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Zesto Audio Bia 120 Class A Stereo Power Amplifier

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SKU Bia120

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Zesto Audio Bia 120 Class A Stereo Power Amplifier

Design Philosophy

With my pro audio background in the recording studio and live concert mixing,
I wanted to build an amp that allowed me to hear music the way I know it should sound.

I wanted it to be easy to use, reliable and with plenty of power to drive the speakers. In short,
I wanted power without compromising the music.

Class A Design

The tubes are always on, so you have power when you need it. Class A is fast and responsive. There is no lag, providing your music more punch, transient response,
better dynamic range and transparency.

Circuit Topology

I choose a Class A Ultra-linear, Push-Pull circuit design to deliver the most precise, enjoyable and faithful reproduction possible.

Unsung Hero

The unsung hero of a power amp is its power supply. That s why my design incorporates a custom Toroid power transformer and a choke-based, dual-mono power supply to deliver
all the slam you can handle.

Easy to use

With Auto Bias, you need no adjustments. It s safe, consistent and the settings are always perfect so you can enjoy your music.

What is Bia

In Greek mythology, Bia is the Titan Goddess of force and power.

Key Features

    • Plenty of power to drive your speakers
    • Pure Class A power is fast and musical
    • 4, 8 & 16 Ohm taps gives you options for your speaker preference
    • Dual Mono gives you less cross talk and better stereo imaging
    • No adjustments with Auto Bias. Its safe, consistent and settings are always perfect
    • Provides enough gain for most standard preamps and accommodate most speakers
    • Choice of either Single Ended RCA or Balanced XLR to suit your needs or cable preferences
    • Transformer balanced XLR input offers true noise rejection and isolation from the preamp
    • Left and Right ground switches on the XLR balanced inputs to help eliminate ground hums
    • No Negative Feedback provides for virtually no compression to your music
    • Custom Toroid provides lower noise with plenty of available power
    • Global mains power supply can work all over the world
    • KT120 compatible
    • Push-Pull circuit design gives you more power
    • Ultra-Linear circuit design provides lower distortion
    • Low noise levels allow really dark black quiet musical passages
    • Non inverting polarity retains the same phase as the input
      (so your trumpets blow and don t suck)
    • Gold pin sockets are more reliable because gold doesn t t oxidize when it heat cycles
    • Matched quad output tubes retain the stereo balance
    • It s ready to enjoy with 50 hours of factory burn in on all circuits and vacuum tubes.
    • Elegantly designed, heavy duty 14 &16 gauge zinc plated steel enclosure
    • Each unit is hand built Made in the USA
    • The wide frequency response allows you to hear the finest passages in your music.
    • High quality gold plated RCA, XLR connectors and 5 way binding posts
    • All fuses are easily accessible


      • Pure Class A
      • 60 Watts per channel
      • 4, 8 and 16 Ohm output taps
      • 8, 5 and 4 Amp Slow blow fuses for outputs
      • Eight 5 way binding post
      • Non inverting output polarity
      • Push-Pull and Ultra-Linear design


      • RCA single ended inputs Left and Right with an impedance of 100K Ohms
      • Transformer floating XLR balanced inputs Left and Right (pin 2 hot)
        with an impedance of 12K Ohms
      • Independent ground lift switches on left and right balanced inputs
      • 2 Volts RMS input to reach rated output

Detailed Specs

      • Dual Mono
      • Auto bias
      • No negative feedback
      • Frequency response 20Hz to 50Khz ~ 2db
      • Total Harmonic Distortion ~ 0.22% at 1W output into 8 Ohms
      • Gain of 23dB
      • Noise level > 0.2 mV RMS into 8 Ohms with input shorted
      • 1% metal film resisters throughout
      • Polypropylene capacitors throughout the audio path


      • Custom Toroidal power transformer with global mains
      • Choke based power supply design
      • 120 Volts AC mains
      • Optional factory installed 220V, 230V, 240V 50/60Hz
      • Power consumption at rated output 300 Watts
      • On/Off switch conveniently located on front panel
      • 3 pin IEC power connector with fuse

Active Components

      • Matched quad set of four (4) KT88 s vacuum tubes
      • Four (4) Gold pin ECC82s (12AU7) vacuum tubes
      • High quality gold pin ceramic sockets

Other Features

    • Each unit is made by hand
    • 50 hour factory burn in on all circuits and vacuum tubes
    • Dimensions 17" W X 20" D X 10 H
    • Weight 66 lbs. (30Kg)
    • 16 and 14 gauge Zinc plated steel enclosure