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Note: this article is partially obsolete. There is now a simpler way.

This is a summary of what we learned during our 100 soundchecks on Clubhouse. We heard around 2000 setups and we made dozens of artists and their instruments. We means two people: Ralf Rottman and myself.

Why is this difficult? iOS handles Clubhouse like a VoIP app, providing bi-directional audio even when put into the background. These apps cannot use USB-connected devices, so anything that connects USB through Lightning does not work. iPadoS with USB-C equipped iPads actually do, but I am describing iPhone setups here.

We have three challenges:

1. We want to connect audio equipment through a TRRS audio adapter to Lightning.
2. We need to bring audio equipment from AUX level down to Microphone input level.
3. We don’t want to send audio output from Clubhouse back into Clubhouse. This is called mix-minus: send everything to the iPhone, minus what is coming from the iPhone.

Let’s start with the audio conversion. Apple sells a small adapter that lets you connect an audio plug to Lightning. Better get something less flimsy. That can be headphones (TRS = tip ring sleeve, left channel + right channel + neutral) or headsets (TRRS = tip ring ring sleeve, left channel + right channel + neutral + microphone). Look at the 3.5mm plug. Does it have three plastic rings or only two? That is the difference between TRRS and TRS. You want TRRS in this adapter.

You can buy a splitter that connects TRRS to TRS headphones and TS microphone. They share neutral on the S connectors. One connector sends two audio channels to your headphones and receives one audio channel from the microphone. No matter what you connect here, you cannot send stereo into the iPhone in this setup.

Some devices can connect to the iPhone directly through a TRRS cable, like the RØDECaster Pro or the Zoom Podtrak P4 which I prefer. They solve all three challenges: TRRS, microphone input level and what we call mix-minus.

Let’s setup a Zoom PodTrak P4:

• Insert two batteries or connect USB-power, turn it on.
• Connect a microphone to channel 1 via an XLR plug. Select whether it needs phantom power or not with the switch under your first dial.
• Connect headphones to the first bottom connector
• Connect the iPhone through a 3.5mm TRRS cable and either the iPhone dock or a TRRS-Lightning connector. Set the switch under channel 3 to the rightmost position.

Start with level 5..6 on channel 1, 10 on channel 3, and 5..6 on the Soundpad and headphones dial. The VU-meter will tell you if you got the level right. When you speak into the microphone you should hear yourself. If you play audio from the iPhone you should hear it if you set the iPhone volume to about 80 percent. When you connect to Clubhouse, everything should work just right.

If you want to connect a second microphone to pick up your guitar, plug it into channel 2 and level it so that the mix on your ears is balanced. People on Clubhouse will hear what you hear.

If you want to sing to playback then use channel 4 and play your background track on your PC into the PodTrak. Set the switch on channel 4 to the rightmost position. As on the iPhone you will need to set the PC volume level. My PC is on 50% and channel 4 is 5..6.

I am not a singer, and PodTrak provides everything I need. I can play jingles from the four soundpads, I can record to the internal SD card and I can record/playback over USB to the PC. But there is one killer requirement for musicians: PodTrak does not have an effects processor and cannot provide reverb. It’s a machine designed to record podcasts, even away from power in the field. Channel 3 can be used to call people into the podcast, channel 4 to connect Teams, Zoom etc.

Now let’s assume, you already have a mixer where your microphone and instrument are connected. For most mixers you need to bring down the instrument level on the main out to microphone level. This is where the IK Media iRig 2 comes into play. It replaces the TRRS splitter mentioned earlier. Plug the output of your mixer into the 1/4″ instrument input, set the volume dial on the iRig2 to maybe 20% and see where that takes you. You can plug your earphones into the 3.5mm plug on the iRig2 but you will not hear yourself.

This is where things get tricky. Connect a 3.5mm stereo plug (TRS) to the iRig and the other end of that cable to a channel on your mixer. Depending on the mixer, you will need two RCA or two TS mono plugs at the other end. You can now monitor your voice, your instruments and Clubhouse on your mixer.

Now you need to solve the mix-minus problem. You want to hear clubhouse, but you don’t want to send out this signal to Clubhouse. A simple DJ mixer does the trick, because it has two busses: one for Main, controlled by the faders, and one for Monitor, controlled by the monitor switch on each channel. Level all channel gains to your liking, open your mic, instrument faders, but not the one for the Clubhouse channel. You have all channels on your headphones, but all minus clubhouse on Main.

I have successfully used a Behringer Flow 8 to do the same. This one does not need an iRig since you can set the output to -10 dBV. I connected Main with a 2x XLR to 3.5mm TS cable to the input channel of the splitter and picked up Clubhouse with a TRS 3.5mm to 2x 1/4″ TS cable. I then mixed Main minus that channel (7/8) and Monitor 1+2 with the channel for my headphones. In the photo above you see the main mix: channel 2 (microphone) is up, channel 5/6 (USB from PC) is up, but channel 7/8 is down.

Your mixer will need different hacks to filter out the Clubhouse channel. The devil is in the details here.

There is one frequent issue: your audio cuts out like it is clipping. What really happens here is that your output level from your mixer is too high. Lower the volume on the iRig to correct for that, or in case of the Flow 8, the level on the Main out.