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Fractal Audio AMP models: USA Pre (MESA/Boogie TriAxis)

yek

Moderator
Moderator
* EDIT: Up-to-date information is available in Yek's Guide to the Fractal Audio Amplifier Models *



USA PRE: based on MESA/Boogie TriAxis

MESA (MESA/Boogie) is a famous amp manufacturer, founded by Randall Smith in ‘71 in California. Company information.

Some of the amps carry the MESA name while others have a MESA/Boogie label.

Randal Smith started off with the “snakeskin” Boogie amp, a modded Fender Princeton with increased gain and sustain, which made Santana famous (or was it the other way around?), now known as Mark The series has evolved. No longer called Boogie, they’re now referred to as the Mark series. Mainly known for their smooth high-gain tones, loved by metalheads as well as fusion guitar players. We covered already the models of the Mark IIC+ and the Mark IV.

The TriAxis is the preamp-only rackmount version of the Mark series, with tubes and an analog path and digital controls and MIDI-programmable. According to MESA it covers tones from the Mark I, Mark IIC+ and Mark IV.

MESA:
“Digital disbelievers scoffed at the very idea of packing five 12AX7’s and 25 years of tube tone heritage into one rack space of pure magic...but there they are...five little tone bottles, glowing quietly-all too ready to rock the house. Eight separate modes deliver the elusive creamy gain of the Mark I, the heralded focus of the Mark IIC+, the scooped Rhythm of the Mark IV, and a modified British lead mode. But these are just a few of the classic sounds at your fingertips.”​

Cliff:
"I have a Mark IIC+, a Mark IV, a Mark V and a Triaxis. They're all completely different. Mesa always says things like "sounds the same as a IIC+" but the circuits are different and, probably most important, the knob tapers are completely different."​

For a long time John Petrucci has relied on a couple of TriAxis units to get his favorite “IIC+” tones on the road, as did Metallica. The TriAxis also was the amp in the live rig of an unknown guitar player, named Cliff Chase.

The TriAxis features these modes:
  • Rhythm/Green: vintage fat clean (Mark I, Blackface)
  • Rhythm/Yellow: modern hyper-clean (Mark IV)
  • Lead 1/Green: vintage Mark I Lead
  • Lead 1/Yellow: vintage Mark 1 gain boost
  • Lead 1/Red: classic British lead
  • Lead 2/Green: medium Mark IV Lead gain
  • Lead 2/Yellow: classic Mark IIC+ Lead
  • Lead 2/Red: “shred”
Its digital controls are: Gain (model: Input Drive), Treble, Middle, Bass, Master, Presence. The Lead modes have another gain control: Lead Drive 1 / 2 (model: Overdrive).

Cliff:
"The key to a good Boogie sound, IMO, is the Fat Switch. This is the treble Pull Shift on the IIC+ and the Pull Fat on the Mark IV. Mesa knew this and the Lead 2 modes on the Triaxis all had the treble shift engaged by default."​

Here’s what the manual states about the Presence control:

“This control usually regulates either brightness or negative feedback in the power section of an amplifier. In the TriAxis a whole new approach to this traditional circuit was taken. An actual dynamic feedback loop that compresses the highs and upper treble frequencies makes this PRESENCE control the first of its kind.​

As the PRESENCE control is increased, more highs are allowed to pass. The lower the signal strength at the input of this control, the more highs pass through it. The lower region of the PRESENCE control dampens these high harmonics. The greater the signal strength at the circuit input becomes, the darker the sound becomes. So...if you set the PRESENCE control high and pick softly (sending a small signal through the PRESENCE control circuit) the highs will be very prominent in the mix.​

If you decrease the PRESENCE control and pick harder (increasing the signal strength at the PRESENCE control circuit input) the high harmonics will be very subtle. In other words, the PRESENCE control helps enhance whichever direction you’re trying to go in with your sound and it does so dynamically! Most players love the way tube circuits react to subtle nuances in style...This PRESENCE control circuit takes that idea a few steps further. When you’re “going off” on the treble strings in a solo and you go for an expressive bend and lay hard into the note...TriAxis works with you! If you picked the note hard with the PRESENCE control set low, that note would become bigger, rounder and more compressed.​

Likewise, if you were doing some low growling work on the bass strings and the PRESENCE control was set high...you could relax into this segment and let the PRESENCE control make the edge. Most everyone that we know always wishes their high notes could be fatter and their low notes to be more discernible and articulate...highs where you need them, lack of highs where you don’t. Make sense...? If not on paper, then you need to plug in and experience the way this dynamic PRESENCE control can enhance your playing, especially when you are soloing.”​

Personal note: while Reading the above quote, it dawned on me that the Presence circuit in the TriAxis may have been the inspiration for Fractal Audio to add Dynamic Presence (and Dynamic Depth) to the Axe-Fx II.

The TriAxis was the reason for Fractal Audio to add a Bright knob (not the Bright switch under treble) to the models.

Cliff:
“Added the “Bright” control to the Amp block. This high treble control is a shelving filter between the preamp and power amp and may be used to darken or brighten the output of the preamp. This control also accurately replicates the “Presence” control found in the Mesa Triaxis preamp when set to negative values (the Presence control in the Triaxis is actually a high frequency cut shelving filter).“​

"I can nail the sound of my Triaxis now by setting it (Bright) around 9:00 - 10:00."​

"10 on the Triaxis would be 0 dB on the Bright parameter. Anything below 10 is equivalent to less than noon on the Bright parameter. The "Presence" control on a Triaxis is always a hi cut, it never boosts. The Bright parameter is not an exact match to the Triaxis Presence control though. It is a fixed shelving filter. The Triaxis Presence control is passive so the center frequency changes with the amount of cut. It also changes the load on the plate which distorts the frequency response a bit too. The Presence parameter should be set to 5.00, which is neutral (see the manual for details)."​

The TriAxis also features Dynamic Voice, which is a preset EQ curve. This is not modeled. You can use the graphic EQ in the Amp block to simulate the 5-band “pre power amp” graphic EQ, present on Mark amps.

Let’s get to the models. Read posts #2 and #3 for quotes from the manual.
  • USA Pre Clean: Rhythm/Green mode. It’s a vintage fat clean (Mark I, Blackface).
  • USA Pre LD1 RED: classic Britishlead, basied on the Triaxis "TX-4 board"
  • USA Pre LD2 GRN: medium Mark IV Lead
  • USA Pre LD2 YLW: Mark IIC+ Lead
  • USA Pre LD2 RED: “shred”
Cliff:
"I used a Triaxis for, shoot, I dunno, over a decade before designing the Axe-Fx. I have two of them. So I'd say I'm pretty familiar with the tones. To my ears (and my measurement equipment), the Axe-Fx models are spot-on."​

"Note that these were modeled with the Triaxis Presence control at maximum as this control is actually a hi-cut control. Also note that the mid control in the model has far more range than the preamp. At a value of 5.0 the responses will match but the amount of mid cut on the Axe-Fx is greater."​

Personal note: LD2 Yellow is my absolute favorite. It’s the IIC+ mode. It has Pull Shift and Pull Bright enabled by default. I find this model easier to dial in than the IIC+ models, and it sounds awesome.

Cliff:
"Mesa claims it's based on the IIC+ but it's different. The bright cap is different, the mid resistor is much greater, the source impedance of the drive "pot" is different, etc."​

The original TriAxis is a preamp without a power amp. The models however do have a poweramp section.

Cliff:
"I did NOT use a Boogie power amp model with these as I always preferred using my Triaxis (I have two of them) with a more typical tube power amp. My favorite power amp with the Triaxis was a VHT 2502 so the power amp model is very similar to that."​

Stock cabs: use the typical MESA cabinets such as 4x12 USA, 4x12 Recto, TX Star etc. Or try the 4x12 Rumble or Petrucci’s cab: #108.




 
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yek

Moderator
Moderator
USA Pre Clean:

“More vintage, “old Black Face” style circuit. A beyond-vintage clean sound with bubbly, elastic highs and big breathy lows. This mode also shines at many other settings as well. As the GAIN and MIDRANGE controls are increased, 5.5 - 7.5 a whole new flavor appears. This hotter region performs as a killer driving, yet still clean, rhythm sound. Bold and pushed, this dynamic range of tones works great for Blues rhythm grooves or more aggressive “alternative” clean parts or lines. This is probably the most powerful and widest of possible rhythm sounds aboard TriAxis, perfect for when it’s your turn in the spotlight. Go ahead...Crank it! Rhythm Green loves to rock.

With the GAIN Control at 10 and the Midrange also high, this mode is one of the coolest solo sounds around. Reduce the Bass a little and dial in the Treble to set your pick attack, and you have a touch-sensitive lead mode that won’t completely saturate your guitars’ natural sound.

This is the sound that helped put Boogies in the hands of widely acclaimed guitar heroes of the 70’s and early 80’s, when Blues/Fusion changed and revoiced rock with tasty medium gain sounds. This circuit was sired by the classic 4x10 Fender Bassman and later redefined in Mark 1 Boogies. Classic, bare-bones, roots players will love how well this setting responds to pickup output. These virtuosos of the volume knob can take or leave footswitching in favor of a circuit that lets them ride the gain from their guitar. Rhythm Green works extremely well for this and will surprise even the most hardcore vintage heads.

NOTE: With a very high GAIN control setting in Rhythm Green, it will probably be necessary to reduce the MASTER Control substantially. The dynamic response of this mode makes it the hottest, output-wise, of the eight modes.

NOTE: The GAIN control has a Dynamic “Bright” circuit built into it. At low Gain settings the upper harmonics will pass freely through this control, producing the sweetest, brightest sounds. The more the GAIN control is increased, the less of these upper harmonics pass through this control and the warmer the sound becomes. All the way up on the GAIN control virtually removes these frequencies from the mix. You may want to use the PRESENCE control to put some of them back at the highest Gain settings. Use the MIDRANGE control in conjunction with the BASS control to balance the warmth with the upper harmonics at low Gain settings and possibly reduce the PRESENCE control until you achieve the desired blend.”​

USA Pre LD1 RED:

“(..) pre-tone-control gain circuits. This means the boosting of gain by progressively “slamming” the 12AX7 tubes occurs before the tone controls. This method of squeezing gain through the tone controls tends to lend itself to a larger, yet slightly less focused sound. Many players rely on this looser, more spread out sound to be able to get emotional with their soloing style. This circuit also delivers large amounts of bass very well. As opposed to a “rear end” style circuit, this type of circuit lets you pump larger quantities of bass through the tone controls without increased flub or cloudiness. Players that lean toward extremely high gain metal or hard rock sounds will find the LEAD 1 modes much more suited to the maxed out regions of gain required to produce over the top, believable crunch and grind.

We especially recommend the Lead1 Red mode for this application. (…) This aggressive mode shares much of the circuitry with both Lead 1 Green and Yellow and then adds extra focus and punch in the upper midrange. This mid-forward voicing lends a more urgent, tight character to the mix and is perfect for showcasing Lead 1’s heavier side. Because of this added midrange, the Red mode slices through a mix in the sonic region where the rock snare lives and is especially great for crunch rhythm in either classic or modern gain realms. Another attribute of this EQ’ing is that higher settings of the Bass control remain tighter and track better at higher gain settings than in the other two Lead 1 modes. This additional bump in the mid frequencies also allows more Treble to be dialed in which increases the gain without sounding thin. Try setting the GAIN to 8.0, BASS on 6.5, the TREBLE on 7.0 and LEAD 1 DRIVE on 6.0 to audition this scheme.”​
 
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yek

Moderator
Moderator
USA Pre LD2 GRN:

“(…) post-tone control gain circuit. (...) With heralded veterans of this design the Mark II-B, II-C+, Mark III, and Mark IV...the rear-end lead legacy lives on...stronger than ever! It is in LEAD 2 that we celebrate these classic lead sounds and offer up a couple variations on the theme. Again, these are the more articulate and focused lead sounds. Some players that grew up playing non-MESA amplifiers may find these dry and stiff at first, but have patience, and you will come to enjoy these modes. There is simply less “slop around the note” in these modes making them a sort of magnifying glass for inaccurate playing. Though at times they are more revealing, you will find that they hold up better in a mix and are much more behaved on a stage full of live microphones. Usually they are also much better for any kind of rhythmic high gain playing where you need urgent attack and tight cut-off points.​

The Green circuit is taken directly from a Mark IV Lead channel. Green is focused gain. It uses the concept of the Mark IV’s Mid Gain, a feature added in 1989, to enhance the attack and to lower the medium midrange “meat” of the sound. By enhancing this part of the spectrum a rich, bold, yet singing quality is produced. Thick would be the best way to describe its’ character, while Punchy would accurately describe its’ attack. It does saturate the note fairly completely, especially at high gain settings, but the attack envelope is so right at lower gain settings, that roots players usually love this Green mode. Its’ thicker midrange punch really helps melody lines played on the high strings, particularly high on the neck. With higher Gain and Drive settings the high notes soar and sing, yet don’t get too soupy to be heard in a big mix. Green is especially helpful in getting rid of unwanted fret buzz or other annoying idiosyncrasies of an instrument that may be set up wrong. It tends to cover up buzz leaving just the note with greater purity. This is most apparent when a weak single coil is used for soloing. LEAD 2 Green is the cure for this dilemma. It adds the needed frequencies and its’ gain is the steroid habit these weaklings need to deliver a bold lead voice. Green is the mode of choice anytime you need to deliver a statement and you don’t have the luxury of several tracks. It is single note authority at its’ expressive best.​

NOTE: As we mentioned earlier in the Lead 1 Red description, the setting of the GAIN control in all modes is crucial to achieving the sound you are looking for. Each mode has its’ magical optimum setting for this control and we can only give you our view and a few factory settings to demonstrate our thinking on this. Ultimately, it may vary for each mode, guitar, player, and environment and it’s on you to discover what fits your situation. In Lead 2 we have come to a simple “rule of thumb” you might say as to where we prefer the GAIN control to achieve the best blend of attack and quality of tone. Try this first, then deviate from there in all three Lead 2 modes. We like to see the Gain at either 7.0 or 7.5 (depending on your instruments output) for lower gain blues sounds or very articulate medium gain solo sounds. When higher gain or straight up radical rock sounds are in demand, a GAIN control setting of 7.5 or 8.0 again depending on pickup output) should be more than enough.​

With higher than recommended Gain settings a flubby, indistinct attack will occur that the BASS control will have difficulty in removing. Lower than optimum Gain settings will produce excessive high harmonic content, thin the notes out and even add a buzzy quality to the sound.”​

USA Pre LD2 YLW:

“This is Boogie. This mode is the sound that started the craze that became what is slanged as the “California” sound or the “L.A.” guitar tone. Lukather, Landau, Keaggy, Lynch, Gillis, Prince, and Metallica catapulted this sound into the forefront of hit making guitar sounds throughout the eighties. Metallica continues to search high and low for pristine C+ Heads to add to their amplifier collection - deeming them essential for recording, but you don’t have to! The Yellow mode is the reincarnation of the fabled Mark II-C+ Lead mode. Its blend of bold punch and evenly stacked liquid harmonics produces a lead voice that transforms any player who spends enough time to let it...into a virtuoso of feeling, soul, and statement. It growls with ferocity in the low range, staying tight and urgent. A “thonk and chirp” is experienced traveling through the midrange frequencies. Then suddenly, as if someone redialed for the highs, an explosive, yet liquid, top end comes ripping out as you squeeze every luscious note out of the treble strings. Sound almost sexual? Primal? Well many a II-C+ junkie...(there are roughly 4500 of them,) will confess...broken hearts are often cured from a couple weeks rocking with a C+. Seriously, the blend of this mode is so amazing that most players are finding new great sounds 2 and 3 years after their first ear to ear grin.​

While the Yellow mode excels at medium to high gain settings because of these nicely stacked harmonics, don’t underestimate Yellow for the rootsier low gain sounds. Sure as you can make high gain sounds chirp and squeal on command, low gain sounds possess the sting essential to tortured blues soloing. Yellow doesn’t get as saturated as the Green mode in LEAD 2 making it the choice for skinnier, more cutting and clean blues lines. The PRESENCE control works extremely well in the Yellow mode dialing in and out the harmonic content of a given preset. At low PRESENCE and TREBLE control settings the sound is more horn or voice like. With higher settings of the Presence and possibly Treble the character becomes much more searing and harmonic.”​

USA Pre LD2 RED:

“This mode is made for shred. In fact, it might be better named LEAD 2 Shred. It is much more aggressive in the top end than its’ yellow counterpart, boasting much enhanced upper harmonics. Though it shares almost identical basic architecture...additional parts switch in when Red is chosen that give this once balanced, well behaved mode a downright ugly attitude. Harmonics are boosted and a bit of lower treble is dipped to give this Red a sizzling edge that is unique to this mode only. The harmonic edge not only benefits high notes...It does wonders for the grinding “Z’s” needed for bodacious low end crunch. This enhances the growl on the low strings as well as it adds cut and sizzle to the higher strings. The frequencies enhanced by this circuit are slightly higher than those found in conventional power section PRESENCE controls.They are also higher, more rebellious and defined than those adjusted by the action of TriAxis’ PRESENCE control. These highs have that out-of-control-vibe to them, that falling-apart-yet-loosely-held-together quality that is often associated with modified early British heads using Euro-style EL34 power tubes for their ponies. This elusive sound affects the feel of the strings and players accustomed to such sounds have difficulty feeling at home on an amp that doesn’t deliver these loose highs.“​
 
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Genome

Inspired
So if I am correct, to use the Presence control correctly you should leave it at 5.00 and use Dynamic Presence and the Bright Knob in conjunction?
 

simeon

Axe-Master
leave pres at zero and pull back the bright param. the dynamic pres is set at a default value, so you can leave it there. increase a little if you want to.

i had a triaxis for years and lead 2 yellow is fantastic for leads. don't forget about the dynamic voice control, which is very powerful on the triaxis. use the mesa 5 band in the amp block and se it to "pre poweramp". the manual shows some of the settings of the dv control when it's at different values. the manual says that the mix is also adjusted, but there was a thread about this, where cliff said that wasn't actually the case. either way, it doesn't matter, just use your ears.
lead 2 red is just great for heavy rhythm. just the right amount of tight bottom end and sparkly highs. also good for leads with a strat on the inbetween positions, imo.

try it out with marshall cabs, instead of mesa ones...it sounds great!


dynamic_voice.png
 

Genome

Inspired
Those EQ graphics are very useful, thanks!

Gonna give these models a try later. Could never quite get it as tight and punchy as I'd like direct, I wonder if I'm not jiving with the VHT power amp model though. Running Lead 2 Red mode through my Mark V power section (essentially a single channel 2:90) sounds incredible.
 

simeon

Axe-Master
the power section is fine, imo leave the master where it is by default...but choose your cabs wisely...sounds great to me through the two recto mixes at the end of the factory cabs and also try some marshalls as well.
 

stm113

Experienced
I am very Mesa-dumb... please forgive my ignorance here.. I've read that one of the modes is basically a Dual Rec, but based on the best version of the circuit. Which mode is that and do we have it in the AF2?
Also which is the "British" mode spoken of? Is that the shred mode?
 

Fl7x

Experienced
I am very Mesa-dumb... please forgive my ignorance here.. I've read that one of the modes is basically a Dual Rec, but based on the best version of the circuit. Which mode is that and do we have it in the AF2?
Also which is the "British" mode spoken of? Is that the shred mode?
There are four different "revisions" of the TriAxis. Each one has a slightly different hardware applied ONLY in the LD1 Red mode. I'm talking about hardware revisions, there were 2 software revisions that didn't affected the tone of the preamp.

The first batch of TriAxis had the original LD1 Red "British Shred" mode. This mode was aggressive and "Shrill" in the upper highs. Is the one used by Petrucci when he used the TriAxis in LTE for Rhythms.
Mesa changed the mode adding a new board (TX-4) that emulated the Rectifier sound and named the LD1 Red "Recto Vintage", and later on they modified the TX4 board to sound warmer and more balanced like the Recto ORGN Mode in a Rectifier... They called that modification "The Fat Mode". This TX-4 board had 4 different revisions (A, B, C, D). Presumably all sound the same... People claims that the "D" is the better sounding (With or without the Fat Mod).

In Q3 of 2004 Mesa run out of supplies to make the TX-4 board so they replaced it with th TX-5 Board and named the LD1 Red "Searing Boogie Lead". That mode is based on the Lonestar. That's the least popular of them all.

If I recall correctly, the Triaxis modelled in the Axe has the TX-4 board and the Fat Mod.

So there you have it:

LD1 Red "British Shred"
LD1 Red "Recto Vintage"
LD1 Red "Recto Vintage" + Fat Mod
LD1 Red "Searing Boogie Lead" [Lonestar]
 

PumpkinKing86

Inspired
I've only messed with the Clean and Lead 2 Yellow models, but they are very nice. Saying that they're easier to dial in than a Mark II is an understatement! :p
 

stm113

Experienced
Some awesome info here. Something mostly off but somewhat on topic...

What "classic" albums/recordings will you find a Mesa (especially one of the Marks) on? I usually assume most 70s/80's albums in the Rock genre are Marshall fueled. I often Google this kind of stuff to no avail.

The only albums that I've found are
Of course Metallica Puppets through...
●Stryper To Hell With The Devil
●Whitesnake-1987
●Blue Murder
 

spx90

Power User
probably best if you just have a look at the manual. it gives a lot of detail about each of the modes and some nice suggestions for settings

https://www.dropbox.com/s/k1mfl6ippfnrddi/Triaxis_meus.pdf?dl=1
great direct link, Simeon
by version 1
the manual had been reduced to the bone
between the first version and the second
there have been several changes
with some sounds revised
and the ability to morph via MIDI / Expression pedal.
what is the most successful version, I do not know
 

TheTrooper

Inspired
Some awesome info here. Something mostly off but somewhat on topic...

What "classic" albums/recordings will you find a Mesa (especially one of the Marks) on? I usually assume most 70s/80's albums in the Rock genre are Marshall fueled. I often Google this kind of stuff to no avail.

The only albums that I've found are
Of course Metallica Puppets through...
●Stryper To Hell With The Devil
●Whitesnake-1987
●Blue Murder

Everything that has John Petrucci on it, has Mesa amps on it (DT, LTE).
Dave Murray used a Mark IV (Combo I think) on some Maiden records (Fear of the Dark I think).
Vivid by Living Colour (Vernon Reid was and is a Mesa artist, had a huge rig back in the '90s)
Steve Vai used tons of amps on P&W (A Boogie was one of them)
Luke had a Mark IIC+ rig in 1985 so some album of that period (Isolation?)

The list goes on and on....
 

Scary

Experienced
Love this thread. I have been a fan of Boogie forever, mostly because you cover so much ground with one amp. All that gain at low volume was such a treat after dealing with amps that required ear plugs to hit the sweet spot.
 

CodeStation

Inspired
I believe so (if 5 is the default value, can't check right now).
Confirmed, this solved a major problem I was having that I was using a PEQ after the cab to try to solve. Major harshness with the Suhr bridge pickup.

LD Yellow 2, presence is at 5
Dialed "Bright" back more than I had done before, to about a value of -8.40 or so

Just spent about an hour and a half with this thing cranked, using the OH Thiele 1x12. Totally there.
 
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