One Pair FirstWatt PASS PCF F7 Class A Power Amplifier Kit / AMP Board 20W+20W

Description: Introduction: FirstWatt F7 is a very good small class A amplifier, with almost no advantage of feedback brute force. It resorts to a strategy that makes the dance a bit more like tango. Appropriate amount of negative feedback and positive current feedback form a balanced impedance close to zero in the output, which improves the transient response and frequency response. Of course, you can achieve a similar effect by using a lot of negative feedback, but I think this is more elegant and sounds better! For the sake of brevity, I will call it "PCF". In addition, you can use more filter capacitors in the power supply and find a clever way to further reduce the effects of high-frequency DAC noise and environmental RF. FirstWatt F7 This is a different amplifier. The diversity of audio flavors and not everyone will like it. I think some audiophiles will like it. In conclusion: If you haven't noticed, I like amplifiers with personality. They don't have to measure perfection, they just have to sound good. This is a very simple small class A amplifier with many personalities, I hope you like it! PCB size: 297mm*35mm Input voltage: DC +/-21V to +/-24V (Transformer uses output voltage AC 16--0--16V to 18V--0--18V) Input impedance: 10K ohm (RCA Input) Output power: 15W --- 20W Gain: 14.5dB Input voltage at maximum output: 2.7V Frequency response:-3 dB 100 KHz Power consumption: 175W Fuse: 3AG Slow blow, 1.25A (240 VAC) ● Available output Power mosfet tubes: Hitachi 2SK1058 and 2SJ162 or EXICON ECX10N20/ECX10P20. ● Input voltage DC +/-21V---24V, single tube current is controlled below 800ma, each channel current is controlled at 800mA---1A. Please ensure a good heat sink, each channel heat sink is not lower than 2.3KG. ● The recommended power of the power transformer: 400W --- 500W. ● If you need a speaker protection board, please install it yourself. The board does not have speaker protection function. ● The PCB provides installation and commissioning instructions, please be sure to operate according to the instructions. ● Power supply filter capacitor (Shared by two channels), Please use a single channel with a total capacity of 90,000uF and above, And a positive and negative power supply with a total capacity of 180,000uF and above. This can ensure a pure power supply and also a good sound for the PCF F7 amplifier Good foundation. Tips: The Class A power amplifier generates a lot of heat, and the radiator is recommended to be above 2.3 kg per channel. Kit includes 2 pairs of Made in Malaysia J74/K170, not Japanese Toshiba tube, but it can replace Dongguan tube perfectly, with the same performance. NOTE: We have Type 2 DIY kit (Optional) ◆ DIY kit (Without tube) ---- All parts need you to solder and test it. (Without output Mosfet tube) ◆ DIY kit (With EXICON tube) ---- All parts need you to solder and test it. (With Mosfet ECX10N20/ECX10P20 tube) ◆ Finished board ---- All parts have been welded and tested OK. Debug Instructions: Positive current feedback F7 installation and commissioning instructions: 1. The Class A power amplifier generates a lot of heat. It is recommended that the radiator be above 3KG per channel. The power tube must be installed with a thermal pad. 2. If you need a speaker protection board, please install it yourself. The PCB does not have speaker protection function. 3. Adjustable resistors R5, R3, and R11 are preset and adjusted when they are shipped. Please solder them directly. 4, 0+ is connected to the speaker output "+ pole", 0- is connected to the speaker output "- pole" (this must be noted that the speaker output "- pole is not connected to GND", must pay attention.) 5. Input voltage: DC +/-21V to +/-24V (transformer output voltage AC 16V--0--16V to AC 18V--0--18V, power 400W to 500W). 6. Before powering on, please carefully check whether the connection is correct, especially the input voltage "V+" GND "V-". When the power is turned on for the first time, the follow-up adjustment work can only be entered without abnormalities. 7. When adjusting the circuit, it is better to have two multimeters, so that it is more convenient to adjust the work. ● Rotate the multimeter A to the DC mV position, and place the test leads on both ends of the R1 resistor; ● Rotate the multimeter B to the DC mV position, and place the test leads on the speaker output two points (0+ and 0-); After power on, observe the value of multimeter B and adjust the R11 adjustable resistance so that the value is 0; at this time, observe the value of multimeter A (the value is very small), then adjust the R3 adjustable resistance clockwise until the DC value of multimeter A starts to increase (1mV corresponds to the working current of the power tube 10mA), at this time the value of the multimeter B should also increase at the same time. Adjust the R11 adjustable resistance again and use the multimeter B value to 0. Repeat this operation (the adjustment of the Class A power amplifier requires enough patience) until the value of the multimeter A is 50mV (50mV corresponds to the working current of the power tube 500mA). The value of the multimeter B is 0. After completion, you can sit down and drink hot tea to rest for 30 minutes, and wait for the power amplifier to warm up and repeat the above overweight again, until the value of the multimeter A is 70mV (70mV corresponds to the working current of the power tube 700mA). Multimeter The value of B is 0 (fluctuations within +/-50mV are normal, of course, if it can be close to 0mV is the best state), at this time, wait for the power amplifier to warm up for more than 1 hour, and then fine-tune again. Ensure that the value of multimeter B is within +/-20mV, and the entire adjustment process is completed. You can connect to the signal to listen to music! 8. When the power tube uses Hitachi K1058 and J162, DC +/-21V power supply, the current is adjusted to within 800mA; when DC +/-24V power supply, the current is adjusted to within 700mA. 9. The adjustable resistor R5 has been adjusted, please do not adjust it lightly. 10. It is recommended to use a temperature gun to detect the temperature of the heat sink. It is best not to exceed 45 degrees. After the power amplifier has been used for a period of time, fine-tune the parts after the aging is completed.

Price: 61.99 USD

Location: FOSHAN

End Time: 2024-08-29T07:10:43.000Z

Shipping Cost: 0 USD