Saturday, October 26, 2013

Doubling The Running Speed: Secret To A Better Cassette Tape Sound Quality?

It may be a “long-shot” but does doubling the cassette tape’s running speed from 1 7/8 inches per second to 3 ¾ inches per second really improve its sound quality? 

By: Ringo Bones 

When it was introduced primarily as an office dictation recording medium back in 1963 by Philips, the compact cassette tape’s rather low 1 7/8 inches per second tape speed was the main engineering challenge of coaxing something approaching high fidelity sound from such an unlikely tape medium. Not to mention the narrow tape width of just 3.8 mm which contrasted with the higher fidelity sounding domestic music recording and playback mediums of the period – i.e. the quarter track open reel tape and the 8-Track tape cartridge’s 6.3 mm tape width. But can increasing the compact cassette tape’s speed from 1 7/8 i.p.s. to 3 ¾ i.p.s. really improve its sound quality? 

Back in the early 1980s, a consumer electronics company by the name of Teac made such the prospect of experimenting to improve the sound quality of the compact cassette tape medium by doubling its running speed much easier for domestic hi-fi enthusiasts by introducing the C-3X cassette tape deck that has the option – via a simple flick of the switch – to be run at 3 ¾ inches per second. But in order for the better sounding DIY recording – on cassette – to be playable other than the lone Teac C-3X cassette tape deck that you probably own (or more likely just afford to own) in your hi-fi rig, your other cassette tape playing equipment that you own or have access to – i.e. your boom box portable, Walkman, car stereo’s cassette tape deck, etc. should also be capable of running at 3 ¾ inches per second, which posed a problem for compatibility to anyone jumping into the “cassette running at 3 ¾ i.p.s. bandwagon” back then. 

As I was fortunate enough to “toy” with the Teac C-3X cassette tape deck in our hi-fi repair shop given that it was very widely available in second hand hi-fi shops across Vietnam during the mid 1990s, running cassette tapes at double its normal speed - the results can be quite spectacular. Using good quality cassette tapes like TDK SA, Sony Metal XR and related tapes – the results can be outstanding and hiss free even without switching in / using any form of Dolby noise reduction. When you can tape at recording levels right up to +10 dB (and even a bit more on the cassette tapes I’ve just short listed since those never saturated on the Teac C-3X cassette tape deck) hiss is no longer an issue. By the way, the best loved rock and pop recordings known for their pristine sound quality from the late 1960s up to the 1970s were recorded and mastered without any form of Dolby noise reduction whatsoever – though its on 2-inch thick open reel tapes being run at 30 inches per second. 

Although the midrange purity on the 3 ¾ i.p.s. cassette tape recordings – both LP test dubs for my own use and live recordings of local Classical and rock musicians via a 12AX7 vacuum tube equipped microphone preamp into the Teac C-3X tape deck – is about half a notch below what’s possible with a well maintained Elcaset deck or a hi-fi 8-Track record playback deck like the Pioneer RH-65 or a quarter track open reel tape running at 3 ¾ i.p.s. Though a metal particle cassette tape running at 3 ¾ i.p.s. on the Teac C-3X is miles ahead in sound quality when compared to a current i-Pod – even when that said i-Pod is playing hi-rez digital music downloads!

Sadly, despite their stellar sound quality – dual-speed cassette tape decks where a short-term innovation of the early 1980s. They contravened Philips standard which stipulates one speed for the compact cassette – i.e. 1 7/8 inches per second – for guaranteed compatibility, so were discouraged and hence since discontinued. Teac finished their line of dual-speed cassette tape decks similar to the C-3X cassette tape deck back in 1984. Were Teac the only ones making dual-speed cassette tape decks back then? 

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