Zesto Audio Bia Tube Power Amplifier

Description

MY TAKE:

The Zesto Bia power amplifier is truly a wonder. Its remarkable sense of clarity and realism is addictive and some would say groundbreaking. - Galen Carol

OVERVIEW: By George Counnas, designer

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.

REVIEWS:

"I am flabbergasted. The more I listen to the BIA 120, the more I am certain this magnificent amplifier is the real McCoy! The BIA 120 is a state-of-the-art tube amplifier. The BIA 120 has superb clarity, depth, neutrality, realism, nuance, elegance, and ultimate definition that a great tube amplifier should have. It has the kind of snap, low distortion, freedom from noise and haze, tight fast bass, speed, and slam you would expect from great solid-state amps. It has none of the troublesome problems or sonic artifacts of either tube or solid state designs. It is neutral like no other tube amp has ever been in my experience. It is a wonder!

"Zesto has created an amplifier that, when placed with the best ancillaries, will give you the experience of the musical performance with ground-breaking intense realism. The only things missing will be the sticky floors and the expensive tickets. I have never heard a better amplifier in my reference system, tube or solid-state. It is the best new tube amplifier to reach the market in the last five years priced under $50,000. That it costs $12,500 is a boon to audiophiles everywhere, and a minor miracle. What a value!

"The Zesto Audio BIA 120 Class A Stereo Power Amplifier is most highly recommended. I urge you to listen to it so you may understand just what a George Counnas-designed tube amplifier is all about.

"In a word, stupefying." - Robert H. Levi, Positive Feedback

2014 Golden Ear Award Winner - "Styled to match its Zeto linestage and Andros phonostage, Zesto’s new Bia 60Wpc, Class A, all-tube power amplifier lands the company the trifecta. Cut from the same sonic cloth as the preamps, Bia’s personality consists in a completely seductive musicality, free from all the usual sorts of electronic colorations and artifacts, for a presentation that never, ever sounds electromechanical, instead always wholly natural. Dynamic range is prodigious: The Bia even drove PS’s inefficient Quad ESL 2805s to clear, clean, unstrained levels (a magnificent combination, by the way). Although the spectral balance stays within the bounds of a broadly defined neutrality, it is not completely accurate, being more beautiful than real. Luscious, velvety, silken, gorgeous, it’s the kind of sound around which audio cults develop, and it’s easy to imagine its owners years, even decades hence treasuring the Bia the way others do classic McIntosh and Marantz components." - Paul Seydor, TAS

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 work with 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

Specifications

Output

• 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

Inputs

• 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

Power

• 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 plated 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
• Chrome steel spike feet