Pocket Operator 33 K.O! Android Backup

26 Jul 2019 . Category . Comments #hardware #outreach #music

Teenage Engineering’s Pocket Operator Series has gotten some good press and with good reason, they’re awesome. However, I’ve had a bit of a struggle backing up my PO-33 K.O! with my laptop or phone, until today.

The key problem seems to be that the phone and laptop headset jacks (TRRS) only have mono microphones, and the data transmitted by the PO-33 is in stereo.

Riffing off a Reddit post that uses different equipment, here’s how it works.

Set up

The cable on the left side plugs into the USB C of my OnePlus 6T phone (disconnected to take the picture). The phone recognizes the sound card (silver box) as a headset and supplies power to it. The PO-33 on the right side (looks like a calculator) sends output through the y-cable into two mono cables. These two mono cables go into the right/left microphone ports of the sound card. The red/ring of the y-cable goes into the right microphone port. The left side of the PO-33 is for input back from the soundcard. Since the input is a stero headset signal, a single stereo cable works.

Part list

• StarTech sound card ICUSBAUDIO7D
• Mediasonic USB C to USB A female adapter. If you have a different USB port on your phone, you’ll need a different adapter.
• Hosa 3.5mm TS patch cables (mono)
• Hosa 3.5mm TRS male (stereo) to 2 TS female (y-cable)
• Pearstone TRS 3.5 male cable
• A smartphone
• A PO-33. My master volume was set to 8.
• Recforge II (v 1.2.7.5g). Go to Settings -> Audio Record, disable compatibility mode, and choose Stereo (Native) and 44khz. Also in Settings, disable AGC.

Steps

1. Start recording in Recforge.
2. On PO-33, press and hold write-sound-play, then release all buttons.
3. The display will start counting up. In Recforge you’ll see input levels in realtime and a trace over time. If you see nothing, check your set up. If the input levels are clipping, adjust your PO-33 master volume (hold bpm and press 1-16)
4. When the display says “End,” stop recording.
5. Check your backup; put the PO-33 in receive mode by press and holding write-sound-record, then release all buttons.
6. Start playing the file you just recorded in Recforge
7. The display will start counting up. If it displays “Err” check your setup and recording. When it finishes it will say “End.”
8. Try playing anything on your PO-33. You should be good to go.