Unison Research Triode 25
Unison Research Triode 25
Unison Research Triode 25
Unison Research Triode 25
Unison Research

Triode 25 Integrated Valve Amplifier

The Triode 25 was born out of the huge success of the long-standing Triode 20 amplifier, and released as part of the 25th anniversary celebrations of Unison Research’s formation.

2 Years


Like its predecessor, the Triode 25 is a push-pull amplifier that utilizes EL34 tubes in the output stage. The push-pull circuit includes a final stage with two power tubes intended for the amplification of the audio signal, and is then followed by a symmetrical output transformer stage that reconstructs the signal into a high-quality linear wave.

Using a push-pull structure in this amplifier design allows for numerous benefits, including higher-output power compared to single-ended designs, improved efficiency and no static polarization of the output transformer for greater performance in the output section. However, for this to work well it is essential that all the individual amplification stages are carefully designed and constructed to prevent the formation of dangerous and compromising odd-order harmonic distortion. This is true for the two semi-output amplifiers, and even more important in the output transformer.

The Triode 25 can operate in two modes: triode and pentode. The latter is capable of delivering a maximum power output of over 45 watts per channel (6Ω load) with minimal harmonic distortion across the entire audio band.

With the use of an Apple lightning to USB connector (not included) you can plug your iPhone/iPod/iPad directly into the Triode 25’s DAC and play your hi-res music files straight from your device.

The addition of a USB input modernises the Triode 25 and increases its appeal to the growing world of computer audiophiles, who use their laptop or computer as a high-quality audio source for their hi-fi. The USB input is 32-bit/384kHz and DSD 128 compliant to support the latest standards in studio quality audio.

Stereo Integrated Valve Amplifier

Output Stage
Push-pull, ultralinear, Class-AB

Output Power
Approx. 45 watt per channel
Pentode configuration
Approx. 25 watt per channel
Triode configuration

Output Impedance
6 Ohm

Input Impedance
47 kOhm / 50 pF

Negative feedback
5 dB or 1.8 dB

Valve complement
2 x ECC83 (12AX7) 1 x ECC82 (12AU7) 4 x EL34 (6CA7)

Power Consumption
300 watt max

T6.3A from 100V to 130V T3.15A from 220V to 250V

30 cm x 45 cm x H. 20cm

Net weight
20 Kg