Harmonia v4 & Harmonia jr 45/2A3/300B

2025 Harmonia v4 - The Harmonia v4 will continue on only as a DHT output stage for source components. A volume control will no longer be supplied with the V4 as a standard but is a standard feature on the Harmonia Jr.

2026 Production pictures posted soon.

Notice: The Harmonia is not a "buffer stage". It is a true DHT output stage. The Harmonia products DO NOT use a cathode follower circuit like other buffer stages on the market where you do not benefit from the full potential of the DHT tube. With the Harmonia you are hearing the full 45/2A3/300B sound. 

The industry's one and only DHT vacuum tube output stage

The Harmonia is meticulously designed to elevate audio systems with the distinct sonic richness that single-ended triode tubes provide.  

 Key Features: 

 1. The DHT tube serves as the core component, delivering the hallmark SET sound.     

2. A relay-based input selector facilitates connection of up to four source components. In the balanced configuration, all inputs and outputs are transformer coupled for optimal performance.     

3. Dual DC regulated power supplies ensure clean DC voltage is delivered to the tube filaments.  

The Harmonia represents a singular advancement in DHT vacuum tube output stage design, focusing on the most revered SET tubes: the 45/2A3 and 300B. 

Over the years, Musica Bella has been dedicated to refining this innovative design, ensuring an unparalleled listening experience.

OVERVIEW
The Harmonia offers several advantages for audiophiles looking to enhance their sound system. 

• Improved Sound Quality: The Harmonia adds warmth, smoothness, and organic characteristics to your music, making it more engaging and immersive.
• Proper Impedance Matching: It restores the proper frequency balance through superior impedance matching, resulting in a more accurate sound reproduction.
• Enhanced Tone and Dynamics: The Harmonia enhances tone and weight without introducing unwanted bloom, and improves the dynamics of source components.
• Increased Detail and Transparency: It increases detail, resolution, and transparency, allowing you to pick up on nuances in your music that may have been lost before.
• Reduced Listener Fatigue: By providing a more natural and smooth sound, the Harmonia reduces listener fatigue, making it more comfortable to listen for extended periods.
• 3D Soundstage Enhancement: It enhances the three-dimensional soundstage of higher grade components and recordings, creating a more immersive listening experience.
• Compatibility: The Harmonia seamlessly integrates with most any source components, including tape loops, integrated amplifiers, and receivers. 

The Harmonia stands as the world’s first audiophile-grade output stage, meticulously engineered around a Directly Heated Triode (DHT) tube. This innovative design remains unparalleled, providing a DHT vacuum tube output stage worthy of integration into even the most sophisticated audio and video systems. It serves as a standalone DHT output stage, enriching your listening experience with the sonic depth and warmth characteristic of the 45/2A3 or 300B tubes.  

For those who have yearned for the Single-Ended Triode (SET) sound but encountered limitations in traditional amplifiers—particularly with today’s more demanding speaker loads—the Harmonia offers a solution. Featuring a high-quality relay-based input selector, it allows for the rich characteristics of a SET output stage to be accessed by up to four source components, seamlessly integrating into high-powered solid-state systems.  

For the V4 series, we have introduced a new regulated DC filament supply that maintains a stable 2.5V or 5V, accommodating tubes that require high filament currents. 

The Harmonia seamlessly integrates with any source component, such as tape loops, integrated amplifiers, and receivers. When positioned after a high-quality CD player, DAC, or phono stage—regardless of whether they are tube or solid-state—the Harmonia imparts a richness, smoothness, and organic quality reminiscent of Single-Ended Triode (SET) systems, all while maintaining the high standards expected from premium audio equipment.   

For those who enjoy experimenting with tubes, we encourage you to explore the use of your favorite Directly Heated Triode (DHT) tube to maximize performance.

Design Features

Signal Stage

- High quality tube sockets 

- Neutrik RCA & XLR connectors insure low connector loss and high signal transfer 

-  Balanced input and/or output transformers (balanced version only)

- Transformer coupling of both balanced and RCA single ended inputs and outputs (balanced version only)

- Quality output coupling capacitors for smooth, full bodied sound while maintaining air, extension and detail. 

- Tube cathode bypass capacitors bypassed with high quality film capacitors 

- XLR/RCA ground switch on balanced version allows for best grounding plan for your application

- Equipped with 2 pieces Sovtek 2A3 tubes

- Volume control available - see (*) note below

Power Supply (5AR4 Tube Power Supply Available On Request)

- High current toroidal transformers.

- Regulated DC tube filament supplies running off separate transformer taps for exact voltage. One for each DHT tube

- Choke filtered

- UF diodes used for rectifying stage

- Each DHT tube is choke loaded on the anode

Applications:

-DHT Output stage for up to 3 source components to be used between sources and preamplifier (recommended), integrated amplifier, solid state receiver, tape loop

- (*) Use between preamp and amplifier to get that DHT emotional sound.

Harmonia Jr. 

• The Harmonia Jr. is the perfect choice for those not in need of balanced connections.
• This unit is available with transformer coupled inputs/outputs.
• Balanced not available.
• Single ended inputs - 3 sets RCA
• Single ended outputs - 2 sets RCA
• STANDARD Output Stage Only - No volume control
• Remote or manual volume available
• Volume bypass switch available
• The hole at front center can be used for the mounting of the "Volume Bypass Switch" or covered in real copper mesh for ventilation.
  

Current In-Stock Chassis
- Aluminum

-Optional 1/4" Thick Acrylic Faceplate. You choose the color

-Custom Charcoal Powder Coat Chassis

- Laser Engraved Aluminum Front Panel Standard

-Heavy damping material applied

Specifications

- Output gain: <3dB
- Output impedance: 180 ohms balanced
                                          150 ohms single ended- 

Gain: <1dB
- Tubes: 2x 45, 2A3 or 300B
- 16" W x 16" D x 4.5" H with feet
                          9.5" H with tubes

Harmonia v4

Price: $4,500 Single Ended

$5,500 Balanced

Volume control - add $100

Remote Volume - add $175

Harmonia Jr.

Starting at: $3,295 - 3 Single ended inputs, 2 single ended outputs, no volume

Manual Volume - add $100

Remote Volume - add $200

- 16" W x 12" D x 3.5" H with feet - Not including tubes

Footnotes:

(*) - Please note that if the Harmonia with volume control is used as a preamplifier or used between a preamplifier and amplifier, there is a slight potential for noise depending on your system configuration.