Wednesday, February 18, 2015

Shades of Tweakdom

There's a spectrum of potential value in audio improvements and "tweaks."

1.  At the most important end of the spectrum are things that are well understand and known to academic audio engineers, such as frequency response and audible reflections, which often have easily measured effects.  In this area, there are well known things that can be done to get better sound…better speakers, better designed room--including speaker and listening position placement, room mode and reflection absorbers, etc.  Many of these effects can be easily measured…but wrt absorbing room modes, it takes far more absorption (such as filling all the corners out 3 feet) than most people would imagine or tolerate.  Meanwhile, the effect of a tiny bit of absorption might be hard to measure simply because it doesn't have much effect.  Also, contrarians may dispute whether improvements are actually being made--in which case we have kind of a fashion competition, with subjective preferences ruling.  Do you like a more or less lively sound?  In any real room, you will be getting some reflection, and reflection isn't fidelity, but some reflectiveness may make for a more enjoyable experience anyway.  Most important is the quality of the reflected sound--how much does it change the frequency content of the original sound?  And there you have tradeoffs such as trading off the frequency balance of reflection for the total amount of reflection.

2.  Then there are things that have measurable differences that are nearly within the normal audible range, but are generally believed to be below the threshold of audibility for various reasons.  For example, distortion below 0.1% is plausibly inaudible, but many seek amplifiers with PPM or less distortion.  All other things being equal, lower distortion would be better.  All other things, unfortunately, are never equal, high order harmonics may be created by attempting to cancel low orders, etc.  Frequency response to 30 or 50kHz may be in this category as well--it is just a short distance, say a doubling or tripling of frequency, from where people have known hearing ability.

3.  Then there are things which might be measured, such gigahertz frequency response, but have very implausible relationship to human listening.  Many high end cables have alleged benefits in this kind of area.

4.  Then there are things that have a plausible explanation (still plausible to a very open minded scientist, for example) but can't easily be measured.  Here I could think of the benefits of PLL over pulse count detectors.  My information loss theory regarding DS decoders may be hard to measure, certainly it can't be measured with standard technical instruments.

5.  Same as 4., but theoretically impossible to measure the effect.

6.  Things that have an explanation, but not plausible to most serious audio scientists.  For example, quantum field generators.

7.  Things that have no explanation, and are only sold on the words "listen for yourself."  These things may be pure con.  Given the high variability of listening, the placebo effect, and more, many people may perceive a worthwhile change even when nothing useful is done.

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