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M-Audio CO2, Toslink <--> S/PDIF converter and back

M-Audio CO2 bi-directional digital audio format converter.

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The CO2 is the rare combination of value and utility. It’s a wonderful little box that converts between digital audio’s two physical formats: coaxial and optical. It doesn’t care whether the data format is S/PDIF, AC-3 or whatever!

Do you have a DVD player that only has an S/PDIF coaxial (RCA) output and a digital receiver with optical (Toslink) inputs? Are you trying to dub from a DAT machine with S/PDIF coaxial outputs to another with S/PDIF optical inputs? Are you trying to interface an external A/D converter with S/PDIF optical outputs to your computer’s audio card that only accepts coaxial? Is your D/A converter appear too far from your computer to use S/PDIF reliably? Do you need to convert optical to coaxial and, at the same time, also convert coaxial to optical? Do you need to feed two devices from one source?

If so, then the CO2 might be the answer to your prayers!

The CO2 is a compact and rugged tool that converts digital audio signals from optical to coaxial, and from coaxial to optical. Its clever 2-input/2-output design passes the original input signal through to one output jack, and the converted signal to the other output jack. This enables the CO2 to be used as a converter and/or repeater. (The CO2 does not manipulate SCMS in any way.)

And with its very low price, you can afford to use several in your studio!

CO2 features include:

-Ultra-compact size: 3.5″ x 2.25″ x 1.2″

-Converts optical-to-coaxial and coaxial-to-optical simultaneously

-May also be used as a repeater for long cable runs

-Two digital inputs: 1 Toslink (optical), 1 RCA jack (coaxial)

-Push-button selects which input is the signal source

-Two digital outputs, both always active: 1 Toslink, 1 RCA jack

-Transformer-isolated RCA output jack prevent system ground loops


The CO2 is housed in a compact, rugged gray steel case and is roughly the size of a pack of cigarettes. It is powered by a 9 Volt ”wall wart” transformer (included with the CO2), and draws approximately 300 milliamps. It can also be powered for more than two hours by a common 9 Volt alkaline battery via an optional battery cable. An LED glows when power is applied.

The CO2 has a three-position slide switch that selects its operating mode.

In the first position (”optical -> coax”) the CO2 has a single data path: it takes an optical input signal and passes it through to both the optical and coaxial output jacks.

In the second position (”bi-directional”), the CO2 has two data paths: the optical input is connected to the coaxial output, and the coaxial input is connected to the optical output. In this configuration the CO2 duplicates the function of the Fostex COP-1.

In the third position (”coax -> optical”), the CO2 has a single data path: it takes a coaxial input signal and passes it though to both the optical and coaxial output jacks.