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| December 1, 2004 Controlling BrightnessThe first step in becoming an audiophile is to learn the lingo. Many different terms are used to describe the characteristics of the sounds emanating from our equipment. Many of these terms are borrowed from other senses: touch (e.g., brittle or hard), taste (e.g., sweet), even smell (e.g., stinks). Most audio terms, however, come from the seemingly universally understood sense of sight. The term brightness is one of the more commonly used audio descriptors for an all-too-common problem. To hear one’s system described as "bright" is the kiss of death, even if your system is otherwise excellent. In fact, it is the pursuit of such audiophile virtues as "focus," "detail," and "resolution" that has led many an audiophile down the road to brightness and perdition, for these virtues are frequently accompanied by brightness. What constitutes a "bright" sound, and what causes it? For such a common ailment, there is remarkably little actual description of the problem to be found in the literature; the best I can offer are my own interpretations. A system sounds bright when there is too much treble energy relative to the rest of the frequency range, or when certain peaks in the high frequencies are unnaturally strong. It is rare, however, that brightness problems can be solved by the use of tone controls or an equalizer. A more common cause of brightness is high frequencies that are compressed, confused, smeared, or otherwise distorted. Many of the highest-frequency musical sounds come from percussion instruments such as cymbals. Get the upper range right, and the complex highs of the cymbal have a weight and articulation and are pleasant to the ear. Get it wrong, and the whole presentation is compromised by bright, irritating hash. Many lower-frequency instruments and sounds also depend on an accurate rendering of the highs -- even the bass, which will sound lifeless and dull without good high-frequency reproduction. The first thing you can do to avoid a bright sound is to not, under any circumstances, buy a component that sounds bright. However detailed it may sound, however good the imaging is, however thrilled you are at being able to hear the roadies scratching themselves in the background, don’t do it. Bright components can be exciting in the short term and painful in the long term. Just about any component can impart brightness to a system: interconnects, speaker wires, power cords, CD players, amplifiers, individual tubes, and speakers. This is not very consoling to those who have already purchased one or more components that tend toward brightness. Don’t despair -- countermeasures exist. If your problem is a sound that is not only bright but is thin or light as well, you may need to first address a lack of bass or midbass. Changing an amplifier’s tubes can make a world of difference, as can different power cords, interconnects, and speakers. I tried the top-of-the-line Transparent PowerLink MM aftermarket AC cord; it’s very expensive, but it knocked my socks off with its tremendous bass and solidity. CD players, particularly older or less refined models, can be deadly sources of a kind of brightness nicknamed digititis. This can be particularly pricey to fix; the finest digital sources comprise costly separate disc transports and digital-to-analog converters. Ultimately, the highs seem to be the easiest frequencies to muck up because of their delicacy, their speed, and the large frequency separation between musical tones in the higher registers. Vibration control is a popular way to address brightness. To this end, many different types of supports -- metal cones, rolling balls, rubber feet -- and isolation platforms and shelves are available, not to mention various magnetic and nonmagnetic objects to be placed atop your components, where they damp vibrations, absorb EMF, etc.
Tubes can be grossly microphonic -- tap them with a pencil and you can often hear the tapping through your speakers. And when I tried some weighted rings that fit over the tube envelopes, I heard the frequency-downshifting phenomenon described above. It got me to thinking: How could I damp the vibration of the tube envelope without making it heavier? My answer was to attach bolts around the circumference of the rigid tube guards on my KR amplifier; I could then carefully tighten down the bolts, thus more rigidly coupling the tubes to the envelope and the envelope to the amp’s massive steel frame. I applied a similar solution to the small input tubes, using metal tabs to hold them against the tube guards. It worked famously. Here at last were the liquid, soaring highs I’d always dreamed of. The greater rigidity of this arrangement probably shifted unwanted resonances not down but up, out of the range of human hearing. The downside is that my amplifier now looks as if it has a set of propellers on it and is about to take off. Ah, well; such is the price of good sound. ...Ross Mantle
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I’ve tried many of these
accessories, and I’ve been generally disappointed in the results. I’m not saying
they don’t work -- they clearly shift the component’s resonant frequency around,
usually downward, particularly when more mass is added to the component. This can tame the
highs, but it also tends to roll them off with a loss of extension and "air." It
also moves the grunge downward into the mids, with undesirable results in that region.
Cone feet have more complex effects, but they still shift the resonances around. Still,
I’ve found that vibration-control devices in general cause a loss of the balance of
resonances intended by the manufacturer of the component(s). If you’re using any of
these treatments, try removing them and see if you get a feeling of relief.