Phasemation SA-1500 Integrated Amplifier

A class-A 9 W SET with 2 x 6SN7 and 2 x 300B in a dual-mono configuration

Single-ended triode amplifiers are an audiophile Holy Grail, and 300B SETs even more sought after. Add to this, beautiful high-end Japanese design, and you have one of the most desirable amplifiers in the world. 

Following the powerful MA-1500 monoblock that uses the revered 300B vacuum tube, Phasemation launched a 300B stereo integrated amp in 2024.  The SA-1500 is a pure class-A self-biased design with an output power of 9 W.

Phasemation made four "commitments" when they designed the SA-1500. Commitment 1 was that it must be pure class-A, prioritizing sound quality regardless of the effort it takes. As Phasemation puts it, "Class-A sound is pure, with a delicate expression, and has vast audio advantages due to its low distortion." 

Commitment 2 was to not use negative feedback, as Phasemation's extensive listening tests showed that zero feedback made for a more dynamic and expressive sound.

Commitment 3 required the use of triode tubes. Phasemation believes there is nothing nostalgic about the sound of vacuum tubes, and that it brings a profound sound impact that can be enjoyed even with modern music. 9 W may not sound like much, and is not much with solid-state, but with tubes and their huge current delivery, 9 W is huge, and can drive a range of loudspeakers.

Finally, Commitment 4 was to follow a monaural design structure. By separating left and right channels, Phasemation keeps crosstalk and other cross-channel effects to a minimum, resulting in excellent imaging and stereo separation.

Features

• No feedback design for rich, direct, dynamic sound
• Individual left and right output transformers made by Lundhal of Sweden
  
• Independent left and right choke transformers for less crosstalk 
  
• Direct mode allows for use as a power amp
• Low-noise, anti-vibration design featuring thick glass and rigid aluminum
• Extensive shielding on power transformer, choke, and output transformer
  
• Uses 6SN7 in the first gain stage, with the 300B as the output tube

Specifications

Input Impedance: 47 kΩ

Gain: 30 dB

Output Power (THD 5%):  9 W 

Output Impedance: 4–8 Ω

Power Consumption: 140 W

Dimensions (W x H x D): 16.93" x 9.45" x 14.96" (430 x 240 x 380 mm)

Weight: 39.68 lb. (18 kg)