Subject:Every loop I make wobbels??

Posted by: ppaul

Date:12/7/2002 11:51:03 AM

I have another problem so I though I'de make a seperate subject on it in case others have this difficulty. When I mahe a 4 bar chord loop, and play it back as a loop it has a bad "wobble" to it. I've tried every possible technique to fix. Telling it to adhere to pitch, Changing pitch of song while making, placing Key at none, making a new song so there won't be other tracks interferring, Uploaded newest Pro 3, Adjusted latency eyc etc etc.

It's funny. I though I had it fixed when I told it to "adhere to track tempo" when recording. Got one loop fine. Then attempted anpther loop and the wobble was there. Recorded yet another that was OK, then went back to listen to the original one that turned out fine, and it was now wobbly?? Again SF has no clue.

My friend dave just got back from his tour with Ray Charles. He's REALLY good with IBM. It's a mystery for him as well??
Many Many Thanks

Paul Adams

Subject:RE: Every loop I make wobbels??

Reply by: dkistner

Date:12/7/2002 12:09:32 PM

Paul, I take it it's nothing so simple as being sure you've got zero loop points at the start and end? I know if I make a loop that's not perfectly faded to zero at both ends, it will sound terrible.

Subject:RE: Every loop I make wobbels??

Reply by: Laurence

Date:12/7/2002 10:32:07 PM

I wish there was a short answer to this. Oh well, here it goes:

When you make a loop yourself, especially if the loop is polyphonic tonal stuff, you usually get a "wobbly" (nice adjective) sound with the default loop stretch settings. Fortunately you can usually get it to sound pretty good with a little tweaking. It will never sound perfect, but you can get it to sound as good as the commercial Acid loops.

When Acid shortens a loop, it's actually cutting out segments of the audio. It does this at intervals defined in the "Track Properties / Loop / Stretch" screen. The default is every sixteenth note. This is done so that musically, any note position occuring down to the sixteenth note will be preserved within a loop. So in other words, when you shorten a loop, each segment plays at it's regular speed for one sixteenth of a beat at it's new tempo, then at the next sixteenth of a beat the sound jumps ahead to the beginning of the next sixteenth of a beat. In addition to the sixteenth not "division points", there is an "extra transient detection" setting that also puts one of these "division points" anywhere where the volume changes above the defined percentage. This works quite well musically in that melodic changes that would make sixteenth not quantization will still be in the right place. The problem is that the sound is also jumping ahead four times every quarter note even when the notes are just sustaining. This is the "wobbly" sound you're hearing.

Speeded up, Acid loops and Rex loops sound pretty much the same. Slowed down, Acid loops get a little more complicated. Whereas Rex files either cut off abruptly or have envelope generator type fades added to the segments that don't last long enough, Acid loops attempt to stretch the sound out to the next segment. In the "Track Properties / Loop / Stretch" screen, you're given three options on how slowed loops will work: "looping segments", "non-looping segments", or "pitch shift segments". You have to choose among these by which sounds best, although I usually end up using "non-looping segments" because it seems to do the least damage to the sound.

So what does all this mean? It means that speeding up loops usually sounds better than slowing them down. It also means that some types of material will sound great as a tempo altered loop, and some stuff won't work anywhere near as well. Percussion loops where the individual sounds die out quickly work the best. Latin percussion works wonderfully for example. Drum loops with ringing cymbals don't loop nearly as well, but often sound passable in a mix. With percussion,the waveform is more random than it is with melodic stuff, and the "wobbly sound" is hard to notice.

With tuned notes, it gets more difficult and you need to do some tweaking. With a loop, notes are held for varying durations. With the default loop settings though, the sound is jumping every quarter of a beat. Any notes sustained through these jumps will sound "wobbly". Ideally, what you want is for the sound to have a jump point only when a note changes. Unfortunately the "transient detection" can only detect volume changes and isn't accurate enough to detect all the note changes.

What I've found works best is to set the "force divisions at" parameter to sixteenth notes, then go through and manually go through and "disable" all the division points that don't have any note changes positioned at their markers. Then I go through and move the remaining marker points a little ahead or behind any time their associated notes were either rushed or dragged a little. I also add extra markers wherever there is a noticable "note off" sound. Bass guitar loops in particular have lots of audible pull-offs at the ends of notes. You want these defined as well. Doing this can make the loops sound way, way better. Single note melodies and bass lines approached like this sound almost perfect speeded up, and often passable slowed down. Chordal stuff where all the notes change together sound pretty good as well. Chorused synth parts have enough confusion in the sound to sound good even when the notes change independantly. Clear tones in a loop where some notes are changing and others are sustained sound the worst. What happens with this type of material is that you need to set the division points to the points where the notes are changing, but you'll also hear the sustained notes in the background jumping at the same points. Finger style guitar is an example of material where the Acid looping will never really sound great.
These loops still sound better with tweaking than they would if they weren't tweaked though.

There are a whole host of frustrations remaining with this process. There might be a way to save these tweaks with a loop, but I haven't found it. I just save the loop tweaks with the song I'm working on. Often the "division points" are unresponsive to movement or disabling / enabling. What I've found is that when you hit an unresponsive division point, repeatedly enabling and disabling it will eventually give you back control of it. I have to do this an average of ten or so times in any given loop. Maybe in the eagarly anticipated "b" revision this will be fixed. What I'd really like more than anything is to be able to set the division points in Sound Forge along with the other Acid Properties, and save them along with the Wav file, kind of like Propellerheads Recycle does, but with Acid's extra tonal abilities.

Is it worth all the frustration? For me it is. I really like doing my own guitar and bass parts, but I'm not nearly a good enough player to play what I hear. Being able to play the parts slowly then bring them up to tempo helps me out immensely. I actually sound like a pretty good player by the time I'm done.

If anyone knows a better way to do this, please let me know. It wouldn't be the first time I've made the long trip around the block just to get next door!

Laurence Kingston

Subject:RE: Every loop I make wobbels??

Reply by: Laurence

Date:12/7/2002 10:47:33 PM

I just did a little experimenting with some commercial loops and I take back what I said about how "you can get it to sound as good as the commercial Acid loops". The commercial loops "wobble" like hell too! I guess I'm just a whole lot pickier with my own stuff! The tweaks I was talking about in the previous post improve commercial loops as much as they do your own custom ones. How noticable the "wobbling" is in a mix is up to you. When I put a piece of music together, I'm pretty particular about how it sounds. I don't listen to other peoples stuff nearly as critically I guess, because I hadn't noticed the extent of the "wobbling" before in any of the demos or Acid planet downloads. As I go over them more criticaly, they're there like crazy though! With a little tweaking though, it's amazing how much better it sounds!

Laurence Kingston

Subject:RE: Every loop I make wobbels??

Reply by: dkistner

Date:12/8/2002 9:51:41 AM

Laurence, thank you for the wonderful education! And Paul, I did not mean to insult you with my reply. I doubted seriously, in your case, it was something so simple. But there are others on this forum who may need to know the simple stuff. When I export loops from Acid, I almost always have to do additional work on them to get them edged right. Of course, you DID say "wobble" and not "whack thwack"! :)

Subject:RE: Every loop I make wobbels??

Reply by: Laurence

Date:12/22/2002 9:02:25 AM

4.0b seems to be a lot better. Now when you adjust division points in a loop, they all respond to the mouse properly. Even more important, you can now resave the loop with the edited division points and the edit points will be embedded in the loop. With the improvements in Acid and a little tweaking, I can now get loops to sound amazingly good. I would also say that while in the past, there were times when the Steinberg Recycle Rex method of looping would sound better for certain types of loops, that now the Acid format can ALWAYS be made to sound as good, and the extra versatility usually makes it sounds better!

Laurence Kingston

Subject:RE: Every loop I make wobbels??

Reply by: Iacobus

Date:12/23/2002 1:44:28 PM

Just wanted to add that with custom loops, you should always go into the track properties and adjust the stretch markers under the Stretch tab. You'll want to add or adjust markers so that they fall on particular strong subdivisions of a beat within the audio. Doing this will make your audio sound much better when it's stretched.

HTH,
Iacobus