How to Record a Roland SP-404 MK2 into Your iPhone

Three things, plus one that is optional but worth it.

• A Roland SP-404 MK2.
• An iPhone. Which cable you need depends on whether it is USB-C (iPhone 15 and later) or Lightning (iPhone 14 and earlier).
• A recording app. Reel is the one I make and use for this, but any class-compliant iOS audio app works.
• Power for the SP-404. It runs on 6 AA batteries, its AC adapter or a USB-C power bank. More on why this matters below.

If your iPhone is USB-C (iPhone 15 or later) you need a single USB-C to USB-C cable. Plug one end into the SP-404's USB port and the other into the phone. That is the whole connection and audio flows both ways over that one cable.

Roland says the phone can even power the SP-404 over this cable. It can, but the SP-404 draws up to 1.5 amps, which is a heavy pull on a phone battery. For anything longer than a quick take, power the SP-404 separately from its AC adapter, batteries or a USB-C power bank and let the cable carry audio only. It is more stable.

If your iPhone is Lightning (iPhone 14 or earlier) you cannot use a plain USB-C to Lightning cable. You need an Apple USB camera adapter in between, specifically the Lightning to USB 3 Camera Adapter, the one with an extra Lightning power port. Connect the adapter to the phone, run a USB-C to USB-A cable from the adapter to the SP-404 and plug a charger into the adapter's power port.

On the Lightning path the adapter never powers the SP-404, so the SP-404 must have its own power from batteries or its adapter. The charger in the camera adapter's power port keeps the iPhone topped up while you record.

You do not need to switch the SP-404 into any special USB audio mode. It sends its output to the LINE OUT jacks and the USB port at the same time by default. Connect it and it is already streaming.

The button people get wrong is EXT SOURCE. That brings audio from the phone into the SP-404 for sampling, which is the opposite of what you want here. Leave it off when you are recording the SP-404 out to the phone. If your recording is silent, this is the first thing to check.

The SP-404 MK2 runs at 48kHz, 16-bit and it is locked there. Set your recording app to 48kHz so nothing has to resample on the way in. In Reel this happens automatically when the SP-404 is connected.

Record it as a stereo input. The SP-404 shows a computer four separate outputs, but into a phone you get its stereo main mix, so set the app to a stereo input rather than hunting for individual bank or track stems.

Once it is connected, arm a track in your app and hit record. In Reel that means plugging in, the SP-404 shows up as the input and each take lands as a clean 48kHz capture you can overdub and mix.

Monitor through the SP-404's own headphone jack, not through the phone. The SP-404 sends the same signal to its PHONES output and the USB port at once, so you hear it with zero latency straight from the hardware while the phone records. Monitoring through the phone adds round-trip delay and, if the phone speaker is involved, can cause feedback.

Reel is the app I use to record these takes, so if you want to see the workflow before you buy, here is a quick overview of how it works.