My 'new' iiB, with many a question and pictures!

[JohnnyK81]

Hey guys! I thought I'd join this forum and dust off the iib I have, which I bought about 10 years ago, but haven't used very much.. So now that I plan on using it, I have many a question!

First question is pretty straight forward.. Does this look all stock? Is there a way to tell if the caps are new, or if it's ever been serviced? It looks to me like the cabinet has been refinished, and I 'vaguely' remember the guy saying it was, but I can't remember if he said anything had been done to the amp!

There is also some orange residue around the solder joints.. I can't tell if this is oxidization, or the flux they used (I mean, I literally can't see that close).. Anyone else have this, or do I have bad luck right here?

Now at some point, it looks like the tubes were replaced with Sovtek KT66's.. From my reading, it appears these draw more amps than the 6l6... Could this amp have been setup for that? Is there a way to tell? Would I be best to go back and get some 6L6's from Mesa? These tubes say 01 11 .. Not sure if that means nov 2001, or, something unrelated.

In addition, the preamp tubes say 12AX7Eh.. a quick google tells me electro-harmonix, but I'm not sure if these are stock, or not? Below 12AX7EH, it says 02 02 .. So I'm wondering if that means Feb 2002, or something completely different (02 MAY coincide with slightly before I bought it! Hard to remember)

Finally, mark2boogie, I think it was, mentioned in another thread about a volume mod, which would make the volumes independent of each, which would be FANTASTIC, since at the moment, the reason I don't use the amp, is because it's not too user friendly when switching between the channels (so usually, I find a good clean setting, and use a DS-2). ANyone have any insight on this?

Thanks guys!!

 

[JohnnyK81]

Mayhaps I did the Master 1 mod wrong? I moved the 2 wires from the center terminal of the pot to the unused terminal on the right (when looking at the rear).

Then I moved the wire that goes to the center terminal of Lead Master (ends at the output junction terminal underneath the chassis) to the center terminal of Master 1, which is what I believe the modified wiring diagram (which I found on this site) calls for.

The Master 1 does seem a lot more linear now, but the distortion sounds pretty terrible now (bassy, not distinct.. Just all in all bad), and the amp, even on all 10's, seems a lot more quiet than it did before.

I'm hoping I wired it wrong, as I had high hopes for a linear master 1 pot! haha Has anyone done this before?

 

[RR]

I'm not an amp tech but here's my assessement. Your Mark IIB bias must have been changed to accomondate the KT66 tubes.

Looking at the amp cabinet, it looks original with the exception of the grill.

There is modification that improves the effect loop and reverb which adds a limit control[?] place in the back. Even if you don't use the effect loop, the reverb improves dramatically.

As for independent master volume control of each channel, I'm not sure I heard of it. But if its out there I would like to hear about it.

Yes, its not a friendly user amp (as well as the Mark I, III and maybe IV[?]) its design is cascading preamp gain. The lead channel signal take also "Rhythm" channel preamp gain, runs through another preamp tube to get you that distortion.

It is not the most quiet amp even brand new due to the cascading gain.

As for flux trace, that's fairly common. These amps were built before MESA Boogie got a solder wave machine so they were basically hand-wire components onto the pc board.

The way you describe the distortion you are hearing is not typical of Mark IIB. The gain of Mark IIB is like having an overdrive stomp box built in. I find these amp as well as the Mark I closes to Fender. The tone stack is like Fenders.

Someone is going to rebuttal and say their Lone Star Classic is very Fenderish. Yes but the stack tones are much different so you have to dial the tone controls for Fender tone. Mark I, II stack tones are quite close to Fender's.

If there's any correction needed here please post. We need second opinions. :wink:

 

[JohnnyK81]

Thanks for the reply!

Which part do you mean must have been modified. I have been reading, and apparently, Sovtek KT66's are just differently branded 6l6's (amp draw, etc).. But I can't tell if the retainers have been modified (After all, I have never owned another Boogie)

I know of the effects loop mod, but don't like the idea of yet another volume control, let alone on the rear of the amp!

Mark2boogie made a note of this Master volume mod, which I have tried, and failed miserably, apparently. haha

The farty distortion tone I have mentioned has since been removed by going back to the way it was wired stock (after my failed volume mod), but still, not a huge fan of the distortion sound.. It's very... 'chunky', I'm not quite sure how to describe it, but I prefer the smooth clean buzz of my DS-2. I'm wondering if a tube change could fix that, but then I'd be back to dealing with this cascading volume control.

I still wish it was a little louder though, not sure if the head is the limiting factor, or if the 2x12 Marshall cab is (I mean, it's loud, and I may be going deaf, but it could stand to be a little louder! haha).

Any way to gauge tube life/newness... as I said, they say 01 11 for the power tubes, and 02 02 on the Electro-harmonix (what I ASSUME to be electro-harmonix) 12ax7eh's.

Thanks again!

 

[RR]

Yes, the KT66s are a different version of 6L6s but they draw different current. An amp tech likely re-bias your Mark IIB to accommodate the KT66s ... or it is possible it never was bias and you're not getting the maximum tone from this amp. :shock:

Mark IIs, if you asks me has the most headroom clean and the loudest MESA Boogie amp I've played. Well mine's a Coliseum 300 Series but my buddy's Mark II 60/100 watt was very loud too. I actually thought the Rhythm channel is too clean. Great for funk though.

I would have to be present to hear the tone you are experiencing.

 

[JohnnyK81]

Well what I mean is i have read that the SOVTEK kt66 only draw .9 amps, or whatever the Mesa 6l6's draw, as they are not true KT66's.. I hope this is true..

 

[b00g13mk2B]

I think the current draw is in reference to the heater current. Not the tube bias. You can search the Boogie Board and the net to see how compatible the KT66 will be with the Boogie's fixed bias.

 

[Rob Lockwood]

I use a MKIIb in a similar way - rhythm channel set up so its just starting to break up at full vol on the guitar then pedals for different flavours of drive & other effects. I have found that sounds better to my ears than the drive channel and it makes the amp easier to use. The MKIIb has a great sound, not too far off Fender but it has a great mid range bark that I really like and seems quite unique to the Boogie.

Anyway the point of my post was that the MKIIb is crazy loud amp. Mine is a 100/60 model but on either power setting I can never have the master volume above 2 on a gig without complaints and usually its at about 1 & 3/4. I would say if you have the first volume reasonably high (6 to 8 seems to be the range most use, below 5 starts to sound a bit muddy to me) and still think its too quiet there must something wrong. The presence control on mine has quite an effect on volume though - below 4 cuts high end and overall volume too.

 

[Rob Lockwood]

Forgot to say - my comments are with an EV fitted combo. Never tried it with Celestions so its possible that the cab is having an effect.