Explore the full potential of your music and enhance your performance with the new AK-4 PRO WORLD SCALE TUNING CONVERTER. With the AK-4, you can create authentic microtonal keyboard music right from your existing gear.

Kelfar Technologies AK-4 world scale tuning converter

We’ve combined all the features you love from the AK-1 and AK-2 Pro with NEW innovations to make the AK-4 better and more enjoyable to use. Innovations include class-compliant USB MIDI interface and Breath Controller/Expression Pedal input (pedals and breath controller purchased separately). It works best with the BCK-1 (Kelfar Technologies Breath Controller).

This easy-to-use world scale tuning keyboard converter is compatible with most major keyboard brands and offers an incredible array of customization options right at your fingertips.


• New, simple, intuitive design that makes it easy to create scale memory

• Universal MIDI interface to connect with Mac and Windows devices via USB port

• Breath Controller/Expression Pedal input with up to 9 factory presets Curves (Linear, 5*Exponential, Logarithmic, S -Type, N-Type)

• A lightweight, compact design, making it portable and easy to carry to gigs, concerts, or jam sessions with friends

• Connect to TWO synthesizers at once

• Adjust the pitch of each note in the octave (C/Do to B/Si) to -64 to +63 cents

• Transpose Two synthesizers at once

• Relay Control Change (CC) MIDI Messages to Two Synthesizers

• Send Breath Controller/Expressional pedal data to 16 user-predefined MIDI channels

• Access Microtonal functions via 18 switches

• Store 12 of your favorite scales (future update) and 8 user detuned scales

• Turn off the Breath Controller instantly

• Program the Breath Controller/Expression Pedal functions via the Short-Cuts mode

The AK-4 PRO (SE) WORLD SCALE TUNING was created from over 11 years of direct, personal experience and feedback from musicians around the world. We listened to your comments, suggestions, tips and feedback, and incorporated them into the redesign of the AK-2. The results? A powerful, simple, and flexible tool to help you create Microtonal music with ease.

Let your imagination soar with the AK-4…

Kelfar Technologies AK-4 side view


• (1) MIDI Input
• (1) Breath Controller / Expression Pedal (Selectable when programming the AK-4 Pro)
• (1) Switch Pedal input for (Korg Pa80, 50, 50SD)

• (2) MIDI Output via USB Interface (software selectable)
• (2) MIDI Output via Standard MIDI 1&M2 (1/8″ to 5-pin din)

Power source:
• 5V USB bus power (USB Mini B)

• 5.5 x 3.6 x 1.1 in. / 139.7 x 91.4 x 27.9 mm

• 0.43lbs / 195g.

Accessories (included):
• (1) USB mini cable (1.2m/4ft)
• (2) 1/8″ to 5-pin din (MIDI) (1m/3.2ft and 1.5m/5ft)

AK-4 Midi Cable sm_c

USB cable

Note: Breath Controller and Expression Pedal are NOT included. The AK-4 works best with the BCK-1 (Kelfar Technologies Breath Controller)

Supported Instruments/Models Firmware 3.0 and up

Korg Pa80, Pa50, Pa60, Pa55Tr, Pa1&2x (Pro), Pa800, Pa3x series, Pa4x series, Pa1000, PA700 series, Pa500, P500 ORT, Pa600, Pa600QT, Triton Classic, Karma, Studio, Extreme, Le, Tr, Micro X, X50, Kronos series (with firmware 2.3 and up), *M3 series, *Oasys, *Trinity, Korg Z1, and Korg Prophecy. *Trinity series works in all modes , and MOSS mode in Universal Mode (with firmware 3.0 and up)

Roland Fantom S, X, G, AX-Synth Shoulder Synthesizer (with firmware 2.6 and up), and models with GS logo, FA-06/FA-07/ FA-08, EA-7

Yamaha Motif ES/MO (preset scale only – Arabic 2) and instruments with XG logo, Tyros/Psr series, Motif XS (Voice, Song, Pattern), and Motif XF (Voice, Song, Pattern), Genos, Montage6/Montage7/Montage8

Ketron VEGA, SD5, SD1, and AUDYA series

Kontakt with a provided script – Kontakt Script (Native Instruments) with Transpose

Kurzweil K2600 and K2000 series

MOOG Sub Phatty and Sub 37

DSI / SEQUENTIAL Prophet X, XL, Prophet 6, 12, Pro 2, and OB-6 (Post-Midi Transpose)

MIDI Tuning Standard firmware 3.0 and up

Equal Tempered Tuning System
Just Intonation
Micro Tuning System
Turkish ( Byselik, Rast, Ussak, Nikirz, Saba, Huazm, Siga, and more)
Byzantine (Modes 1,2,3,4,5,6,7,and 8)
Arabic (Bayati, Rast, Siga, Huseini, Hijaz, amd more)
and more…

FREE lifetime updates are also provided by Kelfar Technologies on this product. Please be sure to register your purchase our Contact Form.
Registration enables us to contact you directly to inform you of updates and upgrades.


AK-4/5 Manual (Firmware V4.2)
Firmware Version 6.2 (new 5/25/2023)
Graphic Interface for Windows
Ploytec GmbH MIDI USB drivers (Windows 32-/64-bit)
Korg Trinity V3 Firmware Guide
Programming and Setup: Yamaha GENOS
AK-4 Pro FIRMWARE 3 Instruments

AK4/5 Pro Kontakt Script (Native instruments) (New 09/25/2020)
Kontakt Script (Native Instruments) (Old)
Korg M3 EXPANDED converted set to work with AK-4 Pro
Korg M3 Guide
Roland Fantom G Guide

Price: $400 + S&H