Dragon Inspire IHA-1 Tube Headphone Amp

Drew Baird (P.E. and President of Moon Audio) and Dennis Had (Founder of Cary Audio) spent over a year perfecting this exclusive Dragon version of the Inspire IHA-1 tube headphone amplifier. Listen with various headphones seamlessly by means of the numerous output options that come as standard upgrades. The Dragon Inspire IHA-1 Tube headphone Amplifier now includes Preamp RCA Outputs as a standard option. No expense has been spared in this Dragon Version by Moon Audio. Endless tube upgrade options are available to purchase to suit the most critical of listeners.

Built By Hand

Each amplifier is hand-built with point-to-point wiring by Dennis Had himself. Each amplifier is hand-signed by him on the bottom plate. Dennis considers this his form of art. Each amp is like a newly sculpted masterpiece. He personally listens to each amplifier, both in the shop listening room and his home listening room, before it is shipped out. This is a passion he has held for over 59 years now, ever since he built his first single-ended 6V6G hi-fi amplifier for the 7th-grade science fair. He never dreamed that retirement was going to be so much fun!

Exclusive Dragon Features:

• Gorgeous Copper Metallic Powder Clear Coat finish
• Stepped DACT 100K attenuator running a pair of 6SN7s at over 1 watt of output power
• Lundahl Input Transformers, now a standard option
• Output impedance of 4.4 ohms
• Transformer Pro Balanced output
• 2 analog RCA input selector positions, including a mute position
• 4-pin XLR Headphone output
• 1/4" headphone output
• Preamp RCA Outputs with a switch that mutes the headphone output
• 5U4 variant rectifier tube is standard
• A pair of 6SN7 comes standard 
• A pair of 6SN7 New Old Stock Tubes is available for an additional $100 (Brand depends on availability)
• Direct coupling and transformer output are included as part of the standard configuration.
• 10 inches wide, 8 inches deep, height varies based on tubes used.
• Weight is 15lbs 

Moon Audio is proud to host and share the return of the legendary Dennis Head to the world of tube headphone audio. This IHA-1 Dragon Version, stereo vacuum tube headphone amplifier, maintains Dennis' philosophy reinforced over decades of listening, designing, and building audio amplification.

As with Dennis' previous designs, his main concern is always the sonic purity of the output signal as perceived by the human ear. The IHA-1 Dragon is vacuum tube amplification in its purest form. It is a very clean, short signal path. There are no capacitors, resistors, or other passive components that make up the circuit. The signal enters the RCA jack, travels to the DACT stepped attenuator, then the 6SN7 tube, followed by the Output transformer and exits via the Headphone Jack or Preamp RCA. The Tubes become very important in this sort of circuit. The better the tub, the better the result. You can also drastically change the tonality based on the tube you choose to use. Each tube has a very different sound signature or flavor.

The Dragon IHA-1 utilizes a 100 K dual DACT stepped attenuator. No matter where one has the volume set, the balance is equal at all times in each channel. The Amp has Pro-Audio outputs on the front panel. You will notice the locking 1/4" stereo output. In addition, we have chosen to have the XLR 4-pin balanced output connector. The IHA-1 is a single-ended design, but as you know, it delivers the output in a balanced form from the output windings of the air-gaped output transformers. Then, a final touch is a dual process powder coat finish in a clear-coated copper.

The input driving signal is directly coupled to the grids of the 6SN7 dual triodes. This signal is amplified and sent to the headphones through a set of special hand-wound air-gapped output transformers. Once again, direct coupling straight through to the headphones. Utilizing the 6SN7 dual triodes, the IHA-1 is extremely linear and offers full bandwidth from 9 Hz to 33Khz without the use of feedback.

The power supply is vacuum tube rectification with dual filter chokes to provide a low noise level, along with a low impedance B+ power supply to the 6SN7 tubes. All in all, he had little concern for how loud one could blast their ears, but an ongoing concentration on full bandwidth, linearity, and a realistic music presentation. Once again, for fear of being repetitive, the new Inspire IHA-1 Dragon version is vacuum tube amplification in the purest form.

For tube rolling, the rectifier tubes should be of the direct heater type, like the 5Y3, 5U4, 274B, or NOS and factory-fresh direct-heated filament types. The indirect filament type, like a 5AR4, is fine to use, but to his ear, they do not even come close to a directly heated filament type.

The output tubes can be 6SN7 variants.  

Because of this purist approach, there is no gain stage or preamp circuit. Thus, the DACT attenuator is the volume control and/or preamp circuit. Thus, with some headphones that are not sensitive or have a higher impedance rating, this will mean a little less flexibility in the number of steps you have to control the volume. Do not get gain confused with output power. The amp has plenty of power for most headphones. For people who are in a situation where they need more gain or volume control flexibility, we offer the Lundahl transformers. The Lundahl transformers, which are input transformers and are placed between the RCA input jack and the DACT attenuator. They offer a 1 to 2.5 ratio. What they do is clean up the incoming signal, as all transformers can do, and increase the gain of the amp. So now, whereas the Inspire might need the volume control set very high to get the desired volume, it is now maybe halfway. This will also boost low-output signals from some Phono Preamps out there, or when using a low-output cartridge that gets very little boost from the Phono Preamp. In my opinion, no one makes a better transformer than Lundahl, and this does not just increase the gain but adds a little more detail and definition to the sound. 

The THD is close to the ultimate vacuum tube perfection, considering zero feedback. The second and all remaining harmonic contents at the 1.125-watt output level into 32 ohms are over 65 dB down. Actually, the only harmonics visible at these levels are the second harmonics down 65 dB, and the other harmonics are in the noise floor. This is actually an amazing output spectrum. One would consider this for the board of health!!!LOL The power levels vary with the impedance of the output load. At the 32 ohm level up through 570ohms, the power is in the 1.125-watt to .750 watt level. Higher power at the lower end of the range. It will drive the 600-ohm cans you have as one of your choices.

We are also offering a Preamp output option. We never thought about using the amp as a Preamp until we released the new Dragon Inspire QMB-25 Mono Block Amplifiers, as seen here. Just to experiment, we used it with the amps and were blown away. Thus, we added input RCAs and a switch to mute the headphone amp, which we switched over to use as a Preamp. All are placed on the back of the unit.

Please keep in mind that this is a direct coupled design without any coupling caps or output attenuation resistors in the signal path. Purity at its best.