Weird frequency introduced into sample...

mal1ce · Post by **mal1ce** » Tue Dec 04, 2007 4:00 pm

I'm building a layered kick comprised of 3 samples.
One of the samples I am adjusting the start time and then adjusting the volume envelope from -inf to 0.
When I do this it introduces a high pitched "squeak" sound to the sample that is not there normally.
Any ideas on how to fix this?

Here are some examples:

The sample untouched:

The sample with its start and volume adjusted:

Here is an audio file of the sample.
The first 4 beats are of the sample untouched, the second 4 are with the start time adjusted, and the last 4 are with the start time and volume envelope adjusted. The final 4 beats is where you will hear the squeak.
http://www.fileden.com/files/2007/10/11 ... SubHit.mp3

laird · Post by **laird** » Tue Dec 04, 2007 11:05 pm

since I can see stair stepping in this drum sample, I'm guessing it either came from an 8-bit source/ lower sample rate source.
Maybe you've detuned this kick drum?

Anywho, all those little squares could be producing aliased overtones, which could be masked by the loud kick transient in the first 4 beats, but become quite noticeable when you turn the volume WAY UP for the last 4 beats... and thus that sqeak really was there all the time?

Also, looks like you COnsolidated that sample, maybe, after cutting off the attack? If so, the "cut off" version looks normalized: i.e. volume is boosted. Which also suggests this squeak was already there (due to aliasing or whatever) and now you've amplified it to an audible range.

mal1ce · Post by **mal1ce** » Wed Dec 05, 2007 5:43 pm

I'm actually pretty sure the freq is not in the original sample.
I created the kick in Logic with Ultrabeat, processed it a little (Comp, Verb, Distort) and then dropped it into Ableton.
Also, I've been playing around with it and if I move the -inf point (in the second pic) closer to the 0 point (or vice versa) the squeak diminishes in volume even though Im not reducing the overall volume of the clip.

Could this possibly be a zero crossing issue?

==edit==

Ok, its an Ableton glitch.
I've just loaded the same sample into an audio track in Logic, adjusted the volume and sample start times exactly the same as the Ableton project, and there is no squeak.
Looks like I'll have to build the kick in Logic and then bounce it for use in Ableton.

meh.

laird · Post by **laird** » Wed Dec 05, 2007 8:37 pm

what sample rate and bit depth did you render the sample at in Logic?

mal1ce · Post by **mal1ce** » Wed Dec 05, 2007 9:50 pm

16/44.1, same as I'm using in Live.