The TriAxis is a variable preamp housing the circuits of successive Mark series in a 1U rack. With multiple modes, its settings recallable by MIDI. A well-made device that compresses Mesa's history into one box.
But what this piece wants to see isn't the TriAxis's insides alone.
The TriAxis is, after all, the front stage. A preamp makes the "raw material" of the sound but doesn't decide the sound itself to the end. What decides is the back-stage power amp.
And the answer prepared as the TriAxis's back stage was the 395 Simul-Class.
Here, I look at the TriAxis-and-395 combination, narrowed to the single point of the division of labor between front and back stage.
The front stage alone doesn't decide the sound
A preamp is, so to speak, "a dictionary of voices."
What distortion tendency it holds, in which band it places the core. Such tonal directions are decided at the front stage. The TriAxis houses several such dictionaries.
But merely looking up the dictionary doesn't make a voice.
The final push, how the harmonics wobble, how the compression grips, how the attack rises. These are decided by how the power amp moves. Even the same front stage, change the back stage and the sound that comes out is a different thing.
That you can't discuss the TriAxis's sound without the back stage is because of this.
The "back-stage physics" the 395 Simul-Class brings
The 395 Simul-Class is a power amp with Mesa's unique operating method.
Simul-Class runs some power tubes in Class A and some in Class A/B at the same time. This synthesis produces a distinctive behavior.
The mid pillar becomes thick and strong. The harmonics wobble yet don't collapse. Compression grips smoothly. The attack rises fast.
These are hard to make with the front stage's EQ and gain. Because they're phenomena occurring on the physics side — how current flows, how the output stage saturates.
Much of why the Mark IIC+'s texture has been highly praised is actually due to this back-stage behavior. That the TriAxis's IIC+-like mode is called "close" is thanks to having the 395 as the back stage.
So the 395 is a device that translates the TriAxis dictionary into an actually-ringing voice.
With the 395's modes, the TriAxis shows a different face
The 395 Simul-Class can switch its operating method. And this changes the TriAxis's sound fundamentally.
The standard Simul-Class, the synthesis of A and A/B, has the largest sound image and the most natural mid density. It's the historical reference sound.
Emphasize Class A and the harmonics wobble, the sound thick and soft. An organicness close to the old Mark series comes out.
Emphasize Class A/B and it becomes tight and fast-responding. A modern, linear push.
What matters is that this isn't an EQ difference. It's a physical difference arising from the very way the current flows changing. Which is exactly why it becomes a domain hard to replace in a modeler.
Keep the front-stage mode fixed and change only the back-stage operation, and the TriAxis shows a different face. The preconception "the sound is decided by the front stage" crumbles here once.
A back stage facing the future, a back stage returning to history
The TriAxis's genuine power amp later shifted to the 2:Ninety.
The 2:Ninety has Deep / Modern correction circuits. A tighter, more modern push, leaning toward the Rectifier direction. Use it and the TriAxis connects to the modern Mesa sound image.
The 395, meanwhile, has no correction. The tubes' raw behavior comes out as is. The Mark IIC+-like mid tenacity is natural, the harmonics don't muddy, and the front-stage mode difference comes out honestly.
Even the same TriAxis, the destination changes with the choice of back stage. The 2:Ninety is a back stage that leads to the future; the 395 is a back stage that returns to history. Not interchangeable — a difference of direction.
Here too, what decides the sound's destination is the back stage.
The meaning of recording this "combination" at CSL
The TriAxis and 395 have an extremely clear division of labor. The front stage handles the switching of circuit and era; the back stage decides the sound's motion — compression, release, and push.
So what has meaning when recording is the "combination" of front-stage mode and back-stage operation.
The difference of moving the front-stage mode, and the difference of moving the back-stage operation. Keep these two separated and you can later hear and confirm "which part of the TriAxis is working." Record only the front stage and the 395's back-stage behavior can't be reproduced.
This isn't a story of "perfect reproduction of the real thing." Now that the 395 back stage has ended production, it's a record of keeping this front-and-back combination as a ringing sound.
In short
The TriAxis is a front-stage dictionary gathering the voices of successive Marks. But what translates that dictionary into actual sound is the back stage.
The 395 Simul-Class, with the physical behavior of Simul-Class, brings out the front-stage switching as a difference of push. The 2:Ninety faces the future, the 395 faces history.
To discuss the TriAxis's sound, you need to see not just the front stage but which back stage it was paired with. Which is exactly why there's meaning in keeping that combination and all, as the real amp's sound.