The HA-Kit headphone amp kit from Nu:Tekt - a new kit brand from Korg is an authorized distributor of the HA-Kit in the US.  You can buy the HA-Kit in the eBay store.

The HA-Kit is priced at $249.00!

(Click on the pictures for a full resolution image)

The HA-Kit is a DIY portable headphone amplifier kit from Nu:Tekt that uses the Korg Nutube.

It's a small, battery powered headphone amp that gives you real tube sound.  A small case - the size of a mint tin - has a transparent cover so you can see the tube inside.


The nutube inside is mounted on a foam suspension system to minimize microphonics.  A standard, socketed 8-pin opamp lets you try different ICs. 

Internal switching power supplies generate the filament voltage and a 26V supply voltage for the opamps, powered from two AA batteries.  Typical battery life is 9 hours.

A bass boost function (EDM) can be enabled that boosts 5dB at 50Hz.

It's easy to assemble - many parts are already pre-assembled when you get the kit.  Here is what you get - it is a complete kit:





Download the manual 


Vacuum tube: Nutube 6P1
Connections: INPUT jack (stereo mini phone jack), OUTPUT jack (stereo mini phone jack)
Controls: Volume, EDM (bass boost) switch (internal)
Output impedance: 10 Ω - recommended load 15 Ω or higher
Power supply: 2 AA alkaline batteries
Battery life: About 9 hours (when using alkaline batteries)
Outside dimension: 111 (W) x 65 (D) x 29 (H) mm
Weight: 110 g (battery not included)
Frequency response: 20 Hz to 50 KHz (within 3 dB)  
Distortion factor: 0.15% (at -15 dBu input)
Signal-to-Noise ratio: 93 dB
Maximum output: 50 mW (when MUSES 01 is used), 80 mW (when using NJM 4580)
Bass boost: EDM SW ON: + 5 dB @ 50 Hz
  ※ Measured at output load = 33 Ω