The ab

















ove l

The Bia 120

Class A Stereo Power Amplifier

Power Without Compromise


  • Description
  • Features
  • Specifications
  • Reviews
  • Downloads

Design Philosophy
With my pro 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.

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 work with the XLR balanced inputs to help eliminate ground hums
•No Negative Feedback provides for virtually no compression to your music
•Customer 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

•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
•Chrome steel spike feet


•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


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

Detailed Specs

•Dual Mono
•Auto bias
•No negative feedback
•Frequency response 20Hz to 50Khz  ~ 1dB
•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
•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 plated ceramic sockets

The 2016 Rocky Mountain Audio Fest reports are in and Zesto Audio is very happy indeed.


Jim Hannon's "Best of Show"

"Best Sound" (for the money)

"It put many more expensive systems to shame."

Jim Hannon - The Absolute Sound, RMAF Show Report - October 2016

Read full report

"Most Coveted Product" and "Auspicious Debuts: Analog"

Jim Hannon - The Absolute Sound - RMAF 2016 Show Report

"Zesto Audio's new Téssera Phonostage made me think I was listening to master-tapes.

One of the best sounds of the show!"

Read more..



RMAF 2016: Would This Stairway Lead to Heaven?

"This was one of those happy, expectation-fulfilling rooms where recordings actually sounded like music."

Jason Victor Serinus - Stereophile - October 2016

Click to read full report

Scot Hull – Part-Time Audiophile – March 7th 2015
Bia 120 Class A Stereo Power Amplifier

….”The amplifier has more than enough power to drive the snot out of all but the most absurd loudspeakers. Chances are, you’re gonna love the way it sounds. Take that, add a healthy dose of style, and you’ve got yourself something marvelous.”  Read entire review

"Bia's personality consists in a completely seductive musicality......"
Paul Seydor - The Absolute Sound - April 2014

Click to read the full Bia review

...."The amplifier has more than enough power to drive the snot out of all but the most absurd loudspeakers. Chances are, you're gonna love the way it sounds. Take that, add a healthy dose of style, and you've got yourself something marvelous."
....."George Counnas is on to to something. With the Bia, Zesto now has an excellent and stylish end-to-end analog package for your prize loudspeakers. An audition is highly recommended."
Scot Hull - Part-Time Audiophile - March 7, 2015
Click to read the reveiw