Late Night Listening

Pupshaw and Pushpaw agree! Musical and very resolving!

The Hegel HD20 DAC meets the CI Audio VHP•2 headphone amp. Listening to Bill Frisell’s My Buffalo Girl on a Macbook pro running iTunes/Pure Music with 64 bit math and power-of -two (88.2 Khz) upsampling. The CI Audio Transient MK II is providing the asynchronous USB-to-S/PDIF conversion, and the Hegel HD20 is doing the Digital-to-analog converting. The headphones in use are the classic Sennheiser HD-600 open ear cans. Stereo guitars, big bottom double bass, and the lovely B-3 organ carry you away – off to dream land…

The New Green Mountain Audio Eos HX

Green Mountain Audio Eos HX
photo by Vahan Baladouni

Associated Equipment:

Source: Macbook Pro running Pure Music with a large variety of recordings and resolutions.

Amplifier: Anthem MCA-2 class A/B

Computer interface: CI Audio Transient II USB to S/PDIF converter and VDC-5 MK II (power supply)

DAC: Crane Song Avocet DAC/Monitor controller (Discrete Class A)

Power: Shunyata Hydra 2 x 2 and power cables (various: copperhead, sidewinder VTX, Hydra VTX…)

Cables: Audio Magic Sorcerer speaker cable, Excalibur II interconnect, DH labs D-75 BNC to RCA, & Wireworld starlight USB

Eos HX

When you think of traditional speakers you often expect a wooden box of some type with drivers arranged inside. Not so with Green Mountain Audio’s Eos HX. In fact, no wooden cabinets here, except for the lovely Cocobolo wood that surrounds the tweeter. By taking a closer look it becomes evident that unique materials were used to build this speaker. The handcrafted Eos HX from Colorado Springs, CO combines artisanal workmanship with engineering refinement.

The Eos HX Tweeter surrounded by Cocobolo wood
photo from Green Mountain Audio

This HiFi meets steam punk design is the brain child of designer Roy Johnson. Mr. Johnson has spent years researching and developing a full range of speakers, and the Eos HX sits at the top of his 2-way designs. Never quite satisfied, the Eos has seen three iterations: the Eos, the Eos HD, and the latest being the HX. 

These speakers are  full of innovation. Starting with the Q-stone cabinet material, these monitors have a unique ability to be shaped in acoustically appropriate ways while also maintaining a low self resonance. The curved shape around mid/woofer allows for the fullest dispersion of sound, and the adjustable tweeter employs wool felt discs to eliminate early cabinet reflections. Without metallic resonances, the lightweight soft dome tweeter from Seas extends beyond 30Khz. The twin ports for the woofer have  been specially designed to more efficiently handle bass pressure. What you end up with is a truly tuneful bass response with an excellent percussive attack.

The heart of the Eos HX is found in its crossover circuit. Through much refinement, Roy Johnson has arrived on a crossover design (1st order) that works at achieving time-coherence  across the audible frequency range. Further sonic enhancements include Marigo internal wiring and Audio Magic nano stream process for the entire crossover circuit (including internal wire and binding posts). All these combined refinements further the speaker’s ability to reproduce nuances in the music.

The Eos HX rear with Vampire Wire binding posts
photo by Vahan Baladouni

Spending some quality time with the Eos HX proved to be very enlightening. While the bass extension rolls off around 50 hz, these 2 way compact speakers (6 inch mid/woofer and fabric dome tweeter) produce an even and smooth marriage between tweeter and woofer. The dual ported Eos HX maintain an accurate and satisfying extension of low-end, especially in smaller listening rooms. Recordings like Count Basie to more modern pop styles of Beach House were reproduced with greater resolution than I had previously heard. Even micro details were more readily heard, but never in an overhyped way. With such a natural sound reproduction of voice and instruments, I found myself hearing much deeper into recordings. The stereo image is quite amazing for a monitor of this size.

I cannot emphasize enough the emotional quality these speakers reproduce. All the attitude and inflection of singers were heard with an obvious transparency.  listening to multiple voices proved to be very revealing, localization and distinctions from singer to singer became more obvious. When I turned my attention to percussion instruments like cymbals, the articulation of attack was easy to hear and subtle differences between strikes were apparent. Cymbals have never sounded so real and fully textured. Whatever the instrument, The Eos HX have an uncanny ability to reproduce it without adding to or smearing the sound. Most importantly, these speakers produced a highly musical and involving listening experience. Without reservation, I highly recommend auditioning the Eos HX.

Pure oxygen free copper directly gold-plated binding posts
Photo from Green Mountain Audio

Further information on Green Mountain Audio can be found here.

Happy Listening!

Green Amplifier Technology Comes of Age


This is the "Greenest" thing I have.

Power Amplifiers for Hi-Fi stereo systems come in a variety of types. Audiophiles often prefer tube or solid state amps, while some like hybrid amp designs.  Having used both tube and solid-state amplifier designs has given me an appreciation for both approaches. Class A, AB solid state*, and tube designs are often the most used amps for high end music playback. I’ll admit that tube amp designs can impart a beautiful tonality on the music, but sometimes the added harmonic content is too much for my tastes.

Although Class D (pulse width modulation) amps have been around since the mid 70’s, they have been mostly used in consumer grade electronics and live sound installations. Many of the home theatre-in-a-box and recent iPod sound docks** also use Class D amplifier technology.

Being energy-efficient, physically small, and running cool makes class D amps very attractive to the consumer market. High end audio companies also took notice. Companies like Lipinski, Bel Canto, NuForce, Wyred for Sound and CI Audio have all worked at making the most musically satisfying class D designs.  The ability to drive most speaker loads and exert extreme control over the speaker drivers make class D very attractive indeed.***

Sonically, I have experienced mixed results with audiophile class D amps. While quiet, fast, and revealing, they can also sound a bit dry or stark. Comparing these current generation class D amps to Class A and AB designs has kept me from recommending any one class D amp for audiophiles.

The Dutch Masters?

A small company in The Netherlands, Hypex, has taken control of the current class D amplifier scene. Hypex  builds many OEM Class D subassemblies that make their way into audiophile amps. A new generation of this Class D amplifier called Ncore is supposed to “surpass the best linear amplifiers – in every way,” according to Hypex. Luckily, 6moons (audio review site) had a chance to try these new modules and speak with the designers. You can read the full article here.

  1. * Audio Amplifier designs explained here.
  2. **Hypex is also known for designing the Class D amp and power supply found in the Bower &Wilkins Zeppelin iPod dock.
  3. ***This is refered to as the Damping Factor of an audio amplifier.