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Grado SR60i headphones Exploding A Myth About Headphones

Sidebar 2: Exploding A Myth About Headphones

Headphones are just little loudspeakers—and everyone knows that a loudspeaker with a higher impedance means an easier load for the amplifier. Why, then, do people always assume that lower-impedance headphones are easier for portable players to drive? Because they're wrong, that's why.

With headphones as with speakers, a lower impedance means a greater demand for current from and thus more stress on the amplifier. In combination with high output impedance, a low headphone impedance can lead to alterations in the 'phones' frequency…

Grado SR60i headphones Associated Equipment

Sidebar 3: Associated Equipment

Analog Source: Thorens TD-124 turntable, Ortofon RS-212 tonearm, EMT XSD-15 cartridge.
Digital Sources: Apple iPhone 3G & iPod Nano (fourth generation), Marantz SA-7S1 SACD/CD player, Benchmark DAC1 D/A converter.
Preamplifier: EAR 834P phono preamplifier.
Integrated Amplifier: Leben CS600 (headphone-amplification mode).
Headphones: Sennheiser HD-650, Westone ES3x custom in-ear phones.
Loudspeakers: DeVore Fidelity Gibbon The Nines.
Cables: Digital: Stereovox HDVX. Interconnect: Q-Audio Tao (unbalanced), Chord. Speaker: Auditorium 23…

Grado SR60i headphones Measurements

Sidebar 4: Measurements

As Jim Austin explains, electrical impedance of headphones is a matter much misunderstood—even among reviewers, who, you would think, should know better. (The Internet has brought forth an entire community of reviewers who seem ignorant of the basics of audio engineering.) I examined the Grado SR60i's electrical impedance (fig.1) with my Audio Precision System One and the headphones sitting against my ears. The SR60i has a minimum impedance of 32 ohms, as specified. A broad rise evident in the midbass and centered at 75Hz is presumably due to the drive-unit's free…

Recording of January 1990: <I>Acadie</I>

DANIEL LANOIS: Acadie
Opal/Warner Bros. 25969-1 (LP), -2 (CD). Daniel Lanois, prod.; Malcolm Burn, Mark Howard, engs. AAA/AAD. TT: 41:19

Why is it that the most US-sounding rock/folk musicians almost always turn out to be Canadian? Neil Young, Joni Mitchell, The Band—even Dylan was born and raised only a few miles south of the border. Perhaps there's something about those long grey winters that cramps the ego and keeps you woodshedding just to stay warm.

And now there's Daniel Lanois. Of course, "now" is misleading—he's recorded with Brian Eno, and masterfully produced albums…

Where We Are and How We Got Here

As another Consumer Electronics Show rolls around, we are seeing some interesting and not-entirely encouraging things taking place in the audio field. The people for whom high fidelity was originally intended—so-called serious music listeners —have abandoned audio almost completely, leaving the pursuit of perfect music reproduction to a group of hobbyists who have more interest in hardware than in music. This, plus the recession, has almost killed middle-fi, which is now flailing out in all directions looking for a new market. Here's how it all came to pass:

1877: A Frenchman named…

Wadia 2000 Decoding Computer

Ain't technology grand! That's what I was thinking while driving to work this morning. Sure, the rain was coming down in buckets, but there I was sitting comfortably in a warm car, listening to music while making tracks at 50mph. A long way from horse-and-buggy days.

Then I got to thinking about Thomas Edison and Emile Berliner. What would they think of present-day playback systems? Laser pickups, digital decoders and all. Wow! We've come a long way, baby.

Of course, some of you think otherwise (footnote 1). Digital is viewed, in the high end, as the plague that hit…

Wadia 2000 Decoding Computer Page 2

Digital processing is based on the presence or absence of digital pulses. If we see a pulse, it's a "1"; if we don't, it's a "0." In all our discussions we assume perfect pulses all over the place. Well, the pulses happen not to be that perfect, and with good reason.

Some of the blame has to be laid at the execution of the digital output at the CD transport side. The spec calls for an output impedance of 75 ohms and a pulse amplitude of 0.5V p–p. Why anyone would choose an amplitude that low is a sweet mystery of standards committees; a higher amplitude would be far more capable of…

Wadia 2000 Decoding Computer Page 3

The Wadia 2000 Decoding Computer executes over 72 million instructions a second in order to get the required accuracy for the output signal. Resampling at 64x, at a sampling frequency of 44.1kHz, results in 2,820,000 calculated points every second (3,072,000/s for DAT). The Wadia 2000 solves a 12th-order polynomial 44,100 times a second.

Please bear with me as I attempt to simplify some of the more basic concepts. For now, you can take their word for it: when Wadia calls their processor a Decoding Computer, they are not resorting to hype.

I owe many thanks to Donald Wadia Moses…

Wadia 2000 Decoding Computer Page 4

Wadia chooses to filter the output minimally by slipping a ferrite bead over the DAC output leads for each channel. They feel that the frequency of the residual component is so high that it will be filtered further and eliminated as soon as it reaches the first preamp stage. Don Moses indicated that the effects of more comprehensive filtering could be worse sonically, and chose this minimalistic approach.

The DACs in the Wadia are proprietary 18-bit units, a "transversal, summed-multiport delay-line" design said to have a perfectly rectangular impulse response. The DACs are connected to…

Wadia 2000 Decoding Computer Page 5

All the connections for the processor appear on the rear panel. Here we find the connector for the fiber-optic cable, the three XLR-type connectors for the power-supply cables—to avoid confusion, these are one each of three-, four-, and five-pin types—and the audio output connectors for the two channels. Tiffany RCA jacks are provided for the single-ended outputs, while three-pin XLRs, wired conventionally with pin 2 "hot," are available for the balanced audio outputs.

The front panel provides display LEDs for indicating the selected sampling frequency, the CPU status—"Standby," "…