LJM PREAMP 9 Single-Ended Pure Class A Transistor Preamplifier board
Input voltage: 0-AC24V (20V-28V ac is ok)
Input transformer power> 5VA
Quiescent current: 25 MA
Voltage magnification = GAIN 10 times
THD + N <0.05%
SNR> 100 DB
Frequency response: 20HZ -20KHZ -0.05DB
FFT test test platform AP SYS TWO, the output voltage signal: 1.06V
PCB size:56*71 MM
PREAMP 9 is the LJM design a new fully discrete pre-amplifier. PREAMP 9 is pure single-ended structure, pure class A design.
Single-ended discrete circuit has always been a representative of analog circuits, has a wider dynamic range than other manufacturers,
Single-ended as a single transistor to amplify the entire waveform of the signal, so single-ended circuit without any cross-distortion,
This means that very weak signals, usually overlooked external signals can also be heard by people.
PREAMP 9 has a warmer, more sweet, and more full sound than an op amp.
Single-ended amplifier circuit is the oldest original amplifier circuit, it has a good tone Yun flavor. But the single-ended circuit on the power supply anti-interference ability is weak,
So PREAMP9 power part is more complex, using a three-level filter,
The first level using MOTOROLA ONSEMI production LM317T as the first level of regulation filter,
The second stage uses a large-capacity inductor-plus-capacitor LC filter, plus a third-stage transistor RC filter. As the P9 front class power supply
Provide a very pure, similar to the battery DC.
PREAMP 9 uses the original imported BC547 C for the whole NPN structure of the pure single-ended amplifier circuit, single-ended circuit is not complementary to the tube, only NPN no PNP tube. Only use the same tube as a magnification circuit, and constant current source load.
PREAMP9 using the whole post design, because the circuit is more complex, in order to reduce the size of the previous class. And the post element has a shorter track distance.
This can be installed in the P9 pre-class amplifier in any of the general inside. Directly installed in the power amplifier after the level of the control panel on it. P9 front level, not including the potentiometer PCB size is about 56 * 71 MM
LJM all products are debugging through the instrument, different components even if the same model, the performance is not the same.
P9 pre-level is entirely sound-based, on any appearance of the landscaping are not.
P9 front main filter capacitor using ULTRA LOW ESR Panasonic black gold new original FC series capacitors.
Regulator with MOTOROLA (M) in mind, ONSEMI and other new original regulator.
All the transistors are imported using imported copper feet tested by the BC547C, all magnifications are around 600.
P9 pre-use the real military manufacturers of PCB,
PREAMP9 pre-level will make the whole audio system to become more pleasant.
Input voltage: 0-AC24V (20V-28V ac is ok)
Input transformer power> 5VA
Quiescent current: 25 MA
Voltage magnification = GAIN 10 times
THD + N <0.05%
SNR> 100 DB
Frequency response: 20HZ -20KHZ -0.05DB
FFT test test platform AP SYS TWO, the output voltage signal: 1.06V
PCB size:56*71 MM
PREAMP 9 is the LJM design a new fully discrete pre-amplifier. PREAMP 9 is pure single-ended structure, pure class A design.
Single-ended discrete circuit has always been a representative of analog circuits, has a wider dynamic range than other manufacturers,
Single-ended as a single transistor to amplify the entire waveform of the signal, so single-ended circuit without any cross-distortion,
This means that very weak signals, usually overlooked external signals can also be heard by people.
PREAMP 9 has a warmer, more sweet, and more full sound than an op amp.
Single-ended amplifier circuit is the oldest original amplifier circuit, it has a good tone Yun flavor. But the single-ended circuit on the power supply anti-interference ability is weak,
So PREAMP9 power part is more complex, using a three-level filter,
The first level using MOTOROLA ONSEMI production LM317T as the first level of regulation filter,
The second stage uses a large-capacity inductor-plus-capacitor LC filter, plus a third-stage transistor RC filter. As the P9 front class power supply
Provide a very pure, similar to the battery DC.
PREAMP 9 uses the original imported BC547 C for the whole NPN structure of the pure single-ended amplifier circuit, single-ended circuit is not complementary to the tube, only NPN no PNP tube. Only use the same tube as a magnification circuit, and constant current source load.
PREAMP9 using the whole post design, because the circuit is more complex, in order to reduce the size of the previous class. And the post element has a shorter track distance.
This can be installed in the P9 pre-class amplifier in any of the general inside. Directly installed in the power amplifier after the level of the control panel on it. P9 front level, not including the potentiometer PCB size is about 56 * 71 MM
LJM all products are debugging through the instrument, different components even if the same model, the performance is not the same.
P9 pre-level is entirely sound-based, on any appearance of the landscaping are not.
P9 front main filter capacitor using ULTRA LOW ESR Panasonic black gold new original FC series capacitors.
Regulator with MOTOROLA (M) in mind, ONSEMI and other new original regulator.
All the transistors are imported using imported copper feet tested by the BC547C, all magnifications are around 600.
P9 pre-use the real military manufacturers of PCB,
PREAMP9 pre-level will make the whole audio system to become more pleasant.
20HZ-25KHZ （-0.05 DB）
10K FFT test：
