The MB90 MkII are valve power monoblocks — the world’s first power amplifiers designed for the modern Tung-Sol KT150 valves. They are the ideal valve alternative to powerful solid-state amplifiers: they combine high power, low distortion, deep bass and a transparent top end with the characteristic, natural sound of a classic valve.
Each monoblock lets you choose the character of operation: ultra-linear mode (115 W) or triode (60 W). The pure Class A, fully triode input stage is based on 6SL7 and 6SN7 valves. The power supply is regulated by a large choke, and the output transformers are made with an additional (tertiary) winding.
The design is entirely hand-assembled, point-to-point, with 4× KT150/KT170 output valves (KT88/KT90 compatible at reduced power), Solen capacitors, silver-plated PTFE wiring and gold-plated sockets. A warm-up/standby switch and a valve cage are included.
| Output power | 115 W (ultra-linear) / 60 W (triode) per channel |
| Output valves | 4× KT150/KT170 (KT88/KT90 compatible) |
| Driver valves | 2× 6SL7 + 2× 6SN7 |
| Signal-to-noise ratio | −90 dB |
| Frequency response | 20 Hz – 20 kHz (±0 to −0.5 dB) |
| THD distortion | below 0.1% (1 kHz, 8 W) |
| Speaker impedance | 4 and 8 Ω |
| Input sensitivity | 400 mV (high) / 1200 mV (low) |
| Input impedance | 100 kΩ |
| Power supply | 230 / 240 V; consumption up to 200 W |
| Dimensions (W × D × H) | 220 × 500 × 210 mm (230 mm with cage) |
| Weight | 20 kg (each monoblock) |
Valve power monoblocks on KT150 valves — 115 W ultra-linear or 60 W in triode, choke-regulated power supply, hand-wired assembly. The first amplifiers designed for KT150.
