Looping Waveforms

Hi All,

1st post here.

I've been experimenting with using my 1k as a sample synth, I've sampled the raw waveforms from a Virus TI and have been looping 1 cycle of sample. for e.g. a saw wave pitch A3

My drama is that i am getting clicking and what sounds like aliasing (almost like a phase running down the note) that I can only put down to a bug in the MPC, the looping is perfect, I just can't work out what could possibly causing this.

I've tried using longer samples of up to 5 seconds where the cycles again are a prefect 360 degrees but i still get a click when the sample loops.

Hope this make sense,

Cheers,

Blinky

this is an issue i'm having toubles with, too. sometimes i think i'm doing everything right to have a perfectly clean loop. everything looks good, but it still clicks. i don't know why...

Yeah, I have this problem, too. It might have to do something with JJ OS.
I have some old loops that worked on Akai OS and now have clicks in them.

Hmm... I'm gonna log it as a bug, see what happens.

Thanks for your help, this is one thing i'd reall ylove to get fixed!

Cheers

Got a reply, can't say i agree with it...

A click noise comes out of change (i. e.Tune:01:00) of a wave-like pitch with steep rising edge.

It is because the frequency component 20kHz or more is included.
Since the sampling rate is 44.1kHz, the waveform containing a frequency component 20kHz or more is normally unreproducible.
(Limit of hardware)

As for the sound recorded using the SAMPLE RECORD function of MPC1000, the sound of 20kHz or more is cut.
Therefore, please LOOP and use the sound recorded by the SAMPLE RECORD function of MPC1000.


: The following waveforms contain the waveform 20kHz or more.
: This waveform is normally unreproducible.
*
* *
* *
* *
* *
**** **************
-->||<--Over 20KHz( Under 50uSEC )

: The following waveforms do not contain the frequency of 20kHz or more.
: This waveform is normally reproducible.

*
* *
* *
* *
* *
* *
*** **********
->| |<-20Khz( 50uSEC )

Sample rate=44100Hz
A3=440Hz = 100 sample point ##### Just 100 sample ####
MPC1000 [Trim] St:0000000 End:100
::: It's play without noize
* *
* * * *
* * * * <- Wave form
* * * *
* * * *
**** * *******
<---100 point-->
__|__|----------__|__|__|__|__|__|__|__|__| <- sample point 44.1K
^

Sample rate=44100Hz
MPC1000 [Trim] St:0000000 End:100
rogram Tune:+02:00 ==> B3=493.8Hz = 89.1 sample point

::: It's play with noize
|<---2040uSEC-----> <---- position actually reproduced.
|<---2025uSEC--->|<------ exact position.
* | *
* * | * *
* * | * *
* * | * *
* * | * *
**** **** *****

<---89 point -->
__|__|----------__|__|__|__|__|__|__|__|__| <- sample point 44.1K
89 90

493.8Hz =2025uSEC
89 point =2018uSEC
90 point =2040uSEC
Since a loop is not made in 2025uSEC
A wave like sound which repeated 2018uSEC and 2040uSeC hears.

*
* *
* *
* *
* *
* *
*** **********
In such a wave-like case, a noise can be heard few.

In a sign wave, a noise cannot be heard.


JJ

so did you try to apply a low pass at 20khz (or 19kHz) on your waveform ? by reading the explanation sounds like it would fix that.

or as JJ said, sample the waveforms using your mpc. (seems to be an even better solution)

I would love to see a start/end cross fade parameter like the one that is implemented in Ableton's Sampler VSTi. It works so nicely, you can make just about any waveform loop seamlessly.

Luke

realtime crossfading presents a problem because the sample will take up double the voices in that brief time when it's crossfaded...

this is a hard problem to solve, but i just play until the click is less noticeable and then run a de-clicking plugin over it post trackout. less than ideal but it works, and it's just another rough sound over other sounds with record pops/etc over em

Yeah, i've tried all this before I submitted the bug report. It works but i think there could be a bit more to it, it doesn't explain why were still getting clicks and aliasing playing the sample at it's original pitch or why it only happens on the 1K but not on the 2000xl.

Ah well...

Sometimes when I am trying to loop a sample on the mpc I have noticed that the waveform display is not perfectly accurate, even when zoomed way in. Sometimes I get a better result (no click) when I move the loop point forward or back, even to the point where it looks like I am getting a little bit into the beginning of the next cycle.

TBonus76 wrote:Sometimes when I am trying to loop a sample on the mpc I have noticed that the waveform display is not perfectly accurate, even when zoomed way in. Sometimes I get a better result (no click) when I move the loop point forward or back, even to the point where it looks like I am getting a little bit into the beginning of the next cycle.

tip: trust your ears, not your eyes. use the display just as a guide because it's not going to be exact.

that's another reason why i hate that you have to click zoom a bunch of times in order to be able to move an end point by single digits. you should be able to change the end point by 1 digit regardless of what zoom you're in.

on the 2000xl, the amount of steps the end points took was dependent on how fast you spun the data wheel. that needs to be brought back since it was an awesome feature. if you spun the data wheel slowly, regardless of zoom, it would change the end point by 1 digit. if you spun the data wheel a little faster, it would change the end point by 10 digits. a little faster than that, and it would change by 100 digits, then 1000, and so on. far superior than the way that the JJ OS does it.

double post

Mike Feedback wrote:
tip: trust your ears, not your eyes. use the display just as a guide because it's not going to be exact.

That was my point.

TBonus76 wrote:That was my point.

gotcha.

i rarely use the waveform display anyway, which is why it's such a pain that i need to zoom in to move end points in single steps. i shouldn't have to zoom in if i'm not even going to look at the waveform, right? it kills my workflow having to click zoom 5-10 times every time i go into trim or switch to a different sample while in the trim window.

Yeah, sounds like that might be the way to go, I didn't know the trim scre4en wasn't alway accurate, thanks heap all!