Loop sync — synchronized multi-track looping from a master loop

Loop sync uses a “master loop” to time the lengths of subsequent loops (which are then multiples of that loop’s length). I don’t have an actual first-hand experience with sophisticated loopers like the Boomerang — but based on some helpful insights from Rob Flax, I think I’m gotten at least some of it right.

There are two patches included:

— a four-track monophonic looper that uses the left input and the left output (stable)

— a three-track stereo looper (is… I think stable now, but I’ve had some crashes while working on it)

I don’t think this is perfect yet; I’ve improved the drift/desynchronization a lot but it still occurs; it is a very complex patch with a lot of moving parts, so to speak, so I’m still catching things and ironing them out.

Please, let me know what your experiences are, and if you have any feature requests — but do keep in mind, the ideal form of those feature requests should be “what if instead of X you had Y?” because CPU is a very real concern (X -and- Y may not be possible), especially for the stereo looper but for both really.

The loops can be overdubbed; the patch should (he says, hopefully) go straight from recording to playback.



Middle stompswitch — cycles through loops with a tap and through modes with a hold (a bit over 500 ms) and release (a UI button on the front page will change color; you can also press the UI button to change modes)

[I thought a lot about stompswitch placement and, while I’m not sure middle is the best stompswitch for this, I also got antsy about placing the reset control so close to the record one. Let me know what you think]

Record mode (indicated in red):

Left stompswitch — record/overdub track — pixels on the front page will indicate if a track is recording (red) or playing (green) or overdubbing (red and green)

Right stompswitch — reset track; note: since track 1 is the “master,” resetting it will reset all the other loops

Modify mode (indicated in… lime? I think; yellow-green):

Left stompswitch — reverse track (UI button on front panel will change from yellow to pink; you can also press the UI button to reverse/un-reverse a track); note: the reversing feature will be cued to the next clock cycle of the master loop and will not happen immediately — this is an effort to keep the loops in sync

Right stompswitch — mute track (UI button on front panel will change from white to … surf? light blue; you can also press the UI button to mute/unmute a track)

Play mode (indicated in I want to say sky — blue):

Left stompswitch — pause/unpause all tracks (because of the way this interacts with the play all command — right stompswitch in this mode — there is no UI indication when the tracks have been paused)

Right stompswitch — play all tracks — this will cause the tracks to begin playback from the beginning of their buffers; note: in the monophonic version, individual tracks can be cued to playback (the indicator for play mode is a UI button; when pressed, it will cause the track to play back from the beginning — CPU wouldn’t allow this feature for the stereo version)

Front panel:

I tried to get as much functionality into the footswitches as possible; there are also some UI buttons that parallel the functions of the stompswitches; they are detailed in that section. But —

Each track has an independent pitch/speed control.

Each track has an independent level control.

There is a UI button that cycles through colors (four of them) as a sort of “visual” metronome; its speed is based on the master clock. When it returns to red, the master clock has cycled back to the beginning.

In “normal” functionality, recording for tracks other than the master will occur at the beginning of the master clock’s cycle, again, indicated when the UI metronome returns to red (if it -is- red, you’ve already missed your window).

There is a “counter” that will show you how many multiples of the master you are recording. It goes up to four multiples/bars but you may exceed this, depending on the length of the master. (Each looper is limited to 32 seconds.)

If, however, you would like to begin recording, you know, whenever, there is a pushbutton called “Bypass pre-roll.” It… messes up the metronome (causes it to go a little nuts) and the counter, but it will still use the master loop’s length as a “clock.”

All overdubbing occurs without pre-roll.

My own thoughts on further development, all of which probably involve cutting the track count (to 3 in monophonic mode and 2 in stereo):

— I would love to add panning, but the CPU, at the moment, isn’t cooperative. I may do a three-track mono version with panning added, though. Or a two-track stereo version. (Or both.)

— Again a CPU issue: I had an early version of this patch that included a clock divider, so that you could produce, for instance, tracks that were synchronized to the quarter note (or an eight note or whatever division you wanted), rather than the bar. I ultimately removed it, but it could be another addition I have room for in a patch with fewer tracks.

— I just couldn’t really figure out a feasible way to add pitch-shifting to the stompswitch control regimen, but if you have suggestions, please let me know.

— There was originally a dry signal level control. I cut it, for CPU reasons. I actually have no regrets about this and would be unlikely to make it a priority in future versions, but if I’m wrong, let me know.

— I might do a version with latching stompswitches. It’s worse for timing, but potentially better for desktop purposes, like how I largely use it.


Revision 1.1 (please read):

MIDI versions added:

— MIDI versions of the monophonic and stereo patch have been added:

Recording for the “master loop” in these patches will feature a delayed trigger that waits for the next MIDI clock beat.

Additionally, the “play all” feature (“play mode”; sky UI button; right stompswitch) also features a delayed trigger, so that if the loops are stopped, they will resume in time with the MIDI clock.

CPU is at a premium, and these additions cut into what little (if any) headroom there was. Testing was stable, except in the case of the monophonic patch when “record to all” was selected. This caused the CPU to… fake freeze; the utility buttons turned yellow, but the patch continued to function. Honestly, you could probably use the patch in this condition without incident, but I did want to report it. Please, let me know if you find any other issues.

— There is a “buggy” behavior to report (affects all versions): track 1 sometimes loads with the green “play” button lit up. If you load the patch and find it in this state, please reset the patch using the right stompswitch. (This should clear the green light.) If you don’t do this, the first track will begin overdubbing immediately following recording (and never stop overdubbing).

I think I know the source of this issue, but I’m not sure it will be easily resolved. That said, just remembering to reset the patch when you load it, is relatively simple. I do this now, whether the light is on or not.

— All versions (MIDI and otherwise) had very minor “under the hood” adjustments. In particular, an error made in the loop buffer for the third track of the stereo version and the fourth track of the monophonic version was corrected.

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  • Category: Effect Sampler
  • Revision: 1.1 -- MIDI added; revision notes at bottom of patch notes
  • License: Creative Commons Attribution Share Alike 4.0
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  • Modified: 3 months ago
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3 comments on “Loop sync — synchronized multi-track looping from a master loop
  • elihu252 on said:

    I love the direction this is going. This is how looping should be if the Zoia is your main looping device (ie: the Zoia sets the clock and the other loops quantize appropriately).

    My requests would be:
    1. latching stomp switches
    2. immediate overdub recording
    3. a bonus would be any cpu overhead

    That’s honestly about it. I can already see this being my most used patch on the Zoia.

  • Christopher H. M. Jacques on said:

    To 2. Most people complain about immediate overdubbing (I actually don’t overdub much, period, and am more likely to simply record another track as an “overdub”) — but I could do a version without immediate overdub recording. Heck, I might as well do a version without overdubbing at all to suit my own preferences. (I’m just planning to iterate; let me people pick their preferences, so the .zip bundle will just get bigger, rather than some either/or proposition). Give me a few days.

    Removing the “move to playback instead of overdub” mechanism should afford some CPU headroom, as this requires a layer of reactive monitoring that while not extraordinarily costly, doesn’t come free, either.

    I almost forgot — yeah, latching stompswitches is an easy change.

  • elihu252 on said:

    The main reason I like immediate overdubbing is so that I can create loops with tails that blend and to avoid clipping. It just makes for really clean sounding loops. Definitely looking forward to the updated zip with new options.

    Thanks so much for creating all of these great loop patches btw.

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