Truncation, a deeper analysis

Here we will take 1102 eq’s low shelf and look at the original preset and then look at a truncated version of that preset with a length of 50ms. Anyone can do the same thing by going into nebula’s Kern page and simply reducing the kern size to truncate the Impulse response. I’ve provided some test tones so anyone can process them and replicate the results. This is for those who don’t believe in plugin analyzers and want to look at rendered responses.

1.In this first example we will take A single sample impulse to test our ringing. You can download all the test tones used in this blog Here. Left example is the original preset and right side is the truncated example. We can clearly see that the tail has a sharp cutoff now, decreasing the accuracy and adding ripple seen in point 3 and causing echo seen in point 2.

2. In the next example we take a a very fast sweep and look at the original vs truncated version. Notice The truncated version has a echo. This is due to the steep cutoff as seen in example 1. The images were produced by looking at izotopes rx Spectrograph. Note because this echo is so fast (50ms) it is less audible than a longer tail truncation (longer echo). This likely to be why some may say that they think it sounds more accurate than them trying to reduce ripple. The real answer is to not truncate at all. A 50ms echo will become more obvious as compression or distortion is added as usually the echo is pretty low in volume, however, Its worth noting the level of echo can change depending on what eq is added and/or where the truncation occurs, this vary’s a lot. At the end of the day it’s best its not there.

3. Lets look at a slow sweep. As we can see the right version has the ripple, again this is due to truncation. This image was produced by looking izotope rx but can be seen in any standard editor.

To finish If anyone really does wish to truncate my libraries with less information and added artifacts because some feel they are correct in saying it sounds more hardware, now you know how!!. Personally I would advise against it.