Compact Cassettes.

Yes. It's better not to pollute analog with digital. But don't tell the "digital mixed with analog" purists.

 

Hello,

once I owned a good cassette deck, I always recorded type II and Dolby B. And played it back that way. Sounded very good.
Dolby B provided just enough noise reduction for normal music.
The extra price for type IV tape material, I only payed for special "master" recordings, say, live recordings on location, or so.
Dolby C would provide some additional decibels of noise reduction, but on the expense of some more or less audible artifacts.
With impulses or transients out of the silence, you could hear the compressor/expander working. However, one would only need Dolby C noise reduction, or better to say, the amount of noise reduction provided by Dolby C, if you really had very low volume sounds and sudden high volume transients on the same program material...
So, the practical use for Dolby C was somewhat limited...

A well aligned and calibrated deck really would provide almost master tape sound quality. Unfortunately, a number of decks were not that well serviced and aligned...

Nevertheless, I would never like to go back to analog. Analog, like cassette tapes, like open reel tape, was good and did it's job when there was no digital invented or on the market, yet. But today, analog just does not do justice to the sound and the music.

I do enjoy analog tapes for the sake of nostalgia, or because some recordings only just do exist exclusively on analog media, like cassettes or open reel tapes.

Best regards

 

Dolby NR (Dolby B) was actually a pretty clever way to reduce, if not eliminate, tape hiss during playback, under ideal conditions. But it had one major Achilles's heel: Tape head alignment (azimuth) and tape speed had to be perfectly aligned and match between the recording and playback equipment. In the real world, that just wasn't possible.

 

No,
playback gain (amount of amplification) before the Dolby processor is crucial to Dolby, because it is a compressor/expander system.

Azimuth and tape speed are crucial to every tape recording or playback compatibility.

In fact, Dolby B almost eliminates tape hiss. The hiss is reduced to levels too low to be annoying.

Best regards

 

I think Dolby S was the one, it made cassette tapes get dinamic range and signal to noise ratio typical of digital, it only arrived too late.

 

Nope, on a good 3 head deck dolby C makes the high end better.

 

Hello,

my milage varies.
Or I don't just get what exactly you mean with "better high end".
From my experience, properly aligned tape decks don't alter the frequency response with or without Dolby. That is, a non-Dolby recorded tape played back with no Dolby has the same sound as a Dolby recorded tape played back with that Dolby engaged. Only, that the tape hiss with the Dolby is largely reduced or almost completely gone.

If playback gain is set a bit to large, than the expander will expand a little less, so the high end will sound a bit louder.

And on the other hand, if the tape sensitivity is a bit too low, or the playback gain a bit too less, the expander during playback will expand a bit too much, and the recording will sound a bit dull.

And on another other hand, using Dolby during record, and using no Dolby during playback (and even, play type-II tapes on the type-I EQ settings) is a simple way to boost the high-end of otherwise dull-sounding recordings or equipment. Or to compensate somewhat for bad azimuth alignment.

Best regards

 

One thing I always wondered is why the need of Type I/II/IV settings when playing normal/ferro, chrome or metal tapes. I do understand the need for those settings when recording, chrome tapes have higher coercitivity (energy to magnetize the tape, measured in Oersted if memory serves me well) and metal tapes have higher coercitivity than chrome tapes, but those settings while pling, I have no clue.

 

One thing I always wondered is why in North America they needed to call them Compact Cassettes, when there weren't any larger cassettes in competition. One other thing I always wondered is why in Europe they needed to call them Musicassettes when they also sometimes contained comedy albums. And I really hated the TV commercials where they advertised "also available on tape or cassette!" like cassettes weren't also tapes. Very annoying.

 

Possibly to differentiate them from reel-to-reel tapes or 8-tracks. *shrug*

 

The three types had different equalization settings to get the most out of each type - the least noise and the most high frequencies.

For playback Type II and Type IV are the same playback EQ even though they are two positions of the switch. You can play either tape at either setting, no difference.

But for recording, The Type II setting and the Type IV setting used different EQ during recording.

So it's just easiest and simplest to have the overall I/II/IV switch.

It would have been possible to have all types of tape playback with the same EQ (which would have been the original, Type I type playback EQ), but even then, there would have had to be different EQ applied during recording and so still a need for the I/II/IV switch. Since you would still need a I/II/IV switch, each setting was optimized for that kind of tape.

The difference weren't just the higher coercitivity, it was the difference in frequency response and lowest noise each type tape could achieve with EQ optimized for the type. I was good, II a little better and lower noise - and more consistent between brands, IV much better highs and even lower noise.

 

Talking about the names for the tapes...

The groove width of vinyl LPs was called the "micro groove", to differenciate it from the "normal groove", which was the groove width of shellack discs.
Todays or in the 80s, nobody knew about shellacks anymore, so that name "micro groove" became a mystery similar to the name "compact cassette"...

Before, around and after the compact cassette, there have been other cassette types available.
The north american 4-tracks and 8-track cartridges. European or american cassettes with the two reels stacked upon each other, instead of side-by-side like the compact cassette. The playtape cassette...

The name "compact cassette" was choosen to emphasize the portability of that new cassette type, when it was introduced to the market, I think. Plus, it really was a bit smaller than these other cassettes, let alone reel-to-reel tapes. Also, the compact cassette employed much less mechanical parts and was a much simpler mechanical construction than the american 4- and 8-tracks, or cassettes with the two spools stacked upon each other. That's why it was relieable, robust, mobile and cheap. All keys to success.

There was an even smaller cassette, the micro cassette for use in dictation machines. Intended for speech when introduced, I think I remember, one or two companys spend engineering work to increase the sound quality of that micro cassette to make it suitable for music recordings...
Sony introduced the "elcassette" in the 70s, with larger reels, wider tape, faster tape speed, and a tape-loading mechanism somewhat similar to that of video cassette recorders, with the intention to increase the sound quality.

Regarding the tape type selector switches: Each tape needed their own equalization during record (and playback), and their own bias settings. You could play type IV on type II settings. I guess that was done to increase compatibility, at least during playback, for the new tape IV formula, when it was standardized and introduced into the market.
There have been that notches on the other side of the cassette, to indicate the tape type: no notch is normal, one small notch is chrome, one wider notch is metal. Decks introduced before type IV (metal) hit the market, would detect type IV as chrome (type II). Maybe that also played a role in making tape IV playback compatible with type II. (And there's the long forgotten type III, ferro-chrome, a mixture of ferro oxide and chrome... that's why we call metal type IV...)


There's always some nostalgia and history in the names. Like the floppy disk symbol on your computer, when you want to safe a file to a solid state hard drive...

Best regards

 

Thank you both for your replies and for solving a long time mistery...

 

Well, it was possible, but not common. Dolby B was the most forgiving of small variances in alignment and EQ. Dolby C was the least forgiving, especially since it also further boosted the highs on encoding, and reduced them on playback.

Tape speed will also alter your frequency response to a degree.

The one interesting thing is that people often mistake the tape hiss for high frequencies, so if they don't hear a bit of hiss, they think the highs are reduced. This adds to the unfair criticism that Dolby gets.

 

I read somewhere some time ago that Dolby C was actually two Dolby B processors connected in paralel, is that true?

 

I believe so.

 

(Not in parallel, one after the other.)

It originated that way, as a business decision pretty well forced on Mr. Dolby, an "offer he couldn't refuse". The second Dolby B processor sortof acted in reverse and was tuned to a different level, a different output db level, of what came out of the first B chip. That's because there were then a few different Dolby B IC parts in production and cheap. So Dolby comes out with the idealized original C, screwing up manufacturing and increasing costs for everyone. So upon "request!!!!!", Dolby retuned the "C" standard to be able to use two B IC chips - letting the manufacturers burn off the older, cheap, existing B chips and keep making them until a C chip was designed and in production. At the right time, they had ICs with the new C standard ready and cheap and still including B which was basically only a tap into the C chip at the B output. Cheap being a relative term, but quickly the C chips cost as little as the B chips. If Mr. Dolby had not retuned C that way, the Japanese manufacturers never would have adopted it.
HX didn't have a lot to do with the B or C chip directly, no mods needed.
By the time of S, Dolby had learned his lesson about how to deal with the Japanese manufacturers for the mass consumer market, but cassette was basically over.

JVC had their own "ANRS" which roughly emulated and equaled Dolby B in a patent avoiding way, and then "Super ANRS" roughly equivalent to C - and some said it was better. If Mr. Dolby had not changed things, the home grown Super ANRS would have been the next wide standard.

 

I wonder how tapes recorded to DBX sounded, I've never listened to one. Why disn't it catch on? Was it because of its prices or maybe BDX encoded tapes sounded weird when played undecoded?

 

That and DBX requires very strict tolerances. If you do a search, Steve Hoffman has had quite a bit to say about his experiences with DBX.

 

And, that was a good decision. First, it worked in reducing the noise or hiss even further. Plus, it was compatibel and cheap. That's important.

German manufacturers often came up with solutions that were maybe a bit better, but incompatible and expensive. Like video 2000 from Grundig. Or HighCom from Telefunken.
Dutch Philips favoured the cheap way, but weren't routinely engineering geniuses. Their noise reduction (DNR, or what was it called) worked on playback only, and simply reduced treble settings a low levels on tape. Fade-outs would fade into muffled and dull silence... Not that good as the clever Dolby system.

Best regards

 

I remember that I was unable to listen to cassettes on my walkman without Dolby because the tape hiss was too noticeable and disruptive. The hiss was not a factor for playing while driving a car or listening at home because the parents never allowed me to listen at levels above ambient music.

 

At least in US, Philips' circuit was called DNL. "Dynamic Noise Limiter". One US deck was released in 1971 under their US Norelco brand, the Norelco 2100. I have never seen (or heard) one, and I have looked for one all these years. DNL was only used for playback. The odd thing is DNL is somewhat similar to the playback function of Dolby B, with different patent-avoiding parameters, and (it was said in the magazines of the time) playing a Dolby B encoded tape on it with DNL playback active was not bad and better than not using the DNL, and DNL could work with any cassette whether Dolby B was used or not. This general concept went back to the 1950s anyway.


Best regards!

 

Some dbx decks were very good, such as my Aiwa XK-007. The results were just amazing, with no discernible "pumping" or "breathing" artefacts often associated with this system, as long as it was played back on the same deck, or deck that was properly calibrated.
This deck was installed in several different recording studios I used to record in back in the day, and I found that there was no problem playing back Dolby B or dbx tapes on it, when it came to transferring to say, 1/4" or digital.

btw the Technics RSAZ-6/7 series from around 1997 was very good for playing back old tapes, and sounded great even with Dolby bypassed - great for pre-recordeds too. My Aiwa dbx cassettes actually played back quite well using Dolby C (it doesn't have dbx). The head was very thin, and was originally used on DCC decks, which apparently alignment errors considerably. If you have a lot of old cassettes that you want to listen to/transfer without fiddling with the alignment all the time, you might want to consider picking one of these up off eBay for $60-70.

 

Likewhise younger people are baffled why CD singles are sometimes called "CD maxis". It's because they are the descendant of the 12 inch vinyl single, which was called "maxi single" in some markets - as opposed to the 7 inch single whose descendant was the 3 inch CD single, but didn't catch on.

And then there was the British pre-WW2 405 line television (377i in digital terminology) called "high definition" in its day, because it was better than the German 180 line system of the era .