iPad-based Zoom Audio Processor

I've recently put together a standalone iPad-based voice and instrumental audio pre-processing system for use with Zoom meetings and other online broadcast platforms. 

I've received some good reviews from others on the quality of the sound produced, so I'm sharing the setup.

The system is designed to plug into the audio input of a computer running Zoom to provide superior audio quality than a microphone alone and has nearly infinite flexibility.  

This iPad-based setup gives me much more flexibility and control of my sound processing during live streaming than my previous analog setup ever could. It will even run on older iPads. I am using an iPad Air from 2013 running iOS 12.4.5. When running the software, the iPad is put in Airplane mode to avoid any interference with the audio software by network activity.

Currently I'm on my third generation of the system, but have included details on the previous versions since they may be useful to others, particularly those who want to use a USB microphone.


1st Generation - Shure MV-88+ USB Microphone


The original setup consisted of a Shure MV-88+ microphone, microphone stand, an iPad (attached to the stand using an IK Multimedia iKlip 2), and an Apple Lightning to USB-3 Camera Adapter. 

The Shure MV-88+ could be connected directly to the iPad via the provided Micro USB to Lightning cable, but the audio processing software would drain the iPad in about an hour. Since I'm typically using the setup for two to three hours continuously I needed a way to both hook up the microphone and power the iPad at the same time.  

To solve this problem, I connect the MV-88+ using a Micro USB to USB cable to an Apple USB3 to Lightning adapter plugged into the iPad. I can then plug a standard Apple charging cable into the Lightning port on the adapter. This allows me to power the iPad while using the microphone. 

To use the MV-88+ via USB like this rather than directly connected to the iPad via the Shure provided Micro USB to Lightning cable, you first must connect the microphone directly to the iPad with the provided micro-USB to Lightning cable, run the free Shure Motiv App, and configure the microphone level and pickup pattern.  This is only required to be done one time.

I initially selected the single front facing cardioid pattern option, but further experimentation had me switching instead to the 60-degree (narrowest available) stereo option for better background noise isolation. Both are good options. I set the microphone sensitivity in the Motive app so that on whistle I'm at nearly max level, but not overloading the microphone. You will also want to turn off any compression or EQ enabled in the Shure Motive app. Once you've done this, the MV-88+ stores the configuration and you can then use the microphone over USB for other apps.

Any other high-quality USB microphone would also probably work with a similar configuration.

To get the sound out of the setup and into Zoom, I run a stereo 1/8″ cable from the iPad headphone output jack runs into a input channel on my mixing board, and then from the board into the input of the audio card in the Windows computer I use which is running Zoom. The mixing board board allows me to set various levels into Zoom as well as control my own monitor levels in the headphones. If you don't have a mixing board, you could just run the output of the iPad headphone jack directly into the audio line-in on your Mac or Windows computer.

The iPad is running AudioBus as a plug-in container app, and the following AudioBus compatible plug-ins in a chain:

AUFX:Push - Compression - Limits and stabilizes the dynamic range particularly when I'm playing louder instruments like whistles.

AUFX:PeakQ - EQ - Allows me to do some voice equalization for that "NPR" radio announcer sound.

AUFX:Space - Reverb - A tiny bit of added room ambience is more comfortable both for me in the headphones and for other people in the Zoom meeting.

Below are screen shots for the setup of AudioBus and each of the AUFX plug-ins:

AudioBus Plug-in Chain
AudioBus Mixer View
AudioBus Settings for lowest latency
AUFX:Push Compressor Settings
AUFX:PEAKQ Equalizer Settings

If the 9.2 db "Peak 1 Gain" boost is excessively boomy, try lowering the value to 6 db or even 3 db.

AUFX:Space Reverb Settings

Additionally, if you need background noise reduction, for example from an air conditioner, and want something more subtle than the hard noise gate in AUFX:Push, I've had some success with putting an instance of Audio Expander AUv3 at the very front of the plug-in chain for use as a downward-expander. A downward-expander does the opposite of a compressor, it takes any sounds below a certain loudness threshold and reduces them by a controllable ratio while passing through all sound above the threshold. It provides a much more comfortable sounding transitions when speaking or playing than using a hard noise gate under the same background noise conditions. Note that this doesn't eliminate the background noise while you are talking or playing, but can quiet it significantly in a controllable fashion during periods of silence. You will need to tailor the threshold and expansion shape settings for your specific situation:

AudioBus Mixer with Audio Expander AUv3
Audio Expander AUv3 Air Conditioner Noise Reduction Settings

Here's a demo video showing the system in action:

Here are links where you can find more information of for each of the components used in the system:

Shure MV-88+ USB Microphone:

https://www.shure.com/en-US/products/microphones/mv88plus

Apple Lightning to USB-3 Camera Adapter:

https://www.apple.com/shop/product/MK0W2AM/A/lightning-to-usb-3-camera-adapter?afid=p238%7CsxGOcO7Q8-dc_mtid_1870765e38482_pcrid_246386725857_pgrid_14874603490_&cid=aos-us-kwgo-pla-btb–slid—product-MK0W2AM/A

AudioBus:

https://audiob.us/

AUFX-4 Plugin Bundle:

https://apps.apple.com/us/app-bundle/aufx-4/id975873181

Audio Expander AUv3:

https://apps.apple.com/us/app/audio-expander-auv3-plugin/id1428297152?ign-mpt=uo%3D4

IK Multimedia iKlip 2:

https://www.ikmultimedia.com/products/iklip2/


2nd Generation - Focusrite Scarlett 2i2 Integration - August 5, 2020


I switched from the Shure MV-88+ to using a Crown CM-310A Differoid condenser microphone connected to a Focusrite Scarlett 2i2 USB preamp/interface and from there to my iPad Audiobus-based streaming audio processor (downward expansion, compression, EQ, reverb) via a Apple USB3 Camera adapter.

The adapter also powers the iPad from a power adapter.

Stereo output of the Scarlett (previously was the iPad headphone out) is then connected to the Mackie mixer and from there to a dedicated M-Audio Audiophile 24/96 audio card in my Windows computer and into Zoom.

The Scarlett 2i2 does require a powered USB hub to use with the iPad.

The Shure MV-88+ USB microphone that I was previously using is awesome, and in many ways more convenient, but the Crown CM-310A mike has some real advantages. For example, I can leave my A/C on in my office while on long Zoom sessions since the CM-310A is both sensitive and very directional and also has built-in background noise canceling features.

The pop filter also helps with voice and whistle plosive noises.


3rd Generation - Dual-Channel Focusrite Scarlett 2i2 - 7 August 2020


In my latest setup, I'm using a Crown CM-310A as my voice/whistle microphone (with a small pop filter) and an Audio-Technica AT3035 condenser as a second instrument microphone.

The AT3035 is very sensitive with a wide cardioid pattern. It is able to pick up both sides of a concertina or accordion, or both the chanter and drones/regulators on my pipes.

I am also now bringing the audio output of my iPhone into my mixer for use in "Celtic Karaoke" play-along sets.

Here's my latest Audiobus setup for a dual input system that has one processing chain for my voice/whistle microphone, and another for the pipes/accordion/concertina microphone:

The Voice/Whistle microphone chain:

ExpanderFX - Downward expander for optional A/C background noise supression

AUFX:Push - Compression

AUFX:PeakQ - Equalization (primarily for voice)

AUFX:Space - Reverb

The Pipes/Accordion microphone chain:

ExpanderFX - Downward expander for optional A/C background noise supression

RoughRider3 - Compression

Zero Reverb - Reverb

Unfortunately, I can't share the AUFX effects between the two input channels from the Scarlett 2i2 as they are single instance apps, not Audio Unit 3 (AU3) plugins. So, to work around this, I had to use a different compressor and reverb plug-in for the Pipes/Accordion chain.

Here's the Audiobus mixer view of the setup:

In this configuration, the workload was taxing the CPU resulting in occasional pops/clicks, so I had to dial back the latency settings from 64 frames@48KHz to 128 frames@44.1KHz:

Here's the apps I use as they would appear on the iPad's desktop. Audiobus 3 is in the dock in this screenshot: