The Nobsound NS-08E Mini Tube Headphone Amplifier is a versatile audio device designed to enhance the sound quality for headphones and can also function as a tube preamplifier. It features a 3.5mm headphone jack that can connect to an amplifier or active speakers, offering flexibility in its application.

Key Features and Specifications:

Function: This device primarily serves as a tube headphone amplifier to improve headphone audio quality. Its 3.5mm output can also be used to connect to a power amplifier or active speakers, allowing it to function as a tube preamplifier.
Audio Input: 3.5mm AUX
Audio Output: 3.5mm headphone jack
Max Output Power: ≥1100 mW (at 32 ohm impedance)
Matched Headphone Impedance: 18-600 ohm
Frequency Response: 20Hz - 30KHz
THD (Total Harmonic Distortion): <0.005%
SNR (Signal-to-Noise Ratio): ≥110 dB
Power Supply: DC 6V/2A

Usage Features:

Connectivity:
- Connect an audio source (e.g., phone, MP3 player, TV, tablet, computer, CD player) to the NS-08E's 3.5mm AUX input.
- Connect headphones, a power amplifier, or active speakers to the 3.5mm output. High-quality 3.5mm cables are recommended for optimal performance.
Powering On:
- Connect the power adapter to the NS-08E and then plug it into a power socket.
- Press the red button on the back panel to power on the device. Allow some time for the tubes to warm up.
Audio Playback:
- Start playing music on your connected audio device.
- Rotate the volume control knob to adjust the volume to your desired level for an enjoyable HiFi listening experience.

Maintenance Features:

Tube Rolling: The NS-08E comes with default 6J3 vacuum tubes, which are user-replaceable. It supports a wide range of compatible tube models, allowing for "tube rolling" to customize the sound signature. Compatible tubes include: 6J1, 6ж1П, 6AK5, 6BC5, 403A/B, 5654, EF95, CV850, 6J2, 6ж2П, 6AS6, CV2522, CV4011, 6J3, 6жЗП, EF94, CV848, 6BC6, 6AG5, 6J4, 6ж4, 6136, 6BX6, 6AC7, 6AU6, 6J5, 6ж5П, CV2521, 6F36, 6AH6, 6AN5, 6K4, EF93, 6K5, 6Κ4Π, 6ΒΑ6, 6DA6, 5749. This feature allows users to experiment with different tube characteristics to fine-tune the audio to their preference.

The Douk Audio U10 Mini Tube Headphone Amplifier is another variant, offering similar tube amplification benefits with expanded connectivity and power features.

Key Features and Specifications (Douk Audio U10):

Function: The U10 is a mini headphone amplifier designed to drive a wide range of headphones, including high-impedance models. It also features a built-in voltage boost circuit for consistent high-voltage operation and pluggable sockets for tube and op-amp rolling.
Audio Input: 3.5mm AUX / Stereo RCA (inputs work simultaneously, but avoid connecting both 3.5mm and RCA inputs at the same time to prevent signal mixing).
Audio Output: 3.5mm / 6.35mm headphone jack (outputs work simultaneously).
Max Output Power: ≥1100mW (at 32Ω impedance)
Matched Headphone Impedance: 18-600Ω
Frequency Response: 20Hz-30KHz
Signal to Noise Ratio: ≥110DB
Input Voltage: DC 5V (≥2A) (Power adapter not included; a high-quality 5V/≥2A adapter is recommended for normal operation).
Working Voltage Inside: DC 24V (achieved via an innovative built-in voltage boost circuit, even with a 5V input).
Dimensions (WDH): 95mm69mm30mm / 3.74in2.72in1.18in
Net Weight: 200g / 0.44lb

Usage Features (Douk Audio U10):

Power Connection:
- Connect the power adapter to the U10 using the provided USB to DC cable.
- Insert the power adapter into a wall socket. (Note: A power adapter is not included and a 5V/≥2A adapter is required).
Headphone Connection:
- Connect your 3.5mm or 6.35mm headphones to the corresponding output jack on the U10.
Audio Source Connection:
- Connect your audio source to the U10's inputs using a high-quality 3.5mm AUX cable or RCA cable.
Power On:
- Rotate the main knob clockwise to turn on the U10.
Audio Playback and Volume Control:
- Play music from your audio source.
- Use the volume knob to adjust the output volume.
Power Off:
- After use, rotate the knob anti-clockwise to its leftmost position until the U10 turns off.
- Disconnect the power adapter.

Maintenance Features (Douk Audio U10):

Tube Rolling and Op-Amp Upgrading: The U10 features pluggable tube sockets for its 2PCS 6A2 tubes and op-amps. This allows users to easily replace the default 6A2 tubes with compatible models for sound customization (e.g., 6J1, 6ж1П, 6AK5, 6BC5, 403A/B, 5654, EF40, EF95, CV850, 6J2, 62П, 6AS6, CV2522, EF11/732, CV4011, 6J3, 6ж3П, EF96, CV848, 6BC6, 6AG5, 6J4, 6ж4, 6136, 6BX6, 6AC7, EF94, 6AU6, 6K4, 6K5, 6K4П, 6BA6, 6DA6, EF89/93, 5749). The pluggable op-amp sockets also enable op-amp upgrading, providing further avenues for sound shaping and personalization. This design makes the U10 highly adaptable for audiophiles who enjoy experimenting with different audio characteristics.

Nobsound NS-08E - Page 2

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