ADAT light pipe interfaces

We are starting to get lots of questions about ADAT light pipe compatible equipment as it relates to bit depth. Since the ADAT is a 20-bit recorder the question arises as to what happens to the extra bits of a 24-bit word when it is used with ADAT products.When a 24-bit word is brought in to a device that only handles 20 bits, the bottom, or LSB (Least Significant Bits) are truncated off. This rarely has a significant affect on the quality of the audio because it is mostly noise that is down in that range anyway. Some devices are capable of truly passing a 24-bit word on their light pipe inputs and outputs. When used with other devices that have 24-bit capable light pipe connection it is possible to have true 24-bit data transfer on a light pipe. The question then becomes, which units have true 24-bit light pipe abilities.Thanks to some research by one of our sales engineers, Nika, we can elaborate.Anything that has the “ADAT” symbol on it uses the proprietary “ASIC” chip from Alesis that only handles up to 20-bit audio. Anything that claims to handle 24-bit audio through a light pipe cable does not use their “ASIC” chip and will not have the “ADAT” symbol on it. For the most part these devices already pass 24-bit words, but in a few cases they may be one software revision away from that capability.For example: The MOTU 2408 does NOT have an “ADAT” symbol on it. The Mackie d8b does NOT have an “ADAT” symbol on it. The Korg 880A/D DOES have an “ADAT” symbol on it. The Korg 880D/A DOES have an “ADAT” symbol on it. The WRADAT (ADAT I/O card) for the Panasonic WRDA7 DOES have an “ADAT” symbol on it. The Spirit Digital 328 does NOT have an “ADAT” symbol on it. The CD8AT (ADAT I/O card) for the Yamaha O2R DOES have an “ADAT” symbol on it. The MY8AT (ADAT I/O card) for the Yamaha O1V DOES have an “ADAT” symbol on it. What about compatibility? Devices without the Alesis “ASIC” in them can still be made to be compatible with Alesis devices. Obviously, in the case of the products above this is a primary concern and they are ALL compatible.

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