On 16 October 2024 13:23:44 UTC, Fons Adriaensen <[email protected]> wrote:
> But now the smooth saturation is almost transformed into
> hard clipping. The sharp bend in the curve occurs when the
> signal amplitude is higher than the bias amplitude.
>
> The only effect that remains in a complete simulation is
> the result of the EQ applied to the signal to be recorded.
> Higher frequencies have a 'self erasure' effect (which is
> nicely reproduced by the simulation) and so need to be
> amplified. The net result is that they will saturate at
> a lower input level.
>
> How much EQ is required depends mainly on tape speed, higher
> speeds need less. At the most popular 'pro' speed (381 mm/s)
> this would be something around 10 dB at 10 kHz. At the higher
> (762 mm/s) speed typically used for 'master tapes' it's just
> a few dB.
>
> So what does effectively remain of the 'smooth saturation
> and compression' that is claimed to give tape recording its
> magical 'warm' character ? Is it just a myth ?
IMO you've nailed it.
The non-mythical aspect is, as you mentioned, the EQ boost, its impact on
saturation, and the *almost* (but not quite) hard clipping. Depending on the
tape setup being used/emulated, the net effect can be anything from mildly
noticeable to completely imperceptible.
Any effect beyond that is indeed a myth.
Is that effect worth the hassle of using tape, or accurate tape emulation?
Almost never. As you point out, there are often simpler ways, today, to achieve
the same effect.
(Plus, great-sounding records have been made without tape or accurate emulation
since the 1980s. Tracy Chapman's 1987 debut album, recorded on a Mitsubishi
850[1], is a prime example.)
> I also simulated the green curve directly without going
> through the complicated full simulation, and honestly,
> to me that sounds just the same. And unless you really
> use very high levels (much more than would actually be
> used) the net effect is marginal. Maybe the hard clipping
> can be useful when applied to individual tracks (e.g.
> drums or bass), but then there are much simpler ways
> to do this than 'tape emulation'.
Again, I completely agree.
But I'd add these observations.
Use-case 1.
Many people are stubborn and irrational. Relieving people of any given myth can
therefore be difficult or impossible. Presenting a person with evidence that
their belief is mythical can upset them, and they may respond by dismissing the
evidence rather than the myth! (Historical examples abound: the Oxford Movement
- the "Puseyites" - explicitly advocated "faith over reason",[2] and that
attitude is surprisingly common in all areas of human endeavour, including
audio production.)
Pragmatically, then, when a person in the chain (artist, engineer, producer,
consumer) believes tape or tape emulation is worthwhile, it may be simpler to
humour them than to risk the recording (or even marketing) process collapsing
against those beliefs. Hence much of the continuing market for tape and
emulators.
(The desire for tape can be due to other factors in addition to "warmth". It
can also come from a desire to avoid post-production. The White Stripes and
their fanbase were an example of this c.2002,[3][4] as were Rage Against The
Machine about a decade earlier.)
Use-case 2.
There are people with access to a PC but without access to tape, who will want
to be able to learn, as closely as possible, how tape sounded. The more
accurate your algorithm, the better it suits this purpose, i.e. as a teaching
tool.
Some of those people will end up concluding, as you correctly did, that there
are often simpler ways to achieve equivalent results. But your emulator will
have been an important part of that education.
Conclusion
Thank you for working on this and for sharing your results!
Sam
[1]:
https://www.mixonline.com/recording/classic-track-fast-car-tracy-chapman-427573
[2]:
https://www.oxfordbibliographies.com/display/document/obo-9780199799558/obo-9780199799558-0049.xml
[3]:
https://www.newcutstudios.co.uk/cant-ignore-the-elephant-in-the-control-room
[4]: https://www.soundonsound.com/people/liam-watson-toe-rag-studios
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