6th-gen Korg Nutube
A triode tube stage for rich overtones and an engaging sound.
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Nutube sound, two ways.
A Nutube amp card for the iBasso DX300 and DX320, with dual 3.5mm outputs: low-noise tube output and high-power output.
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MEET THE AMP13
A Nutube amp card for the iBasso DX300 and DX320, with dual 3.5mm outputs: low-noise tube output and high-power output.
A triode tube stage for rich overtones and an engaging sound.
Low Noise Tube (2.5Vrms) for tube character, or Maximised (4.1Vrms) for drive.
An actively driven ground lowers noise; hand-matched on an Audio Precision analyser.
The iBasso AMP13 is a plug-in amplifier card that brings real tube sound to iBasso’s DX300, DX320 and DX340 players. Built around a sixth-generation Korg Nutube 6P1, a modern miniature triode, it has two 3.5mm outputs, one for the purest tube character and lowest noise, the other for maximum drive, and a three-channel design with an actively driven ground.

Made by Korg and Noritake, the Nutube 6P1 works exactly like a conventional triode vacuum tube and creates the same rich overtones that are sought after in triodes, while using far less power and space. In the AMP13 the Nutube does the voltage amplification, for an engaging, unique tube sound with excellent linearity.

The Nutube’s voltage gain is limited, so higher output needs a second amplification stage. To offer both a stronger tube signature and higher power, the AMP13 has two 3.5mm single-ended outputs. The Low Noise Tube output (2.5Vrms) is taken after the first stage, the Nutube followed by volume control and current amplification, for the strongest tube character and excellent noise control. The Maximised output (4.1Vrms) adds a second voltage and current stage for better drive with headphones and IEMs.


Ordinary single-ended outputs amplify only the left and right channels. The Nutube’s low output and noise control have always been a design challenge, so the AMP13 uses three-channel amplification, with an OPA1622 amplifying the output ground signal: the noise floor drops substantially, dynamics improve and the Nutube performs better.


The amp section of the DX300 and DX320 has its own battery, ideal for the AMP13: two high-performance Linear Technology DC-DC chips provide four supplies, 1.8V for the Nutube’s cathode through a low-noise LDO, 21V for its anode, and +8V and −8V to give the op-amps a 16V swing.

Every AMP13 is tested and matched on an Audio Precision analyser, and engineers hand-calibrate three multi-turn potentiometers on the board for the Nutube’s best performance, for a clean, extended treble and a sweet, engaging sound.


| Tube | Korg Nutube 6P1 (6th generation) with Toshiba 2SK209 buffer |
|---|---|
| Outputs | 3.5mm Low Noise Tube (2.5Vrms) · 3.5mm Maximised (4.1Vrms) · Pentaconn sockets |
| Circuit | Three-channel (OPA1622 active ground) · JRC NJU72315 volume · 4 DC-DC supplies (1.8V, 21V, ±8V) |
| Compatibility | iBasso DX300, DX320 and DX340 |

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Every UK order has a free delivery option, and orders of £50 or more qualify for free next day delivery. Order by 12 noon, Monday to Friday, for next day delivery; orders placed after 12 noon, at the weekend or on a bank holiday are dispatched on the next working day. Stock availability and destination also affect arrival — check the options shown at checkout.
Pre-orders ship when stock arrives; the next day service starts after dispatch. Full delivery information
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