Audio Equipment--Troubleshooting and Repair Guide
Guide to Troubleshooting Consumer Electronics Audio Circuits
Guide to Troubleshooting / Repairing Electronics Without a Schematic
General guide to Audio Electronics
A few forum-member responses (replies) to several of my posts warranted, in my opinion, this "For-the-record/Self-introduction" message.
From some of the replies my various posts have received, it seems there are several forum members who are ardent supporters of the "bit-is-bits" or "pure scientific" ideologies. To them, and to whom it may concern, I note the following:
With respect to "gauging" the quality of digital audio -- notably: coding (software-only) and processing (hardware/firmware) -- I'm split about 50/50 between what I hear and what can be measured with today's science (please note "I" is stressed, meaning this is simply, humbly my opinion on an ideal (for me) listening/evaluation tactic). In other words, and perhaps in the vernacular of some HydrogenAudio discussions, I claim I'm 50% "audiophile" and 50% "scientist". (I would love to be 100% scientific; unfortunately, I feel this, in the current state of digital-audio scientific know-how, is not entirely possible -- see this note).
For example, I claim I can hear the difference between, say, a mechanically-damped XO clock and an undamped one (1, 2, 3). But, perhaps, only because I've trained myself to do so after years of extensive, comparative, somewhat-exhaustive listening sessions, using myriad hardware, software and techniques. In addition (and perhaps more importantly), only because such anal tweaks are
For the record, these subtle differences that some of us anal "audiophiles" carry on about are just that...subtle. Being able to detect these subtleties are a fun and enjoyable hobby for me because I like DIY and I like to tweak (4). These criteria may not be important to you.
Why engage in subjective ("audiophile") tests, such as those based on unmeasured/(putatively) unmeasurable parameters?
In the early days of digital, when everything was "perfect sound forever", many so-called audiophiles and recording engineers complained about certain qualities of digital sound: it was cold, sterile, lacked micro-dynamics, and lacked image focus.
Based on the specs and sales literature digital manufacturers spewed out then, digital sound should've been perfect, right? In reality, the manufacturers didn't give us all the specs (parameters). Not, perhaps, due to outright deception on their part (though, being marketers and money-making organizations, there were definitely elements of this strategy present), but because certain specs/parameters were:
Here is list of some specs/parameters/metrics that were given more attention in digital equipment, starting in the late 1980s and early 1990s:
Further improvements in digital hardware topology (e.g., better processor chips), analog filtering design and recording techniques progressively and evolutionarily have improved digital sound.
I feel that there may very well be other currently-unknown (or unknowable, with present science/technology) metrics/parameters/tests/techniques, hardware (circuit) topologies, and the like, which may be uncovered or elaborated upon in the future, as science and technology improves and evolves (see 11, 12). Further, certain presently-conducted tests may, sometime in the future, be given more weight when engineering digital software or hardware. When more of these metrics/parameters are "uncovered" or better understood, we will then be able to use more science (and less spooky art) to design better-performing digital hardware/software. So, an important goal of audiophile measurement science and responsible audiophile journalism is associating (and, perhaps, ultimately "assigning") solid metrics to audiophile jargon (17). The ultimate goal is, of course, better, more accurate audio reproduction.
CD vs. SACD vs. DVD-A: Is testing across formats valid?
Objectively, no. Singularly, no. Empirically, maybe. When "maybe"? Audiophile clubs and groups conducting listening sessions -- in which more than one person participates -- are often able to qualitatively (perhaps even quantitatively) gauge various fidelity "metrics". Consensus of opinions in these groups can, I feel, be scientifically valid. It is important that no one in the group have financial interests or stakes in these tests or tested products. Other important factors of a group participant is (but not limited to) having:
Audiophile magazines and web sites
Virtually all pre-manufactured "audiophile" equipment, in my opinion, is overpriced, and very often outrageously overpriced. If you crack open the pages of one of the many audiophile rags -- e.g., The Absolute Sound or Stereophile -- you'll find 'em chock full of such gear.
Better (more honest) audio rags are:
Although most products, reviews, articles and editorials in The Absolute Sound, Stereophile and similar "high-end" audiophile rags are way over-the-top (i.e.: over-inflated in terms of value, price, price/performance; over-exaggerated in terms of audiological differences between components; not to mention, questionable lab tests and their respective results, especially with respect to advertiser-based/political biases), I do concur with the thoughts, opinions and, most important, in-depth technical discussions of certain Stereophile articles. On the subject of "Bits is Bits", for example, I somewhat agree -- in context with my DIY-based, self-designed/constructed equipment approach -- with this 1995 editorial from Stereophile's editor, John Atkinson. An incomplete list of Stereophile articles that I have found especially noteworthy are in the References section of this page.
You may have noticed that I've made several references to Stereophile articles. This is mostly because I have subscribed to it for nearly 20 years and know of certain articles' existence from the print edition. Other high-end audiophile rags, like the Absolute Sound, do not delve into the technical side of audio (i.e., they rely, instead, on mostly subjective opinions and evaluations); I do not respect this type of journalism. Also note that I haven't commented on some audiophile-respected rags such as The $ensible Sound and The Audio Critic (21) . I don't have much experience with these rags so I can't comment one way or another. If they don't accept advertising (I don't know which do/don't), then they'll be less biased for sure. Unfortunately, less-biased as they may be, these lower-budget rags are not going to feature a lot of meaty, technical articles (from free samplers, I noted most feature (rely on) highly-subjective articles and reviews) -- mostly because they do not have access to appropriate ($$) test equipment, labs and other resources. Also, the smaller guys are not going to have access to as much hardware and software for review. Convincing product reviewers need to be able to compare/contrast several similar hardware or software components. It's more important for me to know "CD Player A sounds better and has better jitter specs than CD Player B, C, D, etc.", than "CD Player A sounds better than CD Player C." The latter is more likely to come from one of the less-commercial (= "more honest" ?) rags (but, at the same time, one that has access to fewer similar products).
More-commercial audio/video rags, such as Sound & Vision (formerly Stereo Review) do conduct some technical measurements, but don't go so much in-depth. Also, they tend to like (= not criticize) far too much gear. It's a political game of satisfying their advertisers. Be aware that most of a commercial publication's total revenue (including Stereophile's) is generated by the magazine selling ad space in its pages. News-stand and subscription-based sales do not generate as much $.
What about audiophile web sites?
The best audio web sites are ones with forums (aka Bulletin or Message Boards; see References: Web sites below). This is a great way to look at real-world data. True: you do have to sift through the noise of millions of "unsubstantial" posts and messages to get at the really good stuff. So, learn to use a forum's internal search engine, preferably in the "Advanced Mode". Or, in the Google bar type: "site:www.sitename.com keyword" (or, if you're at the site, type your keyword in the Google search box and click the Search this site icon on the right). With some practice, one can become fairly efficient at this.
In terms of the quality of content, popular audio-review web sites like SoundStage.com or Audioholics.com tend to fall somewhere between quality gamut of printed rags such as Sound & Vision (low end) and Stereophile (high end). There will be biases, of course, toward companies sending web site editors/reviewers expensive gear to play with ... and favoritism towards companies who advertise on these sites.
Also, a web site's popularity, as ranked by search engines, is significantly based on original content. What the search engines cannot yet gauge is the quality and authenticity of this content. Let me point out a specific example form Audioholics.com (a web site purportedly run by electrical engineers and devoted to "Pursuing the Truth"). A while back, this superficially technical article appeared on this site:
Let me select a part of this article for criticism:
"... despite the LP having a lower Total RMS Power, it has a higher Maximum - Average RMS Power . Subjectively [my emphasis], the LP does sound slightly more dynamic than either the Linear PCM or MLP versions on the DVD-Audio disc".
First, for subjective evaluations, "peer-reviewed, double-blind, placebo-controlled" tests -- the only kind that are scientifically acceptable in this situation -- are tough to do by yourself.
Now onto a technical analysis of this article's superficially scientific analysis...
While I'm impressed at the over rigor of the tests quoted above,
the minute they deviate from reporting the numbers we reach this written
technical analysis that frankly is so bad one can only laugh. The
DVD-A version of the recording clearly has as much as 30dB more dynamic range.
Given that, the fact that there is a tiny 0.57dB more "max-average" RMS
power (which itself a barely relevant mathematical construct) is hardly
worth getting excited about. Think about it: every time there's a
pop or scratch on the record, that increases the max-average RMS value.
I could construct a record that "pegged the meter" as it were on max-average
RMS by scratching the hell out of it; does that make it more dynamic?
Investigating further, I noted that Audioholics sourced this
article from a private hobbyist-tester:
Folks...Beware of all these things this as you browse hi-fi web sites.
I can't afford to purchase high-$ audiophile equipment. So I build most of my own (speakers, amplifiers), or modify pre-manufactured gear (e.g. CD players) to achieve a certain level of sonic quality. For example, a portable system I currently use consists of a DIY DAP (similar to (6)), a modded Philips portable CD/DVD player (7), a DIY headphone amp based on Tangent's PPA2 (9), and a DIY DAC (8).
I test DIY and modded equipment with a DMM, oscilloscope, PC hard/software (10) and, of course, by ear. In myriad audio-club meetings, I have compared my self-built/modified gear against commercial stuff. I am convinced that my DIY equipment can produce very high-quality sound.
See References: Web sites below for a list of forums I frequent and/or participate in.
So now you know a little about me. If you have questions/comments/remarks, reply, via the forum, referencing this message.
Why I gave you my background info (i.e. the bottom line)…
... to keep you from wasting your/my time/effort/calories ... and this forum's bandwidth.
If you're responding to one of my posts with emotionally-charged and/or one- or two-lined "cryptic" replies** (like this or this), your posts (henceforth) will be (1st) replied to with a link to this message to familiarize you with my background, preferences, topical interests, personally-important criteria, and style. If you continue to post (2nd - infinity) with the tactic(s) noted above, your posts will be ignored by me (though others may choose to respond). So don't waste your time, effort and calories.
** A brief, cryptic response may very well be acceptable/tolerated (i.e., the message's meaning may be completely non-cryptic) to/by those who are more familiar with your style. Or perhaps, you feel you responded in this way because the answer to my original query/remark is blatantly obvious to everyone (i.e. "common knowledge"). If this is the case, then say so. E.g., if I noted: "Lossy-CODEC-based audio is indistinguishable from lossless." And you reply, "Huh? Get a clue! Here are some links..." You are in the right. But if I note, "Lossy-CODEC-based audio is virtually indistinguishable to lossless, in my experience." And you reply with only, "Huh? Get a clue!," then you are out-of-place as you did not note/acknowledge the context.
Those individuals who wish to gain a deeper, more-technical understanding of the issue are urged to check out Ken Pohlmann's authoritative textbook, Principles of Digital Audio. John Watkinson's The Art of Digital Audio is another book worth topical referencing.
Advancements in post-Red Book digital audio technologies -- in hierarchical order: Revolutionary, Evolutionary, Sub-Evolutionary:
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