Drive

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The drive block replicates the effect of classic “stomp boxes”. They range from sublime to intense. Use caution when putting a drive before a high-gain amp as excessive noise and squealing may occur. Drives work best before low and medium gain amps.

Parameters

  • TYPE - Selects the type of drive effect. The fuzz types are based on a hard-clipping distortion and give a raspy sound. The overdrive (OD) types are based on a cold-cathode tube model and give a warm, mellow overdrive tone. The boost types don’t distort much unless the drive is set quite high and are primarily tone-shaping and overdrive devices. The distortion types (dist) are based on a variety of tube and solid-state models and give classic distortion tones. The following types are available:
    • Rat Dist - Based on a high-gain, raspy fuzz good for searing lead work.
    • Pi Fuzz - A more mellow but fuzzy distortion sound
    • Tube Drive - A fairly neutral distortion sound with just a bit of low-frequency roll-off.
    • Super OD - Another Japanese distortion, this model is similar to the T808 model but with more highs and a slightly different tone control circuit.
    • Treb Boost - A bright, trebly sound good for overdriving medium gain amps. Particularly effective on darker amps like Class A. This type has a LOT of treble boost and can easily cause pickup squeal when used with a high-gain amp type.
    • Mid Boost - A custom mid-boost overdrive.
    • T808 OD - A screaming distortion sound good for overdriving low gain amps. Based on the legendary Japanese pedal used by many famous artists.
    • Fat Rat - A thick, medium gain distortion sound with a low-midrange emphasis.
    • T808 Mod - Based on a “modified” Tube Dist type. This type captures the most popular mods done to the famed Japanese distortion pedal. Sounds great as a clean boost in front of a low gain amp with the drive turned down and the level turned up.
    • Octv Dist - An octave distortion effect. This produces an octave above the note you are playing. For best results use your neck pickup and constrain your playing to the 12th fret and above.
    • Plus Dist - Controls can be set to produce low-volume, controllable distortion or increased to achieve a warm, tube overdrive sound. Set to maximum, its pronounced fuzztone combines with long sustain.
    • Hard Fuzz - Hard-clipping 60’s-style fuzz.
    • FET Boost - Clean boost, great for a more musical level shift than a raw volume increase.
    • Tape Dist - Simulates distorion as would be encountered when overdriving a studio reel-to-reel tape recorder.
    • Full OD - Modeled after the modern day classic light OD. Great for a clean boost.
    • Blues OD - Simulates the British pedal. A light OD w/ a break up reminiscent of early non-master volume pedals.
    • Shred Dist - Simulates the British pedal w/ tons of gain and a huge mid-scoop. The original has a "contour" control which allows you to vary the width of the scoop. The model models the scoop with the contour control set halfway.
    • M-ZoneDist - Simulates the BOSS Metalzone.
    • Bender Fuzz - Model of the Sola Sound Tone Bender, first designed by electronics engineer Gary Stewart Hurst in 1965 (based on the Gibson-built Maestro Fuzz-Tone.)
    • BB Pre - Model of the Xotic Pedals BB Preamp, a soft Distortion and Sustain pedal that produces a fat singing lead tone.)
  • DRIVE - Sets the input drive level.

The Drive control has a range of 40 dB irrespective of the model it emulates. Many actual drive pedals have less range than this so there isn’t necessarily a one-to-one correspondence to the knob position on the model and the knob position on the emulated pedal. 5 - 10 for the Drive effect is equal to 0 - 10 on the emulated pedal. For example, an SD-1 has 30 dB of range so fully CCW on an SD-1 is equivalent to 2.5 on the model. A TS-9 (or 808 or 10) has only 20 dB of drive range, so you would need to set the Drive knob to 5.00 to replicate fully CCW on that pedal. With the Drive set to maximum it will always be the same as the Drive set to maximum on the emulated pedal. Same with the Level.

If you want to use a Drive pedal as a boost, set the Level near maximum and the Drive to minimum. Bring the Drive up until you achieve the desired amount of boost.

  • TONE - Controls the tone of the effect.
  • SLEW - This models the slew rate limiting produced by early op-amps. Increasing the SLEW LIMIT parameter limits the large signal frequency response of the virtual op-amp. Adjust to taste. Set to zero to deactivate.
  • LEVEL - Sets the output level of the block
  • BYP MODE - Selects the bypass mode of the block.


Varying the drive/gain

The DRIVE control has too many calculations associated with it to allow a modifier to adjust it in real time. You can adjust gain in a preset in a few different ways, each with their own benefits and drawbacks. Recreating the effect of varying the DRIVE control has a certain set of needs that other techniques won't achieve.

Parallel paths: panning between inputs or mixing between outputs

Neither technique is going to be quite the same as simply adjusting a volume pedal to shift the gain. Panning between the inputs would better approximate this, but isn't much gained (pardon the unintended pun) by using a second setup then. For blending to a different tonality (such as boosted mids and smoother gain) for a solo though, that's a great approach.

Mixing between the outputs can be a nice effect, and useful for other things, but really isn't anywhere near the same as adjusting a gain control. If mixing between a signal and a version that's been pitch-shifted by an octave doesn't get a shift of a fifth. Similarly, gain structure isn't affected by mixing between low gain and high gain. It's a great way to clean up a really dirty sound to get more clarity, but not the same as turning down the distortion.

To think through this stuff, just think about what would happen if one channel was set to crystal clean and the other was a raging fuzz. Panning the inputs would simply fade out the clean while increasing the drive on the fuzz, but there would still be just a blend in the middle of the spectrum. (Again, not bad, just not riding the DRIVE control.) Mixing the outputs, you would just get more pick attack sticking through the fuzz. (Still useful; still not a variable DRIVE control.)

Volume block before the gain block

A volume (or null filter) block at the input of a Drive or Amp block is the way to go. You can set a range in the modifier so it varies between two set points. You can also throw a control at a LEVEL control somewhere further down the line (or another Volume block) to counteract (or further, if that's what you want) the volume boost from pushing everything further into saturation.


List of drive simulations

This is a list of what the drive pedals are believed to be: Here's a list of all Drive models in the Axe-Fx. You can also find a list on the Fractal Audio website.

Axe-Fx drive type Description
Rat Dist ProCo Rat
Pi Fuzz Electro-Harmonix Big Muff Pi
Tube Drive Chandler Tube Driver, neutral distortion with mild low roll-off
Super OD Boss SD-1
Treb Boost Dallas Rangemaster
Mid Boost Custom drive with steep mid boost
T808 OD Ibanez Tubescreamer TS-9
Fat Rat Custom. Similar to Rat, thicker distortion with a low-mid boost
T808 Mod Based on popular TS-9 mods
Octv Dist Tycobrahae Octavia
Plus Dist MXR Plus Dist (MXR Distortion +)
Hard Fuzz Hard-clipping 60’s-style fuzz
FET Boost A clean boost with tone controls. Like the Keeley Katana or ZVex Super Hard-On
Tape Dist Studio reel-to-reel tape distortion
Full OD Fulltone FullDrive 2
Blues OD Marshall BluesBreaker
Shred Dist Marshall ShredMaster
M-Zone Dist Boss Metal Zone
BB Pre (firmware 9.01) Xotic BB preamp
Face Fuzz (firmware 10.x) Dallas Arbiter Fuzz Face. Used by Jimi Hendrix
Master Fuzz (firmware 10.x) Maestro FZ-1 Fuzztone. Used in I can't get no satisfaction by the Rolling Stones