Tuesday, November 4, 2014

Recording CDs To Cassette For A Better Sound Quality?

To those old enough, do you still remember the time when music on CDs tends to sound better when they are recorded onto blank cassette tapes? 

By: Ringo Bones 

Let’s face it early 1980s era CD players may have been built like a tank – like that of cassette tape decks of the period. But when compared to contemporary universal disc players that can play CDs DVDs or any 5-inch diameter disc, the sound quality of early 1980s era CD players leaves much to be desired. Even though in the 1990s we finally have names on the “audio gremlins” that plague the Redbook Spec 16-Bit, 44.1-KHz digital audio – data induced jitter for example – why is it that early 1980s era CDs sound quality improves once it is transferred to cassette tapes, 8-Track, Elcaset or any other analog magnetic recording media? 

Even during the Golden Age of Stereo, audio engineers and audiophiles already know that high-order very steep cutoff low pass and high pass filters are deleterious to perceived sound quality. The reason why CDs – and even low data rate MP3 audio files – tend to sound better when recorded on analog magnetic media like cassettes, Elcaset, 8-Track, etc, is that analog magnetic tapes doesn’t require a high order low pass filter as an “anti-aliasing filter” to remove signals that doesn’t fit in to the Nyquist Criterion of Redbook Spec CDs. Any signals too high in frequency to be recorded in analog magnetic recording media just rolls off gently at a rate of 6 dB per octave. 

Why early CD players tend to sound worse than their more contemporary counterparts is because anti-aliasing filters with very good subjective sound quality were very difficult to design back in 1982. It was Philips of Eindhoven, Netherlands that were the first to come up with an oversampling digital filter – which is all about digital signal processing algorithms – that resulted in a better sound quality than competing anti-aliasing filters of the time, but digital signal processing was still at its infancy in comparison to what we can do during the 1990s never mind today. While Sony in Japan struggled on with impractical ninth-order analog brickwall filters, Philips had no choice as they were unable to make reliable 16-bit converters at the time of the CD’s 1982 CES debut. 

By using oversampling and noise-shaping way back in 1983, Philips could make their proprietary 14-bit converter for 16-bit 44.1-KHz Redbook spec CD work with 16-bit resolution. Even though both Philips and Sony’s CD players costs around 750 US dollars once they became available back in 1983, a similarly priced machine in the mid 1990s can easily show it a clean pair of heels sound quality wise. Today’s similarly priced machines are even better. Would the hi-fi cassette tape decks role during the early days of CD is a “widely available digital-to-analog-converter to make early CD sound better”?

Tuesday, February 18, 2014

BBE Sonic Maximizer: Cassette Tape Friendly?

Eve though many musicians who can see past it’s rather “showy sound enhancement abilities” now hate it, was the BBE Sonic Maximizer cassette tape friendly enough to qualify as its “soul-mate”?

By: Ringo Bones 

During the cassette tapes heyday – in the early 1980s – “affordable” cassette tape decks were notorious for sounding “dull” when compared side-by-side with their upmarket counterparts, thus any after-market audio widget designed to improve the sound of your “affordable” cassette tape deck suddenly became consumer electronic best-sellers. But did the BBE Sonic Maximizer offer something better than other competing products? 

BBE, Barcus Berry Entertainment, Incorporated – which later became known as BBE Sound, Inc. is based in Huntington Beach, California that began operation around the middle of the 1980s. BBE Sonic Maximizers became widely used for audio recording, motion picture sound tracks, TV and radio broadcasting and motion picture sound systems, According to the audio processor’s creators, BBE Sonic Maximizers were primarily designed to improve the sonic clarity of virtually any reproduced sound by correcting / compensating for phase and amplitude distortions produced as your typical power amplifier drives a typical loudspeaker. 

Around 1986, BBE Sonic Maximizers first appeared widely as a stand alone unit to be connected between your source – be it a vinyl record turntable, cassette tape deck, VHS deck, hi-fi tuners and even CDs – and main preamplifier, though better results with cassette can be obtained if your tape deck’s peak output voltage is around 500-millivolts or louder. At the time, the best thing I notice about BBE Sonic Maximizers is that it can make a dull cassette recording sound better by subtly boosting the treble frequencies without appearing to add additional hiss, unlike using the tone controls or graphic equalizer in boosting the treble. 

By around 1991 to 1992, many musicians – like Skid Row, Megadeth, Queensryche amongst others – began using BBE Sonic Maximizers to enhance their recordings and the sound of their electric guitars and electric basses. But later on, “soulful” musicians started to dislike BBE because the BBE Sonic Maximizer box acted like a “heavy handed loudness control on steroids”. Boosting bass and treble frequencies tend to make the overall recording – or your musical instrument – sound as if the midrange frequencies were eliminated giving an impression of that hollow solid state sound that became unfashionable as the early 1990s single-ended triode vacuum tube amplifier craze went “viral”– quite far removed from what loud Marshall electric guitar amplifier playing is all about, which is tons and tons of gorgeous creamy midrange. Even upmarket Nakamichi DR series cassette tape deck owners steered away from BBE starting around 1994.
But to my ears at least, BBE Sonic Maximizers do serve a “niche purpose” where their treble boosting could prove useful. Like providing much needed treble boost to those dull prerecorded cassette tape albums from the 1980s where a “conventional” stand-alone noise / hiss reduction system will only make it duller, FM radio stations with excessive OPTIMOD compression usually sounds a little more dynamic when used with a BBE Sonic Maximizer and pre Burwen Bobcat enhancement era MP3 digital music download files. 

Woodles: The Bane of Cassette Tape Bass?

A “technical term” used to describe the lumpy low frequency response of cassette tape decks, can “woodles” be engineered out or reduced to nonexistence? 

By: Ringo Bones 

The term woodles was first coined by Steve Holding, a hi-fi audio equipment reviewer in Australian Hi-Fi magazine in which the term was used in the March 1998 issue. In this context, woodles means the irregular response in the bass or low frequency section of the audio frequency graph of a cassette tape deck under test. More popularly known in America as the “head contour effect” and is primarily caused by the bending of the tape as it travels around the record / replay head. 

A competently engineered cassette tape deck usually has woodles that deviates no more than plus or minus 2.5 dB below 50 Hz and plus and minus 1 dB above 50 Hz or better. A typical competently engineered modern cassette tape deck manufactured around 1990 onwards has a head contour effect that are usually below plus or minus 2.5 dB below 50 Hz due to modern record / replay head profiles and advances in record / replay head design. 

Historically, the Nakamichi DR series of cassette tape decks were known for having virtually nonexistent woodles or head contour problems since they’ve began making them by the start of the 1980s. It wasn’t until years later – as in the early 1990s – that other cassette tape deck manufacturers began making tape decks that can compete gamely with Nakamichi when it comes to engineering out the “woodle problem”. Like the Teac V-7010 cassette tape deck with a well set up head geometry virtually gave it a woddle free performance. And by the mid 1990s, Technics RS-AZ6 and Technics RS-AZ7 thin film head technology not only engineered out the head contour effect while pricing their cassette tape decks half that of a typical Nakamichi DR series cassette tape decks, but also gave the Technics series of thin film head technology equipped cassette tape decks CD-like bass and midrange without the use of proprietary Dolby S technology.