Purity Audio Design

Harmonia v3

45/2A3  Output Stage

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

There are many challenges in designing high end audio components. First and foremost, a properly design circuit from the power supply to the final output. With Purity, the next step is to come up with something that has never been done before. Leave it to Purity Audio Design to pursue these challenges. Purity has become known for developing true audiophile grade tube buffers providing balanced connection. Now we have continued this tradition with an audiophile grade buffer using SET tubes.
The Harmonia is a unique vacuum tube output stage designed around the two most popular SET tubes; You have a choice of a design based on the 2A3 or 300B tubes. Over the past several years, Purity Audio Design has been working on developing this SET tube output stage.. We now have what we believe is the passionate music lovers dream come true.

The Harmonia was and still remains the worlds first audiophile grade output stage designed around the a DHT tube. This Harmonia is the first SET vacuum tube output stage that is designed to a level that is at home in even the most exotic audio and video systems. It is designed to be used as a stand-alone DHT output stage to bring you closer to your music by introducing the sonic richness of the 2A3 or 300B tube. We have all lusted for the SET sound but found amplifiers using this tube offered limited dynamic control over many of today's heavy load speakers. With the new v2.5 using a high quality relay based input selector you can have the richness of a SET output stage for up to four source components in even the most powerful of solid state systems.

Inside the Harmonia v2.5 chassis you will find that Purity Audio Design continues it's tradition of using only the best parts.  Like our other products, you will not find a circuit board in sight other than the independent dual DC regulated power supplies for the tubes' heaters.  Both the power supply and analog circuit utilize 100% point to point wiring.

The all important circuit contains what we have found to be the best combination of passive components to bring the Harmonia alive. High quality DynamiCap capacitors provide sonic richness as well as maintained extension and detail.

Like all Purity Audio Design products, the Harmonia mk2.5 utilizes a hearty power supply. Starting with the high current transformer to the fully regulated DC filament supplies for each of the tube filaments, the Harmonia's power supply is designed to perform. A new regulated DC filament supply has been designed for the mk2 series allowing a constant 2.5V or 5v and able to handle high filament current tubes. The main B+, filament supplies are all each powered by separate high current transformers. The B+ feeding the tubes utilizes a CLCRC topology with a choke loaded anode for each 300B tube. What does this mean? Rather than feeding the plate from a capacitor or resistor, a choke is used in it's place. Purity Audio Design is known for providing some of the quietest components available. The Harmonia has an extremely low noise floor resulting in a jet black background.

The Harmonia finds it's happiness between any source component and preamplifier. Placing the Harmonia after any high quality CD player, DAC or phono stage, tube or solid state, brings a sense of SET richness, smoothness and organic quality to any system without sacrificing any of the quality traits one would come to expect from a high end audio product.

The Harmonia can transform your dry, fatiguing home theater into a system your guest will think is driven by SET tubes. One thing the Harmonia cannot do is transform inferior components into giant killers. The Harmonia can only enhance and bring forth more of the potential your system has to offer.

As can be seen in the photos above, the tubes protrude from the top panel of the unit making placement more versatile while also allowing for tube rolling ease. Not to mention what will be considered one of the sexiest looking components in your system.

For the tube rollers out there, we highly recommend some experimentation with your favorite DHT tubes
The Chassis is constructed of high quality aluminum.

The Harmonia is available in either a fully balanced or all single ended version.

Please note there is no LED power indicator on the Harmonia buffer. Upon powering the Harmonia up, the #1 input LED indicator will light

Installing the Harmonia into any system is as easy as installing any source component.

The sonic results are as follows:

Restores proper frequency balance through better impedance matching due to its extremely low output impedance.
Improves tone and weight without adding bloom
Adds 300B smoothness, richness and organic qualities to sterile or dry solid state and tube source components
Improves dynamics of source components that do not employ proper impedance matching,
Enhances detail, resolution and transparency.
Reduces listener fatigue.
Enhances the 3D soundstaging of better electronics and recordings.

Design Features

Signal Stage
- All inner signal wire uses solid core copper wiring to provide optimum performance
- High quality tube sockets 
- RCA jacks insure low connector loss and high signal transfer 
- Custom, designed for Purity Audio Design balanced output transformers (balanced version only)
- Transformer coupling of both balanced and RCA single ended inputs and outputs (balanced version only)
- Neutrix XLR connectors
- DynamiCap 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 EH300B or EH2A3Gold Grid tubes

Power Supply
- High current toroidal transformers.
- Regulated DC tube filament supplies running off separate transformer taps for exact voltage. One for each DHT tube
- Choke filtered
- Stealth diodes used for rectifying stage
- Each DHT tube is choke loaded on the anode

- 40% black powder coated aluminum. Powder coat was chosen over anodizing due to the thicker layer of powder coat provides more resonance control over the chassis. 
- Heavy damping material applied

- Output impedance: 180 ohms balanced
                                  150 ohms single ended- Gain: <1dB
- Tubes: 1x 2A3 or 300B per channel
- 16" W x 16" D x 4.5" H with feet
                          9.5" H with tubes

Single Ended



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 DHT preamplifiers on the market where you do not benefit from the full potential of the DHT tube. With the Harmonia you are hearing the full 2A3/300B sound.