Phi 170 Phi 170
Phi 170 with VAC iQ System
Monoblock Power Amplifier

At first glance, the new VAC Phi 170 may seem like a typical 85 watt per channel stereo amplifier. Sure, it can be transformed into a 170 watt monoblock at the flick of a switch, and it has a fully balanced input mode, but the real breakthrough is inside, for the Phi 170 is equipped with the revolutionary patented* VAC iQ Continuous Automatic Bias System.

Product Brochure
Phi 170
  • The VAC iQ is the only system able to hold each output tube’s true underlying idle current perfectly steady at all times, no matter how much you turn up the volume. Say goodbye to manual tweaking, bias drift, thermal tracking effects, dynamic load-line shift, runaway tubes, and blown fuses. Say hello to more detail, increased extension and punch, lower noise, less distortion, and high reliability.

    It will even tell you when it's time to replace weak tubes.

    The Phi 170 with iQ System. Superior sound. Only from VAC.

    * US Patent 8.749.310. International patents pending.

  • Type

    Vacuum tube power amplifier with transformer coupled output


    • VAC iQ Continuous Automatic  Bias System ™
    • Class A1 triode input & driver stages
    • Direct coupled input & driver stages
    • Low feedback design (6 dB)
    • 12 volt trigger
    • Detachable power cord

    Switch Settings

    Fully balanced or single-ended input
    Stereo or mono operation

    Power Output

    85 watts/channel stereo continuous
    170 watts mono continuous

    Speaker Matching Taps

    1-2 ohms, 2-4 ohms, 4-8 ohms

    Frequency Response

    4 Hz to 71 kHz, +0/-3 dB

    Full Power Bandwidth

    15 Hz to 63 kHz, +0/-3 dB

    Residual Noise

    Typically > 95 dB below rated output

    Input Impedance

    • 200k Ohms, Stereo, Balanced
    • 100k Ohms, Stereo, Single Ended
    • 100k Ohms, mono, Balanced
    • 50k Ohms, mono, Single Ended


    • 30 dB, Stereo, Balanced
    • 33 dB, Stereo, Single Ended
    • 31 dB, Mono, Balanced
    • 34 dB, Mono, Single Ended

    Output Polarity

    Balanced input is Pin 2 positive.

    Tube Complement

    • 4 x type 6SN7
    • 4 x type KT88
    • Compatible with KT120
    • Compatible with KT150

    Operating Voltages

    Available factory set for 100, 120, 220, or 230/240 volt operation


    • Cardas rhodium RCA jacks
    • Neutrik XLR jacks
    • Cardas rhodium binding posts


    • 17.8" W x 14.2" D x 8.5" H
    • 452 mm x 361 mm x 216 mm
    • Excluding connectors


    68 lbs. 
    31 kg


    Designed & manufactured exclusively in the United States of America by VAC


    *Specifications subject to change without notice.