MIDI SYNC Question

I’m building my own Master MIDI Clock device and I have a question about MIDI SYNC = ON while Aeros is in STOP Mode. Note that I’m only using the Aeros, not BB, so my questioning might be related to some interaction between these two that I do not know about.

If my intention as a user is to use an External Clock and an external START/STOP command, is there any purpose for Aeros to receive the external clock first? (ie: MIDI SYNC= ON while Aeros is in STOP Mode?) Or is it the same practical result to send in MIDI START and also begin the MIDI Clock at the same time? (nearly the same time … I know). The later is what I’ve been doing with other external clock devices and it has worked fine, but my custom device has the ability to begin the MIDI Clock without sending START … I can keep those actions independent or combine them into one action.

Or to put it another way: with MIDI Clock being received, but the Aeros in STOP mode, is Aeros doing anything other than acknowledging that clock is being received by displaying MIDI SYNC = ON? Is it using that clock in some way while Aeros is stopped to help solidify the playback once it starts? Is it so that Aeros can sync to a clock while also offering the ability to Start using it’s own command instead of an external Start command? (<= if it’s that reason, and it seems likely, I have some other observations about that, but will avoid that discussion for now)

I’m actually not running into any roadblocks, everything is going great with my custom external clock device. I’m really just wanting to understand a bit more about the purpose and intention for MIDI SYNC = ON while in STOP Mode because there might be something about it that will spark an idea or help my device be more future proof.

Through further experimentation I realized that sending MIDI CLOCK without a START command (MIDI SYNC = ON) also sets the BPM of the song automatically in Aeros.

That’s what I was missing. I suppose it’s this way primarily for how BeatBuddy and Aeros can interact, but can also be beneficial for use by other external devices. It was only observable by me once the external device’s clock and transport controls had independence.

(I realize now that sending Clock without Start is also a way to work around the loop length bug I’ve seen in the past … where you had to make sure Aeros was already set to the same BPM as the external clock. I remember MIDI SYNC=ON being discussed in some BB related threads, but I was missing some of the nuance since I don’t use BB.)

Hello there, sorry for the delayed response,

Interesting questions

Yes, the best way to use the Aeros is with a continuous clock source, otherwise you may have hiccups in certain situations. This is why we have allowed the BB to have a setting to send clock even while stopped.

In essence you should be able to get most behaviors to work normally if the device is setting the Aeros to a BPM that is close to the current BPM displayed on the Aeros as it receives that start command and the clock.

My guess is that it could potentially desynchronize in some cases if the tempo change is too extreme and Aeros does not adapt fast enough, but I can’t say for certain. You will certainly lose the ability to set up a recording before the first beat of the measure (which may or may not apply to you).

Yes, we do support the ability to have Aeros “listening” to the clock to keep it better in time and to constantly resync if the BB changes tempo while stopped. This may be more of a solution to a problem when using machines like the BB that have their own playback timing. If the clock source you are using does not actually produce sound or is restricting playback, it likely should cause no issue (other than that possible tempo jump I brought up).

That’s it!


Thanks, it’s good to know what the thinking was there even though I had worked it out. It was pretty clear once I got the right kind of external activity happening.

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My pleasure thanks for the question!

@BrennanSingularSound Another question here! :slight_smile:
When the Aeros is receiving midi clock, will it send that tempo thru the midi out port too?


I am just getting up to speed on Aeros and MIDI. Has been on the shelf, unused, but I am at a point of sell it or use it (hopefully the latter), and I am encouraged by the MIDI commands I see.

I am used to setting up presets for songs with my Pigtronix looper, often able to the same preset for multiple songs. You don’t set the tempo, just things like time signature and for their device things like series or parallel mode. I run the tempo from a clock source (I use Bandhelper on my iPad), and I play a backing drum track recorded at that same tempo, while a MIDI file runs in the background, turning loops on/off/record/play, etc… This works well.

From what I am reading, sounds like for Aeros I will have to almost create a “song” (a preset if you will), for each song I perform because of the need to set the BPM, otherwise things may get off. If I am understanding the above correctly, Aeros might adjust to an incoming MIDI BPM different from that set in the song, but that would likely create drift since I am playing to a track.

Anyway, not exactly a deal breaker, however why not have the ability to modulate BPM via MIDI, and add the setting to the BPM section for songs where Midi clock is a third option? For a set-up like mine it would allow me to create dynamics in song parts, and change the BPM on the fly.

Because it’s not that simple. Audio changes pitch when sped up or slowed down. There are complicated processes used to speed up up or slow down audio and have it retain pitch. These processes require more powerful computing engines than you can normally put in a pedal. Tempo change with midi is not that big of a deal, when you are triggering midi samples. The samples are pre-pitched. But tempo change with audio requires some serious computing power.

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No, I understand that, and I do not expect the Aeros to correct pitch with tempo change. What I expect it to do is to be able to adjust to tempo change from the standpoint of MIDI tracking. That is extremely useful if you’re playing to backing tracks. I understand they have their beat buddy option, but some of us do not use that. By keeping pace with tempo changes, you can have a song where perhaps there are dynamics such as an increase in tempo when the chorus hits.

If you were just using a loop for the verse, then when you go back to the verse it will have its original tempo. As I type this I realize one limitation of the Aeros system. Because tracks are tied together on the Aeros, almost like a sequencer, I don’t know whether it would be possible to record a verse and a chorus at different tempos. I guess that could work with parts, so hopefully, as long as you recorded, say the verse part, at 120 BPM, and then the second chorus part at 126 BPM for Dynamics, it might be able to work.

Again my point would be you are switching tempo before recording the part, and every time you go back to that park, the tempo matches up. There would be no need for pitch changes. But the way Aeros arranges loops, and ties tracks together, I assume you could not have track one at one tempo and track two at the other. Understand that the way I am using the Aeros myself Is sometimes to have multiple tracks that may not overlap or be played at the same time. Just the ability to have multiple loops that I can pull in and out. Sometimes they will be in series, sometimes they will be in parallel. Obviously any tracks running in parallel absolutely have to be at the same tempo. But if I have several tracks that I play in series, that would have to mean that either the Aeros could change tempo for parts, or perhaps you could even record tracks at differing tempos and solo the track you want to hear at the right tempo, then change tempo and solo the track that was recorded at that tempo.

I hope all of that makes sense.