What is Dolby Digital (AC-3)?

AC-3 (Currently known as Dolby Digital) is a 5.1 channel discrete digital audio encoding standard from Dolby Laboratories. Developed to provide high-end audio for the big screen, it has been in use in many home-theaters for quite a few years now. AC-3 encoded audio is available on hundreds of hit movies on LaserDisc, DVD, and according to rumor on one or more of the mini-dish satellite systems in the near future. The ATSC (Advanced Television Systems Committee) has standardized on AC-3 as it's audio codec standard (for HDTV). Discrete digital audio is here now and is THE standard.

To experience AC-3 audio you will need one or more of the following:

(1) Source Material - LaserDisc, DVD, something else?

(2) Decoder - To turn the digital bitstream into 6 channels of audio.

(3) Receiver/Amp(s) - Able to handle up to 6-channel input and drive that many speakers.

(4) At least 4 speakers - Left/Right/LeftSurround/RightSurround (Optional center & Sub).

Our Modification Product:

What we offer is an AC-3 modification "kit". What it includes is a small circuit board about the size of a postage stamp, 5 pieces of wire, a capacitor, an isolated RCA jack, and 3 pages of installation instructions. The circuit board itself is professionally produced and includes all surface-mount components. Sold as a DIY (Do-It-Yourself) kit it is $75 + $5 S&H. If you'd prefer to send your player in to us for installation it's $175 + $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-wrap 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.

Returns are subject to a 40% restocking fee.

Questions & Answers:

Q. What type of cable should I use as an interconnect?

A. Most AC-3 decoders that support an RF input come with a cable. Generally this cable will be more than sufficient and replacing it with a better one will not improve the sound quality. As long as the cable is at the correct impedance and can pass all the signal necessary for the decoder to decode the audio it carries, that's good enough. The cable should be 75Ohm and a composite video interconnect cable will work better than an audio interconnect cable.

Q. My LaserDisc player already features either a TOSLINK Optical or Coaxial Digital output. Can I hook that to an AC-3 decoder and enjoy discrete digital sound?

A. No. LaserDiscs store the AC-3 digital bitstream as analog data on the right analog audio track. It is output from the player to the decoder as an RFmodulated signal. The RF data is then demodulated into digital AC-3 data and then decoded into 5.1 channels of audio. The TOSLINK or Coaxial Digital output transmits the PCM Digital data stored on the L/R Digital tracks of an LD (or CD) [appropriate for a DTS decoder or external DAC].

Q. Are all AC-3 decoders the same? Is there anything I should watch out for?

A. No they are not, and Yes be careful. Some of the newest decoders hitting the market offer ONLY digital inputs. The manufacturers have dropped the RF input for laserdisc players in an apparent cost-cutting effort. Most all of the ones that have done this offer an extra RF demodulator for LD player owners which will need to be purchased in addition to the decoder.

Q. How do I know if my Stereo/AV receiver will work with AC-3 decoder model XYZ?

A. Many receivers are being advertised as "AC-3 Ready". Generally this means that they come with a DB-25 input connector to deliver all 6 channels of audio from the decoder to the receiver on one cable. If yours does not have this type of connector, it will need to have 6 individual RCA input jacks (as one input source, not counting 2 for TV, 2 for Tape, 2 for CD, etc...) Some decoders have multiple output RCA jacks and others only output via a DB-25 connector. DB-25 to 6 RCA convertor cables are available as well.

Questions about the LaserDisc player modification:

Q. Do I need to have my player modified or will it support AC-3 as is?

A. Check your owner's manual. Also, check the back panel of your player for a single RCA jack usually labeled as "AC-3 RF Output". If present you just need a decoder or receiver with AC-3 decoding built-in.

Q. How difficult is this modification?

A. Check the "Player List" page for both a list of supported players and their complexity level. As a general rule, you should be fairly mechanically inclined with some soldering knowledge/experience.

Q. If I go the DIY (Do-It-Yourself) route, what will I receive and what tools/time will be required.

A. You will receive a "kit" that contains all necessary components, wire, etc... You will need a soldering iron/solder, screwdriver, and perhaps some small pliers. A small hole will need to be drilled in the back panel of the player. A drill (or preferably drill press) and 3/8" drill bit will be necessary for this. Generally count on spending from between 30 minutes to 2 hours to complete the mod.

“Dolby”, AC-3, and the double-D symbol are trademarks of Dolby Laboratories
DTS is a trademark of Digital Theater Systems