ADAT vs SPDIF (Differences & When To Use Each)

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Are you connecting audio and wondering what the terms ADAT and SPIDF mean?

In this article, we’ll go over what the two audio terms mean and how they may affect your audio setup for your home or business.

ADAT and SPIDF are audio connection protocols used to connect audio between multiple devices.

Each one is better in certain scenarios but both are standard and used in audio systems worldwide.

The main difference is that ADAT allows for 8 channels of audio while SPIDF allows for 2 channels. 

What Is ADAT?

History

ADAT was a product released in 1992 by Alesis. The first ADAT recorders could record 8 channels and synchronize together 8 other ADAT machines, adding up to 128 possible tracks.

Synchronization was possible with earlier machines, but Alesis was the first to offer this with sample-accurate timing.

The low cost of this product, compared to competitors of $3995, played a huge role in the rapid increase of audio studios in the 90s.

How Is ADAT Used Today?

ADAT is a standard digital audio connection now. The most common application is for manufacturers of audio interfaces.

They add ADAT ports to their audio interfaces to enable users to increase the number of inputs.

For example, if someone buys a cheap audio interface with only two mic inputs, they can also buy a multi-channel mic preamp with an ADAT output that can increase the number of mic inputs compatible with your DAW from 2 to 10.

What Is SPDIF?

SPDIF is a consumer audio connection standard used to transmit digital audio signals in a number of different formats. The most common formats are 44.1khz and 48khz.

SPDIF allows the original word clock to be extracted from the audio signal and has no defined bit rate.

The SPDIF connection standard allows you to use both SPDIF optical and SPDIF coaxial connections.

Optical Cables

SPDIF optical cables can be equipped with two different types of connectors: Mini Optical and TOSLINK.

SPDIF optical allows immunity to electrical RF interference and ground loops with low signal attenuation that allows for long-distance connections of up to 50m.

Coaxial Cables

Coaxial cables require RCA phono connectors and a 75 Ohm coaxial cable to comply with specifications/operating standards.

Coaxial cables are shielded and thus more durable than optical cables, but they also have less overall length. 

Which Is Better: Optical Cables Or Coaxial Cables?

It depends on what you’re trying to do. Optical cables are usually thinner and more fragile than coaxial cables, so if you need a portable connection or the cables may be damaged more easily in a scenario, coax might be the way to go.

Also, in a scenario where longer cables may be needed or there is going to be a source of EMI interference, optical cables would likely be the preferred choice.

What Is The Difference Between ADAT vs SPDIF?

SPDIF (Alesis Digital Audio Tape) is a two-channel protocol that was designed for electrical transmission, while ADAT is an 8-channel protocol designed for optical transmission.

ADAT’s sample rate is 48kHz/44.1kHz while SPDIF’s (Sony/Phillips Digital Interconnect Format) is independent of sample rate; the master clock is embedded in the protocol and is recovered by the receiving end.

Is ADAT Or SPDIF Better?

It depends on what you prefer, but both should work in most scenarios.

The advantage of ADAT is that you get 8 channels rather than 2, so that makes it better when working with multiple devices and more equipment.

But SPDIF is more durable and is less susceptible to interference and may work better at a live venue.

FAQ’s

Is ADAT Compatible With SPDIF?

No, the two are not compatible. SPDIF uses a coax cable or optical that does not work with ADAT optical cables.

Is ADAT Digital Or Analog?

ADAT is digital. Its counterpart, SPDIF, is also digital.

What Is An Optical Cable In Audio?

Optical cables are a means of transfer for digital audio connection. The output signal travels through a cable that is changed or converted from an electrical one to an optical or light-based one from send to receive.

After the signal has reached the optical receiver or input, the signal is converted again from optical to electric. The benefit is that it does not lose signal over long distances.

What Is A Coax Cable In Audio?

Coax is the most common digital audio connection. A digital coaxial connector looks similar to an RCA connector but instead transmits digital data rather than analog signals.

It has a higher bandwidth but is more expensive than RCA. The cable is thicker than a typical audio cable because it uses the same type of shielded coaxial cable(like tin foil around the cable).

It is also used for internet and television.

What Is A Word Clock in Audio?

Similar to video and film, digital audio signals have frames. When interconnecting digital audio with ADAT and SPDIF formats between multiple devices, we have to make sure that the frames are in sync.

If they are not in sync, the audio may pass through but you will get clicks and pops in the sound.

To eliminate clicks and pops, you must make sure your connected units are following the same clock (word clock) so that their frames start at the same time.

It is called a word clock because it clocks each audio sample, and audio samples are then represented by data words. 

Wrapping Up

When comparing ADAT vs SPDIF, the important part to note is that ADAT has 8 channels while SPDIF only has two.

Both digital audio connection protocols will work just as well in most scenarios and both utilize 48.1kHz and 44.1kHz sample rates.

They also both use optical cables, however, SPDIF has the ability to use both optical and coaxial cables, allowing for more versatility in certain scenarios.