Audio Cassette To CD
More Fun Than You Can Imagine!

Audio cassette to CD?!!

Why bother??!!

It's amazing the amount of information packed into any analogue storage medium, even one like the 'lowly' audio cassette.

Of course, it needs to be a half decent recording job in the first place.

There are numerous reasons for an audio cassette to CD conversion:

• you have a one-of-a-kind performance that only happened to be captured on cassette
• an artist has lost her source master and all that's left is a commercially duplicated copy or (better) a studio reference cassette dub of the mixdowns
• for sentimental reasons: a cherished family recording, for instance, that's wearing out from repeated plays would certainly benefit to CD conversion.

Of course, there is the inevitable issue of tape hiss. This can be handled with mastering software like Voxengo's Redunoise, WaveLab's DeNoiser, or software by iZotope and Waves.

Then there is the question of Dolby B. Many older audio cassettes may have lost much of their high frequency information which is where Dolby did most of it's work on. If I'm unsure about applying Dolby B on an audio cassette marked as being encoded that way, I'll make two passes if there's time: one with Dolby B engaged and one without, and decide later.

But there are times when it's pointless to engage Dolby at all because of excessive high end loss.

Either way, some restorative EQ is going to come in to play usually with software like Harbal and Roger Nichols' 'Uniquelizer”.

Speaking of Dolby, there is another problem that will crop up very frequently with audio cassette to CD transfers, and that is the question of left-right balance of the stereo image. Because of the thin-ness and narrow-ness of cassette tape, the left and right channels often are not recorded on with equal levels. Since Dolby is a two stage encode/decode process and 'assumes' it is printing on to tape at equal levels, at playback time there are going to be additional high frequency loss problems when Dolby 'over-decodes' the channel with lower levels!!

The solution (if it's warranted) is an expensive one, and that is with a professional outboard Dolby B decoder – an increasingly rare item. This would give the ability to separately adjust the playback decoding levels so that both channels get restored properly.

Of course, if Dolby could produce a decoder type plug-in(!) that can handle independently decoding channels, a lot more projects would be restored properly!

Dolby and noise reduction aside, I feel the most crucial element when transferring an audio cassette to CD, - and I've already mentioned this – is the stereo image.

Get that right and half your problems are solved. (What do think I've been going on and on about left/right levels for?!! - remember, we're trying to create or re-create a master).

But it's still more than just levels.

It's about azimuth.

Put more simply, the left and right channels must play back in proper time alignment.

We're talking fractions of micro-seconds, folks!

The start of this problem can be caused by the cassette shell – the construct of which can be of varying quality

Or a slightly mis-aligned record head on the originating cassette machine.

The solution is with Voxengo's Sample Delay plug-in followed by its Mid-Side-Encoder-Decoder – or just 'MSED' - plug-in.

And I'm going to give you two techniques to restore the image – although they're really variations on the same theme.

While the audio is playing, using the MSED, sum your playback to mono. Adjust the sample delay until you hear the greatest, clearest high end possible. Be sure that the MSED is after the Sample Delay. This will be the correct adjustment for that file.

The other technique works as well if you're sure that, say, the vocalist is supposed to appear exactly in the centre of the mix. With the same chain as in the previous set-up, set the MSED so that you're only hearing the side elements this time. Then adjust the Sample Delay until the vocalist is at his weakest possible level.

Yes, weakest!

Depending on the mix you may just hear the echo effect of his voice. This is the correct adjustment for the track.

Once finished, this is little tweak alone really increases the “Wow!” factor from my clients.

From here on, you can correct the left/right balance, adjust the image width, EQ and so on. Some upward multi-band expansion can work very nicely to bring back life to cassette transfers.

It's a sense of great personal satisfaction for me to watch the initial expression of a client who may have been in despair of ever recovering a lost masterpiece turn to one of un-containable 'enthusiasm'!

When transferring an audio cassette to CD, that little effort is well worth it!

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