Wednesday, November 13, 2013

High-end Soundstages - Part 1

Stereophony, the reproduction of music from only two loudspeakers, has a history entrenched in early names of the industry like Bozak, JBL, Altec Lansing, Klipsch, and many others. Stereophony grew from Monophony, aka monophonic audio, was the original method of sonic reproduction involving only one audio source (a wax cylinder later replaced with the round disc) and one speaker (a wood or metal horn directly attached to the stylus on a turntable).

Early Monophonic Turntable

With the introduction of vacuum tubes, mechanical amplification was displaced with electronic amplifiers just after electric lighting gained acceptance in homes. Long before the National Electrical Code was born, audio enthusiasts cobbled together amplifier kits from manufacturers such as Heathkit.

Heathkit Monophonic Amplifier

Literally doubling the amount of equipment required, stereophony was initially slow to gain acceptance being viewed by most as a fad rather than a step up in quality or convenience until the introduction of the console model from manufacturers like Zenith, Magnavox, Philips, Grundig, and many others. Consolidating two channels into one chassis lowered production costs and reduced the expense required to double the equipment and cable count. Adding features like built-in reel-to-reel tape recorders with improved electronics and speaker designs found acceptance even in the mid-fi and hi-fi market with its historically-documented and politically incorrect Wife-Approval-Factor (aka WAF). Blending furniture with function allowed stereophony to gain significant inroads into the typical living room providing an acceptable compromise between hi-fi desire and aesthetics.

Early Stereo Console Models

Early high-end component stereophony found its way into state fairs and other public venues where because of the sheer volume of attendees the opportunity for a few to be bitten by the high-end “bug” clearly presented itself. The hi-fi fever gradually grew finding more equipment and more speakers added in an attempt to recreate the feeling of being there. Software manufacturers introduced quality recordings of trains, airplanes, boat whistles, and the like to fuel the fire of this growing industry of audio enthusiasts. Commonly referred to as a “wall of sound,” the early soundstage was born.

Bozak Console Separates

Strictly two dimensional, the wall of sound clearly depicted the ability of two-channel audio to recreate sound from the left, right, or a space in between. This was magic for early audiophiles where sound could be perceived as sound coming from apparently no speaker at all, a first in the hi-fi realm. 

In 1940s, three engineers at Bell Telephone Laboratories (John Bardeen, William Shockley, and Walter Brattain) developed the first theoretical ideas for the transistor that eventually found its way off of the chalk board and into reality. Scribbling down an idea on the back of a napkin during lunch in 1947, Walter Brattain took this crude idea and made it a reality: the first solid state device was born. Called the “point-contact transistor,” this first-ever device still stands in the lobby at Murray Hill, NJ, as a reminder of this pivotal contribution to science.

The First Germanium Transistor

Now that high-heat tubes could be replaced with low-heat transistors, the remaining hurdle with acceptance of high-end stereophony was breached and audio manufacturers started cranking out equipment. McIntosh, Pioneer, Sony, Ampex, basically everyone transitioned to the device and an era in affordable audio was christened. Shortly thereafter, a growing group of high-end enthusiasts started comparing the sound to the convenience and the hard-core high-end audio enthusiast was born. Finding that sonic accuracy was closer with tubes than the fledgling transistor, early audiophiles clung to the sound rather than the sensationalism of transistors despite their drawbacks.

Improvements in loudspeaker design with the introduction of the lower-efficiency acoustic suspension woofer made high-power transistor amplifiers more suitable for driving these power-hungry lower-impedance speakers. Amplifiers with hundreds of watts per channel soon hit the market from manufacturers like Phase Linear, Bob Carver, Crown International, and others.

The Mighty Crown DC-300 Power Amplifier

But louder did not translate into a better soundstage. Frustrated by this diversion into the insanity of miniscule distortion measurements, early software connoisseurs ramped up the technology and introduced a series of audiophile-quality discs focusing instead on accuracy rather than sensationalism. Returning back to the fundamentals, companies like Sheffield Lab, Reference Recordings, Mobile Fidelity Sound Labs, and many others jumped on the bandwagon of what was termed “direct-to-disc” recordings. Removing the intermediate multi-track and mix-down steps in favor of “live” recordings directly onto the lacquer “master,” this software process provided astounding realism to musicians and audiophiles alike. Not only capturing tonality and timbre, a 3-dimensional psychoacoustic illusion of “being there” was also masterfully produced with these early recordings when played through a high-end system.

The Cutting Lathe of Sheffield Labs

Now the hardware and software have achieved a sufficient level of refinement where, along with sonic accuracy, a realistic soundstage was possible revealing not only a left-to-right presence but also a front-to-back realism. The "stage" was literally set. Early pioneers in Europe, Brittan, and the US focused their designs to capitalize on this psycho-acoustic phenomenon and atypical speaker positions helped encourage this highly desirable effect. Soon, the primary focus of a high-end system shifted away from technical measurements and reviewers employed subjective terms in an attempt to describe these observed psychoacoustic effects.

This shift set up an immediate split in the audiophile camp: those who listened with their eyes to electrical measurements and technical data, and those who listened with their ears to the sonic virtues and the ability to recreate this 3-dimensional psycho-acoustic effect (or the lack thereof). Such is the price for preconceptions and belief systems and both camps believed the other to be wrong. This split remains today where huge disagreements persist between the objective and subjective camps using terms such as snake oil and tin ears to describe the other.

But the fact remains that both camps are correct in their own realm. Low distortion of individual pieces translates to higher accuracy but 3-dimensionality relates to an overall system distortion. In other words, individual components that measure well may not reproduce this psychoacoustic illusion as well as other components that measure less well. Therein is the dilemma: what meaningful measurements describe how well a system will create a highly-detailed soundstage?

This is an excellent question and one I will investigate more thoroughly in Part 2 of this description.

Links to the entire series:
Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7

Yours for higher fidelity,
Philip Rastocny 

I do not use ads in this blog to help support my efforts. If you like what you are reading, please remember to reciprocate, My newest title is called Where, oh Where did the Star of Bethlehem Go? It’s an astronomer’s look at what this celestial object may have been, who the "Wise Men" were, and where they came from. Written in an investigative journalism style, it targets one star that has never been considered before and builds a solid case for its candidacy.

My other titles include:

Copyright © 2015 by Philip Rastocny. All rights reserved.

Tuesday, November 5, 2013

A Resistor Review? You Bet!

When it comes to coaxing that last bit of fidelity from your speaker design, sometimes people overlook the importance of the modest resistor. Typically used as attenuators in crossover networks, notch filters, and Zobel networks, resistors play a huge roll in their ability not only matching individual acoustic output levels between multiple speaker drivers but also to uniformly pass high frequency signals. Using inexpensive wire-wound resistors is tempting because of their low price and in some cases they may work fine. But the higher the frequencies that are involved in using a resistor, the more likely there will be an audible effect of using wire-wound resistors as opposed to non-inductive types.

For example, if you are attenuating a screeching low-quality HF driver, you may want to use wire-wound resistors to help roll off the HF content to this driver and tame its fingernails-on-the-blackboard edginess. But if you are using quality home speaker drivers, always use the non-inductive varieties to achieve the most open and natural sound.

The results of using non-inductive resistors in audio circuits are well worth the insignificant incremental price difference. I personally use T-pad attenuators not only to match acoustic output levels of drivers but also to reduce the effects of standing waves between the amplifier and crossover network. Several online calculators are available, of which this one is my favorite:

The issue with the simple resistor is that it is non-linear, that is, as the frequency changes so does the value of the resistor. Some resistors are more stable than others, that being the non-inductive variety. HAM radio technicians understand this issue well where very high frequencies play havoc on stable equipment, but high-end audio gear can benefit from it also. Some folks may say that the frequencies are too high to impact the audio spectrum and with current understanding of the physics involved, they are correct. BUT as it is with thoroughbred horses and formula one race cars, trying to get that extra edge means trying things that are unconventional and certainly contrary to conventional wisdom. Such attitudes win races and in audio, similar attitudes create really good sounding gear.

All resistors "work" and the cost-to-return ratio steepens as audio nirvana is reached. One way to get an edge on this curve is to swap out those pesky low-cost resistors. Give it a shot: they're pretty cheap and you may be surprised what a simple 1:1 substitution will achieve.

Yours for higher fidelity,
Philip Rastocny 

I do not use ads in this blog to help support my efforts. If you like what you are reading, please remember to reciprocate, My newest title is called Where, oh Where did the Star of Bethlehem Go? It’s an astronomer’s look at what this celestial object may have been, who the "Wise Men" were, and where they came from. Written in an investigative journalism style, it targets one star that has never been considered before and builds a solid case for its candidacy.

My other titles include:

Copyright © 2015 by Philip Rastocny. All rights reserved.