Using Saturation

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Re: Using Saturation

Post by blinddrew »

I'm with Wonks, I've always thought of it as 'tape saturation'. Probably because, until your post above, I've never understood what transformer saturation actually was.
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Re: Using Saturation

Post by ef37a »

blinddrew wrote: Mon Aug 15, 2022 10:34 am I'm with Wonks, I've always thought of it as 'tape saturation'. Probably because, until your post above, I've never understood what transformer saturation actually was.

Few do. "They" don't even really mean "saturation" on tape, really somewhere around 4-6% THD I would guess. Most machines were lined up for ~3% THD at +4dBu but then we would have to delve into the history of tape flux levels!

Actually saturating a tape would sound 'king awful!

Ooo! Have a look at "saturable reactors".

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Re: Using Saturation

Post by merlyn »

If we think how this would be done in DSP ...

We need a non-linear function. Inverse tan would do it :
Image

The saturation is that at a certain point increasing the input doesn't increase the output.
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Re: Using Saturation

Post by ef37a »

merlyn wrote: Mon Aug 15, 2022 12:08 pm If we think how this would be done in DSP ...

We need a non-linear function. Inverse tan would do it :
Image

The saturation is that at a certain point increasing the input doesn't increase the output.

That looks very like a flux v magnetizing force curve.

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Re: Using Saturation

Post by James Perrett »

Here's a typical B-H curve showing how a magnetic material behaves under different field strengths.

Image

If we are talking about tape then there are all kinds of other effects involved - notably bias levels. Under-biasing can produce some interesting distortion effects.

(Diagram taken from https://www.electronics-tutorials.ws/el ... resis.html)
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Re: Using Saturation

Post by Hugh Robjohns »

ef37a wrote: Mon Aug 15, 2022 8:51 am ...to mean a mild form of distortion when in fact, electronically it is the most extreme form of distortion you can get.

That's clipping, surely?

Many engineering terms have become corrupted in popular usage.

To most, 'saturation' means a benign and moderate level of musical distortion, well below that introduced by more severe forms of distortion like clipping or A-D overload.
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Re: Using Saturation

Post by ef37a »

Hugh Robjohns wrote: Mon Aug 15, 2022 12:42 pm
ef37a wrote: Mon Aug 15, 2022 8:51 am ...to mean a mild form of distortion when in fact, electronically it is the most extreme form of distortion you can get.

That's clipping, surely?

Yes, same thing because the transformer/valve/transistor/tape cannot supply any more signal.

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Re: Using Saturation

Post by Martin Walker »

ef37a wrote: Mon Aug 15, 2022 8:51 am But, like "rms" bloody watts I suppose I shall just have to live with the term!

I still chuckle at a loudspeaker review I read many years ago in a 'hi-fi' magazine, that referred to its power rating in Watts WFT.

When asked to elaborate on this unfamiliar term, the reviewer replied that it stood for 'WishFul Thinking' :lol:
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Re: Using Saturation

Post by Guest »

More like WTF.
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Re: Using Saturation

Post by Folderol »

As an effect, tape and transformer saturation are very similar. Fundamentally it's the same magnetic behaviour, although the tape curve is 'fatter'.

You can also get a very approximate saturation effect with two germanium diodes back-to-back fed via a fairly high value resistor - although there is no hysteresis at all of course, so it's never going to be quite right.
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Re: Using Saturation

Post by Martin Walker »

Folderol wrote: Tue Aug 16, 2022 10:05 pm You can also get a very approximate saturation effect with two germanium diodes back-to-back fed via a fairly high value resistor

Ah, the components so beloved by electric guitarists everywhere (it sounds so much more natural then silicon diode clipping ;) )
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Re: Using Saturation

Post by Sam Inglis »

To return to the OP for a moment, typically I'd only apply noticeable levels of distortion or saturation to electronic instruments such as synths and drum machines, the occasional weedy-sounding bass drum, and hand percussion such as shakers and tambourines. Distorted vocals have become a bit of a cliché to my mind. When I do use saturation I'll usually also roll off a lot of top end to stop something becoming too harsh (especially on a tambourine).

I often use a clean tape emulator on the master bus, but I think of that as a form of compression and tone shaping rather than saturation really.
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