[Vintage-Audio] Possible Cause Of CDRW Audio Distortion

[Duane Fischer, W8DBF]

Hi All,

A friend of mine who is an electronics engineer decided to run some audio 
sources through some of his test gear and "see" what the scopes displayed.

He had some NOS (New But Old Stock) C60 audio cassettes, as well as some 
high end metal cassettes and some new three year old low noise cassettes.

The blank tapes did not show anything unusual, regardless of their age or 
type. However, when he checked some older audio cassettes that were recorded 
on ten+ years ago, he noticed something curious. There were occassional 
audio spikes? in the frequencies above eighteen thousand Hz! Since the human 
hearing frequency range is supposedly 20 HZ to 20,000 HZ, almost nobody 
other then a small child can hear above 18,000 HZ, such a sound would go 
unnoticed.

His thought was that I needed to find a new vinyl album to ponder about, get 
hooked up with a female who liked old men who were blind and retired 
Magicians or ... He is suspicious over the type of electronic switching used 
on some of the cassette decks. Especially those using the older forms of 
Dolby.

When he tested a deck that used mechanical switching, he did not see that 
high frequency audio spike!

For what it is worth, there you go.


Duane Fischer, W8DBF - WPE8CXO
E-Mail: dfischer at usol.com
Hallicrafters web site: www.w9wze.net
HHRP web site: hhrp.w9wze.net