REISSUE Rumor: Mark IIC+ and 2ch Recto

[bandit2013]

The variac note on the EL34 with the Mark V, we can include the same for the MWDR and Roadster (they recommend tube rectification only for EL34).
Mostly due to issues with the EL34 and their variants back in the day. Even Marshalls were having issues with the tube quality so they decided to shift to 6550 tubes instead.

Current production EL34 like the STR447 (EH EL34) or the Gold Lion KT77, EH 6CA7, Tung Sol EL34B They can tolerate the higher plate voltages without sudden death. When dealing with NOS tubes, I would consider them to be of concern. That includes the MESA NOS STR450 Siemens EL34. Tried a set of those and ended up having to ship back the TC50 after the fuse blew out and amp would not function even with the stock tubes and new fuse. (strobe mute circuit took a dive but Mesa claims it was not due to the tubes. Strobe mute will not blow the fuse but the old EL34 will as that amp runs 450V plate voltage.

In other words, the Variac power mode note on the V and the tube rectifier for the Dual Rectos is just a CYA notice. Most of the other manuals indicate if you decide to run with EL34 power tubes, have several sets available due to their shorter life span or unpredictable reliability. However, no mention of such with the TC or Badlander. However, it may explain why you get a volume drop when using 6L6 tube sin those amps.

 

[bandit2013]

As for the IIC+ compatibility with EL34 tubes. depends on the extended class A sockets and their bias points. I did not see any EL34/6L6 bias switch. If they worked out the details with the amp, it may be possible to run EL34 tubes in the extended class A spots. Probably best to get a direct answer from Mesa or wait and see if any details are in the manual regarding power tubes.

I found it made no different in tone or character when I ran the one Mark VII with EL34 and the other with 6L6 tubes. They both sounded the same. The STR445 are voiced like the JJ 6CA7 tube in some ways. So if the amp cannot run a mixed quad, keep the STR445 in the Class A sockets and run a pair of STR448 or STR441 in the class AB sockets. Then again, not sure what 6L6 tubes will sound best in this new amp. Just speculating as I did that with the Mark VII (blend of STR448 and the STR445). I am now running a full set of the STR445 (yellows) in both Mark VII. It did have merit to run the STR448. I did try a pair of the STR415 in the Class AB sockets.

So we will find out what we can use once they publish the manual.

 

[tbonesullivan]

IMHO the "Single Chan Dual Mode" design deal with the II & III is always going to be a bit of a compromise between Ch 1 and the lead chan. If the reissue mimics a real IIC+ in function (as it should) then yea I'd expect it's going to present the same challenge. If I set my IIC+ Ch 1 to a more spanky and sparkly clean then there definitely is less gain to work with on the Lead Chan. Personally I feel the Lead chan has a ton of gain and that makes up for it but I could see why it may be impossible.

I have found that the definition of a "Good clean channel" seems to vary quite a bit from person to person. My definition is pretty much fender blackface. I don't want any break up, no grit, no "super warm" type of sound. I want a jazz clean. For others it seems like "clean" includes a little bit of breakup. Now I've never gotten a chance to play any of the early marks, but I would assume running the input volume on the "clean" mode at 7 would have a decent amount of grit in the sound.

 

[spawnofthesith2]

I have found that the definition of a "Good clean channel" seems to vary quite a bit from person to person. My definition is pretty much fender blackface. I don't want any break up, no grit, no "super warm" type of sound. I want a jazz clean. For others it seems like "clean" includes a little bit of breakup. Now I've never gotten a chance to play any of the early marks, but I would assume running the input volume on the "clean" mode at 7 would have a decent amount of grit in the sound.

I’m also in the pristine cleans camp, with my III and the input volume at 7 I achieve that, but I guess pickup type will have impact on that as well. Sure bridge humbucker full bore has some dirt to it. But I would never use a bridge humbucker for my clean sounds anyway. My go to clean config is a dual humbucker guitar middle position coils tapped. My CE24 semihollow especially sounds amazing for this. No hair or breakup at all

 

[rarebitusa]

I’m also in the pristine cleans camp, with my III and the input volume at 7 I achieve that, but I guess pickup type will have impact on that as well. Sure bridge humbucker full bore has some dirt to it. But I would never use a bridge humbucker for my clean sounds anyway. My go to clean config is a dual humbucker guitar middle position coils tapped. My CE24 semihollow especially sounds amazing for this. No hair or breakup at all

Yea, I'd agree WRT PUs. My IIC+ Ch 1 gets gritty pretty quick. Can't set it near 7 more like 5 and yea you can't slam the input at all. A compressor, which sounds sparkly on the LSS just breaks up on the IIC+ acts almost like a boost pedal.

 

[Joey1970]

Sylvania 6CA7's (STR-616) won't give any problems. https://reverb.com/item/31049775-me...illips-sylvania-6l6-gc-el34-6ca7-mark-iii-iic

 

[Eevil]

I have found that the definition of a "Good clean channel" seems to vary quite a bit from person to person. My definition is pretty much fender blackface. I don't want any break up, no grit, no "super warm" type of sound. I want a jazz clean. For others it seems like "clean" includes a little bit of breakup. Now I've never gotten a chance to play any of the early marks, but I would assume running the input volume on the "clean" mode at 7 would have a decent amount of grit in the sound.

This

Sometimes squeaky clean is nice and sometimes crackly clean works wonders..

 

[Tal C.]

Guys excuse my poor playing i made a lil jam yesterday night nothing serious really just to check out how it compare a bit before the real comparison starts with more serious setup when the first batch of RI's arrives to players...

I copied the same settings and played the same riff shown at the 00:49 mark on MESA's video using my '83 IIC+ DRG + dirty fingers pup equipped explorer type guitar.

Recorded on my phone directly to a 1x12

Just a heads up really

What do you guys think?

 

[spawnofthesith2]

Yea, I'd agree WRT PUs. My IIC+ Ch 1 gets gritty pretty quick. Can't set it near 7 more like 5 and yea you can't slam the input at all. A compressor, which sounds sparkly on the LSS just breaks up on the IIC+ acts almost like a boost pedal.

Interesting! I've never played any type of II so don't have a frame of reference there. I forgot to add that I always have my keeley compressor plus on too. Been too long since I had the red stripe so I don't remember my settings there, but I wonder if maybe this is part of the "more mellow" nature of the purple stripe

 

[Fiveband]

Guys excuse my poor playing i made a lil jam yesterday night nothing serious really just to check out how it compare a bit before the real comparison starts with more serious setup when the first batch of RI's arrives to players...

I copied the same settings and played the same riff shown at the 00:49 mark on MESA's video using my '83 IIC+ DRG + dirty fingers pup equipped explorer type guitar.

Recorded on my phone directly to a 1x12

Just a heads up really

What do you guys think?

It does sound really close.

 

[rarebitusa]

It does sound really close.

Yea it does... cool

 

[Theresa]

As for the IIC+ compatibility with EL34 tubes. depends on the extended class A sockets and their bias points. I did not see any EL34/6L6 bias switch. If they worked out the details with the amp, it may be possible to run EL34 tubes in the extended class A spots. Probably best to get a direct answer from Mesa or wait and see if any details are in the manual regarding power tubes.

I found it made no different in tone or character when I ran the one Mark VII with EL34 and the other with 6L6 tubes. They both sounded the same. The STR445 are voiced like the JJ 6CA7 tube in some ways. So if the amp cannot run a mixed quad, keep the STR445 in the Class A sockets and run a pair of STR448 or STR441 in the class AB sockets. Then again, not sure what 6L6 tubes will sound best in this new amp. Just speculating as I did that with the Mark VII (blend of STR448 and the STR445). I am now running a full set of the STR445 (yellows) in both Mark VII. It did have merit to run the STR448. I did try a pair of the STR415 in the Class AB sockets.

So we will find out what we can use once they publish the manual.

So, if we refer back to the first mention of mixing the EL34/6L6 tube compliment, I defer to the Mesa Boogie Mk III manual paragraph Tube Switch...

"This is the "Class A/Simul-Class" switch or the "60/100" watt switch, depending on amplifier type. In the Simul-Class amplifiers the power (before clip) is much less in the Class A position - mere 15 watts. But the unique way the system is wired allows you to achieve a much greater degree of power tube distortion than with most other amplifiers ... and it is still very loud! In Class A, only the outside (outer left & outer right) pair of tubes - the EL-34's will be on. The inner pair - which are 6L6's - will also be turned on when the switch is in the Simul-Class position. In addition to this obvious difference, the biasing and control circuitry of the socket pairs are radically different ... and this is the heart of the now famous (and patented) Simul-Class circuitry. It is worth noting that almost all of the major players who have gone over to Boogie have chosen the Simul-Class power design!

NOTE: In the past, MESA/Boogie advertised the "interchangeable power tubes" feature of the Mark III Simul-Class. We told players that they could use either EL-34's or 6L6's in the outer (Class A) power sockets. However, in recent years we've observed a much greater reliability factor with the use of EL-34's in these outer sockets, with much fewer incidents of tube failure. Therefore, today we strongly recommend using EL-34's in the outer sockets and 6L6's in the inner sockets of your Simul-Class Boogie."

If I read this correctly, the IIC+ EL34/6L6 complement was not a "thing" until the MK III happened on the scene. I have always used EL34's in the outer position and the 6L6 in the inner positions for all my Mark series amps with the exception of the VII. This kind of explains a good many things as to whether the reissue will accommodate the Tube Mixing/Tube Switch or not. Further exploration also discusses transformer impedances (Soldano discussions on mixing EL34 vs. 6L6's and compatibilities).

Further reference of Tube Mixing is outlined in the MK IV manual as follows:

"This procedure is in keeping with Mesa/Boogie’s quest for ultimate versatility. As you know, different tubes offer different sounds and playing characteristics and your new MARK IV offers four choices:

FIRST: the standard four 6L6’s which produce by far the best all-around performance. They deliver the most powerful clean sounds along with the richest distortion.

SECOND: Type 5881 is similar to the 6L6, but these tubes are just slightly less powerful. Although they will produce a somewhat rounder, more “vintage” tone.

THIRD: For those seeking the traditional British edge to their overdrive sounds, EL-34’s can replace the 6L6’s in the end two sockets (outer-left and outer-right). When running the amp in class A, only the two EL-34’s will be operating. In Simul-Class, a combination of two 6L6’s plus the EL-34’s produce a louder, fatter sound while retaining the British edge. (Expect the clean sound to suffer a bit whenever EL-34’s are used.) All combinations of Triode, Pentode, Tweed and Normal power can be used with this EL-34/6L6 combination.

FOURTH: Those of you who recall the great sounds of old Fender Deluxes will be delighted to know that four 6V6’s can also be used in the MARK IV...but, ONLY when TWEED and SIMUL-CLASS are selected. Also, to reduce tube wear when using 6V6’s, the 8 ohm speaker should be plugged into the 4 ohm jack. However, please note that Mesa/Boogie cannot accept responsibility for any blown 6V6’s incurred during such usage! Proper operation depends totally on the correct setting of the aforementioned switches and this will be impossible to verify for warranty tube coverage. So please exercise caution when using 6V6’s! Incorrect setting of the switches won’t usually cause immediate tube failure, but the strain caused is far in excess of recommended ratings."

Regards....

 

[bandit2013]

It all depends on the circuit design if the IIC+ Reissue can support the EL34 in the class A sockets?

The Mark V90 was the first amp where Mesa abandoned the use of mixed quads. Mark IV was the intro to pentode/triode on the class A sockets. they also added a screen resistor. That amp could run EL34 in the class A sockets but perhaps they were running on the cold side. Never realized the IIC+/III simul-class amps did not have a screen resistor on the Class A sockets until I looked at the schematic. It has been a long time since I had the Mark III, too bad I did not take any gut pictures. Looking online at gut shots, some DRG have screen resistors, and some do not. Not everything was captured in the schematics. I am not claiming to be an expert on the subject matter, just making observation from schematics without the actual amp to look at.

IIC+/III are basically the same. -67V bias voltage with a 220k/380k voltage divider on the control grid. Brings the bias down to -42, Mesa marked it with -45V. Also note there is no screen resistor on the tube. That may be a bit hot for 6L6GC tube, but the manual did indicate you can run a full quad of 6L6tubes. I did try that, and it worked but did not run it for long that way as I felt the EL34 added some better gain characteristics. Hopefully I am not breaking any rules here. The IIC+ circuit is the same as the III but there could be differences in the stripes of the III as well as change in transformers over the years.

When the Mark IV came out, I suppose the screen resistor was needed to run in pentode mode. So now there is a 1k screen resistor on the class A tubes. With that in the circuit, the class A power output was raised a bit more than the 15W of the IIC+ and III. Bais voltage on the class A tubes is closer to -51V but it may be less than that if measured on the amp itself. Mark IVB could be run with EL34 + 6L6 tubes just like the Mark III, but I assume the bias may be on the cold side for the EL34. Also, there may be an error in the schematic for the IVB. Perhaps not? the 1k screen resistor on the class A socket in pentode mode appears to connect directly to the screen of the CLass AB tube and that all current will pass through the 470 ohm resistor to the B voltage. Makes me wonder if that is how the amp is really configured.

The Mark V90 is very similar but the 220k was changed to a 150k and the bias voltage was reduced down to -51 (well on paper anyway). Not what I measured with mine. Here is a table of tube voltages. the class A sockets have -47V on the control grid, Sort of makes you think it will support a mixed quad of EL34 and 6L6 tubes. I would not doubt it would work, and some have tried it. So why did Mesa not state this in the manual? Reliability issues? Not sure if the transformers are the same between the Mark IVB and the Mark V90. They may be different. Plate and screen voltages may be the reason. Still above 450V on the screen. Also, it could be due to the 10W mode (there will be no grid bias voltage on the tubes used in Class A 10W except for one that is used as a ballast. The 2009 Mark V schem can be found on the net. Not the 2010 version and I do not want to be the one to provide it. But for reference to the table, what the 2009 states is V7 is actually V8. V9 is actually V10, V10 is actually V11, and V8 is actually V9. The old schem has two V7 tubes. One is the phase inverter and the other is a power tube.

There have not been any leaks on the Mark VII schematics. Even if I had them, I would not dare make them public. I don't have them so no worries.

If one could run a mixed quad of 6L6 and EL34 in the Mark VII, not willing to try it. I am sure the EL34 tubes will work but will be running on the cold side (assumed) like they were with the Mark IVB. Not sure about the Mark V90 as I never tried to experiment with that. I personally am not willing to find out what would be the end result of the Mark VII with a mixed quad (6L6 + EL34). I have run mixed quads but they are all 6L6GC tubes. It did not make much of a huge difference though and only 90W was it notable.

Since the IIC+ lacks a bias switch, is this to assume it is possible to run a mixed quad of tubes? No manual out yet so best not to jump to conclusions until they release the manual assuming it is correct and without errors. Would not be the first time that happened but will at least give you a head up.

Just for reference, the STR445 tubes do have some similar traits to the 6CA7 in tone but it depends on the amp in question. Same tubes in the JP2C, it is ok, not the same characteristic sound I would prefer. Sort of has a thin sound. In the Mark VII it has more depth and character. the STR415 in the JP2C adds in controlled depth and character I would think gets closer to the real deal but does not have Vol 1 for pre-gain tailoring. Sort of wonder if the gain pulls alter the voltage divider used to replace the Vol 1 pot. Swap in the STR415 into the Mark VII, not bad but sound on the boxy side. Would not say they are epic in that amp. It may just be the difference between the Class AB 100W and Simul-class 90W. What does seem to sound very close to the STR415 loaded in the JP2C is a Quad of Mesa STR454 (=C= 6L6GC). That adds in some depth and cuts a bit of the 6CA7 mids a bit just enough to the point the JP2C (STR415) is about the same as the IIC+ on the Mark VII (STR454). I became fond of the STR445 in the Mark VII. Actually, the STR447 (with bias set to EL34) sounds much the same. Unlike the Mark V where you can actually tell the difference and note the change in power tubes and characteristic tone of the EL34 tubes from the 6L6GC tubes. Then again the STR440 have their own sound to them. STR441 was a step in the right direction. Actually, I tried a quad of those in the Mark VII and thought it was decent. Nothing like the STR454 tubes though as they added some depth to the grind I was getting with the STR415 loaded in the JP2C. Still, the STR445 are holding up well and they have gone through plenty of abuse. It does bring be back to the Mark III DRG days but that was one amp I probably could not figure out. Never realized how Metallica made use of the IIC+ so if I knew the trick, I would have tried it. BTW, it works on the Mark VII but lack of Vol 1 may be the missing link with the VII and JP2C.

So, when the IIC+ Reissue rolls out the doors, reality will set in how this amp sounds. I am not expecting to sound identical to a IIC+ DRG, I do not have one to compare it with. Do I care? NOPE. Hearing it in person will reveal is it real in sonic character or just a copy that fell short due to compromise in design? There may be some reason to hold off on getting NOS tubes from the 80's-90's until you find out how it performs with the tubes it comes with. I have the STR415, perfect for the JP2C, just not so epic in the Mark VII. Just in the description of the amp, I have a hunch it the output section will be similar to the Mark VII but that is just an assumption.

 

[CoG]

nvm double post

 

[CoG]

Just needed a paradigm shift from innovative company to stale company

It's not even 'stale', it's 'pivot to being a boomer swag brand' just like Gibson guitars. These are man-cave accessories.

 

[robvoyles]

I do believe eventually Some mesa amps will be produced outside of the USA and they will justify it by simply saying "we" did this " Gibson " to make them affordable so that everyone can enjoy a boogie. Thats just something i do believe will happen eventually.

 

[VisaL]

all of the pictures I've seen are using 4 6L6's , will the class A slots on this one take EL-34's?

If not then it’s not reissue, merely look-alike. They are not using similarly spec’d tranny if it cannot take the higher heater current of the el34.

And if now they are shipping with current production 6L6 that’s also a sign it’s not 1:1 copy of the original. Remember last time around they moved away from using 6L6 on the outer position because they realised modern tubes cant take that sort of beating and started recommending el34. And i assume that’s because all being equal el34 will be bias little colder. Still very hot. As i understand it, if outer pair was cathode biased class A, there would be no problem, but the problem is that despite their marketing, simul-class is not class a. It’s fixed bias class ab, just like the inner pair, it’s just biased ridiculously hot.

Nonetheless it’s interesting to see the schematics once someone reverse engineers it.