LA5 MOS-FET pure A headphone amplifier

Foreword: If you need a headphone amplifier comparable to 10,000 yuan, please read our introduction carefully. If you want to quickly understand the features of LA5, just look at the following lines:

1. The positive and negative 26V 260mA power supply guarantees the output power of the amp. The amp is the amplifier first, and the confidence must be sufficient!
2. The perfect combination of OPA2604+ high-power field effect tube.
3. The MCU microcomputer controls the input switching, gain switching, and output impedance switching, while realizing the full-featured headphone protection function of the headphone.
4. Talema 50VA ring cow, ALPS27 potentiometer, Nover fever capacitor, Panasonic FM capacitor and other materials.
5. High-end appearance design, all touch button operation.

• General parameters:

1. Output Power（1KHZ sine wave equivalent undistorted power）::&Amp;nbsp;300mW/600 ohms, 1200mW/32 ohms.
2. Signal to noise ratio: > 102dB.
3. Output impedance: 10 ohm, 47 ohm, 120 ohm can be switched.
4. Voltage amplification gain: 10 times in standard gain mode, 18 times in high gain mode.
5. Maximum output voltage swing: greater than plus or minus 13V（Equivalent to 26V）.
6. Input interface: two RCA audio inputs, switching on the MCU front panel.
7. Output interface: 6.35 headphone output.
8. Average power consumption: AC220V<20W.
9. volume:220*52*191
10. Net weight: 2.8 kg.

• Interface instructions:

1. Front panel control operation instructions（From left to right）

• Power: Power switch
• InSel: Input selection switch, used to select the two analog inputs InA, InB of the amp
• Gain: Gain selection switch, used to select the voltage amplification gain of the headphone amplifier
• Impedance: output impedance selection switch, used to switch the output impedance of the amp
• Phone: Headphone output
• Volume: volume control

 2.In addition to the AC220V input and power switch on the rear panel, there are two sets of RCA terminals, which are responsible for the two audio inputs.

• Advantages of LA5 MOS-FET

1. Pure Class A circuit, the quiescent current of the final stage tube is 260mA! It can put an end to the distortion caused by the switching of the power tube, the sound is warm, and at the same time it has good damping characteristics and perfect control.
2. Use OPA2604 fever op amp as the voltage amplifier stage. This famous op amp has a unique advantage, that is, it can be powered by plus or minus 24V. This machine uses plus or minus 22V to power the OPA2604. What are the benefits? The advantage is to greatly increase the output voltage swing of the amp, which can drive high impedance（600 euros）A prerequisite for headphones! Also, OPA2604 this op amp can only shine under high pressure, which is the consensus of enthusiasts.
3. The high-power field effect tube is used for current amplification, which works at a quiescent current of plus or minus 26V and 260mA to ensure the output power of the headphone amplifier. There are two advantages of using a field effect tube. One is that the field effect tube has the inherent advantage of sound warmth, without the dry digital sound of the transistor; the other is that the field effect tube is a voltage drive component, which can make the driving burden of the op amp fundamentally Reduce, so that the quality of the op amp can be fully utilized.
4. The power supply of the voltage amplifier stage adopts a shunt voltage stabilizer circuit, which is unmatched by any voltage stabilizer circuit. Its internal resistance is low, the ripple is small, and the transient characteristics are good. It provides a good foundation for the sound of the voltage amplifier stage.
5. The gain is adjustable, headphones with different impedances and different sensitivities have different requirements on the gain of the amp. LA5 uses the microcomputer MCU control to switch the high and low gains through the Gain key on the front panel, which is suitable for the needs of different headphones.
6. The output impedance is adjustable. This is a very important point. Many fans believe that the amp should be paired with headphones, such as Lehman with HD650, A1 with DT880, etc. In addition to circuit reasons, the gain and output impedance are the amps. It is a very crucial point to match the headset. Different output impedance allows the amp to be used for different damping, and the adaptability of the earphone will be higher. In actual tuning, the medium impedance output of LA5 is perfectly matched with HD650 and K601, and the high impedance output can be well adapted to the 600-ohm DT880.
7. MCU full control, this amp uses a microcomputer to control the amp’s output selection, gain selection, output impedance selection, touch the button to switch and have a memory function, and at the same time, it has a perfect earphone protection function, all of which are switched by internal relays It is a million-dollar headphone amplifier, and the design is difficult to surpass!
8. Regardless of the cost, as long as the materials for the sound quality:
   • In order to have an excellent source of power for the amp, the imported Talema 50VA transformer is used, which is the same as if you buy a BMW, you must use 97 gasoline!

• Using the best ALPS 27 potentiometers and feverish electronic components, old enthusiasts, we know what you know, but we also know that good components are just a prerequisite for good sound. Design and tuning depend on skill!

• High-power FETs have better linearity, lower distortion and more power!

•  The workmanship is comparable to imported amp, please see the picture

• A few additions:

1. Not all earphones need amps, such as Senhai’s Big Bun, IE80, AKG’s Q460, etc., which are all designed for direct push. You might as well buy a good player. This kind of earphones, even if you use the amp, Not necessarily a big improvement; LA5 MOS-FET is designed for high-end headphones, such as HD600, HD650, HD800, DT880, T1, K601, K701, etc. We have reference tuning for most headphones.
2. All components of this amp are designed specifically. You should not consider polishing the machine or replacing the op amp. This is especially important, because the LA5 op amp works with dual 22V voltage, most of the op amp will be burned directly, and more Severe damage to the machine.
3. When you use low-impedance and high-sensitivity headphones, it is recommended to turn down the volume when switching the gain or output impedance to avoid sudden loud noises.
4. Regarding the sound quality of the LA5, I can only describe it as excellent. The super linearity of Lehman and SOLO, both of which were compared and tuned in my hand, were defeated. Her voice is strong and gentle, wide sound field, clear image, calm and calm,The resolving power is very good transiently, and the DT880 with tuning from HD650 HD800 to 600 ohms has excellent performance!

Regarding the freight: the amp is heavier, and the logistics weight is more than 3.5 kg. Fans in Beijing and Tianjin have contacted me to reduce the freight. Friends who are far away from Tianjin, such as Xinjiang, Tibet, and Guangxi, please contact me, and the freight will increase. Otherwise, pay directly, and the seller has the right not to ship the goods!

This machine provides a one-week trial and can be returned within one week. If there is no quality problem, the buyer only needs to bear the round-trip freight.

This machine is guaranteed for one year, and there is no service fee for repairs within one year. The buyer and the seller will bear half of the freight. Repairs outside the warranty period only charge the cost of the components, and the buyer will bear the freight.

Please do not disassemble the machine without the buyer''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''s consent before confirmation, otherwise the seller has the right to refuse the return.