Lipo Battery (3.7V) is essential but not included in this item. Please find it at your local reseller. Any capacity (1000mAh-2000mAh are best) will work.

What is it?

This is the best headphone amplifier ever I made!! The sound is like a power shovel running 300km/h (hard to explain but excellent).

All new designed Nutube headphone amplifier. Now Nutube is driven by 20V DC, which is generated by onboard voltage booster. The high power operation provides very rich vacuum tube sound than before. Moreover now the power source is Lipo (3.7V) battery. No need buying 006P or some batteries anymore. Recharging can be done just connecting USB connector to your PC or general AC/DC adaptor..

Why did you make it?

A few months ago, I had a lucky opportunity to talk with an engineer of KORG. He has been engaged in the Nutube development since the very early stage and I could get lots of wonderful information. He brought a prototype amplifier (it is now sold by KORG) running by double NiMH AA, meaning 2.4V operation with proper voltage booster. The sound quality was really great and I asked how, and he replied "Nutube has another characteristics (sound quality) for higher anode voltage"...

So I decided to make new version of headphone amplifier by Nutube, not just imitating KORG's great headphone amplifier.

What makes it special?

• Anode voltage of 20V operation. The voltage booster is onboard, generating from 3.3V.

• The power source is Lipo battery. Battery charging is through mini-USB connector. Just connecting USB cable to PC or AC/DC adaptor is enough. No need of waste of battery anymore.

• 1.6MHz fast switching voltage booster does not make any interference to audio quality.

• The sound quality is marvelous!! This is the BEST headphone amplifier ever I made. I can feel "high horse power" with very comfortable vacuum tube's mellow sound. You will see new aspect of Nutube by high voltage driving!

Lipo battery is NOT optional but the essential part for operation. Please find single cell Lipo battery (3.7V). Any capacity will work. The Lipo battery for the operation is NOT USB power pack (USB battery).

CAUTION: This amplifier can provide very "loud" level to any general headphone even low impedance, but please never try "direct speaker drive". The operation voltage of Op-Amp (MUSES8920) is also 20V and over-loading (like passive speaker with loud level) leads to breaking MUSES8920. The VDD-GND ohmic value of broken MUSES8920 gets very low value and it leads to voltage booster breaking. Again, any headphone can be drive by wonderful sound quality but never try passive speaker drive.