thought of as a tone sucker within the design of a guitar amp because it lowers the gain to all of the other preamp tubes.

-The pentode/triode switch would be for the tubes of the Simulclass sockets. Normally in Mark III, the pair of tubes for Class A operation are wried in triode. I believe Mesa modded the final Green Stripe to be in pentode which would increase headroom and give some more power. Would be a pretty useful mod for recording.

-The EL34 mod is probably as labeled. This would mean that the amp is only operating with the 6L6 pair as the power tubes in Class A/B as a 60 watt amp. Does the switch for still operate as a 3 way switch or a 2 way switch? If the switch has been changed to a 2 way, then it would probably operate as the original Mk 1 heads did with 100/60 switch and take the outer sockets out of the power section. The sound would also be a bit more aggressive in this mode.

Just picked up a Mk III Red Stripe that I am looking to do the R2 mod on. Except for a couple of preamp tubes being microphonic, the amp sounds pretty awesome.

Do you know if these modifications were done by Mesa or a Mesa authorized service center?

 

[kwirk]

Yeah. I'm not sure what the reverb thing is yet. I'm positive it's not the R2 mod. There was another guy on this forum with the same issue but I don't think anyone figured it out. There's probably just something wrong with the tank. Although I don't see how that would effect the gain/mids.

The pentode/triode switch does nothing. I A/B'd it, recorded it, played it back and heard no audible difference. I'm just going to assume the amp is at fault because there's probably a lot of fixing up that needs to be done on it.

EL34 switch is a two way and also has no effect on the sound.

I think the outer tube sockets have poor connectors because I get almost no sound when I have just those two running. I've opted not to ship it out to Mesa because there's a few Mesa authorized repair shops around here and one of them looks to be pretty promising. Hope the servicing doesn't cost too much, as it seems like the type of place that would charge a ton, otherwise I would have just bought a Mark IV had I known I needed to do all of this to it.

Thanks for all the help though.

 

[zodiac272]

if you send it to mesa,

Shipping both ways about $120
cap job and service/restoration $200-$350.
total somewhere between $350 to $500, but call them to get a better idea

After that, it should be beautiful and work for a long time without much trouble. Mesa factory tech knows everything there is to know about that amp, way more than 99% of even auth mesa repair guys IMO. I'd say it's worth it again IMO. Plus, if you sell, it will be easier with the yellow RA service slip.

scott

 

[kdorsey]

Having an authorized service group locally is nice, but do yourself a favor and just call Mike B at Mesa. You'll instantly realize the level of personalized service you get from these guys. Try that at Marshall or Fender! They'll give you the straight story and options available. Shipping is a PITA but I've not had enough faith in my local shops to send my 'baby' anywhere but Mesa...not that I've had to.

Get the story straight from the masters. Then make an informed decision.

 

[kwirk]

I've heard nothing but good things from everybody who's brought a Mesa down to this place, Savage Audio in Minnesota.

At the moment I'm still in debate as to what I want to do with it. Right now I'm seeing if the seller will take it back as he didn't mention that anything was actually wrong with it. If that doesn't work, I may sell it as is. Can't justify spending over $1000 on this amp at the moment.

 

[DarkCloud]

Kwirk,

Those mods do sound a bit whack. For sure in simulclass mode, my amp is quieter, but not too quiet. I did change a few of the preamp tubes around and ended up with a much better sounding amp. I also had a few Tesla EL34 and Philips 7581A tubes around that behave well under major load in the amplifier.

Have you tried putting in some different preamp tubes if you have any extras around? Changing V1 and V5 made a huge difference in tone of my amp. I will have a tech friend check it out and look under the hood as my amp comes from the original owner who had only replaced a couple of preamp tubes.

Hopefully your amp only needs some minor work.

 

[kwirk]

Yeah. I put different tubes in it but they made no real difference. I even put the old preamp tubes in a different amp, and that amp still sounded fine. The seller gave me a small refund but I'm still stuck with a non working amp. Bleh.

Thanks for the replies.

 

[kramerxxx]

If I have had to guess what the EL34 switch did, my guess would be this:

On the front of the amp you have a Full/half power switch. That turns the 2 inner power tubes off on a typical Simul-Class or 60/100 Mark amp. This gives you 15watts on a pre-Green stripe, (*25watts Green-stripe) and around 1/2 power for a 60/100.

Someone could have wired a switch in to turn off the EL34 power tubes on a Simul-Class amp to give you 60watts, instead of the expected 15watts. This would give you either 15watts or 60watts, depending on which switches were On or Off. Actually if this works, it is a great idea because you could switch between not only the different power settings but also each of the two different power tubes for a different output sound. Brilliant!!!

Try this: Put the in Standby, with the amp on, turn Volume to 7, Master to 2, Lead gain and master at 6, pulled on so there is no footswitch needed. Now with the front panel switch set to Full, set the back panel EL34 switch to On, plug in your guitar and see if the amp has volume. It should be very loud at this setting. Now if you switch the front panel switch from Full to 1/2 you should hear a notice a subtle decrease is over volume with the tone/sound not being as full. OK? Now reach around back and switch the EL34 switch to Off, the amp should go quiet. OK? Now if you switch the front panel to Full you should be turning the Inner power tubes back on.

Let us know what you find.

 

[DarkCloud]

Yeah. I put different tubes in it but they made no real difference. I even put the old preamp tubes in a different amp, and that amp still sounded fine. The seller gave me a small refund but I'm still stuck with a non working amp. Bleh.

Thanks for the replies.

Bummer. Maybe the power supply needs some readings and see how stable it is. As I have said before, I think I will eventually get some of my looked at, but it sounds pretty good. FWIW, I have had a Savage Audio product, and it was well put together. Have you contacted them about getting an estimate?

Funny how the above post echoes my idea of the EL34 switch is for. I think the mods really need to be looked at. Good luck and hopefully it is only a minor fix.

 

[kramerxxx]

One other thing: To check my idea about the power tube off/on reference, make sure you are switching the toggle above the Direct Out jack, not the 3-way ground switch. The EL34 label is above ground switch, could be confusing.

 

[kramerxxx]

-The EL34 mod is probably as labeled. This would mean that the amp is only operating with the 6L6 pair as the power tubes in Class A/B as a 60 watt amp. Does the switch for still operate as a 3 way switch or a 2 way switch? If the switch has been changed to a 2 way, then it would probably operate as the original Mk 1 heads did with 100/60 switch and take the outer sockets out of the power section. The sound would also be a bit more aggressive in this mode.

Sorry, I didn't read your post and I think you are right on the mark.