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This amp definitely has a problem. It needs to go to a tech. You have a string of blown tubes and it sounds like it is repeatable. Once on his work bench, a decent tech ought to be able to quickly find the cause of repeatable problem like this. Chip

This is not meant to be insulting...but your comment about the EL-34 has me worried. Is your amp simul-class? If not, your amp can't take EL-34 at all. It might throw off all of the voltages within the amp and, perhaps, cause problems with the pre-amp tubes. If your amp is simul-class...

Being in the states, I'm blissfully unaware of the difficulties of international shipping. So, what's the major difficulty with shipping your amp to California? Cost? Legal stuff (customs or whatever)? Remember, that when you ship your amp to MikeB, you only ship the metal chassis that holds...

A couple years ago, I sent in my IIC to MikeB to get upgraded to a IIC+. As part of the upgrade and general overhaul, he replaced the old power tubes with new Mesa STR-440s. They were OK, but didn't really get me going. Of course, the amp was new to me, too, so I didn't really know what it...

I notice that this Rectifier no longer has a tube rectifier. The presence of a tube rectification (along with diode rectification) was the original genesis of the whole product line (hence the name). Buh bye. Oh well...as long as it sounds good... Chip

Hi Fear, Just in case it wasn't clear from the posts above, the "extra" two sockets are for more 6L6 tubes. This amp is designed to use six 6L6 tubes, not four. I would always run it with the six tubes in place. I would not run it with four. You might damage your amp. Depending upon the...

Wow, you've got it really saturated out. The effect of the mid pot can be subtle, and with that much saturation, it's tough to hear any impact that the mid pot might have. So, if you're concerned about the mid pot in particular, and if your mid pot happens to be working again, could you turn...

I only listened to "Part 3". I listened through a good set of headphones. I thought that his tone on Channel 2 was excellent. Actually, I thought that it was killer. As for this Channel 3 tones, he definitely does not go for the conventional Mark lead tone. If he were going for the...

Only a Mark IIC can be converted to a IIC+. In the olden days, when boogie still had extra pre-amp PCBs laying around, they could convert any Mark II to a IIC+. Those days are long gone. Now it's just the IIC that can be converted because its existing circuit board is close enough that MikeB...

I had a 2C that I had upgraded to a IIC+. It was a 60/100. Apparently, when it was a IIC, the power tubes weren't in great shape, 'cause MikeB replaced them. That might shade my opinions of the IIC. The reverb tank was shot as well, but that's easier to ignore when comparing the two amps...

McBarry I have a Mark IIC that has been upgraded by MikeB at Boogie to a IIC+. It's a 60/100, not a Simul-Class. It does have Reverb and GEQ, though. It's pretty rockin', but I actually find myself playing my (heavily modified) Fender Deluxe Reverb Reissue more often. Weird. Chip

>Photi G<: Thanks for the detailed reply. I appreciate it. With respect to Relay 1B, with the relay in the position shown in the schematic, it shows M+ as being routed (through the relay) directly to ground. I don't know what M+ is (I don't have the full schematic), but it is drawn as if it...

McBarry: I actually don't have a Mark III. I have an older Mark. I'm just a guy who's really interested in the circuit changes over the years I like to mod my own amps, so this kind of comparative study helps me understand what changes can make what kind of sound. Chip

Also, On the bottom half of your latest page (page 3), the traces are a bit confusing to me. Could you recheck your drawings in the following areas: 1) Relay 1B: You've shown nothing powering the coil. Also, you've shown M+ being attached to the signal pathway, both of which are connected to...

Hi, Thanks for the work. I see that your images clearly state that this is for a blue stripe, yet the file name of the pictures says red stripe. Is blue the correct one? Chip

Yes, in my opinion, the high voltage (40-50V) is the key to the Boogie EQ. You'll need to put a lot of 9V batteries in series to get that kind of voltage in a pedal if you're going to try to implement the Boogie EQ circuit. Also, because the design for the Boogie EQ is so old, it also uses...

You can also get the schematic for the Mark series EQ from any of the schematics on the web for the Mark II through Mark IV. The EQ design has been tremendously consistent over the years. Just google for "Mesa Boogie Mark IV schematic" or something. My understanding is that it can be...

In my opinion, there's a lot of demand out there for two "lead" channels on the Mark IV (or V)...one for metal/rock rhythm and one for metal/rock solos. Completely separate from the Petrucci discussion, I'm a little surprised that no one has suggested this modification before. Back on the...

In all the pictures of his rig, it has always appeared to me like his Mark IV amps were modded to yield two lead channels. I also know that he always claimed that his amps were not modded. I've always had a hard time reconciling these two opinions. Here's how what I chose to believe... I...

@ryjan, Do you know how Petrucci's amps were modded to give two lead channels? I always assumed that the whole amp was wired in lead mode and that the switching of the front end was modded to simply toggle between the tone stacks and gain knobs of the lead channel vs rhythm channel. That way...