Thursday, November 29, 2012

Where Does Tape Hiss Come from?

Even though there’s already a number of ways invented to reduce it to near inaudibility, but can you still remember when last time you asked: “Where does tape hiss come from?”

By: Ringo Bones

Believe it or not, all forms of electronic devices generate noise largely because a noise voltage is generated by the random state of movement of free electrons since they tend to dodge to and fro from atom to atom in a random manner. Thus all current-carrying components can contribute to the overall noise signal but those at the front-end of the channel of high amplification devices (like phono head preamplifiers and tape head amplifiers) are the most critical.

The noise produced by the electrons whizzing about within the electronics – including the power-supply hum of a well designed cassette tape deck – however is negligible compared with the noise produced by the tape passing over the replay head. In most situations, the noise level of the main power amplifier electronics is approximately 15dB below that of the combined noise generated by the cassette tape deck’s front-end preamplifier and tape hiss. Thus it is the tape noise which is the most troublesome in audio systems built around hi-fi cassette tape decks.

Tape noise or hiss – whether from analog based tape systems like open-reel tapes, 8-Tracks, cassettes or even Sony’s famed Elcaset – primarily results from the lack of homogeneity of the metal coating or other magnetic medium used. Tape hiss actually has a frequency that starts from 500-Hz, the annoying level, and then extends within 2,000 to 3,000-Hz, the unbearable level. Even though tape noise steadily remains constant with increasing frequency, the hiss that irritates most hi-fi enthusiasts the most mainly lie within the 500-Hz to 3,000-Hz part of the audible spectrum thanks to the Fletcher-Munson Equal Loudness Contour response of the human hearing that makes the 2,000 to 3,000-Hz region the nexus of human hearing audibility.

At present technology, the ferrous particles – or other “advanced” magnetic formulations – can never be distributed absolutely uniformly throughout the coating and the resulting aggregation of the discrete magnetic particles create their own discrete magnetic fields which during replay manifest itself as a noise electromotive force or EMF at the playback head and thus be amplified along with the desired audio signal. And by the way, noise is also produced from the mild irregularities in the traction of the tape towards the record head pole pieces during recording – which explains why during much of the 1980s, the heyday of the cassette tape, manufacturers made increasingly elaborate shell structures and internal mechanisms of their flagship blank cassette tapes as a way to further reduce tape hiss.

Thursday, November 15, 2012

Was Sony’s Elcaset Better Than Philip’s Compact Cassette?

Was this now largely forgotten intended for domestic use audio recording format really much better than Philip’s compact cassette?

By: Ringo Bones

Yep, Sony’s Elcaset is one forgotten sad failure of a domestically intended audio / music recording format supposedly launched as a much better engineered “replacement” for Philip’s compact cassette. Even a Time magazine tribute to former Sony Corp. CEO Akio Morita back in December 7, 1998 never mentioned Elcase while William Lear’s Eight-Track tapes and Peter Carl Goldmark’s 33 1/3 RPM vinyl LPs were mentioned. But is or was the Elcaset truly better than the compact cassette as an audio and music recording medium?

At the time – during the early 1970s - when Sony intended to launch a more user-friendly domestic audio recording format that is of higher fidelity than Philip’s compact cassette, cassette tape formulation technology, as we know it by the 1980s, was still in its infancy. Metal / Type IV position cassettes were yet to be invented – and even TDK’s famed cobalt-doped Super Avilyn Type II high-bias position tapes were still years away from being invented and marketed. Even Sony’s own top-of-the-line hi-fi cassette tape decks manufactured under license from Philips has a high-frequency bandwidth that barely crawls above 16,000 Hz. And don’t forget Sony’s “jealousy” with the runaway success of the compact cassette by the start of the 1970s finally made their engineers hatch a plan to launch a “better-sounding” replacement.

Maybe as it was the only format launched by Sony that was bigger than its intended competitor that might have contributed to its failure, the Elcasete – due to its higher tape speed – at 3 ¾ inches per second twice that of the compact cassette’s 1 7/8 inches per second – easily exhibited better wow and flutter characteristic than its smaller competition. And using tape that’s the same thickness, 6.3 mm as standard quarter-track open reel tapes (like those Barclay-Crocker open-reel tapes) – compared to the compact cassette’s 3.8 mm thickness – Sony’s Elcaset easily exhibited better signal-to-noise ratio, higher recording levels – which amounted to way better sound quality than the Philip’s compact cassette. Elcaset decks easily reached 25,000 HZ during tests at the time – in 1976 – where most top-of-the-line 1,000 US dollar compact cassette decks can barely crawl past the 16,000 Hz mark. Running more tape at higher speed past the head easily gave Elcaset a greater potential performance advantage over the compact cassette, even if bulk and cost were the price to pay. But why did Elcaset fail?

According to hi-fi enthusiasts old enough to experience the format launch first hand – back in 1976, Sony never made and marketed prerecorded music Elcasets for them to compare wit their do-it-yourself audio and music recordings. Not to mention audio enthusiasts at the time never “wanted” anything better than their quarter-track open-reel tapes, which was the “ultimate” in domestic audio recording and music playback at the time. Sony’s Elcaset uncomfortably fell somewhere in between – hardcore hi-fi enthusiasts consider “closed cassettes” with lower-fidelity convenience. And even while running at 3 ¾ inches per second, audiophile quality open-reel prerecorded tapes – like those from Barclay-Crocker – ran at 7 ½ inches per second, easily providing better sound than Sony’s Elcaset. At around 18 or so months after its release, Sony Elcaset tape decks – like the EL5 and EL7 recording decks and even their ELD8 “walkman-type” portable Elcaset player were soon heavily discounted, and by 1979, Sony’s Elcaset dies with barely a whimper.

These days, one can sometimes find old but still in perfect working condition Elcaset decks being sold in weekend hi-fi swap-meets  at around 10 to 12 US dollars or so – even with a complementary set of 10 or more unused blank Elcaset tapes still enclosed in their original shrink-wrap unopened probably since 1976. Surprisingly, the Elcaset blank tapes often given away as freebies on second-hand Elcaset decks are, more often than not, the premium Ferrichrome type. I managed to buy use one myself back in the mid 1990s and all I can say is that Elcasets are way better – sound quality wise than Philip’s compact cassette. Modified cassette tape systems that ran at 3 ¾ inches per second – twice that of the standard cassette tape speed of 1 7/8 inches per second – still can’t compete with Elcaset especially in the critical mid-band region, which the soul of music resides.

 Even when recording from a CD Redbook standard 16-bit 44.1 KHz sampled Sony Super-Bit-Mapped release of Miles Davis’ Kind of Blue album, Sony’s Elcaset obliged me and most users I assume, with that hard-to-define “out-of-speakers” quality that was so appealing about open-reel tapes – or high-end vinyl LP replay and 1990s era CD set-ups that cost over 5,000 US dollars. If you are lucky enough to find a still pristine 2-channel open-reel first generation master tape to dub from, Sony’s Elcaset could probably provide better sound quality than Super Audio CDs!