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VAC Phi 170iQ Stereo/Mono Power Amplifer

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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.




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