Preventing Hearing Damage

Noise pollution is all around us, especially in the major cities of the world. experiencing this cacophony of sound is often disorienting and fatiguing. From the moment we step out our front door we are bombarded with a cluster of city sounds. Unlike our eyelids, we cannot close our ear canals with similar organs. Rather, we must voluntarily use a device that will reduce the passage of sound into the ear canal – earplugs. It makes you wonder if we had “earlids,” would our hearing be better?

– Headphones/Earbuds

The use of portable music players/Ipods allows us to drown out the sounds of the city. These earbuds and headphones serve two purposes. First, they provide music reproduction for listening pleasure. Second, they passively (and sometimes actively) reduce sound from the surrounding environment. While reducing unwanted noises is welcome, directly injecting sound into your ear can pose some risks.

Although hi-fi speakers can be turned up to ear damaging levels, they have the advantage of not being strapped directly to your ear canal. Even more, speakers produce sound that travels through the air before it reaches your ears. Since air is an excellent absorber of sound, the overall sound pressure level will be reduced before it hits your ear drum. Private listening sessions on headphones and earbuds can be enjoyable, but you must excersice caution not to listen too loudly. A great article on “preventing hearing damage with headphones” can be found here.

–Hearing Protection

Our hearing is an integral tool used for communication, balance, and localization. The human auditory system is truly remarkable and sensitive. An audiologist can advise you on hearing protection options to help maintain the longevity of your hearing.

Happy Listening!
Photo by: Vahan Baladouni

Advertisement

A Great Album Revisited

Bill Frisell/gone, just like a train

One day I was looking through the CD section of Tower Records* when some album artwork caught my eye. Bill Frisell/ gone, just like a train  with album art by Jim Woodring  was just begging to be listened to. Being familiar with Jim Woodring’s art prompted me to take a chance on this album. Bill Frisell is often classified as a Jazz guitarist, but his sound is full of folk, blues, and rock influences. More importantly is how Frisell weaves these styles together with a gracefulness that is soulful and sweet.

With Victor Krauss on bass and Jim Keltner on drums, Bill Frisell (guitar) creates an intimate and mysterious sound that carries the listener away. Guitar notes echo by and shift in pitch while a solid upright bass keeps moving along. Jim Keltner (drums) maintains the syncopation while adding his own signature to this wavering soundstage. Without mistake, this see-saw of sound and melody is enchanting while also very familiar.

The first track, Blues for Los Angeles**, starts off like as a train building steam. Slowly, but steadily this trio pulls out for the long drive.  Rhythmically being held in check by Keltner and Krauss allows Bill Frisell to paint the town with his powerful guitar improvisations. Soon we are greeted with huge bluesy guitar tones that pour out of an enchanting and deep stereo field. Careful not to overplay, Frisell manages to strike a tasteful sustaining of notes and silence just where it fits the music.

Another great track, Lookout for hope, starts with a repeating bass line while the drums slowly slip into the beat. Not long after, Bill Frisell plucks a few notes, then begins the melody. You are carried through this journey with steady deep bass and drums that scatter and realign the song’s direction. That direction of music, so well maintained by Frisell, allows these musicians to explore the haunting melody.

Other tracks, such as Verona, Egg Radio***, and Girl ask Boy (part 1 and 2) have a familiar blues/folk influence while also keeping a uniqueness all their own. The bottom line is that Bill Frisell delivers with this album on all fronts. Musicianship is grade A, song writing is amazing, and the recording is exemplary.

*Tower Record was a retail store that sold physical media that contained music recordings for the public to buy.

**Song sample here

***Song sample here

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.

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.