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!

Crane Song Avocet…now you know

Most audiophiles will not be familiar with the brand Crane Song. That’s because David Hill, the chief designer,is known more in the pro audio world for producing quality compressors, EQ’s, AD/DA’s, and mic pre amps. He even tackled transparent audio monitoring with a Class A studio controller named the Avocet. Although other pre amps and monitor switchers exist, the Avocet provides accuracy and features that truly set it apart from other stereo monitor/DAC devices.

The DAC provided on the Avocet accepts sample rates up to 192Khz. This type of DAC locks to an incoming PCM signal and upsamples the data to reduce jitter while then running through a class A output path. The quality and sheer resolving power of the Avocet’s DAC is quite an achievement at this price point. You would have to spend considerably more to surpass the digital conversion contained onboard.

The Avocet ($2,800USD) comes in two pieces. A 2U mainframe houses all the physical inputs and outputs; 3 XLR analog, 3 AES/dual wire,1 RCA digital, 3 XLR analog outputs, and a headphone jack.. The RS232 compliant remote contains square buttons that are color coded. Speaker selection buttons are provided (expandable for surround), while other features include; dim, mute, phase, mono, and 16 bit truncation functions, even a talkback function. The highly accurate volume level is achieved through remote-controlled relays within the main chassis. A large green rotary knob on the remote has 24 LEDs and 2 dB level markings surrounding its perimeter. Even though only 24 LEDs surround the knob, 48 dB of level range is displayed by one or two LEDs being illuminated at a time. All in all, you are given a 48 dB range in 1 dB increments.

All the six inputs buttons serve a dual purpose. Pressing the button once selects that input. When you press and hold that button again, it begins to flash. This indicates level offset mode. Adjusting the level of that input is available in 0.5 dB steps. This is especially useful when comparing various sources. The way a mix sounded prior to the mastered (version) output with levels matched allows a mastering engineer to make qualitative assessments on his or her work. More so, this is a way audiophiles could compare various hardware and software sources. By level matching the two sources, you can easily switch between them and hear possible sonic differences. This is a great way to level match and assess various outboard DACs, SACD players, speakers, even different versions of the same recording.

Whether you work professionally with audio or use various sources to enjoy music, the Crane Song Avocet will provide you with original inventive features while always maintaining sonic integrity. This pre amp/monitor selector truly stands out with features that bring the user closer to the original recording.

-My highest recommendation!

Crane Song Website

Computer Hi-Fi

Achieving bit perfect playback with zero interference is the goal, right? I will use this post to explore my findings with computer based stereo systems. Here’s some of the equipment I tested out.

For this test I used an Apple Macbook Pro for my audio playback system. The Macbook Pro supposedly has better RFI (radio frequency interference) rejection than the Mac Mini. PC’s are also possible playback computers, but this article will relay my Macbook pro experiences.

Building a Hi Fidelity computer based audio server/player can often present some challenges. While iTunes organizes music well, it doesn’t play it back with the highest fidelity. Enter the software developer. In recent years we have seen a variety of playback software come onto the audiophile market. This software, such as Pure Music** and Amarra allows iTunes to open and be used as a GUI while pure music handles all the audio processing. Features like RAM memory playback, upsampling, and turning off handshaking allows digital music to be reproduced with less artifacts/jitter.

Computers are notorious for producing noise. Not only do the fans make acoustic noise, but also the graphics card, processors, and other components produce power line noise. This hash is transmitted down USB, Firewire, and other ports that transmit DC power. The sensitive clocks that produce the sample rate in these USB/Firewire DACs are affected by the noise transmitted down the busses DC leg.

The German-made Yellowtec Puc 2* USB audio interface converts USB to AES for the Crane Song Avocet DAC. Providing clean power to the USB powered AES interface is of utmost importance. In order to tackle this issue I first start by separating the digital and analog audio gear. Shunyata hydra 2 units are used for this purpose. The DAC/Monitor controller gets AC power from one hydra 2, while the stereo amp is plugged into the other Hydra 2. If I had the ability, I would place each of the Hydras on their own dedicated AC circuit. Furthermore, I have the computer on a separate circuit with a surge protector.

Other products exist from companies like AQVOX that allow you to lift the DC power from the computer and insert a separate power supply for your USB device.

I will continue to relay my findings as I explore this topic more. Stay tuned…

The Yellowtec sounds best when operating on internal clock, as do many converters. The Puc 2 also benefits from clean power via the previously mentioned methods.

*The Yellowtec Puc2 is asyncronous and can be locked to an external word clock via AES-3 connection. The Benchmark ADC-1 was tested and provided rock solid clock to the Yellowtec Puc 2. Rock solid when locked to 44.1 and 88.2 via AES-3 signal from ADC-1. At higher sample rates, the Puc2 seems to prefer its internal clock.

**Pure Music sounded best when used in 64 bit mode and power of two upsampling enabled. For redbook CDs that were 44.1 SR, upsampling to 88.2 via Pure Music provided the best sound. The 88.2Khz Clock was provided via the Yellowtec Puc2. DSP functions on Pure Music “off” except for upsampling/meters off and in “Less is More” mode.

*** All USB ports on the macbook and mac mini are not created equal. Some of the ports share other busses such as isight, IR, and bluetooth. You can also disable the IR receiver in system preferences.

A usb cable that separates the DC power leg from the data wires with spacing and shielding is recommended. I use a Wireworld usb cable with this key design feature.