Technical parameters:
Output power: AB Class is 250W / 4 ohm load; A Class is 90W/4 ohm load (Total harmonic distortion THD + N <0.3%)
Speaker Impedance: Available 4-8 ohms.
PCB size: 42 * 236MM.
Power supply: DC Dual 18-50V transformer 200 watts or more， the need to replace withstand higher voltages higher capacitance.
Discrete Tube: 2SA1943 2SC5200 OR NJW0302 NJW0281， classics on the tube(Actual delivery of boards).
The default is 2SC5200 2SA1943， you can leave a message to change of NJW0281 NJW0302， the same price!!
Description:
1 There are 1% precision resistors metal film resistors (apart from 1W to 5W 5% accuracy and no external sense resistor)， the use of CBB capacitor P hilips Cbb capacitors， mica capacitors.
2 electrolytic capacitors have a Black Edition， there ELNA and Nichicon， R ubycon and other famous capacitance. To ensure the stability of the circuit， and noise removal clean.
3 Select the audio coupling capacitor 1uF Weimaraner capacitors imported from Germany， to ensure that each channel to ensure that the small signal clean and clear sound.
2SC5171， 2SC1930 T oshiba bipolar transistors， the role is to promote the tube.
A970， C2240 T oshiba is a low noise， high power audio transistors dedicated amplification.
2SK246， 2SJ103 T oshiba good quality foundation dedicated sound field of high-power differential line pipe.
2SD669 H itachi imported NPN silicon tube， 2SD669 is working in a single-ended Class A status， the positive and negative half-wave signal alone by 2SD669 completed， so there is no crossover distortion， but also rich in even harmonics， timbre there are some moist role， and thus enlarged board very resistant， while 2SD669 is working in a big 50mA current status (normal op amp， amplification integrated only a few milliamps)， to deal with large dynamic music signals easy to get the most realistic sound performance ! Play limit the effect! .
Technical Parameters:
Output power: 250W (4Ω) 250W Mono class AB CPI 90W， 150W (8Ω) 150W Mono Class A 50W class AB
Frequency Response: 20Hz ~ 20kHz3Hz ~ 150kHz (1W output)
Total harmonic distortion: 0.05% (20Hz ~ 20kHz)
Damping: 120 (8Ω， 50Hz)
SNR: 110dB (RCA inputs)
93dB (balanced input)
123dB (input stage)
Gain: 128dB (after stage amplifier section)
Stereo headphone output impedance: 8 ~ 100Ω
Parts DIY Commissioning notes :
1) After completion of welding heat sink installed (note the tubes and fins to be well insulated)， adjust VR1 (1K precision adjustable resistors) quiescent current makes about 50MA， namely: the output voltage across V1 and V2 point about 11MV (R30 output voltage across the resistance 0.22 Ohms resistance value is divided by this quiescent current)， both of which located in the output (OUT) side. VR1 counterclockwise quiescent current becomes large， clockwise then reduced! Power on the proposal before the first clockwise twist laps after power quiescent current to avoid excessive and insufficient heating huge heatsink! Security! Do not install anti adjustable resistance! Install anti-clockwise quiescent current is bigger
Supporting fins quiescent current is adjusted to 50-100MA more appropriate (ie， 11-22MV)， the bass is very vigorous and effective!
2) the midpoint of zero， adjust VR2 (500R close adjustable resistor)， so that the output (OUT) on the ground (ie， the amplifier output terminals at both ends) is close to zero mV; resistor is not inserted in the wrong can be adjusted to 0MV， at worst can be adjusted to several millivolts.
Product pictures:
Note that this amplifier power is rectified and filtered DC power supply after a double， not directly connected to the transformer oh
Recommend shop rectified and filtered with a trumpet-protected power strip:
You can choose to buy the power supply filter board with speaker protection，click the picture !!
List of components， including all components of the board
Black 3Pin is AC power input terminals: +V GND -V select Dual 18-50V DC voltage.
recommended dual 35V DC
Higher voltage， then we would replace the high capacitance voltage value
Green 2Pin 5.04MM is mono input terminals: IN GND ， Audio input connection
Black 2P 8.25MM terminal is Audio output : GND OUT，directly to the speaker
The default is 2SC5200 2SA1943，
you can leave a message to change of NJW0281 NJW0302 ， the same price!!
Amplifier board size， very suitable for the machine， the sound quality is also very Ok， well-known machine circuit! !
accuphase circuit is performance and sound is good， with 0 noise when you close the VOL
Board needs to work with a heatsink，
Heatsink and IC do insulated enclosure
This link is not in include the heat sink
This link is a price channel， requires two channels made of 2.0， please take two links. Thanks a lot.
Circuit design for reference
Friends interested in the reference circuit for learning and communication!
