The ADAT optical audio protocol helps you transfer digital audio between different audio devices without the need to transfer from and to analog domains. This audio connection protocol is suitable for higher channels of audio transfer, whereas the S/PDIF is a two-channel audio protocol.
So, is ADAT the same as optical? Not necessarily. ADAT protocol is used to transfer digital audio in 8 channels with a high sample rate. But, the S/PDIF optical is limited to only two channels. Besides, these protocols have other differences. We will tell you about their characteristics, use cases, and differences in detail. Let’s get started.
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What Is ADAT?
ADAT stands for Alesis Digital Audio Tape. This was introduced by Alesis in 1991. Till then, ADAT digital audio protocol has become highly popular for transferring digital audio between interfaces and peripherals. As the need for more channels increased while transferring audio, ADAT proved its credibility to be a suitable digital audio protocol.
The sample rates for different versions of ADAT are different. It opened a new horizon in synchronization because of the sample-accurate timing. And this is the reason audio studios boomed in the 90s.
The main use of ADAT today is for audio interfaces. Audio interface manufacturers add ADAT ports to the equipment so that users can increase input channels. With the ADAT digital audio protocol, input channels can be expanded by up to eight channels.
ADAT lets users record eight tracks of digital audio at the same time. The optical interface protocol of ADAT is known as ADAT Lightpipe. It uses optical cables and TOSLINK connectors. This protocol can transfer audio signals in different formats, such as 44.1kHz and 48kHz.
What Is S/PDIF Optical?
S/PDIF stands for Sony/Phillips Digital Interface and it is a standard audio connection protocol for transferring digital audio signals. This protocol can transfer audio signals in different formats, such as 44.1kHz and 48kHz.
Both optical cables and coaxial cables can be used to transfer audio using the S/PDIF protocol. And this can use two different connectors like the ADAT protocol. They are the mini optical and TOSLINK connectors.
But this protocol transfers digital audio in two channels. And the transmission type is electrical here. The S/PDIF protocol has no specific sample rate for transferring because the master clock is embedded in the protocol.
Now that you have a basic idea of what ADAT and optical are, we will show you their differences.
Differences Between ADAT and Optical
ADAT and optical have two key differences. Let’s focus on them here.
- Number of Channels
ADAT gained popularity because of its capacity to transfer digital audio in 8 channels. Depending on the sample rate, it can transfer 4 or 8 channels of digital audio without the need to compress the signals. That requires two optical cables for input and output, one for each way.
But if the audio interface has more ports, more input and output cables can be added to transfer digital audio in 8 channels, regardless of the sample rate. S/PDIF protocol has only two channels for transferring digital audio through electrical transmission.
It may use optical cables just like the ADAT protocol. But it can also use coaxial cables, which isn’t possible in the case of ADAT protocol. So, ADAT and S/PDIF optical aren’t the same.
- Sample Rate
In ADAT protocol, the standard sample rate can be 44.1 kHz or 48 kHz when transferring audio in eight channels. But if you use four channels, the sample rate can be increased to 88.2 kHz or 96 kHz. When more ADAT optical cables are added for input and output, the sample rate will still be high at 88.2 kHz or 96 kHz, but the number of channels will be increased to eight.
But for S/PDIF optical, it is a two-channel protocol that isn’t dependent on the sample rate. So, the number of channels won’t increase or decrease even if you change the sample rate.
- Use Cases
As the ADAT protocol has more channels, it is suitable when you need to connect multiple peripherals and interfaces. Especially, when you work in a studio environment, ADAT protocol is much more useful. It gives all the channels you need at a high sample rate, so recording audio through interfaces and transferring it between devices becomes easier.
But when you are working in a live environment, ADAT protocol can be prone to interference. S/PDIF optical will be a suitable option in that situation. It is less prone to interference and more durable than the ADAT protocol.
Similarities Between ADAT and Optical
Even though these digital audio protocols are different, they share some characteristics. Here is a quick overview of their similarities.
Both ADAT and S/PDIF protocols transfer digital audio signals. So, you can effortlessly use them between a wide range of interfaces and devices to transfer digital audio. No conversion to and from analog domains is required while using ADAT or S/PDIF protocols.
What Is TOSLINK in ADAT Optical?
TOSLINK stands for Toshiba Link and it is an optical fiber connector. It is also known as optical audio because it is used to transfer digital audio signals between interfaces and devices. It carries digital audio signals in two channels and the signals are uncompressed.
In the ADAT Lightpipe, commonly known as ADAT Optical, an optical cable similar to TOSLINK is used for digital audio transfer. That cable has the same JIS F05 connectors as the TOSLINK.
But, the TOSLINK cable used in the S/PDIF optical format isn’t compatible with the ADAT protocol.
ADAT or Alesis Digital Audio Tape is a well-known digital audio protocol that is used to transfer digital audio signals between interfaces and devices. Though S/PDIF is also a digital audio protocol, it differs from the ADAT optical protocol because it has a lower number of channels.
ADAT can transfer audio in eight channels, whereas S/PDIF optical has only two channels. Both protocols use optical cables, but the TOSLINK cable used in the S/PDIF protocol isn’t compatible with the ADAT protocol. Plus, the S/PDIF protocol can use a coaxial cable, which isn’t the case for the ADAT protocol. So, ADAT isn’t the same as optical.
Check answers to some commonly asked questions about ADAT and S/PDIF optical protocols.
Q: Is ADAT and TOSLINK the same?
No. ADAT is a digital audio transfer protocol while TOSLINK is an optical fiber connector. The S/PDIF protocol uses TOSLINK connectors but the ADAT protocol doesn’t.
Q: Is ADAT an optical cable?
ADAT is a digital audio transfer protocol that uses optical cables to transmit digital audio signals through optical transmission. The optical cable isn’t called ADAT. Instead, the way the cable transfers signals is called ADAT.
Q: What are the limitations of ADAT?
For better recordings with less interference, ADAT optical cables shouldn’t be longer than five meters. But S/PDIF has no such limitations.