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The LM-503PA mono power amplifier has been inspired by an original design of Western Electric. It uses a single ended 845 output stage with a 300B driver and 5U3C rectifier. The pre-amplifier stage use a special Line Magnetic tube, the 310A.

Available on back-order

SKU: LM-503PA Category:


The power line is filtered by two special chokes. Bias is easily adjusted for the 300B and 845 tubes with a specific vu meter located on the top plate.

Line Magnetic’s LM-503PA mono power amplifier received the German Red Dot award In March 2017. This award is informally recognised as the “Oscar for International Industrial Design” rating this amplifier among the best in the world.

Some Highlights
– Single-ended design
– Class A amplifier
– Point-to-point wiring
– High quality components

Tubes used in this amplifier
Input stage: 1x 310A
Rectifier: 1x 5U3C
Drivers: 1x 300B
Power stage:  1x 845

Hand-made construction with the finest point-to-point wiring
SoftStart and time-delay circuit – 30 seconds
Specially designed EI transformer for power supply
Two EI output transformers with wide bandwidth

Tubes supplied         Common replacements
300B                              300A, 4300B
845                                845 A/B/C
310A                              Soviet Union/om12C, WE310A

Class A amplifier – 1x 24W RMS
THD: 1% (1kHz)
Signal/Noise ratio: 87dB (Weighted A)
Frequency response: 15 – 35,000 Hz (-1.5 dB)
Sensitivity: 1000 mV
Input Impedance: 100kΩ
Load impedance: 4/8/16Ω

1x Line input RCA
1x Line input XLR
1x Screw terminals compatible with banana plugs

Included Accessories
2x Fuses
1x Remote control
1x Detachable power cord

Dimensions (W x H x D)
Dimensions: 287 x 279 x 574 mm
Weight: 30 Kg
Finish: Silver

Additional information

Weight 36 kg
Dimensions 69 × 40 × 40 cm


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