We’re spoiled rotten! Audiophiles have a wealth of riches at our beck and call, many of which deliver performance within a hard drive’s throw of the best you can get for far less than the cost of traditional top tier products. If you’re thoughtful, patient, and realistic, you can acquire the components of a wonderful computer-based audio system that provides 90+% of the sound quality and functionality of “the best” for about 10% of the cost. Just do your homework, which now includes reading this series!
CONTENT AND APPROACH
Almost all Audiophile Stylers know far more than the average bear about consumer audio, and more than a few can teach the rest of us a fair amount. But this series takes a structured approach to the subject, so a uniform fund of knowledge among all readers and participants may add extra value to the effort of reading it.
We begin with a discussion of the origin and maturation of home audio, putting evolutionary emphasis on the structure of audio playback systems and the essential elements comprising them (including the functions they provide and their relative costs). This includes a comparison of analog and digital systems based on the signal path from archived source material to your ears.
After we lay out the systems and processes in simple terms, we’ll examine each node on the signal path in detail. We compare multiple hardware and software alternatives for each, after 5 months of downloading, installing, buying, borrowing, tweaking, combining, and generally wringing out dozens and dozens of devices and programs.
We start with retrieval of static archived files and their conversion to the clocked, dynamic data streams that serve as input into the system. We look at front end hardware and software in separate articles, installing, evaluating and comparing several of the open source software players you can install on current devices like SBCs. We include legacy devices like that old laptop in your closet, many of which can still pump some fine sound files into your system, especially if made after 2003 (the start of generally available 64 bit home computing).
We move through the playback chain to line level digital-to-analog conversion and the many inexpensive alternatives for getting digital music files into analog amplifiers, including both onboard DACs in motherboards and several “digital interfaces” designed and sold for use by musicians for digital recording. We also include several surprisingly fine, basic audiophile DACs priced under $500.
Once the data file leaves the front end as an analog waveform, it’s just another line level AC signal seeking volts and amperes to power the engine that pushes audible air pulses to your ears. As this part of the signal path is the same for analog and digital source reproduction, there’s already a wealth of information out there on pure analog amplification. We’ll confine our discussion to equipment with specific advantages and suitability for use in computer-driven systems.
Of more interest here is a large and growing market for digital amplification from source file to output, with conversion to analog occurring only in the output stage. More and more such devices are reaching the market at prices that make them ideal mates for SBCs, legacy devices, white box PCs etc. Many are found in the pro audio and recording sections of musical instrument stores. Some are sold for sound reinforcement or other industrial uses, and they compare well with more expensive consumer pieces. The manufacturers may be unknown to home audiophiles, but many are pillars of pro audio.
The last area of interest is the “bargain bin”. A lot of high quality professional audio equipment is available at very low cost because it was discontinued, traded in, pawned, or otherwise disposed of in a nontraditional manner or location. Amplifiers like the Alesis RA100 and the Stewart PA100B can be bought used for under $100 in excellent condition – and they sound far better than most products sold new for anything close to that price. The astute but impecunious audiophile can free up crucial dollars for more or better stuff by buying wisely. So we scour pawn shops, sale racks, used equipment bins etc to find worthy bargains.
HISTORICAL PERSPECTIVE
This is not about being cheap for cheap’s sake. It’s about the new value proposition in audio: sound quality and cost are no longer directly proportional. At the dawn of hifi home audio, price was a fairly accurate reflector of quality. I built my first amplifier for less than $10 from parts I bought at Radio Shack in 1958. The 1958 RS catalog offered a 10 watt Realistic integrated amp for $30, while an Eico 50 watt integrated amp was $70 as a kit and $110 assembled. A Dyna MK III (a womderful 60 watt power amp) was $80 as a kit and $100 assembled – and the Dyna preamp was $40 as a kit. In the same catalog, a Mac C preamp and MC60 power amp were a combined $300. For reference, the newly introduced Chevy Impala started at $1735 and median US household annual income was about $5k.
We first year baby boomers were literally born with and grew up alongside the phenomenon called “high fidelity”. Equipment got better and better, and there was more & more variety in each price category. And the cost structure of retail audio stayed about the same well into my college years (mid-1960s). My first “proper” stereo amplifier was a Realistic SA-203 I bought for $15 assembled, and it went to college with me in 1964. But Radio Shack had an after-Christmas sale that year, at which I got Eico stereo preamp and 70 watt power amp kits for about $100 and built them both in a 2 day binge during our intersession break. That was serious money for a college freshman in 1965 (as was the $35 I got paid for playing the guitar at a wedding) – and it was also seriously good sound! For reference, median US household income had risen to $6900, and $100 in 1965 are worth $810 dollars today. But today, you can build a computer-based system with excellent overall sound quality, wonderful ease of use, and amazing flexibility for even less.
AUDIO SYSTEMS, THEN AND NOW
The same options exist that we had 50 years ago - systems can be assembled from components or integrated in one box - with speakers, if so desired. At the dawn of “high fidelity”, we had entire systems in self contained consoles:
We still do. They take up a lot less space, but they serve the same purpose – they play music well for people who want a one box solution.
Serious audiophiles could assemble component systems of amazing complexity back in the day...
...and we still can:
The choices are equally varied and exciting, and the building blocks do the same things whether analog or digital. They turn a stored image of music into a living presentation of the original performance. But size no longer matters. Cost correlates less tightly with sound quality. Most of us can have audio that pleases us greatly in smaller, less expensive, less complex systems than ever before. This series is a guide to finding the stuff that will do it for you in some of the simplest, least expensive packages possible.
THE ESSENTIALS
In the digital age, we no longer have to buy dedicated audio hardware to listen to music at home. A computer, tablet or smartphone will do the job with no added hardware beyond external speakers if needed and/or desired. No additional purchase is necessary to stream internet radio or play CDs and digital files - it’s never been easier or less expensive to listen to music at home! Most of these devices come with at least one music player embedded in the installed software. Beyond these, there are many open source alternatives available at no cost, to give you alternatives for functionality and user interfaces. I can’t encourage you enough to support the creators and maintainers of the open source software you like. Visit their web pages and consider a donation (no matter how small) to help them do more.
You can get pretty good sound from your computer with a little tweaking and a nice pair of powered speakers. But once you decide to go beyond your legacy devices for audio, the sky’s the limit. There are many excellent choices among the parts of a modern audio system, and sound quality improves far more rapidly than cost, especially at the lower end of the spectrum. As that relationship often reverses in the upper reaches of cost, the thrifty audiophile can decide how much is enough…..and stop there. Once you understand the components of an audio system and their functions, you can make some great sound for peanuts. In most categories, 85 to 90% of the best possible sound can usually be had for 10 to 15% of the most expensive alternative.
Some of you are asking “How is this possible?”, while others are muttering unkind things about me. If you’ll all suspend disbelief for a little while, many of you will find some useful information you can use to optimize your sound while meeting your budget and expectations.
SYSTEM STRUCTURE
The basic architecture and function of home audio systems haven’t changed at all: program material enters the system from storage media and is optimized for transformation into an audible signal of air pressure waves pushed to the listener by transducers at the other end of the signal path. We just do it differently now, in ways that add tremendous value at every point in the signal path.
Analog sources are tangible representations (physical, electromagnetic, optical, etc) of program material, while digital sources represent the exact same material in data streams. Both analog and digital archives have to be optimized and transformed into a stream of pulsatile air pressure so we can listen to them, and the stages are functionally similar despite drastic differences in how they work.
Designing and building systems to convert program material into audible sound requires both strategy and tactics. Strategy is an action plan for achieving a goal, and tactics are ways of using available resources to implement that strategy. Whether the source is digital or analog, the “strategic plan” is pretty much the same. Turning a static representation of music into a waveform we can hear is done in a simple, logical chain of conversions, transformations, and transductions. Only the “tactics” differ – the same tasks are done in different ways by different systems.
The form of signal storage dictates how we physically convert, transform, and transduce the acoustic energy of live performance into reproduction of a dynamic listening experience. Whether analog or digital, the static image has to be converted to a flow of physical energy through the air around us. Audio systems transform a stored, static image into an energy form that we can shape as we wish (EQ, DSP and other manipulation) before using it to recreate the original source signals with sufficient power to be heard.
Figure 1 shows signal flows from recorded archive to reproduced program material for both analog and digital domains. It charts the steps in conversion of a static archive to audible sound, along with the kinds of devices used at each step. If the metaphor holds, you’ll see how the tactics are overlayed on a strategic framework that takes you from source to stapes.
The next installment focuses on the front end. We evaluate and compare several OEM and open source players for ease of installation and setup, usability, flexibility, library management, program presentation, practicality, etc – and, of course, sound quality.
FIGURE 1 - High Quality PDF here
FROM PERFORMANCE TO PLAYBACK
Program material goes through only one basic transformation to get from stage to speakers: the signal goes back and forth from a dynamic flow of energy to a static archive of that flow. Sonic energy is created by performers as a complex series of time-aligned molecular pulsations in air. It is heard as one waveform resulting from summation of all generated frequencies, along with secondary sonics resulting from the performance (e.g. intermodulation, room acoustics etc). That waveform has periodicity and a flow rate determined by a conductor or the performer(s) if without conductor, and that timing is what aligns the content so it is recognizable and repeatable. This is the first basic transformation: a static archive of the entire flow of sonic information (the musical score) is made dynamic by the performer(s) in a data transformation controlled by a clock.
The data:
The clock:
The energy flow:
That energy flow causes mechanical deformation of structures in our ears that is transformed into an electrochemical energy flow to the auditory pathways of the brain. This flow is yet another analog of the source waveform and is interpreted in real time by our central auditory apparatus as the sound of the performance. It’s also encoded into our cerebral molecular archives as memory (another static data archive of the source data), so we can remember and later recognize the sounds of individual instruments and works of music.
Substitute a microphone for the auditory system and we have another energy transformation, this time from mechanical energy into electrical energy. Once again, it’s (theoretically, at least) a perfect analog of the source waveform that can be processed and turned into a durable static archive. This is done using the signal paths and processes described in figure 1, resulting in one or more of the forms of music storage with which we’re most familiar. Reproduction is then generated from those static archives with yet another animation of the data snapshot, clocked and transformed back into analog AC signals powering electromechanical engines (speakers) to push audible air pulsations to the listener.
Archive:
Clock:
The same factors are critical to fidelity in the delivery of data at every stage, starting with the accuracy and stability of the timing process for interconversions of static archives to dynamic flows of information. Remember wow and flutter? They’re simply mechanical deviations from constancy of the rate of data feed from the vinyl archive to the output of the cartridge. Another form of mistiming occurs when rotational speed of the playback device differs from that of the archiving system, e.g. when a turntable fails to spin at exactly 33 1/3 RPM or a tape drive capstan motor fails to move the tape past the heads at a rate of exactly 7 ½ IPS. Similar timing errors occur in digital audio, e.g. accurate generation of a reproduced waveform requires perfect clocking of the data feed from the archived binary file.
So, as can easily be seen, capturing, storing, and reproducing music requires similar processes regardless of the medium. The tactics differ, but the strategy is the same for analog and digital media. Having enumerated and explained these, we will use this framework to examine each system and process in the chain, identifying and prioritizing the factors most critical to faithful signal transformations. We can then search for value at every stage in the chain of audio reproduction, identifying products with great performance at favorable worth-to-cost ratios.
The next topic will be an examination of the front end of the computer audio system. We’ll look at several alternatives for retrieving and pumping the content of digital audio files into the amplification chain, e.g. small box computers like Raspberry Pi and Beaglebone, Chromeboxes, and legacy computers lying in wait in your closet. We’ve installed and tested over a dozen audio-oriented packages on older PCs & laptops (both 32 and 64 bit), along with comparative evaluation and listening of several open source players on multiple SBCs. We’ll compare operating systems as audio platforms, focusing on the Linux family because most SBCs run on a Linux distro and most of the ad hoc audio software / OS packages are Linux-based or derived.
Soon to come: finding value in computers for audio!
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