Digital Audio Interconnects

Types of Digital Outputs

There are two types of digital outputs available on most consumer audio gear: TOSLink and Coaxial. TOSLink is an optical interface which uses plastic optical cable as it's interconnect. Coaxial is generally in the form of an RCA or BNC connector and uses fairly standard coaxial wire as it's interconnect. An RCA connector is the most common coaxial output connector and is usually color-coded orange. TOSLink usually has a small square plug installed to keep the red laser light from bouncing around the insides of your HT room. Be careful not to look directly into the light, any laser light can be dangerous to your eyes!

How it Works

Audio that you hear is inherently analog. The digital audio data stored on a CD or Laserdisc must first be converted to analog for your ears to be able make sense of it. Generally a CD or LD player has a built-in DAC (Digital to Analog Convertor) to convert that data from Digital to Analog. Commonly though this built-in DAC is not of the highest quality. External DAC's are sold that feature much greater precision and features generally not present in the LD or CD transport. Technologies like HDCD and DTS make use of the digital output and decode the digital data into their respective audio formats as well.

Laserdiscs many times have both analog and digital audio tracks present. The analog tracks are read and played with no conversion necessary. The digital tracks are read and then must be converted to analog for playback. With the advent of AC-3, the right analog track has been replaced by the AC-3 digital information. If you have an analog-only LD player, you must listen to the left analog track in mono. A player capable of reading the digital tracks (all modern ones) can still playback stereo sound from the digital tracks, even without an AC-3 decoder. DTS discs on the other hand replace both digital audio tracks with the DTS encoded data. Viewing a DTS laserdisc without a DTS decoder would require listening to the analog tracks.

The digital data stored on LD's and CD's is of course computer data, ones and zeroes. After it's read from the disc it is commonlly converted to S/P-DIF which is a standard for exchanging digital audio information between different pieces of equipment (Sony/Phillips Digital Interface Format). Many modern players have a DSP (Digital Signal Processor) chip which produces this signal, but they commonly do not make it available outside of the player.

Our Modification Product

What we offer is an upgrade "kit" to make the digital audio data available via a coaxial RCA connection (BNC optional). We strongly prefer coaxial for a few different reasons. Coaxial requires the drilling of a "round" hole in the player's back panel to mount the RCA/BNC jack. TOSLink would require a "square" hole which would add greatly to the complexity of the install. Also, coaxial is considered to be of higher quality than TOSLink. TOSLink utilizes an optical connection which you would think would be better, but being based on multi-mode plastic optical cable it is prone to jitter (the timing of the digital to analog conversion becomes incorrect). The electrical coaxial digital interface is considered to be higher in quality than TOSLink since the amount of jitter is generally much less. There are professional interfaces available that are of even higher quality, inquire via email if interested (Fiber ST, AES/EBU).

Our "kit" consists of a small integreated circuit board, coaxial interconnect wire, hookup wire, an insulated RCA (or BNC) jack, mounting hardware, and three pages of installation instructions. The circuit itself is about 3/4" x 2" and utilizes surface-mount technology. Sold as a DIY (Do-It-Yourself) kit it is $95 + $5 S&H. If you'd prefer to send your player in to us for installation it's $195 + $20 S&H. Be sure to package your player very well (in it's original box or in a large box with plenty of bubble-warp or other good packing foam) and send it insured to:

Precision Laserdisc
2890 Boones Creek Road, Suite 2
Gray, TN 37615
Turnaround time for a player sent in to us is generally 3 days. Be sure to Email us any package tracking information and alert us that your player is in transit.

Regular shipping for a DIY kit is $5, UPS Blue (2-day) is $10, and UPS Red (1-day) is $15.

Leave a note in the comment section of the order form if you want anything quicker than regular ground shipping.