6th Gen Korg Nutube
Offered by KORG and Noritake, the 6th generation Nutube works exactly like a conventional triode tube and offers the same characteristics including rich harmonics. In addition, the Nutube provides lower power consumption, significant miniaturization and quality improvements over a standard tube. The iBasso AMP13 completes its voltage amplification via the Nutube, thus providing a round and warm sound while ensuring excellent linearity.
Dual single-ended outputs
- The voltage amplification capabilities of the Nutube 6P1 are however limited. Two stages of amplification are necessary to obtain a comfortable power output. So, in order to take advantage of both the sound signature of the tube and a nice reserve of energy, the AMP13 adopts a double 3.5mm jack output with a low noise tube output and a second one offering more power.
- Low noise tube output: The AMP13 uses a Nutube 6P1 voltage amplifier. This is followed by a digital volume control and a current amplifier. This low noise tube output comes directly after the first stage of amplification. It allows to take advantage in a more important way of the sound signature offered by a tube amplification and has an excellent noise control (2.5Vrms).
- Maximized output: This second output first goes through the Nutube amplifier stage and is followed by a second level of amplification. It allows the AMP13 to take advantage of a greater voltage and current amplification, allowing to accompany most headphones (4.1Vrms).
Three channels of amplification
The single-ended output of conventional players usually has only two-channel amplification. Here, to enhance the performance of the Nutube 6P1, the AMP13 uses three-channel amplification. An OPA1622 PDO amplifies the output ground signal, allowing for a significant reduction in background noise while improving the dynamics and capabilities of the tube amplification.
Dedicated battery & Dual DC-DC power supply
The DX320/DX300’s amplifier section has its own battery power supply, which is perfectly suited to power the AMP13 module. The AMP13 uses two high-performance DC-DC chips from Linear Technology, for a total of four DC-DC power supplies. The first one offers a voltage of 1.8V for the cathode, via a low noise LDO, the second one provides 21V for the anode of the Nutube, and the last two have a voltage of +8V and -8V, constituting the 16V voltage oscillation feeding the AOP.
Tested and adjusted by hand
Each AMP13 unit is tested and optimized using an AP audio analyzer. Three multi-turn potentiometers on the board are calibrated and matched by engineers to provide optimal performance. As a result, the AMP13 delivers clear high frequencies and an overall smooth, balanced sound.
- Amplification type: Tubes
- Tubes: Korg Nutube 6P1
- Outputs: 2x Jack 3.5mm
- Output buffer: Toshiba 2SK209 field effect transistors
- Compatibility: DX320, DX300