Mark III Black stripe in need of service

[IXIStreakIXI]

I'm going to take my baby to an amp tech. The guy who I'm taking it to is a certified Mesa Dealer/repair dude. Now, I'm looking into modding my amp. I want a few things done and I was hoping some of you more educated gear junkies out there could help tell me what I'd be getting. I plan on modding the black stripe into a Blue stripe [OH NO BLASPHEMY] and then having the C+ mod done on that. After that I want the R2 volume mod since I don't have a reverb tank and the reverb controls are sitting there doing nothing. My question is... What exactly would I be putting my current Mark III Black stripe 60/100 watt Simul-class GEQ through. Like, specifics. What's going to be done to it and how much would this potentially cost? The reason I ask is because I want to be educated on what exactly the dude is going to do to the amp. I don't wanna just go in, hand him my baby and say have at her and not know what he's gonna do. Thanks in advance to anyone who can help out and elaborate on the processes I'm looking to undergo.

 

[camsna]

Maintenance:
Replace a bunch of caps
Clean pots
Clean and re-tension tube sockets
Etc.

Black to Blue:
No idea

C+ Mod:
No idea. But they don't give this out to the warranty guys. AFAIK it has to go to the factory for Mike B to do it. And each one is done a little different. Plus - it's unnecessary. It still won't sound like a II C+, and it'll lose a bit of the mojo of the Mk. III. This mod is like 400 bucks at the factory.

R2 Mod:
Replaces a resistor on the board with a 250K pot. He'll remove the resistor and run 2 wires from the pot to the pads on the board where the resistor once was. Cheap and easy and necessary!

Recommendations:
Adjustable bias mod. So that you can install whatever tubes you want and bias them however you want.

Cam Mod. Done by Monsta-Tone on this board. Ask him about it. It's foot-switchable, but I NEVER turn it off

 

[IXIStreakIXI]

I read up on the C+ mod and I've decided I don't want it. I like the tightness of my MKIII. As far as the bias mod goes, I don't think it's too necessary [at this moment].

The cam mod. What does it do for you? I know nothing about it. Tonally, what are the differences? Obviously it's named after you, lol. What's it done for you?

 

[trem]

No need to make it into a blue stripe. What's wrong with being a black stripe anyway? If you're still not satisfied, just send it to Bendinelli for a IIIC+ mod and a complete overhaul, plus some necessary mods like R2 volume pot and reverb. If your amp has the revered 105 power transformer (only early black stripes do), then you're in for a treat. I really don't get the "mojo" thing.

 

[IXIStreakIXI]

How can I tell what output transformer I have? I can take pics if anyone needs 'em.

As far as me not being satisfied... I think I have never heard this amp with new caps. I'll probably get the sound I want with just a maintenance job. I'm kind of afraid to send it to Bendelli for a complete overhaul only to find a bill that cost more than I paid for the MKIII itself. I'm trying to stay local and have a tech do it [OR anyone that's willing to do it for cheap]

 

[CoG]

yeah, honestly I'd just get the cap job and the R2 mod done. There's also a reverb mod that's worth doing if you like LOTS of reverb, but since you don't have a reverb tank, don't bother. Play it like that for a while and then if you feel like there's something missing there's other stuff that can be done later.

As an aside, Mike B.'s prices are actually very reasonable for what you're getting. He'll talk you out of stuff that he doesn't think is worthwhile.

The only danger is that he'll do stuff you didn't ask for that he thinks is an improvement :lol: In addition to fixing a couple of borked LDRs in my purple, doing some caps, and a couple crackly GEQ sliders he also made the outside sockets pentode, did the reverb mod, and did something to the GEQ so it sort of does a short fade-in/out when I footswitch and sounds like it's running in parallel instead of in series. Technically it seems like a step up from the simple on/off on the green and it's much more organic-sounding now, but if I'd been trying to get br000talz out of it, I'd have been disappointed.

 

[Monsta-Tone]

The "Cam" mod is simply cutting the Negative Feedback Resistor in half when it is on. You could also place a pot across the NFB with this mod and have it adjustable, but I found that it acted too much like the Presence knob on the Mark III.

This makes the amp have tons more harmonics and headroom. Unfortunately, if you plan on using it as a Lead boost, you will need the pot instead of the fixed resistor.

It's really simple to do, takes about 3 or 4 parts and a few wires.

 

[IXIStreakIXI]

Well, I basically wanted to get all this done because my MKIII is sounding very flabby. I have to put the treble up way high and even introduce a an outside EQ into the loop to sound a LITTLE like how I want it. My MKIII isn't sounding aggressive at all and it bothers me because people love it for it's raw open-ness. Any specific suggestions on what I should do in order to get the sound I want? I sort of want the cleans a LITTLE cleaner but not at the expense of the lead channel. I don't really like chimey cleans too much either. I like nice warm full toned cleans. Like, the bass response is very nice in my cleans right now BUT when the lead is turned on, it gets very muddy and flabby very quickly. And no, it's not my settings. No matter how I set the knobs or GEQ, it's just muddy.

 

[tony777]

Did you replace the tubes?

It's the most important thing you can do.

For two years I didn't like my simul C+ as much as my 60 watter, and I did everything to nail the grailtone, and in the end I discovered I had the wrong set of preamptubes in her. Several forum members told me to replace the tubes, but I ignored them, because the ones I had were brand new, and I believed they were the same as my 60 watter, but no, they weren't, they looked the same, but had a different voicing, and sounded very different.

Since I got a Mark III today, I threw in a completely new set of Mesa (russian 2) 12AX7-A tubes to be absolutely sure that everything was ok. and now the preamp and power tubes are exactly the same as my simul C+ and now I can compare them equally.
As the manual says; 90% of the time failure are tube related.

I am not saying you should throw in the mesa tubes, but you should absolutely replace the tubes if you haven't done so yet.

Good luck

 

[EleventhHour2139]

What is your eq set up like? I've found that making a major cutback below 80hz really helps remove alot of the flab, as well as cutting a bit of 200hz.

Also, if you have a 1x12 combo, consider that it isn't a very "tight" sounding rig by nature, or less so than I have found with a closed back cabinet. Maybe you could post your settings and such, alot of the aggressiveness and gain of the Mark III comes from the Volume 1 and Treble. Either way good luck!

 

[IXIStreakIXI]

I have replaced the tubes. All the tubes are brand new. The power amp section is made up of the latest stock Mesa 6l6's and EL34's. The pre-amp section is all Tung-sol 12ax7's. The rig is... The MKIII into a 1960B cab. An old one, not a new one. It has the vintage G12-75's. or whatever they are. It's wired in 16 ohms which sounds better than 4 to my ears.

 

[CoG]

Back the lead drive and lead master down to like 7 and 5. Turn the master up to 3.5. Pull the Deep, the Lead Bright, the Bass SHift, and the Treble Shift. Lose the extra EQ pedal.

If that doesn't crunch, you need your amp looked at, bad...

 

[IXIStreakIXI]

It doesn't. In fact, there's hardly any distortion on it. It sounds like R2 should. That's what's been my problem the whole time. I'm running EMG's into this beeatch. Not the standard 9v EMG's. All my guitars have the 18v mod. It's always baffled me how weak it sounded. I only get a saturated lead sound if channel 2 is pulled on lead mode but then it gets way too dirty and I get lots of feedback. Lots of people have problems describing their tone into words. I think I can do it, lol.

When palm muting on a good amp that has great crunch, you sort of get a "JT JT JT" or a "CHT CHT CHT" sound. What I am getting NOW is a "Pwoh pwoh pwoh" Or if the mids are raised, I get a "Pweh pweh pweh" I'm looking for some aggressive, percussive, machine gun firing chugging sounds, man. On a side note, I've noticed my higher notes to be searing and not pleasing to the ear what so ever. Even if I'm on the neck pickup. For instance, the Master of Puppets interlude harmony solo... Man it sounds god aweful, even if I turn down the 6600, which makes everything sound terrible imho. =[

The only reason why I ever introduced the extra EQ was because surprisingly, the GEQ never satisfied the sound I wanted to get. I just think I bought my baby off of a previous owner who didn't know SH!T about the amp. When I first got it, he told me that all 5 preamp tubes were not necessary. That the v4 tube wasn't necessary because there was no reverb tank. When I bought a new tube, I think him having the amp on without the V4 tube fried some parts because I used to get a really bad 60hz cycle EARTHQUAKE. Once that happened, the amp died out. I unplugged it, checked it, turned it back on and the tone's been different ever since. I could've blown a resistor or something. I think I'm just going to take my baby into a tech to fix anything up. How much am I looking to pay here?

How much would overhauling the caps and whatever parts necessary be? I'm not entirely sure on whether I should get it fixed or make it new. Get me?

 

[trem]

That really doesn't sound right. That thing is a crunch machine! Definitely take it to a tech. Not sure what the rates are over there, but parts are cheap. Best to call the tech directly.

 

[Monsta-Tone]

Yeah, it sounds like 1 of 2 things, or both:

Needs Caps

or

Needs LDR's


I've noticed that some of the earlier channel switching Mesa's are extremely hard on the LDR's. The LDR's are the small black parts that you can see in the amp. They do all of the switching functions for your particular amp. It's possible that it is never truly switching into the Lead channel.

Also, I don't know if it works on your model, but on several of the older Mesa amps, the jacks can get dirty and cause signal loss in the Loop.

A good way to check this is to run just a cable (no pedals) from the Send to the Return. Like I said, this doesn't work on all Mesa amps, but it may help pinpoint the problem so that your tech bill is lower. Troubleshooting takes time.



If you have it looked at, I almost always recommend replacing the LDR's and the Caps. Make sure that he replaces the Caps in the Bias Circuit as well. I have had a couple of amps come through my shop that had the Bias Cap fail a month after I replaced all of the Filter Caps. It is part of every Cap Job that goes across the bench now.

 

[IXIStreakIXI]

Thanks alot, Monsta-tone. I have a question, though. It's possible for the amp to switch HALFWAY into the lead channel? It's odd because some days the crunch sounds great and full and others, it sounds wimpy and soft. That's crazy if it can just change half way.

Anyways, thanks again, man. I'll make sure to have him check the LDR's and caps.

 

[kiff]

when I changed my M4's preamp tubes recently I had a similar problem. When I used tweed power I wouldn't get the gain from the lead channel. full power worked fine. putting back the original tubes in v1 and v2 fixed it...

 

[Monsta-Tone]

The LDR is a Light Dependant Resistor.

Basically, it changes resistance when light is applied to it.
As they age, or if the voltages are a little too high, they will start to not open up as much as they used to.

For instance, if it used to have a resistance of 500 ohms in the signal path, but now has a resistance of 10,000 ohms, there will be much less signal passing through it.


I've seen a lot of older amps suffer from this syndrome. I actually bought a DC-3 for just over $300 because it would not change channels.

$40 in parts and it worked beautifully.

 

[IXIStreakIXI]

Thanks alot, man. This is exactly the kind of elaboration I wanted to know my amp a little better.

 

[kiff]

Basically, it changes resistance when light is applied to it.
As they age, or if the voltages are a little too high, they will start to not open up as much as they used to.

do the preamp tubes have any relation to this? I'm guessing no, but if they do, could the new tubes I used (that reduced my lead's gain) be showing the symptoms of the ldr's?