Onkyo 905, can it handle AC3 ?

Automan · 04-21-2008, 03:33 PM

As the title... can my Onkyo 905 handle a AC3 signal from my LD-Player ? Just wanted to know if you heard anything about that, cause i can't find anything about if it can or not.

Thanks in advance for any help.

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Walter Kittel · 04-21-2008, 03:46 PM

Unless it specifically has an AC-3 RF IN connection (which I doubt), you will need to have an external RF demodulator installed between the LD and your Onkyo.

http://www.precisionlaserdisc.com/newfaq.html

- Walter.

Automan · 04-21-2008, 04:08 PM

Thanks, that was what i thought... i guess i can't do it without that RF demodulator then, nevermind.. i havent that many AC3 LD's anyways.

Nice to watch these LD's, brings back old times.... many movies have a real great sound in them, but the picture is not that bad, it's something i wont ever sell, have to many movies.. couple of hundred i guess

have always liked that format, so it will stay in my homecinema.

Philip Hamm · 04-22-2008, 07:37 AM

Quote:

Originally Posted by Automan

Thanks, that was what i thought... i guess i can't do it without that RF demodulator then, nevermind.. i havent that many AC3 LD's anyways.

Nice to watch these LD's, brings back old times.... many movies have a real great sound in them, but the picture is not that bad, it's something i wont ever sell, have to many movies.. couple of hundred i guess

have always liked that format, so it will stay in my homecinema.

Me, too. I have about 500 LaserDiscs and they look good enough to me on my 96" X1 to continue to enjoy. Also, they sound fairly terriffic.

RF demodulator can be somewhat expensive. Another option, if you're not particularly interested in "DVD-Audio" or "SACD" multichannel music formats, is to get an older Dolby Digital decoder which is equipped with a LD RF input and hook it up to your receiver's multichannel in. That's what I do, and it works great. Older Dolby Digital decoders can be had for fairly cheap. There's an Adcom decoder on ebay right now, I've used that model and it's quite nice.

JohnRice · 04-22-2008, 10:27 AM

This is such a journey down amnesia lane. I had completely forgotten that a DD (AC3) output from LD was different than now. Maybe someone can remind me. The AC3 output was really just a video RF (coax) output, wasn't it? Wasn't the extra info actually in the mono audio channel or something, and the video had to be demodulated and stripped off? I've never had a LD player with an AC3 output.

Walter Kittel · 04-22-2008, 10:34 AM

From the link in my first post...

Quote:

In the early 90's Dolby Laboratories and Pioneer developed a way to place a full 5.1 channels of discrete digital audio on a laserdisc. Since the standard was in place and there were already 4 separate 'tracks' for audio they couldn't add a new one for this data since it would probably break backwards compatibility. Older analog-only players they figured were few and far between so they decided to replace the right analog audio track. A mono soundtrack for the movie could still be placed on the left analog track with the regular standard stereo and/or Dolby Prologic encoded data on the two digital tracks. In place of the right analog audio track they placed a compressed digital signal which contains ALL of the 5.1 channels of Dolby Digital (DD for short) AC-3 encoded data. If you play a DD encoded disc and switch to analog audio you'll probably hear a 'hissing' sound in the right channel. This is the digital data for the DD 5.1 audio.

What many people are thinking is "Why can't I just hook a cable from my right audio output jack to the DD input of my receiver/decoder and get the data to it in that way?". You could IF it was not filtered and processed by the player's audio circuitry. Thd LD player does not know you're sending that data to an outboard processor for decoding. That output is supposed to be delivering formatted audio for a human's ears, not for input to a processor for further decoding.

Other people are thinking "Why can't I just hook a cable from the existing Coaxial Digital or TOSLINK Optical output on my LD player to the appropriate input on my receiver/decoder and get DD 5.1 sound that way?". Remember from the description above WHERE the Dolby Digital AC-3 data is stored on the laserdisc physically. It's on the RIGHT ANALOG audio track. The Coaxial or Optical digital outputs on an LD player output the PCM digital data stored on the two digital audio tracks of the disc or of course the digital audio data stored on a regular audio CD. There is no Dolby Digital AC-3 data stored on the disc on those two digital audio tracks and therefore any existing digital outputs on the player will NOT have any usable data as far as the receiver/decoder will be concerned.

How do you store "digital" audio data on an "analog" audio track? Dolby Digital as the name implies is a purely digital audio specification. Powerful computer chips take a stream of compressed digital audio and decode it and split it into anywhere from 1 to 5.1 channels of audio. This is performed inside the receiver or Dolby Digital decoder if the receiver doesn't have the decoder built-in. DD data is stored on the laserdisc in an RF (Radio Frequency) form. Technically it's QPSK modulated and resides within the 2.8Megahertz space allocated for the right analog audio track.

An LD player that came stock with an "AC-3 RF OUT" connector OR a player that has been modified for it output the same type of signal. It's a buffered RF signal which technically is analog. That analog data however represents the digital data in much the same way a modem can move digital data across an analog telephone line.

- Walter.

Walter Kittel · 04-22-2008, 10:44 AM

Haven't played an AC-3 title in some time; but I still have a number of AC-3 and DTS LD titles that I recall as having sounded just wonderful.

- Walter.

Automan · 04-22-2008, 03:45 PM

Quote:

Originally Posted by Philip Hamm

Me, too. I have about 500 LaserDiscs and they look good enough to me on my 96" X1 to continue to enjoy. Also, they sound fairly terriffic.

RF demodulator can be somewhat expensive. Another option, if you're not particularly interested in "DVD-Audio" or "SACD" multichannel music formats, is to get an older Dolby Digital decoder which is equipped with a LD RF input and hook it up to your receiver's multichannel in. That's what I do, and it works great. Older Dolby Digital decoders can be had for fairly cheap. There's an Adcom decoder on ebay right now, I've used that model and it's quite nice.

I still have the standalone decoder (Sony EP90ES) from my old setup, still have my old H/K rec and H/K signed amp etc.

I would like the clean setup i have now, but i could as you said use that decoder again.... if just for the AC3 input, hmmmm..... I really have to think about it, if it's worth hooking that unit up to all my new stuff just to get that AC3 sound. Don't get me wrong, it sounded real good what i remember, but i have a very nice dvd player and a blu-ray player in my system, and that big nice Pioneer CLD98 laserdisc player... i just have to think about if it's worth it, it wont take much space and so on, but it has a manual power-switch on the unit, and the on/off is not controlled by the remote, other then that it looks nice and have no other "faults". It's just that it feels so stoneage having to puch a button on the unit to set it on/off.... or maybe im lazy

Sure miss those days when i bought movies on LD, just the right size, was real nice to look at both the cover, and pulling out those big shiny disc's.... the disc spinning up and then movietime

that feeling of the weight and size was perfect.
Even if they where kinda expencive, it sure felt like you bought something, not like today when you buy a dvd/blu-ray small packages and feels like you bought a music-cd by misstake or something.

Automan · 04-22-2008, 05:07 PM

Moderator please erase this, no need for two post that is the same.



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