Phasemation MA-5000 Vacuum Tube Monaural Power Amplifier

WE-211 parallel single pure class-A monaural tube power amplifier with WE-300B driver stage, Lundahl transformers, and transformer-type balanced attenuator

The Phasemation MA-5000 is a built-to-order vacuum tube monaural power amplifier created to deliver the highest-quality sound from a 211-based design. Using a parallel single-output stage built around highly regarded PSVANE WE-211 tubes, the MA-5000 is engineered to draw out both the realism of recorded music and the emotional intent of the performer. A rigid 10 mm aluminum chassis, TAOC cast-iron insulators, and a distinctive front glass tube cover decorated with traditional Japanese cloisonné underline its role as a true flagship component.

At the heart of the MA-5000 is an all-triode, non-feedback circuit built around an ECC803 input stage feeding a PSVANE WE-300B driver, which in turn drives the WE-211 output tubes via a Lundahl interstage transformer. Each WE-211 has its own separate fixed-bias supply, with operating points set and monitored via direct meter readings for optimal stability. A specially designed Lundahl output transformer is optimized for 4 Ω–8 Ω speaker loads, while a dual power-transformer supply, double-choke high-voltage rectification using two 5R4G tubes, and fully DC-heated filaments all contribute to low noise and clean, dynamic power delivery. Recognition from Stereo Sound, Audio Accessory, Analog, and Stereo magazines confirms its status among reference-level amplifiers.

For system integration, the MA-5000 offers both balanced and unbalanced inputs, feeding a transformer-type attenuator that also acts as a balanced-to-unbalanced converter. Standard gain can be reduced by -3 dB, -6 dB, or -10 dB, with an input OFF position providing effective mute for safe cable changes or system adjustments. A one-minute power-on timer with dual-color LED (red during warm-up, blue in operation) ensures gentle start-up for the tubes, while Furutech audio-grade speaker terminals with torque limiters maintain secure, low-resistance connections to your loudspeakers.

Specifications

Type: WE-211 parallel single monaural power amplifier

Rated Output: 45 W (THD 5%)

Frequency Response: 10 Hz–40 kHz (+0, -3 dB)

Input Impedance: 47 kΩ

Gain: 30 dB

Residual Noise: 200 μV or less (A-NET)

Output Impedance: 4–8 Ω

Power Consumption: 350 W

Accessories: AC power cable, screwdriver for trimmer adjustments

Dimensions (WHD): 14.57" x 13.62" x 25.04" (370 x 346 x 636 mm)

Weight: 110.23 lb. (50 kg)