Stranded Copper Wire vs. Solid Core Copper Audio Wire

Evidence Audio and Mogami Balanced audio cables

Stranded Copper Wire vs Solid Core Copper Audio Wire

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.

Project Nourished

I am currently designing the sound for a gastronomical VR experience. Participants will wear a virtual reality headset and use tracking enabled utensils while aromatic components and sound stimulate the mind…or trick the mind. Please visit the Project Nourished website to learn more and stay up to date on developments.

Project Nourished Virtual Reality

Project Nourished Virtual Reality

Channel Islands Audio D-500 MK II Monoblock Amplifiers

CI Audio D500 MK II front

CI Audio D500 MK II front

Audio power amplifiers provide the juice or alternating current for our speakers to move in and out, creating positive and negative pressure (Sound). This electromagnetic induction
relies on the marriage of speaker drivers, cabinets, crossovers, and, of course amplifiers. While various amplifier topologies exist, designing one that accurately portrays music can be a challenge. Channel Islands Audio, has been cooking up high-quality audio designs for over 18 years, and I recently had the opportunity to audition a pair of their 500 watt monoblock amplifiers. The Channel Islands Audio D500 MKII mono block power amplifiers currently in their 2nd iteration have been powering my system for a couple months now.

Channel Islands D-500 MK II monoblock amplifiers

Channel Islands D-500 MK II monoblock amplifiers aerial view

The Class D design of this audio amplifier allows it to run very efficiently. In fact, they run cool to the touch. I can recall many class A amplifiers that raised the room temperature by several degrees, add a room full of studio equipment and you get a hot and sweaty audio engineer- no fun.

The foot print of a D500 MKII is a tidy 8.5

The foot print of a D500 MKII is a tidy 8.5″w x 4.0″h x 13.5″d

Each amplifier and massive power supply is housed in a separate steel frame and aluminium chassis. Don’t think you have room for monoblock amps? With a height of 4 inches and a tidy footprint of just 8.5 wide by 13.5 inches deep, these amps will tuck away more easily than you think. The casework is tight fitting aluminium with non-magnetic steel hardware and an On/Off push button with a blue LED surround.

Rear XLR or RCA inputs and speaker binding posts, IEC power, triggers

Rear XLR or RCA inputs and speaker binding posts, IEC power inlet, triggers

Moving to the business end, the D500 MK II provides XLR or RCA line-level inputs, 5-way speaker binding posts, trigger inputs, and an IEC power inlet. For my listening, I connected to each amplifier via balanced XLR connectors from my monitor controller. I used a pair of 2-way (1st order xover) speakers for listening and a well designed room at a hollywood mastering studio. As far as after market power cables go, we found these amps sounded best/most balanced with the cord supplied (i.e. nothing fancy).

After warm up, we fed a variety of studio quality masters through these monoblock amplifiers. I started with a favorite, Muddy Waters Folk Singer. In this hard panned early stereo recording very distinct tracks of guitar, vocal, bass, and drums can be easily distinguished. A great recording true, but the dynamics of the vocal really stress the ability of amp and speakers to communicate the space (echochamber at chess records) and impact of this album. The CI Audio amps did not let me down. Not only was the control over the music’s dynamic fluctuations handled well, but they did so with ease and lightning fast response. Hearing the space around the music is important for feeling an honest connection to the performance. No where is it so obvious as with Mumtaz Muhal, a stereo recording done in a chapel with three musicians. This recording features Taj Mahal performing songs like Stand By Me with Indian classical instrument accompaniment. The Mohan Vina, a slide-like sitar follows the vocal massaging of Taj Mahal like a second voice gently ascending. The natural space of this recording is preserved and replayed over the CI Audio monoblocks with all the emotional connection and tone intact.

Playing back a 24/96 transfer of Stevie Wonder Songs in the Key of Life showed how these little beasts grip your speakers and provide extended tight bass. Listening to the track I Wish showed off these amps ability to clearly portray all the tracks in this loaded mix. A wide and appropriately deep soundstage was achieved using the D500 MK II amplifiers. Even when the overall sonic energy of a song’s mix was full, these amplifiers reproduced clearly and without any strain. Side Note: I’ve been playing these amps for over 8 hours and they are cool to the touch!

Listening to full orchestral pieces from Beethoven’s 9th symphony truly showed off these mono block amplifiers ability to further handle complex and dense musical passages. The quietest passages arose from a black background and when the double bass stepped in, it did so with stride and control usually unheard  in my small speakers. Through the roll of the timpani and onward, the full orchestra was handled with an even and accurate tone. Localization of instruments was obvious and portrayed the stereo microphone technique clearly.

For a wider variety of instruments and sounds I pulled out Beck’s Sea Change and Tom Wait’s Swordfishtrombones. Reproducing the raspy voice of Waits or the somber melancholy stylings of Beck, The D500’s were true to all the fleshy midrange detail. Moving up the frequency range, even the extended response of cymbals was smooth and never overly bright or etched.

While we did not have other speakers to directly power from the CI Audio amp, we did have several other systems in place for monitoring audio. The Lipinski Sound amps and speakers were compared to the Channel Islands Audio amps and GMA Eos HX speakers. Myself and other engineers concluded that the sound of each system were both resolving and usable. The Channel Islands D500 MK II proved to be a clear musical amplifier with a place in the audiophile as well as professional markets. Happy Listening!

Channel Islands D500 MK II Specs:

Power Output 500 watts @ 8 ohms/800 watts @ 4 ohms Bandwidth 50kHz

Frequency Response10Hz – 20kHz, +0dB/-0.5dB

Damping Factor>1000Input Impedance100k ohms Gain 38db or 32db

Dimensions 8.5″w x 4.0″h x 13.5″d

Weight 28 lbs (each)

Warranty 5 Year Parts & Labor

Associated Equipment: Crane Song Avocet, SADIE, Lipinski Sound, GMA Eos HX

EQ Your World with “Here Active Listening”

Doppler Labs just raised $17 million to produce a wearable bionic hearing device. Here Active Listening is being dubbed the first true “hearable tech.” These are not earbuds for listening to music, but rather a kind of bionic hearing device for engaging with real world sounds around you. By using two ear buds with microphones and internal processing, an individual user can curate his/her own listening experience in various acoustic environments (with the aid of a smartphone app). Noisy environment, bad mix at a live concert- any situation where you are engaging with real-world sounds.

Here, Hans Zimmer (film composer) discusses the future of sound and how wearables may change our perception of sounds around us:

Trance sounds of the Hang Drum and Gubal from PANArt Hangbau AG

-Historical Background

Originally conceived (early part of the 2000’s) in Bern, Switzerland – the Hang drum is a steel melodic percussion instrument that can be called a musical sculpture. From what I understand, sheet iron is chemically treated to craft this saucer-like disc instrument. The evolution of this musical scuplture has brought forth a new design called the Gubal, also designed and built by PANArt Hangbau AG. The initial  percussive attack and subsequent resonant pitch stands alone or with other musical accompaniment. Information about the (no longer produced) Hang Drum and the newer creation, Gubal can be found hereFor authentic (rather lovely) sound recordings of the instruments made by PANArt pleases follow this link.

Demonstration of another Hand Pan Design:

This video demonstration of the Gubal and how each person’s touch brings out a new expression. A meditation for the player and listener.

-And now for the gorgeous Gubal with saxophone accompaniment:

The Focal Spirit Professional – Accurate/Natural Sounding Closed Back Headphones


The Textured Finish of the Spirit Pro

The Textured Finish of the Spirit Pro

The bottom line for most field recording engineers goes something like this: “what I hear, better be what I get on this recording.” While great microphones are responsible for the actual pick-up of sound, an accurate pair of headphones is the key ingredient to making sound judgements. Whether one intends to record dialogue or stereophonic information, truly hearing the microphone(s) is essential for quality recording. Strapping headphones over your ears is always a compromise when compared to listening over speakers/monitors, but in some environments it is just unavoidable.

Enter the Spirit Professional headphones from Focal:

Over the past several years Focal has introduced several headphones, and their latest offering is aimed at the professional audio market. These cans sport a textured black spackle-paint for durability and memory foam headband/earpads. The speaker drivers are made of a mylar/titanium material which claims to have a balance of rigidity/lightness and high damping properties. All this engineering is to ensure the transducers are capable of delivering dynamic natural sound reproduction.

Fit and Comfort:

The shape of the ear pads are circumaural, that is, they are designed to rest around the ear. After using these headphones for weeks in the field, I have to say they offer excellent passive noise isolation, but the ear pads tend to press on the outer edges of my ear more than say the Sennheiser HD-600 circumaural design. While the foam used is comfortable , I find the pressure coupled with the slightly smaller pads to limit my use to 45 min- before removing them for relief. This is not a complete deal breaker, as I don’t wear headphone all day and often remove them when between recording takes. Still, if maximum long term comfort are your goals in a sealed headphone, you may want to investigate other options.


My first test for these headphones involved using direction microphones. Both Schoeps cardiod and shotgun mics were employed to record a variety of male and female voices in various acoustic environments. Schoeps are know for having an even frequency response across the polar patern. Even so, I was impressed with the Focal Spirit Pro’s ability to translate the slightest of off-axis positions to the human voice being picked up. Yes, the Schoeps have a wider sweet spot than most directional condensers, but getting the best position was aided with use of the Focal headphones.

The Spirit Pro’s also held up well when making stereo microphone adjustments. When I found myself without speakers to monitor, the Focal’s presented enough front-to-back depth and imaging to make appropriate balance adjustments. I certainly still prefer to do this type of balancing with speakers, but to my surprise the Focal’s closed-back design permitted me to hear into a recording, rather than just being a completely flat soundstage, or blob of sound. These headphones also have an excellent frequency response. Even though they are strapped close to your ear, I could hear problematic rumble from infrasound and wind more easily than my previous Sony 7509/7510. With Sound effect recording, these cans reproduces all the nuance that I so often find glossed over with professional headphones.

Focal Spirit Professional-circumaural, memory foam, detachable cable

Focal Spirit Professional-circumaural, memory foam, detachable cable

Listening to Music: 

For the audiophile or music lover that insists on headphone listening, the Spirit Pro’s tell the truth. That is, flaws in recordings stick out, and well engineered recordings sound gorgeous. The comfort of these headphones will prevent most users from wearing them for long periods, and the precise nature of the Focal’s means that most details are more upfront than cans like the Sennheiser HD-600( I know the HD-600 is an open back design, but still a reference from my orchestral recording). As an engineer I don’t mind that the Spirit Pro’s aren’t as gentle or sexy as the HD-600’s. Rather, I’ll take sheer resolution over a laid back sound.

Aside from my own recordings, I chose some familiar recordings such as Buena Vista Social Club, Karajan Beethoven. For Modern recordings I used tracks from Beach House and Stereolab. Listening to orchestral recordings made in halls with lovely acoustics sounded fantastic on the Focal Spirit Pro. Where as modern pop recordings could sometimes benefit from the gentler presentation of the HD-600’s.  While engineering decisions could be made with the Sennheisers, I felt the Focals’s allowed me to more readily hear any issues going on with a recording. For pure listening pleasure, I might look elsewhere as the Focals are more a tool than a pure pleasure listening headphone.

Included Cables; coiled, straight w/ smartphone mic, 1/4 screw on adapter

Included Cables; coiled, straight w/ smartphone mic, 1/4 screw on adapter

If you are looking for a headphone that will help you make decisions about mic placement and EQ adjustments, then the Focal Spirit Pro ranks high in my book. In addition to being solid and neutral in sound, they also do a superb job with passive noise isolation. On the other hand if you are more interested in long term comfort I would look at other models. Even though I have been disappointed with headphones for making sonic decisions in the past, I can clearly say the Spirit Pro gives me an assured even response that allow me to work effectively and efficiently.


Associated Equipment:

Sound Devices 744t

Great River MP-2NV

Benchmark Media ADC1

Crane Song Avocet

Meridian Explorer