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Michael Covington's Audio Technology Notes
Welcome!
This page comprises a few notes about audio technology and a collection of useful links. Links to pages other than my own are in gray.I've been interested in audio electronics since childhood. Today, my work involves (among many other things) speech research and hence digital audio. But I am not a high-end audiophile; I'd rather have reasonably good sound at reasonable cost. Fortunately, today's mid-range and even low-end equipment is often better than the best available a few decades ago.
Michael Covington
Some of these files are in PDF format for viewing with Adobe Reader, which is available free of charge from Adobe.
Digital audio
- How to digitize your records and tapes to make audio CDs and MP3 files
(Details of how to use GoldWave are included.)
- Digitizing records and tapes with Adobe Audition
(Supplement to the above, for those using different software.)
Internet radio
- Radio-Locator
- BBC 3 (classical music)
- KJUL (oldies)
- How to record Internet radio without special software
Phonographs and records
- Limitations of vinyl records – an essay by a recording engineer
- Homemade stylus pressure gauge (scroll down to it)
- Audio-Technica AT-PL120 turntable and how to fix the loose dial that indicates stylus pressure
- Phono-Art portable record player, c. 1959
- Discography of The Current Event (c. 1970)
Analog electronic equipment
- Line level and other levels explained
- Decibels explained
- Analog Devices decibel calculator
Interconverts peak and rms voltage, dBV, dBu, dBmW, etc.
For calculations involving dBmW (dBm), note that the impedance of an audio line is not 50 ohms; it may be 600 for microphones.
High-impedance audio signals are always specified in voltage units (Vrms, Vpeak, dBV, dBu, not dBmW). "Line level" is -10 dBV (0.3 Vrms) for consumer equipment and +4 dBu (1.2 Vrms) for professional equipment.
- Converting phono inputs to line-level (so you can feed the phono input of your amplifier from a turntable that has built-in preamps, or from a CD player or other line-level signal source)
- Good places to buy electronic parts for analog audio:
- MCM Electronics
(exceptionally large inventory; will ship small items Priority Mail, which is cheap and fast)
- Parts Express
(another good audio parts supplier; some browsers will not go to its web site because the letters "sex" occur in "partsexpress"!)
- Antique Electronic Supply
(parts for tube equipment, antique radios, etc.)
- Nikko STA-5010 receiver schematic circuit diagrams: Part 1 Part 2
(I will be glad to remove these if the copyright owner objects.)
- Service manuals and schematics:
- Sams Technical Publishing (independent publisher of service manuals for all brands of equipment)
- Service manuals can also be purchased from manufacturers. You may need to contact them rather than just relying on web sites. A service manual is not the same as a consumer instruction manual.
- Shure technical bulletins (lots of useful knowledge!)
Some audio-related items in my blog
Note: My blog, or Daily Notebook, covers a very wide range of subjects. Most of it is not audio-related.
- Better RCA phono jacks
- Audio-Technica AT-PL120 turntable
- Sound Blaster overloads on line-level input
- Sherwood RX-4105 receiver
- CD player does not open or close (repair notes)
- Adding a ground screw to a Recoton phono preamp
- Dual cassette deck cleaning tip
- One stylus, two styli, no stylii (a matter of spelling!)
- The source of an obnoxious noise (with an MP3 of cell phone noise, so you can learn to recognize it)
- Getting music from vinyl, and even wax (including homemade stylus pressure gauge and kluge to fit a 78-rpm stylus on a Pickering ATE-2 P-mount cartridge)
Sound cards
- If you are having any kind of problem adjusting levels, make sure you have the current (or best) driver for your sound card. With a Creative Labs Sound Blaster 16 PCI, we found that the driver provided by Microsoft with Windows XP was apparently the wrong one (intended for a different model of Sound Blaster) and would not let us set the "line in" level low enough. The driver from the manufacturer's web site worked fine.
- Tomi Engdahl's sound card tips (excellent site, but infested with pop-up ads which Opera doesn't block).
Miscellaneous
- Hiss in your headphones? If you hear hiss in your headphones, and you have to use your equipment with the volume turned nearly all the way down, this is not a defect. It simply means that your headphones are very sensitive.
To get rid of the hiss, add an inline attenuator or volume control (such as Radio Shack's $6.99 volume control cable for headphones). Turn the volume up to mid-level on your equipment and turn it down to normal listening level using the inline volume control.
- "Glory, Glory To Old Georgia" for computer programmers
(how to play music with any programmable tone generator)
Copyright 2005, 2006 Michael A. Covington. Caching in search engines is explicitly permitted. Please link to this page rather than reproducing copies of it. This page is not in any way connected with or endorsed by any manufacturer or vendor. Many of the product names that appear on this and related pages are registered trademarks of their respective owners.
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