Bia 120 Class A Stereo Power Amp
You will be amazed how great your system can sound! Finally!
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
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
- 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
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 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
Bia 120 Class A Stereo Power Amplifier Scot Hull – Part-Time Audiophile – March 7th 2015
….”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 reviewBia 120 Stereo Power Amplifier Paul Seydor – The Absolute Sound – April 7th 2014
“Is the Bia perfect? Well, of course, nothing’s perfect, but no matter what I threw at it, I couldn’t make it sound anything less than beautiful…” Read entire reviewBia 120 Class A Amplifier Positive-Feedback Online – November 2013 – Robert H. Levi
“…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.” Read Robert H. Levi’s full review in Positive Feedback on line.Read entire reviewTHE ABSOLUTE SOUND BUYER’S GUIDE TO ELECTRONICS 2015
Download the guide scroll to see Zesto Audio on pages 74, 75 and 76.Bia 120 Stereo Power Amplifier Paul Seydor – The Absolute Sound – April 7th 2014
“Is the Bia perfect? Well, of course, nothing’s perfect, but no matter what I threw at it, I couldn’t make it sound anything less than beautiful…” Download the guideBia 120 Reviewed by Paul Seydor – The Absolute Sound – April 2012
“Its sound is unbelievably smooth and velvety; harmonically rich, full, and vividly textured; marvelously rounded, tactile, and dimensional, with great body and solidity; and completely natural in its musicality and freedom from any of the usual sonic hype, audiophile style.”
EROS 300 Class A Monaural Power Amp
Powerful and musical, with the absolute authority to drive your speakers!
Design Philosophy
The challenge designing the Eros 300 was the conflict created when you want a lot of power, low noise and most importantly you want it to be musical. It took over 3 years to develop the Eros and 79 circuit designs later. I always look at the design from two points of view, as an audio engineer and an electrical perspective. Each design phase is based on a 50/50 balance between the technical spec and listening to each component change. Ultimately, the final design must sound good because who listens to sine waves anyway?
Class A amplifier design
Class A has less cross-over distortion and therefore is more musical. 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.
Secret Sauce
The secret to a good power amplifier design is matching the circuits of the power supply to the amplifier. The Eros 300 is a choke based power supply with a custom toroid power transformer that gives you maximum power with no compression. It’s the most musical design because it retains all the dynamics from your sound source.
Lots of choices
How many tubes is enough? How much power is enough? I decided that 6 KT88’s and 150 Watts of Class A power was a good balance. More tubes and more power didn’t actually sound better, in fact, worse. Adding more tubes would have created more heat and less reliability.
What is EROS?
In Greek mythology, EROS is the God of Love and Desire.
Key Features
- Class A topology is the most musical of all amplifier designs because it has the lowest distortion.
- Unlike solid state, this tube amp efficiently transfers power by matching the output transformer to the impedance of your speakers using 4 & 8 Ohm taps.
- Two parallel options for your speaker cables; the binding posts or the SpeakOn connector.
- The Eros 300 is easy to use. There are no adjustments or tweaking with Auto Bias technology on the output tubes. It’s safe, consistent and the settings are always perfect so you can relax and enjoy the music.
- Transformer balanced XLR input offers true noise cancelling and rejection as well as ground isolation from the preamp.
- Should you need to eliminate a hum? The Eros 300 has a XLR ground switch installed for your safety. This eliminates the dangerous temptation to lift the ground from the mains.
- The combo of Push-Pull – Ultra Linear output circuit design gives you more power & lower distortion.
- No Negative Feedback in the circuit design provides better dynamic range because it doesn’t compress the music.
- Non Inverting Phase Polarity retains the directional information from the original source which gives your system punch.
- A robust choke based power supply creates maximum immediate power with no compression.
- Custom Toroid power transformer provides lower noise with plenty of available power.
- The circuit design creates low noise levels with a wide frequency response. You will notice this in the really dark, quiet passages in your music.
- Gold pin sockets are more reliable because gold doesn’t oxidize when it heat cycles.
- A matched sextet (6) output tubes provides a synchronized balance for the lowest distortion and maximum output of power.
- An extensive grounding scheme is designed into the power supply, wiring and all tube circuitry.
- Elegantly designed, heavy duty 14 & 16 gauge zinc plated, fully grounded steel enclosure isolates external noise and vibration.
- All fuses are easily accessible
- It’s ready to enjoy with 50 hours of factory burn in on all circuits and vacuum tubes.
- Each unit is hand built “Made in the USA”
Specifications per Amp
Output
- Pure Class A
- 150 Watts per amp
- 4 and 8 Ohm output taps
- 8 and 5 Amp Slow blow fuses for outputs
- Three 5 way binding post
- One SpeakOn connector
- Non inverting output phase polarity
- Push-Pull and Ultra-Linear design
Inputs
- Transformer floating XLR input
- Balanced inputs with pin 2 hot, impedance of 12K Ohms
- Single Ended input, impedance of 100K Ohms
- XLR ground lift switch on balanced input
- 1.8 Volts RMS input to reach rated output
Detailed Specs
- Monaural
- Auto bias
- No negative feedback
- Frequency response 20Hz to 50Khz ~ 2db
- Total Harmonic Distortion ~ 0.43% at 1W output into 8 Ohms
- Gain of 26dB
- Noise level > 5 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 360 Watts
- Power consumption at idol 348 Watts
- On/Off switch conveniently located on front panel
- 3 pin IEC power connector with fuse
Active Components
- Matched sextet, set of six (6) KT88’s vacuum tubes
- Two (2) 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 64 lbs. (29.03 kg)
- Shipping weight 80 lbs. (36.28 kg)
- 14 and 16 gauge Zinc plated steel enclosure
- Two year limited warranty
- Six month warranty on vacuum tubes
“This gear has Authority! I’m very proud of the EROS 300 and I know I’ve achieved something when everyday I can say, Wow I never heard that level of detail before in my system. Happy listening.”