6K4 Tube Preamplifier Hifi Tube Preamp Assembled Board Featuring Three Levels of High-Fidelity

6K4 Tube Preamplifier Hifi Tube Preamp Assembled Board Featuring Three Levels of High-Fidelity

Read Before Purchasing:
Because it is a tube preamp board, it must be used with active speakers or power amplifiers. It cannot be used in cars. It cannot be connected to passive speakers, speakers, headphones or phono preamps.

Features:
- Its circuit uses a DCDC boost circuit. When the power supply is DC 12V, it can be boosted to more than 120V for power supply; the current of a single DC 12V1A (DC12V1A) is not limited, and the voltage does not exceed 16V
- Preamp magnification: The voltage is amplified by 5 times, and the magnification is a bit large. Users who hear distortion effects can turn down the volume
- Preamp frequency response: 5HZ-500KHz
- Preamplifier working state: full frequency output
- Preamp sensitivity: up to 3V without distortion
- Adopt the principle design of the American X-10 circuit, plus reasonable optimization, its performance is more stable than that of the original machine, and the use effect of the electronic tubes is improved by 10%
- Adjustable Hi-Fi effect; Adjust toggle switch with three positions
- Support any low-level signal input
- Restoring the real voice: the preamp amplifies the vocals

DC Boost Version:
① The working principle of power supply: as soon as the power is turned on, the filament of the electronic tube starts to heat up, and the voltage starts to increase from zero at this time. When the filament of the electronic tube is hot, the voltage just finishes rising.
② Filament principle: A good power supply system will not have current sound. The filament is powered by DC 12v. The filaments of the two tubes are connected in series. DC power supply is also used to reduce noise.

Core Technologies:
- Potentiometer Switch: Rotate the knob clockwise, when you hear a "tick" sound, the indicator light of the board is on, and the volume is at the minimum. Continue to turn the knob clockwise to turn it up.
- Tube Filament: The tubes should be plugged into the bottom. Turn on to see the tube filament glowing red. The tube preamp can only be operated when the filament of the tubes is on and the backlight is also red.
- Audio output and input: Output ports, next to its socket, should be connected to a power amplifier or an active speaker; and the input ports should be connected to an audio source: support low-level signal input, such as mobile phones, CDs, computers, TVs, and MP3

Specifications:
- Item name: Tube preamp
- Product size (without the size of potentiometer): 87 x 75mm/3.4 x 3" (LxW)
- Tube: 6K4
- Power supply mode: DC12-16V current 1A and above
- Finished board: no soldering required

Package Included:
- 1 x Main Unit
- 2 x Tubes

Note:
- Because the tube preamp is in a class A amplification state (that is to say, it is always in a state of amplification), it is recommended to use a shielded line, otherwise it may produce interfering sound.
- Please peel off the protective film on its acrylic board surface before use.

Tips for Starters:
1. The tube preamp has amplification function. If your audio source has noise, it will amplify the noise from the audio source, so please use a good audio source to test this product.
2. If a signal cable used is not shielded or the power supply is not well filtered, noise may be generated. It is recommended to use a shielded cable and a clean power supply to test this product.
3. Products have passed rigorous testing before shipping. In addition, the machine do not have its own noise. If you encounter the problems mentioned above, you can use the exclusion method to test.

Instruction for Use:
- The electronic tube buffer is amplified by about 5 times. It is connected between the audio source and the preamp and power amplifier, which can effectively filter unnatural sound, enabling better human voice and more natural and pleasant sound. It is cost-effective.
- DC input via DC3.5/5.5*21 socket.
- Left- and right-channel inputs are audio signal input terminals, which can be connected to low-level signal input.
- Left and right-channel outputs are audio signal output terminals, which can be connected to the audio signal input of power amplifier and active speakers, providing more natural and pleasant sound to the power amplifier and speakers.