Benchmark’s AHB2 Stereo Amplifier

DSC00383

Achieving the full performance/responsiveness out of my speakers has motivated me to examine various amplifiers designs lately. In this quest to squeeze the last sound molecules from my speaker drivers, I have been comparing class A, Class A/B, Class D, and now this hybrid Class H and AB design from Benchmark and THX.

Delivering clean power with an exceptionally low noise floor are the key ingredients to Benchmark’s new Amplifier. The AHB2 is a 2 channel audio amplifier with 100 watts of power into 8 ohms, and 190 into 4 ohms(bridged mono mode 380 watts/8ohms). This super quiet amplifier topology allows for a signal-to-noise ration of 130dB unweighted. The distortion is also quite low, at 0.00011% THD in stereo mode.

With a clean and tidy footprint, The front panel allows access to 1 power button, and several LEDs that indicate proper operation. Benchmark built into the AHB2- a power supply fault protection to monitor voltage, current, and temperature. If issues arise, the fault circuit mutes both channels to protect the amplifier and speakers. The clip lights will illuminate when occasional clipping is present (something that never happened for me), and the fault protection kicks in when severe overdrive occurs- to protect speakers.

DSC00387

On the business end of things, connectivity is straight forward. Other than the addition of Speakon connectors, the Balanced XLR inputs and speaker terminals are standard. One dip switch on the right controls mono or stereo operation, while the 3 position switch on the left controls input sensitivity – a welcome feature. Matching the input sensitivity allowed me to optimize the Gain control between Avocet monitor controller and the AHB2.

Technically speaking, the AHB2’s Vanishingly low noise floor can be compared to the dynamic capabilities of a 22-bit digital system. Most current professional and audiophile DACS can also achieve very low noise floors – a match made in audiophile heaven.

I used the Crane song Avocet and several other DACs to feed Balanced stereo program material to the AHB2. For speakers I used my Green Mountain Eos HX 2-way speakers. All cabling was balanced solid core copper.

DSC00408

The tidy AHB2 Amp runs cool

I gave the Benchmark amplifier some time to warm-up and have had it in my system for several weeks. My initial reaction was in the form of a grin, as I heard my music amplified in a clear and coherent manner. The extremely low noise floor became revealed as orchestras truly faded to the acoustic space and black was truly black – no residual noise whatsoever from speaker drivers. Even more obvious was a clarity to the amplification. This amplifier runs like a high-performance sports car. I was amazed at the AHB2’s ability to keep up with dense music mixes and never sound congested or lacking. In fact, this tidy beast produced some of the tightest low end I’ve ever heard in my 2 way speakers. The midrange was articulate and clear with an obvious clarity that bested my current class A/B amplifier. Extending to the high frequencies were equally clear and distortion free, no hype here- just honest clear reproduction.

Listening to Beck’s “Morning Phase” (24/96) was ear opening and lovely on the AHB2. The track “Morning” enters with  acoustic guitar strumming and stereo vocals, and leads into lovely strings with reverberant stereo space all around. Even with this wash of sounds, the hit of the Floor tom, or the crisp full fleshed out sound of the snare was colorless and clearly projected.

The Royal Liverpool Philharmonic’s performing Hovhaness’ Mysterious Mountains (Telarc 16/44.1) was sublime. Mount St. Helens Andante, Grazioso unfolds gracefully and with tip top double bass walking the piece along. The bass holds true and rings out even as the full strings come into glide the momentum along. The expansiveness of this orchestral recording is deep and wide with excellent localization. Acoustically, the AHB2 performs so cleanly and quietly that it resolves the hall and space between musicians distinctly- something professional engineers and audiophiles can equally appreciate.

The Benchmark amplifier allowed for dense music mixes to be fully appreciated. Micro-dynamic detail was never lost or distorted, even as complex passages competed. Orchestral and Popular music mixes equally excelled on the AHB2 with authority, control, and balanced sonic presentation. If you are looking for an amplifier that can reveal your source material and DAC without flinching, then the AHB2 is a top choice.

Happy Listening,

HiFiQC

 

Benchmark Media’s AHB2 Audio Amplifier

FrankAHB2

Frank reveals the Benchmark Media AHB2 Audio Amplifier

For the past couple weeks I’ve been auditioning the Benchmark Media AHB2 amplifier, and will be featuring a full review soon. Inside the tidy footprint and magnetically shielded casework of the AHB2 are a host of unique advances in audio amplifier design….and boy is it quiet!

Stay Tuned -HiFiQC

Allen Toussaint 1938-2015

A Young Allen Tousaint

Allen Tousaint 1938-2015

Yesterday, Allen Tousaint passed away after playing a concert Monday night in Madrid, Spain. Toussaint was a a prolific song writer, performer, and producer. His contributions to music are numerous. He nurtured and produced some of my favorite New Orleans artists like The Meters, Earnie-K-Doe, and Dr. John. Thank you for enriching the lives of so many, you will be missed.

Get Out My Life Woman, Allen Toussaint

For more about Allen Toussaint listen to Gwen Thompkins and Music Inside Out.

Crane Song Debuts Avocet IIA with Quantum DAC at AES 139

Crane Song Avocet IIA with Quantum DAC

Crane Song Avocet IIA with Quantum DAC

While I was making my way through the exhibition floor at AES139, I ran into owner/designer, David Hill of Crane Song Electronics. I have been a user and big fan of Mr. Hill’s designs and today I was in for a treat. The Avocet monitor controller had undergone some upgrades and David Hill was excited to tell me about it. I was first treated to a comparison of the upgraded DAC, and then we shot a short video describing the various updates to the Avocet IIA Quantum DAC.

My first video for HiFIQC

139th International AES Convention

Audio Engineering Society's 139th Convention

                                             

Professional audio users from around the world will descend on New York’s Jacob Javits Center next week. The 139th Audio Engineering Society convention will surely be a treat for the ears and eyes. I will be doing the ground work, covering new developments and product releases. Microphones, amplifiers, digital converters, EQ, compression….Keep it tuned to Hi-Fidelity Quality Control for all the latest AES news, from the floor.

Solid Core Copper vs. Stranded Copper Audio Cables

Solid Core Copper Cable by Evidence Audio

Solid Core Copper Cable by Evidence Audio

The way audio cables are constructed can certainly make a difference to their sonic characteristics. Over the past several years I have been comparing the sound transmission characteristics of different copper conductors. In addition to the conductors, different geometries, dielectric material, and shielding can make a cable sound different. While these can influence the sound, I feel the primary sonic impressions I have been hearing have to do with the interaction of conductors carrying an audio signal. Using both stranded copper and solid core copper audio cables in a variety of setups has allowed me to hear the differences.

Stranded Copper Wire

Stranded Copper Wire photo from Jimmy’s Junkyard

We use stranded copper wire in pro audio applications for a  couple of reasons. One main reason is that flexibility is important when dressing microphone and instrument cables. A stranded cable will be much more robust when repeatedly coiled up and unwound. The many strands of thin copper can withstand more bending than a single solid core copper wire. It’s the transmission characteristics that differ. With all those strands the signal tends to jump from strand to strand, and with a single solid core conductor this cannot occur. The sound characteristic of stranded copper vs solid core may seem minute, but any well trained ears should hear the difference. This example from Evidence Audio compares stranded monster cable vs. their solid core cable using a bass guitar.

SG

Gibson SG with Evidence Solid Core Lyric HG

Having heard the difference between stranded copper and solid core copper in my pro audio monitoring chain, I was curious to examine the sonic difference with electric instruments. For this, I employed the help of a 1973 Gibson SG and a Dr. Z MAZ 18 (non-reverb version) tube amplifier. After playing for some 30 minutes with a Mogami stranded copper cable, I switched to the Evidence Lyric HG. My first impression was that a haze had been lifted from my guitar sound. As I continued to dig into this new-found sonic experience I also noticed that my SG had become more responsive to my playing. Rather, a dynamic contrast now clearly existed and I was in control of the shading.

Switching back to the stranded copper cable immediately sounded blurred. The word that comes to mind is distortion, or disruption of the original signal. The guitar sound was now less pure. I want to avoid using words like darker or brighter, because what I was hearing had to do with the signal integrity. Yes, the stranded cable might sound darker, but I feel blur is a better word. On the other hand, the solid core guitar cable was clear and did not adding anything to the original signal.

A4

Analog Synthesizer with Evidence Audio Solid Core Cable

To further examine the sonic benefits of solid core copper cable, I pulled out an analog synthesizer. The Elektron Analog Four is capable of producing a variety of sounds with its analog oscillators, filters, and beyond. For this test I chose to use a simple sawtooth waveform and  a sub oscillator from this analog synthesizer. After using the stranded Mogami cable for the initial listening, I swapped it out for the Evidence Lyric HG balanced cable. The clarity of the sawtooth wave when transmitted over solid core wire was evident, but when I began adding sub harmonic oscillators, the difference truly stood out. Sonic integrity comes to mind. While adding sub harmonic oscillators to the original sawtooth waveform I was very pleased to experience a more (obvious and clear) layered sound.

These solid core cables from Evidence audio truly allowed me to hear the various harmonic additives I was creating on this synth. Moving back to the stranded copper showed me that the full tonal characteristic of the synth was lessened to a degree. Adding in the sub harmonic oscillator with a stranded cable is easy to hear, but the delineation of harmonic content (clarity) was not as good as with the Evidence Audio cable.

Happy Listening!

Stranded Copper Wire vs. Solid Core Copper Audio Wire

EvMo

The way audio cables are constructed can certainly make a difference to their sonic characteristics. Over the past several years I have been comparing the sound transmission characteristics of different copper conductors. In addition to the conductors, different geometries, dielectric material, and shielding can make a cable sound different. While these can influence the sound, I feel the primary sonic impressions I have been hearing have to do with the interaction of conductors carrying an audio signal. Stay tuned for a full write-up on stranded copper vs solid core copper audio wire.