How do 8 tracks get recorded on a compact cassette?

Question

AFAIK 4 tracks can be recorded on a compact cassette as the recorder uses both the channels of both the A and B side of the tape. But how does this Tascam 488 recorder records 8 tracks onto a compact cassette that only has 4 'tracks' ?

Answer 1

This is a common misconception about tapes and tape recording.

Tape is a magnetic medium and it's not divided by anything.It's particles are (at first) scattered and unordered.

What dictates the channel count is the recorder tape head.

This is a basic example of how the tape recorder works:

So for example let's say we have a 2 inch tape.

And let's also assume we own 2 machines.

An old MCI 2" 16ch , and a studer a800 2" 24ch.

That means that both machines are loaded with the 2 inch tape but the first will record 16 channels and the 2nd will record 24 channels.

After one machine has recorded let's say 16 channels (MCI) we can then easily take the tape out of that machine, load it in the studer and record 24 channels (16 previous are overwritten of course).

This is as far as recording goes.

For the reproduction there are the same number of channels in the "Repro" head.

Both heads must be aligned very well so there are no repro and/or recording problems.

So as you'd understand by now , a cassette is a tape only 1/8" width but it's the exact same technology as the 2".

On the "normal" cassette decks this is what's going on:

You can also check more Tape Layouts Here

A Revox Tape head of 16 channels:

So you might wonder why we can't record 24 channels in a 1/8" cassette. Well , first of there are physical limitations. Also the tape would have a lot of crosstalk as one channel would affect the other because of the very small channel width. And lastly there would be too much noise, this is why smaller tape formats use denoisers as a standard , The 488 example uses dbx denoiser and others like Fostex 250 uses the Dolby S.

So narrow tape path means:

1. More noise
2. less Headroom
3. possible crosstalk

But as we discussed before a lot of these depend on the machine! There are larger format machines that have crosstalk and vice versa.

Other formats like 16ch 2" , or 8ch 1" are considered simply as the holy grail of recording as they help by offering great depth , dynamic range , headroom and noise characteristics.

So keep in mind that for the most part , the machine dictates the outcome, the tape is just a medium that the "data" is saved if you will.

Feel free to ask questions :)