A perceptual approach on clipping and saturation

[teemuk]

Just bumbed to this little whitepaper.

T. Serafini S. Barbati, "A Perceptual Approach on Clipping and Saturation", 2002

http://www.simulanalog.org/clip.pdf

Short (4 pages) and written in layman's terms. It basically tries to address the issue that "musical" special effects can't be evaluated with same principles as high fidelity sound reproduction and therefore some pre-established concepts about "good" or "bad" harmonics/clipping need to be reconsidered depending on application. Totally worth reading.

[J M Fahey]

Interesting and thanks for posting.

What they describe ends up trying to explain sound "warming" by recording on analog tape; fine, and I bet some clever digital guy will write the proper DSP algorythms to simulate it.

[teemuk]

Yeah, it seems to be written with largely final studio mastering stages etc. in mind, so it's not really addressing "warming" of individual instruments, like electric guitars. Nevertheless, I think the overall concept - which is trying to address that there is no "good" or "bad" clipping, or "good" or "bad" harmonics, when all that is largely dependent on application and related preferences - is on point.

[teemuk]

Oh, I also like how the article is written largely from very objective theoretical point of view. It addresses certain phenomenon as is, and does not even try to pull the discussion about them into discussion about digital vs. analog signal processing, solid-state vs. tube amps, or anything of that manner (at least any more than neccessary).

[LateDev]

Interesting and as far as warming on a tape is concerned, I tend to think that statement is both true and false at the same time.

I must admit I have not read it all as I did some research into this many years ago, so can see where the writer is coming from.

In the 80's there were always those that either swore by analogue or by digital. The analogue sound being truer to a live performance, hence warmer, and the digital notably different as having no warmth.

With this article the writer talks about different types of wave modification, the easiest is of course a straight clipping. Even then this will produce complex harmonics which can either add or subtract from a sound.

What is being said is where an instrument has distortion of any nature the waveform is complex and should not be thought of in terms of a fundamental sine wave. When you then mix this complex waveform with other complex waveforms, the harmonics of the accumulated waveforms adds warmth to the sound.

This happens in any analogue mix and the medium to which it is being recorded can either add or subtract from the overall effect.

The best signal for any tape player is where the signal is near saturation. basically this is because of the way a tape is recorded. You need a maximum flux density induced into the tape so that background noise is obliterated

I will go back to my earlier statement of the warmth coming from the tape being both true and false. Its false because the warmth starts earlier in the process and true because then it is added to, by recording on the tape.

An interesting article that deserves an in depth read


 

[gbono]

 Unfortunately, most people do not consider quadratic equations (parabolic function describing soft saturation) a layman's explanation. The section on symmetric/asymmetric transfer functions and their related harmonics is nice and they didn't involve Fourier transforms in the discussion.