playingitloud
Active member
- Joined
- Apr 19, 2023
- Messages
- 28
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- 20
The MKV was a used amp that came with EL34's.I found the trick with the Roadster, Mesa 1990's 12AX7 Chinese Military 6N4-J Bejing Square foil getter tubes. Then top it off with the STR440 reds. Holy crap that amp now rips. Has a tighter low end and not so swampy with the sub harmonics such that I was able to use the 7 string guitar with it, no external aids like boost or distortion pedals. Same preamp tubes and then switched to the STR445 yellows, they were a bit over the top and killed the use with the 7 string but it was a beast on its own. I am glad I did not sell the Roadster, it has much more to it than I though. I did try using a parallel 39k resistor on the cold clipper to see if that would have much effect with a dop to 19.5k on the cathode, it neutered the amp completely, no more distortion and sounded like crap. Too much of a shift in the load line and raised the operating point more central so it was no longer creating the distortion in the cut-off region. Bad move unless you change the plate resistor too. So what if the cold clipper has less gain, it is not the gain that creates the distortion, it is where the operating point is on the load like that matters. No point in messing with it as it was prefect without the mod. Just the change in preamp tubes had a more desired effect.
Have not explored the STR445 in depth with the MWDR yet. I still like the STR440 grays in that amp.
Back to the topic at hand, Mark talk
I actually love both the Mark VII and the JP2C. Each have their own take on how the tone stack effects the level of distortion (what everyone calls gain). JP2C pull on the CH2 gain knob, almost feels like there is a shift in the opposite direction but not. You lose a bit of that detail but it is something useable, just have to dial the amp in differently. CH3 is the trick with the gain pull or pushed in. It is one of the few Mark amps that has the ability to switch from IIC+ to (IIC+IV) characteristic. Not a boxy sounding amp so change in power tubes just gives you that same good stuff. It may behave differently at bedroom level (STR440 and STR443 both have more low end bloom at reduced volume settings, compensate with the Shred mode) but more predictable or balanced tone with the STR445, STR448 and STR415 (running at bedroom level will have a similar tone like you get at gig level and no need to compensate using the shred mode).
I found the Mark VII to take on a boxy like tone with the STR415, STR448 and the STR440 tubes. Did not try the STR443. I did give the STTR441 a go and they sounded good, different than the 6CA7 tone you get from the STR445 which is to my liking actually. STR454 (=C=6L6GC sounded really good in the VII too, hard to get so I do not use them much, same would apply to the STR415).
I was not aware they were shipping the Mark V90 with EL34 tubes. I thought the Stockers to be the STR441 tubes. I did try the other tubes with the Mark V90 ice pick machine. I did not personally like any of them except for the STR441 or SED =C=6L6GC (Mesa STR454 tubes).
I wish that I would have checked to see what version of Mesa Boogie EL34's were in it before I sold the amp.