L1969 Phone SE Pure A Headphone Amplifier
Blue 48 yuan: It is the PCB and all the components above, and the parts need to be soldered by themselves.
Black 128 yuan: for the finished amp machine with the installed casing,The transformer is not included, and the transformer needs to be photographed separately. There are two options of switching power supply and linear power supply. It is strongly recommended that you use a wired power supply!.
If you buy a kit, you may need the following accessories:
- Matching chassis(Matching purchase, free thermal silica gel): Http://item.taobao.com/item.htm?spm=686.1000925.1000774.31.3i8yCm&id=40670889140
- Supporting 15V 1A transformer: http://item.taobao.com/item.htm?spm=686.1000925.1000774.43.3i8yCm&id=40634819924
- Supporting high-quality linear power supply, with greater dynamics, smoother sound, and higher signal-to-noise ratio:http://item.taobao.com/item.htm?spm=0.0.0.0.gukWhc&id=43281727624
The circuit in 1969 has been popular in the HIFI circle for more than half a century, and it is still being talked about by old fans today, and it has its own reason. This headphone amplifier adopts 1969 circuit prototype design. This circuit, rich even harmonics creates a beautiful and unique charm, is the stone machine circuit closest to the tone of a tube amplifier, and this circuit is used for headphone amplifiers without power amplifiers. The problem of soft feet and lack of momentum, the sound is very soft and durable, and the dynamics and sound field are perfectly reflected.
- Output Power(1KHZ sine wave equivalent undistorted power):: 80mW/300 ohms, 200mW/120 ohms, 650mW/32 ohms.
- Signal to noise ratio: > 98dB.
- The internal resistance of the amp: 10 ohms. DC1
- Voltage amplification gain: 8 times in standard gain mode.
- Maximum output voltage swing: greater than 12V(When DC15V power supply).
- Input interface: RCA audio input.
- Output interface: 6.35 headphone output.
- Input voltage: transformer AC110-220V. DC9-15V(Recommend DC15V)
- Volume: 100*70*23.5mm
- Net weight: 120 grams.
- PCB size: 98*66mm
Features of this machine:
- Pure A, its biggest advantage is that the output tube will never enter the cut-off state, so that there are no unpleasant odd harmonics. Many circuits on the Internet now claim that they are Class A. I will give you a parameter that Pure A can’t make false. , That is, the quiescent current of Pure A must be greater than the output current!
- CLC filtering is added to the power supply part, plus the super adaptability of the 1969 pure A circuit to the power supply, even if it is powered by a switching power supply, the unit will also have a very soft and audible sound.
- The power tube is installed in reverse, and the heat dissipation of the case is used cleverly, so that large current can be realized in a small case(180mA at 15V)Working point.
- The material of this machine is also fever-level, a large number of Panasonic FM capacitors, chemical high-frequency capacitors, the coupling adopts 2.2uf film, the output adopts 680uf FM gold master, the use of imported A50K potentiometer, ON Semiconductor MJE340G fever tube, each component All carefully selected.
- Four MJE340G, because this tube has good consistency, our shop will match within 1% at the working point of 180mA!
- The sound of this unit is warm and mellow, and the even harmonics are rich. What is the even harmonic? Think of the same violin, if it is different on the street and in the concert hall. This amp should be a warm color, but it is by no means a sound without high and low frequencies and resolution.
- It is impossible for this machine to hear the bottom noise, as long as you are from the earth!
- Reminder: The 1969 circuit needs a few minutes to stabilize. It’s not as good as a warm-up when it’s just powered on. The machine works for 10 hours at a room temperature of 28 degrees. The measured temperature is about 45 degrees, which is much lower than the power amplifier.
Key points of kit installation and debugging:
- This PCB is close to the two 47K resistors of the 200K adjustable resistor, please use 18K, so that the circuit is more linear.
- The kit will send two more 22P compensation capacitors, connected in parallel to the 2K2 resistor with two holes.
- After the circuit is welded, connect the DC input and adjust the two 200K adjustable resistors so that the GND voltage of the two test points of VL and VR is half of Vcc. For example, if your input voltage is 15V, then VL and VR should be 7.5V.
- If you buy the matching case in this shop and install the four ON Semiconductor MJE340G pipes in reverse, the shop will give you a piece of thermally conductive adhesive. Refer to the back of the PCB to make the power tube and the case radiate heat through the thermally conductive adhesive.
- There are two small holes beside the potentiometer, which are grounding points. Print a copper wire to connect with the potentiometer shell
- After the circuit is adjusted, it is recommended to replace the 200K adjustable with a fixed resistor as close as possible. Of course, this step can be omitted.
After-sales service and freight:
- The finished machine can be auditioned and returned within one week, and the buyer shall bear the return shipping cost.
- The finished machine is guaranteed for one year, and repairs outside the warranty period only charge component costs.
- Please understand that you will lose the warranty service if you buy a finished machine, disassemble the machine and polish or modify the circuit by yourself.
- The user who purchases the kit, please consider it by yourself. The installation of this kit requires relevant electronic professional knowledge. The owner of the remote can not do too much counseling for you. Please do not give praise because of the unsuccessful installation. Thank you for your understanding; the schematic diagram is already below Publish, please refrain from asking for electronic drawings.
- Fans from Hong Kong, Taiwan, foreign countries, and friends far away from Tianjin(Including Xinjiang, Tibet, Guangxi, Yunnan, etc.), Please contact the owner to modify the shipping before payment, otherwise you have the right to refuse delivery!
Circuit principle
fineProcessed amp shell, elegant appearance
Integrated PCB design
CLC filtering
Materials disproportionate to the selling price
Directional installation heat dissipation diagram