1. Introducció
This manual provides essential information for the safe and effective operation of your Nobsound NS-02D EL34-B Hi-Fi Stereo Tube Amplifier. This Class A, single-ended amplifier is designed to deliver high-fidelity audio with a warm, rich sound signature characteristic of EL34 vacuum tubes. Please read this manual thoroughly before initial use and retain it for future reference.

Imatge 1.1: Frontal inclinat view of the Nobsound NS-02D EL34-B Hi-Fi Stereo Tube Ampvidador, espectacleasing its vacuum tubes and brushed metal finish.
2. Informació de seguretat
Per evitar incendis, descàrregues elèctriques o danys al producte, observeu les precaucions de seguretat següents:
- Vol. Alttage: Això amplifier operates with high internal voltages. Do not open the casing or attempt to service the unit yourself. Refer all servicing to qualified personnel.
- Calor: Vacuum tubes generate significant heat during operation. Ensure adequate ventilation around the amplifier. Do not place it in an enclosed space or cover ventilation openings. Avoid touching the tubes during or immediately after operation.
- Humitat: No exposar el amplifier to rain, moisture, or excessive humidity. Keep liquids away from the unit.
- Font d'alimentació: Connecteu el amplifier only to a power supply of the specified voltage (240V 50Hz, as indicated on the rear panel).
- Connexions d'altaveus: Ensure all speaker connections are secure and correct before powering on the amplifier. Incorrect connections can damage the ampmés alt o altaveus.
- Col·locació: Col·loca el amplifier on a stable, level surface away from direct sunlight, heat sources, and strong magnetic fields.
3. Configuració
3.1 Desembalatge i inspecció
Traieu amb cura amplifier from its packaging. Inspect the unit for any signs of damage during transit. If damage is found, contact your retailer immediately.
3.2 Tube Installation (If Required)
The vacuum tubes may be pre-installed or require installation upon arrival. If installation is needed, carefully insert each tube into its corresponding socket, aligning the pins with the socket holes. Apply gentle, even pressure until the tube is seated firmly. Refer to the markings on the amplifier chassis for correct tube placement (e.g., 5Z3P, 6N9P, EL34B).

Imatge 3.1: De dalt a baix view illustrating the layout of the vacuum tubes and transformers on the ampxassís de lifier.
3.3 Connexió d'entrada d'àudio
Connect your audio source (e.g., CD player, DAC, preamplifier) to the 'AUX IN' RCA jacks on the rear panel of the ampamplificador amb cables RCA d'alta qualitat.
3.4 Connexions d'altaveus
Connect your speakers to the appropriate speaker terminals on the rear panel. The amplifier provides terminals for both 4 Ohm and 8 Ohm speakers. Ensure you connect the positive (+) terminal of your speaker to the corresponding positive terminal on the amplifier, and the negative (-) terminal to the common ground (0) terminal. Use high-quality speaker cables.

Image 3.2: Rear panel of the amplifier, detailing the 'AUX IN' RCA jacks, speaker output terminals (4Ω, 8Ω, and common ground), and power input.

Imatge 3.3: Primer pla view of the gold-plated speaker binding posts, showing the 4Ω, 8Ω, and common ground (0) markings for proper speaker connection.
3.5 Connexió d'alimentació
After all audio and speaker connections are made, connect the supplied power cord to the amplifier's power inlet and then to a suitable wall outlet.
4. Instruccions de funcionament
4.1 Encès
Ensure the volume knob is set to its minimum position. Flip the 'ON/OFF' toggle switch on the front panel to the 'ON' position. The tubes will begin to glow, indicating the amplifier is warming up. Allow approximately 30-60 seconds for the tubes to stabilize before increasing el volum.
4.2 Control de volum
Slowly rotate the 'VOLUME' knob clockwise to increase the audio output. Adjust to a comfortable listening level. Avoid setting the volume to maximum for extended periods, especially with highly sensitive speakers, to prevent distortion or damage.

Image 4.1: Close-up of the front panel volume knob, indicating its minimum and maximum settings.
4.3 Apagat
Before powering off, reduce the volume to minimum. Then, flip the 'ON/OFF' toggle switch to the 'OFF' position. Disconnect the power cord from the wall outlet if the ampno s'utilitzarà durant un període prolongat.
5. Manteniment
5.1 Neteja
Espolseu el amplifier regularly with a soft, dry cloth. For stubborn marks, use a slightly damp drap i després eixugueu-lo bé. No utilitzeu productes químics agressius ni netejadors abrasius.
5.2 Ventilació
Assegureu-vos el amplifier té ample space for airflow. Do not block the ventilation holes. Proper ventilation is crucial for tube longevity and stable operation.
5.3 Substitució del tub
Vacuum tubes have a finite lifespan. Over time, their performance may degrade. If you notice a significant change in sound quality or if a tube fails, it may need replacement. Consult a qualified technician for tube replacement to ensure proper biasing and safety. Always replace tubes with compatible types (5Z3P, 6N9P, EL34B).
6. Solució De Problemes
Si teniu problemes amb el vostre amplifier, consulteu els següents problemes i solucions habituals:
| Problema | Causa possible | Solució |
|---|---|---|
| Sense sortida de so |
|
|
| So distorsionat o feble |
|
|
| Soroll de brunzit o brunzit |
|
|
| Tubes not glowing |
|
|
If the problem persists after attempting these solutions, please contact Nobsound customer support or a qualified audio technician.
7. Especificacions
- Model: NS-02D EL34-B
- Potència de sortida: Triode 8 W x 2 (default) / Standard Connection 12 W x 2
- Impedància de sortida: 4 Ω, 8 Ω
- Altaveus compatibles: 10-100 W, 88 dB (or higher sensitivity)
- Rectifier Tube: 5Z3P (J-class military tube)
- PreampTubs lificadors: 6N9P × 2 (J-class military tube)
- Tubs de potència: EL34B × 2
- Canals: 2.0 estèreo
- Dimensions (L x A x P): 380 x 160 x 230 mm (approximately)
- Pes: Aproximadament 9 kg
- Material: Tubes, Electronic Components, Metal Chassis, Wood Side Panels
- Compliment: CE
8. Garantia i Suport
Nobsound products are designed for reliability and performance. For warranty information, please refer to the documentation provided at the time of purchase or contact your retailer. For technical support or service inquiries, please reach out to Nobsound customer service through their official channels.





