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Dual Mono Mics

How to record two separate mics into one clean two-channel file that is never blended — the two-lapel-mic interview setup. What hardware you need, steps, getting separate files, and limits.

Dual Mono Mics

Dual Mono is the classic two-microphone interview setup: interviewer on channel 1, guest on channel 2, both saved into one file with both voices kept fully separate — never merged, never mixed. Each mic gets its own channel, its own level meter, and later its own exported file.

Use it for:

  • One phone, two lapel mics (wired or wireless)
  • Two wired mics on a USB-C interface
  • Two people at a table, each with their own mic
  • Stage and sound-board captured separately
  • Any time you want to isolate one voice later

What you get

  • One recording, one Library entry, one two-channel file. The app does not make two entries or "two tracks" — it records the two mics as the left and right of one file, and reports the channel count measured from the actual file. If the hardware only delivers one blended channel, the app says so and records mono — it never pretends.
  • One level meter per mic while recording — watch each mic separately and catch distortion on either side.
  • Separate Tracks export — later, Recording Detail → Export As… → Separate Tracks writes one separate 24-bit WAV per mic, kept in exact sync with the original, never blended, never auto-leveled together: Interview_CH1.wav and Interview_CH2.wav (true stereo sources get _L / _R).
  • Exact sync — both sides stay locked sample-by-sample with the original, which is what editors need when lining up sound with video.

What hardware you need

Dual Mono needs a mic setup that truly delivers at least two live channels to the iPhone. The Dual Mono switch only appears when the phone confirms it. Examples that work:

  • USB-C audio interfaces with two mic inputs (delivering 2 channels)
  • Two-lapel-mic wireless receivers set to stereo/split mode (each mic on its own channel) — for example, the BOYA Mini 2, whose two mics arrive as two genuinely separate channels (Amazon link — affiliate link). Note: some two-mic sets (e.g. the GoorDik J3) mux both mics into one channel at the mic level — the iPhone only ever sees one blended channel, and no receiver setting can split it. Those sets work fine for single-mic recording but can never do Dual Mono.
  • Wired two-mic adapters that deliver two channels
  • 4-or-more-channel interfaces also work — the app follows the hardware (CH 1, CH 2, and so on) and exports one file per channel

Why these two mics? They were picked for being affordable and good — not as high-end recommendations. Plenty of mics at every price range do this job; these are the two that proved cost-effective in real testing. One extra perk on the GoorDik J3: its receiver base has a spare USB-C port, so you can charge the iPhone while the mics stay plugged in.

What does not give you two channels:

  • The built-in iPhone mic — always one channel, no matter how many little mic holes the phone has. The iPhone reports it as a single channel, and the app respects that (it never invents channels).
  • A Bluetooth headset mic — phone-call audio path, one narrower-quality channel (the app warns you about this).
  • Two separate Bluetooth headsets — the iPhone uses one mic input at a time. Not a two-channel path in version 1.
  • A receiver in mono mode — if the receiver blends its two mics together, the iPhone sees one channel. Switch the receiver to stereo/split mode.

How to use it — step by step

  1. Connect your hardware — plug in the interface or receiver so the iPhone sees two channels.

  2. Check the facts on the Recorder screen. The line under the mic shows the real connection, channel count, and quality — for example, USB Audio · 2 channel(s) · 48 kHz. If it says 1 channel(s), the hardware isn't delivering two channels yet. Fix the hardware or its mode, not the app.

  3. Turn on Dual Mono. The card reads:

    Dual Mono (isolated channels) Keep two microphone sources separate as CH 1 and CH 2. Channels are never mixed.

    If you had a one-channel (mono) preset selected, the app visibly switches you to its two-channel version (AAC Stereo, ALAC Stereo, FLAC Stereo, or PCM Stereo) — Dual Mono is never recorded as one channel. Your choice is remembered for next time.

  4. Place the mics — one per speaker. Do a test take and watch both meters. Set levels so neither side distorts (24-bit recording gives lots of room, but a truly clipped loud peak can't be fixed).

  5. Record normally. Pause, resume, stop — same as any recording. If the mic setup changes mid-recording (a mic unplugs, Bluetooth drops), the app safely saves what it has and offers Continue Recording, which starts a linked Part 2 — the two pieces stay clearly labeled.

  6. After you stop, the recording is one Library entry with two channels. For the separate files: Recording Detail → Export As… → Separate Tracks → share through the iPhone share sheet. Each file is a 24-bit WAV named after your recording (for example, Interview_CH1.wav, Interview_CH2.wav).

Recording detail actions — rename, trim, transcribe, share, Export As…

What you can't do in Dual Mono (version 1)

  • Noise Reduction + Dual Mono is currently blocked. The per-mic cleanup is written and lab-tested, but the final real-hardware test — a two-channel receiver delivering two fully separate channels — hasn't passed yet, so the app refuses this combo rather than guessing. Turn Noise Reduction off (or record with one mic) and you're good. The app will re-enable this the day the hardware test passes — one cleanup pass per lapel mic is the intended end state.
  • No per-mic mixing, solo, balance, or tone controls. RecordLog is a recorder, not a mixing app. It gives you two clean, in-sync files; you mix in your editing app.
  • No separate per-mic playback in the app. Playback plays the two-channel file as recorded. The split into two files happens at export.

Questions

"I have two lapel mics but Dual Mono doesn't appear." The app only shows Dual Mono when the connection proves 2 or more channels. Check the line on the Recorder screen: 1 channel(s) means the iPhone isn't seeing two channels. Common fixes: put the receiver in stereo/split mode, switch the interface to 2-channel mode, change the input in Settings, unplug and replug the USB-C cable, or try the other USB-C port. The app reads the hardware — it never fakes a channel.

"I have one USB receiver with two mics — will that work?" If the receiver delivers two channels to the iPhone (split mode), yes. If it blends both mics into one channel, no — the iPhone sees mono and the app records mono. The receiver's mode decides it.

"Where are my two files?" There is one file — the two-channel recording. Export As… → Separate Tracks makes the two separate WAVs whenever you need them.

"Can I get noise cleanup on each lapel mic?" The moment the pending receiver hardware test passes, yes — one cleanup pass per mic, independently. Until then, this exact combination is refused with a clear reason. See the Noise Reduction guide for what works today.

"What if one mic dies mid-interview?" The connection change safely saves what you have (nothing disappears), and Continue Recording starts a linked Part 2 from that point. The audio before the problem is kept exactly.

"Does Dual Mono make the written transcript better?" Transcription reads the whole recording, not one mic at a time. Dual Mono is about clean, separable audio for editing and mixing — not about transcription.

"Will a 4-channel interface give me four files?" One recording with four channels, and Separate Tracks exports one file per channel (CH 1 through CH 4). Noise Reduction doesn't apply to multi-channel setups in version 1.