Purity Audio Design
Harmonia 300B Balanced Vacuum Tube Line/Buffer


We will be adding additional Q&A's as they come through. If you have any questions or concerns regarding the Purity Harmonia and don't see an answer to your question below, please don't hesitate to contact us.

Q: What is a tube buffer stage?

A: A tube buffer stage is a zero-gain/very low gain tube stage that is placed between two components to offer better impedance matching and sonic enhancements.

Q: Tube buffer stages have been around for a while, what makes the Purity any better?

A:  Yes, the idea of a tube buffer stage has been around for many years. Most audiophiles are aware of the reputation tube buffers have obtained over the years. In the past, tube buffers have been known to roll of the upper end, diminish the sound quality, character, and sustain of your system. They were also known to cause premature signal decay, lack of transparency, resolution and details as well as flat dynamics. Another main attribute of past buffer stages has been an unacceptable noise level. In the past, these inferior buffers we simply used to take the edge off of lesser quality electronics and/or provide better impedance matching between audio components and did only a mediocre job at that.

All these negative attributes held true until the release of the Purity Harmony fully balanced vacuum tube buffer design several years ago. The Harmony was the first true audiophile grade buffer stage to be introduced into the Hi-Fi industry. In 2014, Purity releases yet another industry first, the Harmonia vacuum tube buffer based on the infamous 300B vacuum tube.

Q; Why 300B tubes?

A: Why not? The 300B's sonic characteristic has become know world wide as one of the most sought after sounds. Until now, with the introduction of the Harmonia, the 300B sound was only available in power amplifiers and more recently, preamplifiers. But what if you wanted that 300B richness combined with dynamic power and authority of solid state system? You were out out of luck. Now you can have the best of both worlds.

Q: Why would I need the Harmonia tube buffer?

A: There are a few different parts involved with the answer to these questions

Impedance synergy:

The Harmonia has high input and low output impedance. The output impedance is < 180 ohms allowing it to mate a linestage/preamp with high output impedance with an amplifier with a very low input impedance. Why does this matter? Improperly matched components will yield rolled-off high frequencies, muddy bass and poor dynamics. The minimum preferred impedance ratio between preamp and amplifier is 10:1. In other words, the input impedance of the amplifier should be at least 10 times higher than the output impedance of the driving component (such as a preamp). At Purity Audio Design, we believe that ratio should be at least 20:1 with 40:1 being closer to ideal. The higher the better.

With the very low output impedance of the Harmonia line/buffer stage, you can now mate a preamp with virtually any amplifier. Given the minimum ratio, you could theoretically have an amplifier with an input impedance of 1300 ohms. The lowest I have seen in a solid state amp is 5K ohms.

Sonic Richness

Plain and simple, the 300B tube adds sonic richness and midrange liquidity rarely found from other tubes. The Harmonia allows you to add these traits to most any system.

Q: Can I use the Harmony Line/Buffer as a preamp

A: No. The Harmonia does not have any level control.

Sonic Integrity:

Buffer stages of the past  helped in impedance matching but fell apart when it came to enhancing or even maintaining sonic integrity. The Harmony spent several years in the R&D stage assuring it would be a top contender in the high end industry.

With the use of transformer coupling at both the inputs and outputs (balanced version), which also allow balanced connection, the Harmony provides a level of transparency, resolution and detail never before experienced in buffer stage and is on par with some of the best tube preamps.

 The used of advanced circuit topology, power supply design and properly selected audio grade components puts the Harmony in a class of its own.

Q: Where would I use it:

A: If you have improper matching of impedance between you preamplifier and amplifier, the Harmony will allow these two components to work in harmony (pun intended) as mentioned above. The Harmonia can be used after the highest quality preamplifier, CD/DVD/SACD player, Digital to Analog Converter (DAC), Phono Stage or any other component you may have in your system. You can even use the Harmony to bring to life your iPod or computer based system or TV cable box.

Used between any source component and your preamplifier, integrated amp, home theater receiver or home theater processor the Harmonia adds 300B richness and resolution to an otherwise dry and sterile presentation.

The Harmonia will bring to life a system based around tubes, solid state or a combination of the two as seen in most high end systems these days.

Home Theater applications:

The Harmony will transform your system when placed between you CD/DVD player and home theater receiver.

Q: My system is all single ended. Why should I consider the balanced version

A: The balanced version of both the Harmony was a very popular addition to many single ended systems. Like the Harmony, the Harmonia provides full transformer coupling for even the single ended inputs and outputs. This transformer coupling provides a greater sense of resolution, detail and transparency to both balanced and single ended systems. The Harmonia is equipped with both single ended and balanced inputs and output for this reason.

Q: There are two sets of inputs on the balanced version. Can I use them both at the same time.

A: No. Only one set of inputs can be utilized at a time. Two are provided only to provide you with the option of XLR or RCA input connection as many of our customers have chosen to go with the transformer coupled, balanced version to install in their single ended system.