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Korg AX30G

Guitar Multi-effects By Paul White
Published February 1995

Korg's new pedal box features a novel pressure pad that lets you change performance parameters while you play. Paul White gets in his annual half‑hour guitar practise session checking it out.

In the beginning, guitar players wanted their effects units on the floor so that they could get their feet on them. Surprisingly enough, studio owners wanted their effects bolted securely into racks, precisely so that guitarists couldn't get their feet on them! Though some guitar effects have successfully made the transition from floor to rack, most players still feel the need for something to stomp on, which is why integrated floor units such as Korg's AX30G have become so popular with today's players. Not only do integrated units do away with the problem of separate pedals and all the wiring that entails, they also offer programmability, which avoids all that embarrassing stooping down between songs to twiddle knobs. They also save a small fortune in battery costs!

Realising that a significant proportion of musical equipment spends all its life in the studio rather than on stage, Korg have wisely included an amp simulator in the AX30G, allowing it to be patched directly into a mixing desk, which makes it equally at home in recording and live performance environments.

Powered via the familiar wall‑wart power supply, the AX30G allows up to six effects to be set up simultaneously, the effects themselves being divided into two blocks of three. You don't actually have full freedom to decide what effects to put in the chains or in what order, but with six permutations available for block 1 and four for block 2, there are 24 possible ways of configuring the effects. In addition to the two effects blocks, there's also a noise gate, designed to keep the unit quiet during musical pauses.

As with most programmable units, there are both preset patches and user‑editable patches. The 16 user patches are configured as four banks of four, directly accessible via the unit's footswitches, while 50 further preset patches may be called up using its front‑panel controls.

Block 1 comprises up to three of the following effects:

  • Compressor
  • Distortion 1
  • Distortion 2
  • Wah
  • 3‑Band Equaliser
  • Hyper Resonator

Block 2 may include up to three effects from the following groups:

  • Amp Simulator
  • Mod 1
  • Mod 2
  • Ambience

Each group has further sub‑divisions of effect type, so, for example, Mod 1 breaks down into chorus, flanger, phaser, vibrato, tremolo and ring modulator; and Mod 2 includes modulation delay, stereo modulation delay, stereo phaser, random step filter, pitch shifter, pedal bender, and panner. Each of the effects has its own set of variable parameters, though these tend to be far simpler than in a typical rack multi‑effects unit.

The circuitry of the AX30G appears to be an analogue/digital hybrid. Level controls are provided both for the input and outputs. A single LED window shows the bank number (or note name in tuning mode), while a two‑line LCD readout displays the program name and chain details. In edit mode, this is used for parameter editing. No provision is made for MIDI control, but one distinguishing feature of the AX30G is the inclusion of a pressure control pedal. You could compare the effect of this pedal to that of keyboard aftertouch (except that you tread on it). There are three different parameters in effects Block 1 that may be assigned to pressure control by this pedal, and 19 in Block 2; if a pressure parameter is operative, the Pressure legend above the pedal lights up in red. distinguishing feature of the AX30G is the inclusion of a pressure control pedal. You could compare the effect of this pedal to that of keyboard aftertouch (except that you tread on it).

Korg's pressure control gives you another dimension in performance, allowing you to, for example, apply pitch bend for pedal steel/Hawaiian effects, emulate a wah‑wah pedal, change modulation speed, overdrive level, delay feedback, and so on. The AX30G also has a pair of sockets which take conventional volume pedals, one of which may be used in place of the pressure pedal and the other to control volume. These pedals must be connected via specially‑wired Y‑leads, as shown in the manual, otherwise you're greeted by the message INVALID PEDAL. Finally, there's a headphone output and an aux input, allowing stereo backing tapes or CDs to be mixed with the guitar sound.

The Sound

Guitar players can be put off an effects unit immediately if its distortion sound is poor, so I'll start with that. In conjunction with the amp simulator, the AX30G's overdrive sound is actually very convincing, with plenty of saturation at higher settings — but it doesn't entirely convince me at low overdrive settings, where it seems to lose some of its bite. If you're a blues player, this is pretty serious, but if you're a rock player, I think you'll be quite impressed by the range of overdrive sounds which, in conjunction with the EQ, can range from a creamy sustain to an ear‑shredding rasp.

The modulation effects are all fine and sound much like their individual pedal counterparts, though the pitch‑shifter suffers from the usual lumpiness when used to create harmonies or octaves. On the other hand, it seems to work really well in conjunction with the pressure control facility, and with a little practise, you can create quite convincing pedal steel sounds. The stereo delays (with a maximum delay time of 500mS) have the benefit of HF damping, which helps recreate that authentic tape echo effect. Up to 1S of delay time is available in mono delay mode, and this mode has a hold function to create continuously looping sounds. Mono delay also offers ducking, so that the delay level is loudest during pauses in the playing. Reverb offers only room, hall and plate variations, but up to 100mS of pre‑delay may be added, and the maximum reverb time is 10S, which provides plenty of range. Used with guitar, the reverb quality is very good and is infinitely more versatile than the now antiquated (though still charming) spring reverb usually found in guitar amps.

Of the less obvious effects, I like the random step filter, which emulates the old sample‑and‑hold synth filter treatment, though the ring modulator setting invariably creates dissonant results, which are useful only infrequently as special effects.

There are three types of amp simulator, named after three types of output valve. I can't vouch for their authenticity, but at least they add a little more variety. For sparkling clean guitar sounds, the Amp Sim block can be switched to operate as an exciter, accentuating frequencies between 500Hz and 8kHz.


As you've probably gathered from the above, even though the AX30G's individual effects may only have between two and eight user adjustable parameters, there's still plenty of scope for experimentation with this little box. On the whole the sounds are good, though for the performer flitting between the stage and the studio, I feel that some form of global speaker simulator on/off facility would have been a nice addition; as it is you either have to store two versions of each patch or delve into editing mode to make the necessary changes.

On the ergonomic front, I'm not completely won over by the pressure pedal; though it's possible to get some very good performance effects with it, it requires rather a lot of pressure to operate, and though this might be OK when you're standing, it is quite difficult to use if you're seated. But given the modest price of the AX30G and the quality of the effects it provides, it gets my qualified thumbs up.


  • Easy to use.
  • Good range of standard effects.
  • Effective amp simulator.
  • Pressure pad can produce some nice performance effects.


  • Only 16 user presets.
  • Pressure pedal not easy to use while seated.
  • Mild overdrive sounds a bit weak.


A versatile and cost‑effective processor for the guitar player involved in both live and studio work.