What is OTG audio?

What is OTG Audio?

OTG or “On-The-Go” audio refers to the ability to output audio directly from a smartphone or tablet to an external digital-to-analog converter (DAC) or amplifier. This allows you to bypass the built-in DAC and amplifier in your mobile device and use higher quality external audio hardware.

OTG requires a specialized USB OTG adapter cable or connector which allows a mobile device to become a USB host. This allows the mobile device to connect to USB peripherals like a DAC or amplifier. Once connected, audio signals can be sent directly from the mobile device to the external DAC which then converts the audio and outputs it to headphones or speakers ¹.

Benefits of OTG Audio

OTG audio provides several key benefits for improving audio quality from mobile devices like smartphones and tablets:

Bypasses built-in DAC of phone/tablet for higher quality – The digital-to-analog converters (DACs) built into most mobile devices are often low quality and can degrade the audio signal. Connecting an external DAC via OTG bypasses the built-in DAC, allowing for much higher fidelity playback.

Allows connecting external DACs and amps – OTG enables you to connect specialized external gear like USB DACs, headphone amplifiers, or portable players to your phone or tablet. This expands your options for higher quality audio.

More control over audio quality – With OTG, you have more hardware choices to customize your audio experience, rather than relying on your device’s basic onboard audio circuitry. You can choose components optimized for your headphones, music preferences, and listening needs.

How OTG Audio Works

OTG audio works by using a USB OTG (On-The-Go) adapter to output digital audio from an Android device via USB. The OTG adapter allows the Android device to act as a USB host, enabling connectivity with USB audio devices.

Here’s an overview of how OTG audio functions:

An OTG adapter is connected to the Android device’s micro USB or USB-C port.

The adapter allows the Android device to recognize connected USB devices like external DACs (digital-to-analog converters).
Music apps on the Android device output audio via USB to the external DAC.
The external DAC converts the digital audio signal into an analog signal for headphone amps or headphones.

This allows you to bypass the Android device’s internal DAC and analog circuitry, providing higher quality audio.

So in summary, the OTG adapter enables digital audio output via USB to an external DAC, which converts the signal to analog for improved audio quality compared to the smartphone’s headphone jack.[1]

OTG Audio vs Bluetooth

OTG (On-The-Go) audio has the potential for higher audio quality than Bluetooth audio due to the increased bandwidth available over a wired USB connection. Bluetooth audio uses lossy compression like aptX or AAC to transmit audio wirelessly, which can degrade audio quality. The maximum bitrate for Bluetooth audio is around 350 kbps, while USB audio can support bitrates of up to 9.6 Mbps.

According to an article on Diymobileaudio.com, “Wired Android Auto is capable of better sound than Bluetooth.” The article notes that using a wired connection for Android Auto results in better quality compared to streaming over Bluetooth in the same car (source).

On Reddit, users also report noticing improved audio quality using wired Android Auto versus standard Bluetooth connections. One user asked “Does androidauto have better audio quality than regular bluetooth?” and most respondents agreed that wired Android Auto does sound better (source).

While OTG audio may offer higher fidelity, Bluetooth offers more convenience and flexibility since it doesn’t require a wired connection. As noted in a New York Times Wirecutter article, the fundamentals of the headphones or speakers will make a bigger difference than the transmission protocol. But all else being equal, OTG audio has the edge over Bluetooth for audio quality (source).

Setting Up OTG Audio

Setting up OTG audio on your Android device requires a few key pieces of hardware and some configuration in your phone’s settings.

First, you’ll need a USB OTG (On-The-Go) adapter. This allows you to connect USB devices to your Android phone or tablet. You plug the OTG adapter into your device’s USB port, and then plug your USB audio device into the adapter. Most modern Android devices support USB OTG.¹

In addition to the OTG adapter, you’ll also need a USB DAC (digital-to-analog converter). The DAC takes the digital audio signal from your device and converts it into an analog signal that can be amplified and played through headphones or speakers. Some popular portable USB DAC options include the Audioquest Dragonfly and the Chord Mojo.

For headphones or powered speakers, the DAC may be all you need. But for passive speakers, you’ll also want a small USB-powered amplifier between the DAC and speakers.² Having an amp allows you to control the volume and provides enough power to drive the speakers.

Once you have the required hardware, connect them together – OTG adapter to your phone, DAC to the OTG adapter, and amplifier if needed. Then in your phone’s settings, you’ll need to enable USB audio routing. This sends the audio out through the USB port rather than the headphone jack. The setting may be called “OTG audio” or something similar depending on your device. Configure any required audio apps to also output via USB.

With everything connected and configured, you should now be able to play audio from your phone through the external USB DAC, amplifier, and speakers or headphones. Adjust volumes on each component as needed to obtain the optimal listening experience.

Choosing OTG Audio Hardware

Choosing the right OTG audio hardware involves picking the best DAC (digital-to-analog converter) and amplifier for your needs. Here are some key considerations:

DAC

The DAC chipset is crucial for audio quality. Top options include ESS Sabre chips like the ES9038Q2M or AKM chips like the AK4493. These provide very low noise, distortion and high dynamic range. The power source is also important – some portable DACs use USB power which can introduce noise, while others have onboard batteries for clean power.

According to What HiFi, top portable DAC picks include the Chord Mojo 2 which uses an FPGA chipset for excellent quality and the iFi Zen DAC V2 which utilizes dual AKM4377 chips.

Amp

A quality amplifier provides sufficient power to properly drive your headphones. Power output between 200-1000mW is ideal for most headphones. Low-impedance models, like earbuds, need less power than high-impedance over-ear headphones.

The size of the amp also matters for portability. According to Wirecutter, top portable options like the Fosi Audio DS1 strike a balance between power, quality and compact size.

OTG Audio Quality

The audio quality when using OTG audio depends on several factors:

The quality of the source audio file – Higher bitrate and resolution files like FLAC will sound better than lower quality MP3s. Using a high-res source like Tidal HiFi can provide better sound quality [1].

The DAC (digital-to-analog converter) used – An external USB DAC like those from Audioquest or Dragonfly will usually provide better conversion and amplification versus using the smartphone’s built-in DAC [2].

The amplifier – Using a dedicated portable headphone amp can further improve the analog signal and provide power for high-impedance headphones.

Overall, OTG audio solutions typically provide higher quality than the built-in audio hardware in smartphones. The ability to add audiophile components enhances the signal chain and allows users to get the most out of high quality music files [3]. However, OTG audio is still limited by the quality of the source file and components used.

OTG for Audiophiles

OTG audio allows audiophiles to get desktop-level audio quality on their mobile devices. By using an OTG cable, high-end external DACs (digital-to-analog converters) and headphone amplifiers can be connected to smartphones and tablets.

This brings the superior audio quality that audiophiles demand to their mobile listening experience. Dedicated external DACs and amps offer far better performance than the integrated audio components in most mobile devices. Audiophiles often invest thousands of dollars into their headphone gear, so being able to use it with mobile devices is a major benefit of OTG audio.

There are OTG cables designed specifically for audiophiles, like the iFi 90° Type-C OTG Cable that focuses on fast data transfer speeds and clean audio signal transfer. This allows audiophiles to get the absolute most out of their high-end gear when using OTG audio.

By bringing desktop-quality audio to mobile listening, OTG audio is a game-changer for audiophiles. It allows them to get stunning audio fidelity from their expensive DACs and headphone amps anytime, anywhere.

Limitations of OTG Audio

While OTG audio has many benefits, there are some limitations to be aware of when using this technology:

The most obvious limitation is that OTG audio requires external hardware like a USB DAC or audio interface, so it’s not as convenient as simply plugging headphones straight into your phone. You’ll need to carry around extra devices and cables in order to take advantage of high quality OTG audio.

Android support for OTG audio also varies between devices and versions. While newer Android phones tend to have better support, you may run into issues like bitrate limitations or resampling on certain models. Doing your research is important before purchasing gear for OTG audio.

There are also some power limitations to consider. Your phone’s battery will drain faster when outputting audio over USB, so you may need a portable battery pack for longer listening sessions.

The Future of OTG Audio

As OTG audio technology continues to advance, there is potential for wider adoption as audio quality increases. New codecs and audio transport protocols optimized for OTG connections could emerge to deliver studio-quality audio with minimal latency. Manufacturers are already producing premium external DACs (digital-to-analog converters) and amplifiers designed to connect via OTG directly to smartphones and tablets for audiophile-grade playback.

We may see new OTG standards and hardware introduced that further improve transfer speeds and power delivery beyond current USB specifications. The USB Implementers Forum recently announced USB4 Version 2.0 that doubles bandwidth up to 80 Gbps and offers new power delivery profiles. While intended for computing, display connectivity and storage, this shows the potential for OTG audio to also benefit from the latest advancements. As OTG audio matures, consumer electronics companies and audio vendors will likely continue innovating to make OTG connections the preferred way to achieve studio-quality mobile audio.