What TriAxis version do I have?


What TriAxis version do you own? - TriAxis History as of 3/17/2016

The TriAxis has been in the MESA lineup since October of 1991 and as you might imagine, there are a great number in use throughout the world. While there have been very few changes to this famed preamp over the years, there are a few significant differences in TriAxis preamps made at specific points of production. The following provides an overview.

Version 1:

Serial #1 to #1630 - 10/1991 - TriAxis Preamp introduced as a single space rackmount unit with five 12AX7s in an analog signal path that is controlled digitally and allows players to program 8 legendary Boogie voices into any of 90 user presets. Early software versions include 1.4.92, 1.6.3, and 1.6.5. These are generally lumped together and considered as Version 1. Continuous Control is not a feature of a Version 1 TriAxis. The Phat Mod does not apply, as there is no TX4 Recto board installed.

Version 2:

Serial #T1631 to T5199 - 1/25/1993 - Version 2.0 Software & TX4 Recto circuit board installed. The new software allows for Continuous Control of parameters via midi and these parameters scroll faster than in Version 1 units. With the TX4 Recto circuit board for Ld1 Red is added, Ld1 Red Mode is changed from the “British Lead” circuit to the Recto Vintage circuit. The Lead modes have their levels increased (to balance with the Rhythm modes), and the Record Outs are matched for Stereo use. The taper and value of the Bass, Mid, and Ld1 Drive are also changed, along with their respective calibration settings. Many units prior to #1631 have since been updated to Version 2.0/TX4. The easiest way to tell is that when the unit is first turned on, the parameter windows will show “2.0” for a couple of seconds before indicating their settings.

Serial #T5200 to T8278 - 3/1997 - Phat Mod. The Phat Mod offers a tonal change, affecting some aggressive upper mids in the Ld1 Red mode for a smoother top end. All units between #5200 and #8278 left the factory with the Phat mod. Many units between #1631 and #5200 have been Phat Modded and some units with the Phat Mod have had it removed. The only true way to tell if a unit does or does not have the Phat Mod is to remove its lid and check to see if parts (resistors & capacitors) are missing from the top left corner of the TX4 circuit board (as you face the TriAxis) or to perform a play test comparison with a known unit. Missing TX4 components indicate the unit has the Phat Mod. All units after #5200 have new Ld1 Red Factory Presets programmed into the Eprom. These Factory Presets were added to coincide with sound of the Phat Mod. Adding or removing the Phat Mod does not change the Eprom or these Presets:

New Phat Mod Presets - Ld1 Red Mode Only - After Serial# 5200

         Preset          G    T     M     B      LD1    LD2     M    P     DYN

            #1           6.0   6.5   7.5   8.0   5.5    0.0     4.5   5.0    0.0

            #10         6.0   6.0   7.0   8.0   2.0    0.0     5.5   2.0    0.0

            #11         6.0   6.5   7.5   7.0   5.5    0.0     4.5   5.0    0.0


Serial #T8279 to current production - 10/2004 - TX4 board removed because parts needed for it are no longer available. The Ld1 Red sound reverts back to the “British Lead” style (same as a Version 1 TriAxis). This also means that the Phat Mod no longer applies. No unit before #1631 or after #8279 can now be modified with the TX4/Recto board (the parts just aren’t available) and no unit with the TX4/Recto board can have it removed. All units shipped after #8279 have the Factory Presets manually defeated, and a new Preset #1 programmed to coincide with the change to Ld 1 Red:

New Preset         G      T     M     B     LD1    LD2    M     P    DYN

            #1           8.0   7.0   2.0   3.5   6.0     0.0    4.5   3.5   1.0

Click here for more about the current TriAxis.

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