If you haven’t come across them already, Pocket Operators are tiny battery-powered sound modules made by teenage engineering. Don’t be fooled by their bare PCB design and calculator-style screen, these little modules pack a punch that defies their toy-like appearance.
There are 9 unique modules to choose from, outlined in Our Guide to Pocket Operators blog post. Each one fulfils a different role, whether it’s a synthesiser, drum machine, or sampler. They all feature a built-in sequencer that allows you to play sounds and perform with patterns without a computer or controller.
Pocket Operators are standalone devices, but each one is really a piece of a larger puzzle. Imagine instrumentalists in a band - you might have a drummer, bassist and keyboardist. One Pocket Operator could fill one of those positions. If you had three, you would have a whole band.
But can your band of Pocket Operators talk to each, and play in time?
Yes, they can!
Not only can you synchronise them, but they also sound great together too - as we explored in our mini-series on Youtube - PO-COMBOS.
A simple, but clever bit of design allows Pocket Operators to be synced with each other and external devices. It's not MIDI, or USB, so what is it that keeps them firmly 'in the pocket'?
In this blog post, we’ll explain how it all works, and how you can get your Pocket Operator jamming along to the beat.
Before we start connecting Pocket Operators together for a synced-up jam session, let's answer some fundamental questions on how it all works:
What protocol do Pocket Operators use to stay in sync?
Rather than MIDI or USB Sync that we’re used to seeing on electronic instruments, Pocket Operators use a trigger based control voltage signal called PO-Sync. This signal is made up of electronic pulses with evenly spaced time intervals. The time interval between each pulse determines the tempo at which the Pocket Operator plays. It’s a similar method used in old school sequencers or modular equipment where you might see it labelled as ‘clock’ or ‘trigger’ output.
Where does this PO-Sync signal come from?
In simple terms, a ‘Master’ Pocket Operator will generate a PO-Sync signal using its own internal clock. This can also be generated by other external devices (we’ll cover this later). When you set the tempo on the 'Master' device, it generates a PO-Sync signal at the same relative speed.
How does a Pocket Operator use PO-Sync to stay in time?
The 'Master' Pocket Operator outputs PO-Sync signal, and a ‘Sync’ Pocket Operator will receive it. The pulses from the signal trigger the 'Sync' so it runs at the same tempo as the 'Master'.
How does PO-Sync get from the 'Master' to the 'Sync'?
All Pocket Operators have two 3.5mm stereo jack sockets on the back. Looking at the front side of a Pocket Operator, the socket on the left is the input, and the socket on the right is the output. A ‘Master’ will output PO-Sync through the output, and the ‘Sync’ will receive it through its input.
Rear view of a Pocket Operator.
Will I need a special cable for this?
Nope, all you need is a regular stereo 3.5mm jack to jack cable (aka Aux Cable). These tend to be unnecessarily long when your Pocket Operators are next to each other, so teenage engineering have developed some that are more like miniature patch cables. You can find them here - MC-3 Mini Cables
If I connect a ‘Master’ and a ‘Sync’ together, how will I hear the 'Master' Pocket Operator?
The connection between ‘Master’ and ‘Sync’ is stereo. It can therefore carry 2 separate channels - the left channel will be PO-Sync, and the right is mono audio. The audio from the 'Master' will pass through the 'Sync', and audio from both Pocket Operators will be mixed at the output.
But wait, if the left channel is PO-Sync, won't I hear it?
When you plug in headphones to a solo Pocket Operator, you hear audio in both ear pieces. However, we've just said that a 'Master' Pocket Operator uses one of those channels for PO-Sync, so why don't we hear that? This is where we use Sync Modes.
Stick with me here, hopefully this will all become clear in the next section...
Sync Modes configure the input and output signals from a Pocket Operator. Because PO-Sync and Audio rely on the same cable connection, it's important to be able to change the signal path depending on the Pocket Operator's position in a chain of devices. Otherwise you might end up getting an earful of sync signal from a Pocket Operator at the end of a chain.
Have you ever tried listening to a sync signal? It’s not very nice - so let’s try and avoid that!
There are 6 Sync Modes in total, allowing you to create a chain of any number of Pocket Operators in any order. On the Pocket Operator, they appear as SY0 - SY5. We've created a table to summarise what each mode does:
| Sync Mode | Input | Output | Chain Pos | Use |
|---|---|---|---|---|
| SY0 | A / A | A / A | n/a | Solo PO (default) |
| SY1 | A / A | S / A | Start | Master PO |
| SY2 | S / S | A / A | End | Sync PO - Ext Device |
| SY3 | S / S | S / A | Middle | Sync PO - Ext Device |
| SY4 | S / A | A / A | End | Sync PO - PO Chain |
| SY5 | S / A | S / A | Middle | Sync PO - PO Chain |
Key: A=Audio, S=Sync, PO=Pocket Operator
To help visualise how this all works, we put together some example configurations for each Sync Mode in this short video:
In this video on Pocket Operator Sync Modes, we give you a quick overview of the different sync modes and examples of where they are used.
In case that went by a little quick, we've taken a screenshot of each example and added a description to explain a bit more about what's going on:
No sync in or out. This is the default mode when you switch on a Pocket Operator. Stereo audio out, and audio can also pass through from the input
Sets the Pocket Operator as a ‘Master’ device. The stereo output is split between mono and sync. Audio can also pass through the PO in this mode
Pocket Operator receives Sync from an external source. It only accepts PO-Sync in, and only outputs audio. In this example, the PO Sync Signal is being generated by the oplab module in OP-Z. Find out more about oplab here
Similar to SY2, except PO-Sync and audio are coming through the output. This means you can attach more Pocket Operators to the chain. In this example, K.O! Is reading PO-Sync from the input and outputting it to the Factory. Factory is set to SY4 so that it only outputs audio.
Sets Pocket Operator as the end of the chain. It receives PO-Sync and Audio, but it outputs Audio only. We’ve used the PO-Sync and Audio out from OP-1 to demonstrate this (more on this later).
This mode sets the Pocket Operator as a link in the chain. It allows PO-Sync and audio to pass through. In this case, it’s creating a bridge between OP-1 and another Pocket Operator set to SY4.
So, we've covered every PO-Sync Mode, and shown you scenarios to use them in. Now we need to put this into practice. Here's what you need to do to set up your Pocket Operators ready to sync:
To change the sync mode, hold the [func] button and press [bpm]
The [func] button has a different name on every Pocket Operator. For example, it's labelled [solo] on PO-24 office, and [chord] on PO-20 arcade. Whatever its labelled as, it will always the button immediately below the right encoder.
As you change sync mode, be aware of the SY number on the top right of the screen.
The SY number appears momentarily as you change sync mode. It's worth noting - if you don't have a cable plugged into the input, you can only select SY0 or SY1. It is assumed that your Pocket Operator will be using its own internal clock, and therefore won't work in SY-2 to SY-5. As soon as an input cable is detected, you can access all 6 modes.
The am & pm indicators show when a Pocket Operator is receiving a Sync Signal.
You can tell if a ‘Sync’ unit is receiving a sync signal correctly by looking at the behaviour of the am & pm indicators. They should flash in time with the Master device's tempo if it's working correctly.
It’s not easy to remember all these modes. Chances are, if you already use multiple pocket operators or sync them with external gear, you’ll remember the ones you use most frequently. You can always cycle through modes until your chain works if you can't remember.
Perhaps it's better to make a cheat sheet, or refer back to our blog post… maybe bookmark it now to be sure...
Now that you're armed to the teeth with all this PO-Sync knowledge, it’s about time you set up your own dope Pocket Operator chain.
It's not just Sync Modes that you'll need to be thinking about. You will also need to consider how your Pocket Operators will interact with each other.
Referring back to our band analogy, one member is going to be in charge of keeping time, and another one is going to want to be the loudest. Luckily, your the manager, so you get to make these decisions!
To keep this simple, we’ll talk about each of these points as though you're setting up a chain of 3 Pocket Operators
Choose your Master Device
This could be a Pocket Operator, OP-Z, OP-1 or anything that transmits PO-Sync. Pick something that’s going to be constantly running.
In the case of our 3 Pocket Operators, pick the one that you would most likely leave running for the whole jam session.
Decide your device order
Pocket Operator’s sync modes allow them to be placed anywhere in the chain as a ‘Master’ or ‘Sync’ device. It’s worth experimenting with a few different orders to see what works for you.
Balancing your audio levels
This is an important consideration when setting up your Pocket Operator chain.
Let's go straight to our 3 Pocket Operator example. Imagine all 3 are already playing together, with each one at full volume. 1 is the master, 2 is the chain and 3 is the output.
This happens because the Pocket Operator audio passes through the chain in series, with each Operator controlling volume of the devices before it. Experimentation is needed here to see what works best for you.
We recommend putting the Pocket Operator that you want to be most prominent at the end of the chain. The least prominent Operator should be placed at the start of the chain. That way, you can always have the last Pocket Operator as loud as you need, and reduce the volume of those before it.
Here's another method to balance your levels - start with the volume of each Pocket Operator at zero. Turn up the volume of each one individually, starting at the end of the chain and moving to the beginning.
Pressing Play
Pocket Operators can send PO-Sync to keep devices at the same tempo. However, they are unable to signal start / stop and reset of the pattern position. This means that they'll always be in time, but they might start out of phase with the Master if triggered at the wrong moment.
If you want your Pocket Operators to start playing at the same time, you’ll need to press play on the Sync units in the chain first, then press play on Master. This ‘cues’ your Sync units, so they are ready to start from beat 1 when they receive PO-Sync signal.
If one of your Sync units has started in the wrong place, you can always stop them and restart them on the beat while the master is playing. You could also press stop on all the Pocket Operators in your chain, then recue all of your Sync units ready to start with the master.
So long as the Master device is running, you can start and stop the Sync units at any time without interrupting your jam session.
We've already mentioned that Pocket Operators can be synchronised by external devices. PO-Sync is just voltage impulses at regular intervals, so it's not as complicated to reproduce as you might think. In fact, some devices already do it. Let's divide our external devices into 2 categories - TE Devices and Non TE Devices.
Teenage engineering's other synthesisers, the OP-1 and OP-Z, can both be used as ‘Master’ devices to synchronise your Pocket Operators. They can both produce a PO-Sync signal, but in slightly different ways.
OP-1
The OP-1 can output PO-Sync and Audio in the same way that a Pocket Operator does in SY1 mode. To activate this PO-Sync on the OP-1:
Press the metronome button
turn the green encoder clockwise until a Pocket Operator icon appears with ‘PO Sync’ underneath.
When PO-Sync is active, the sync signal will transmit from the line output when you press [play]. Plugin a Pocket Operator set to SY4 and the two will run in sync.
OP-Z
OP-Z requires an additional component to create PO-Sync. You guessed it - oplab is the magic link you need. It is capable of producing PO-Sync signal, here's how you make it work:
With the OP-Z switched off, open the back cover of the unit.
On the oplab module - set the out switch to ‘PO-Sync’.
Install oplab into the expansion slot (if you haven’t already)
Put the back cover on and switch the OP-Z on.
When you press play on the OP-Z, the out port on the module should be flashing evenly - twice per quarter note. That indicates the port is generating the PO-Sync Signal. Connect a Pocket Operator and set it to SY2. This port generates PO-Sync ONLY, It does not output any audio from the OP-Z
So, what's the deal if you don’t have any other devices from teenage engineering?
There are some electronic instruments out there that already use the same type of sync signal as Pocket Operators - some Korg instruments for example. They can interface directly with Pocket Operators in SY2.
Other devices such as CV converters, hardware sequencers & eurorack modules can be configured to generate an equivalent of PO-Sync. If you're looking explore this option, you might want to check the following list of specifications to make sure it will work correctly:
Check the voltage output of the sync signal
The manual states that impulses generated by the sync signal should be no more than 5Vpp (volt peak-to-peak). This means that the difference between the minimum and maximum voltage of an impulse should not exceed 5V.
Stronger signals could cause incorrect triggers or in extreme cases damage the Pocket Operator. If your signal is weaker than 5Vpp, it might not be enough to trigger the Pocket Operator at all. Your best bet is to aim for 5Vpp or slightly below.
Make sure the impulse length is correct.
The impulses in the sync signal also have to last for the right amount of time. If they're too short, the impulse won't trigger the Pocket Operator. If they're too long, the Pocket Operator's sequencer will start to skip steps. When we tested it, the sync signal worked correctly when the impulse time was between 3-67ms. This range will be pretty normal for most clock signals, so don't worry if it's not a configurable option!
Use the correct interval relative to tempo
For every 2 pulses from a sync signal, the Pocket Operators sequencer advances 4 steps (or quarter note). You might see this written as 2ppqn (pulses per quarter note). This means your clock needs to output 1/8 note intervals (quavers) to sync a Pocket Operator correctly.
If your sync signal ticks these boxes, you'll have your Pocket Operators synced up and ready to jam in no time!
Synchronise your Pocket Operators in parallel
Want to mix / record you synced Pocket Operators separately rather than in series? Try sending the same sync signal to multiple Pocket Operators individually. If your Master device doesn't have multiple sync outputs, you could use a signal multiplier like this one. Using this method, you can keep your Pocket Operators in time, and control their audio independently.
Use your Pocket Operator as a ‘Master’ sync device for an external device
Why not use your Pocket Operator as a 'Master' for other devices. Using a y-cable like this one, you can split the output signals. This means you can send sync to the external device, whilst still sending audio out to a mixer or interface.
Sync your Pocket Operator with your DAW
You can create a bridge between your Digital Audio Workstation and Pocket Operator so that they are in sync. There are a few methods you can follow to achieve this, one of which involves OP-Z & oplab.
Connect your OP-Z to the computer using a USB cable. Send MIDI sync from your DAW to your OP-Z so that they're synchronised. When you press play in your DAW, OP-Z will start playing too. At the same time, the oplab module will output PO-Sync to your Pocket Operator - thus syncing it to your DAW too!
Despite there being some slightly more complicated aspects to syncing Pocket Operators, the idea is relatively simple. Using a sync signal from another Pocket Operator or external device, you can ensure that all your Pocket Operators are locked in to the same beat.
We hope you’ve enjoyed reading this post, and that it’s been helpful to you.
Want to hear what Pocket Operators sound like together? Check out our PO-COMBOS mini-series where we combine 2-3 Pocket Operator for a short jam.
PO-COMBOS Ep. 1 - PO-14 sub x PO-33 K.O!
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