Mark IV-Anyone know how to simulate EL34 in outer sockets?

S

stm113

Power User
For some reason I've started lusting for a real life Mesa Mark IV, but since I am short of funds I will live vicariously through my AF2 and be just fine. One thing I would like to do if I were to ever have a real world Mark IV would be to mix 34's and 6L6's. I tend to gravitate towards amps with 6L6's but I did at one time have a Randall MTS head that had both and it was amazing. With all of that said, does anyone know how I could simulate this in our AF2 models?
Thanks to anyone that can help.
 
Set up 2 mark iv amp blocks and change the tubes in the power amp section of 1 to el34s and blend together to taste.
 
stm113 said:
For some reason I've started lusting for a real life Mesa Mark IV, but since I am short of funds I will live vicariously through my AF2 and be just fine. One thing I would like to do if I were to ever have a real world Mark IV would be to mix 34's and 6L6's. I tend to gravitate towards amps with 6L6's but I did at one time have a Randall MTS head that had both and it was amazing. With all of that said, does anyone know how I could simulate this in our AF2 models?
Thanks to anyone that can help.
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Basically all you have to do is run 2 of the same Mark IV models in parallel, one with the Tube Type (Amp block's "PWR" page) left at the default 6L6/6CA7 type (or Ideal Tetrode, if you prefer), and the other with the Tube Type changed to the EL34/5881 type (or Ideal Pentode).

That's it. :)
 
Yep that should do it. Difference is somewhat subtle in my old Mark IV head. Maybe a bit more upper midrange bark and little less low end. Mesa amps generally have their fixed bias set on the cold side, so the difference is not as much as you might expect. Their power amps run very clean unless they are cranked up to very high volume levels, so the power amp section imparts less character than something like a non-master volume Plexi.
 
stm113 said:
For some reason I've started lusting for a real life Mesa Mark IV, but since I am short of funds I will live vicariously through my AF2 and be just fine. One thing I would like to do if I were to ever have a real world Mark IV would be to mix 34's and 6L6's. I tend to gravitate towards amps with 6L6's but I did at one time have a Randall MTS head that had both and it was amazing. With all of that said, does anyone know how I could simulate this in our AF2 models?
Thanks to anyone that can help.
Click to expand...

I used to run my Mark IV like this. Best way to describe the difference is that 4 6L6's were a bit bassier/looser and seemed to favor using higher mid eq settings (no classic V scoop).

Adding the 2 x 34's seemed to tighten up the bass response, gave it a bit more girth and I found it easier to dial in the sweet spot for channel 3. Didn't seem to muddy up the tone as auickly or easily as you could with 6L6's.

I will definitely try this and see if it compares!
 
stm113 said:
For some reason I've started lusting for a real life Mesa Mark IV, but since I am short of funds I will live vicariously through my AF2 and be just fine. One thing I would like to do if I were to ever have a real world Mark IV would be to mix 34's and 6L6's. I tend to gravitate towards amps with 6L6's but I did at one time have a Randall MTS head that had both and it was amazing. With all of that said, does anyone know how I could simulate this in our AF2 models?
Thanks to anyone that can help.
Click to expand...
I don´t think using two amps will be equal to having one amp with two different tubes in it. In fact you are actually hearing one amp but with the sum of tube charactaristics. I guess you could fool around with tube hardness/bias/transformer-match/neg feedback and get close. In most cases 6L6 have less gain than el34 wich means that the el34 will get more neg feedback-effect and also they have softer characteristics. I also think Mesa have another transfomer-matching on those two tubes(separate windings). The bias is also set higher (class A).

I would try decrease tube hardness-increase tube bias-change transformer matching (don´t know direction)-maybe even decrease variac setting to simulate the lower headroom in the outer el34:s.
 
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At one point I had two Mark IV's, a head with 6L6's, and a combo with mixed types. Honestly I don't remember there being much tonal difference between the two (the C90 combo speaker might have made it less noticeable, but I would occasionally run it through my Mesa 2x12 and 4x12 cabs). It certainly didn't make it sound like a Marshall. :D I wound up selling the combo when I got the Axe-FX Ultra, as I felt it was essentially redundant and didn't need a backup Mark IV.
 
I thought changing tube type wasn't all that you had to do to make the amp sound like is running different tubes? Like if you have the JCM800 model and switch it to 6L6's, that isn't the same as a real JCM800 running 6L6's, as some other advanced settings would change on using different tubes.

That's what I read a while back (probably like 2+ years to be fair, I think cliff may have said something on the subject). Has anything changed there?
 
mr_fender said:
Mesa amps generally have their fixed bias set on the cold side,
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Yes very cold at times! My Mark IV with EL34's in the outer sockets measured about 5 watt's per EL34 or lower at times. If you put 6L6's back in, it was more in a normal range. Still I could not argue the end results in simul-class with 6L6/EL34 it was a nice flavor!
But my overall choice was (4) 6L6's. (Most of the time) But, preferred running class A (outer sockets only). All four 6L6's running through that simul-class transformer didn't always agree with me, for reasons mentioned above by other's. Running in class A took away some of that boomy-ness and in general just found it to be a more focused (but not harsh) sound.

John
 
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