Tom Cumberland - Engineering
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| Senior Electrical Research Engineer Tom Cumberland in the newest additions to Axiom's testing regimen is a special temperature and humidity chamber. |
Axiom Audio has always been about science and engineering—the science of loudspeaker design and accurate music reproduction, based on careful anechoic chamber frequency-response measurements of prototype speakers backed up by double-blind listening comparisons in our Axiom listening room. Out of Axiom’s research, which evolved from the original standards of speaker measurement developed by Dr. Floyd Toole at the National Research Council Physics division in Ottawa, came a set of performance standards that all of Axiom’s speakers must meet.
Without standards of acoustical and electronic design, where would we be? Very likely in the land of conjecture, smoke and mirrors and casual opinions. The latter, of course, can be fun to read, and over the years have certainly fueled the content of some high-end magazines and web sites. But if a designer or manufacturer is serious about producing superior products, then real electrical and acoustic standards must be applied to measure real performance gains, and disregard those aspects of performance that can’t be detected or heard under realistic playback conditions.
When Axiom recruited Tom Cumberland, our electronics engineer, research and design engineer and resident "conehead," we got ourselves hitched to a serious engineer with impressive credentials dating back to his work with NASA and the US Dept. of Defense, followed by electronics he designed for Luxman, Infinity, JBL, Mark Levinson, Lexicon, McIntosh Labs, Niles, and Bang & Olufsen. Among his many accomplishments, Tom invented the concept of "multi-zone" home audio applications for Lux (he coined the term) and currently participates in a CEA multi-room A/V sub-committee because of his early years doing multi-room engineering for B & O.
Setting Standards
Tom sits on the audio standards committee (R3) of the Consumer Electronics Association (CEA) and co-chairs the Home Audio Board. His input and activities for the CEA and his work for Axiom demonstrate how a small entrepreneurial company can participate in global research and the development of specific standards of measurement for amplifiers, AV receivers and of course loudspeakers.
What is the CEA?The CEA is the preeminent trade association promoting growth in the $173 billion U.S. consumer electronics industry. The Home Audio Division in particular focuses on developing and promoting "the adoption and application of high-resolution audio." The Audio Standards committee sets standards for output testing and measurement of audio components, speakers and audio systems. |
Why Are Standards Necessary?
The history of audio points to many companies playing fast and loose with the specifications and measurements of their products’ performance in order to gain a perceived performance advantage over a competitor. Most everyone has seen ads touting a "1,000-watt" AV receiver in which the power output of all channels is added together with no mention of a distortion specification. (It’s easy to triple the rated power output of an amplifier if you measure it at 10% distortion. This might not bother you in a portable boombox but in a hi-fi audio component, 10% distortion is very audible and fairly horrendous.) Besides inflated claims of amplifier power output, it’s just as easy to claim that a loudspeaker has "frequency response down to 20 Hz" when in fact the speaker’s cone may move slightly at 20 Hz, but if the speaker’s real-world output at that frequency is –15 dB from its output at 100 Hz, you won’t hear the 20-Hz tone. That’s why standards of frequency response qualified by a dB specification are essential to accurately represent real performance in a loudspeaker or a subwoofer.
Axiom at the Cutting Edge of Standards
While all these credentials sound impressive, what sort of influence does Axiom’s Tom Cumberland have on setting audio standards?
With Tom sitting on the R3 board as a voting member, Axiom helped set global standards adopted by the IEC (International Electro-technical Commission) and other technical organizations on loudspeaker measurement, amplifier testing, and defining multi-room wiring. For example, one of the issues currently facing the board is establishing real amplifier measurement standards for the Federal Trade Commission (FTC). How many channels do you measure? Five? Seven? Do you apply the same measurement standards used for the front channels to the surround channels and measure all channels at full power output? "Probably not," says Tom, "because it’s not realistic to expect the surround channels would have to deliver the same high power output as the front left, center and front right. If not, then what weighting do you give to each channel?"
When the new standards are in place, then a manufacturer who claims he has a "3,000-watt" Home Theater in a Box or subwoofer will have to prove such outlandish claims or withdraw them. (Long-term AudioFile readers will know the example is impossible because you can’t draw that much power from a domestic wall socket).
Another standard being developed by the speaker output working group is the all-too-common "20 to 20,000 Hz" frequency response, which is essentially unqualified. The unqualified 20 to 20,000 Hz will be replaced by frequency response specifications qualified by + or - dB, and any claims about high SPL (Sound Pressure Levels) will have to be measured with a new set of standards.
New Standards for Grounding
Tom Cumberland also chairs the Voltage, Impedance and Grounding of Consumer Audio Devices committee. In the past, only standards of voltage and impedance were specified - there have been no standards for grounding, which explains why ground-loops/hum are such a pervasive problem in consumer audio/video. So the new grounding standards should help eliminate ground loop hum which all of us have experienced at one time or another when interconnecting audio and video gear.
