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DIY 5.1 decoder
DIY 5.1 decoder
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Old 8th February 2001, 02:21 PM   #11
Eric is offline Eric  United States
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DIY 5.1 decoder
Lightbulb Dolby Digital Decoder

Promitheus, I have a Marantz DP-870 dolby decoder that I picked up used for about $250. You can find used equipment at Audio Review and AudioGon. One drawback to the Marantz unit if you don't already have a Marantz Pre/Pro is that it does not come with a remote control. This isn't a problem for me, but it might be for others, depending upon how it is installed (ie: either between the preamp and amps, or plugged into the 6-channel input on a receiver/preamp).
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Old 12th May 2001, 12:12 AM   #12
kev31mc is offline kev31mc
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For my senior EE design project my partner and I made a surround sound decoder. We used the Crystal CS49326 DSP which is in the home theater chipset line. We were able to license the Dolby Digital application code under an educational agreement but didn't have any luck with DTS. We used a Crystal CS8414 line receiver and CS4340 DACs and laid them out on a 4 layer board.

I am new to the whole DIY realm (this project turned me on to it) and consequently the HW for the project probably isn't very optimal and needs a board revision. However the board works and we finished the entire thing in a semester(~14 weeks).

Our design is online and has the code (sans the AC3 app code), schematics, and a picture of the board with 4 of the 6 channels populated on one of our boards.

Check it out <a href=https://www-s.ece.uiuc.edu/ece345/cgi-bin/view_project.pl?spring2001_1>here</a>

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Old 9th January 2002, 09:07 AM   #13
Dave is offline Dave  New Zealand
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DIY 5.1 decoder
I guess if you knew what you were doing with a DSP chip and had the decoding algorithms for whatever formats you wanted it would be do-able.

The hardest part would be getting hold of the algorithms especially if you wanted the latest such as DTS 24/96.
It sure would be a great project.

kev31mc - you're link doesn't work, I'd like to see it.
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Old 13th January 2002, 04:48 PM   #14
Petter is offline Petter
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Default Extigy -- and then break the warranty

How about getting into a SoundBlaster Extigy at about $150 or less. Then you can break the warranty and start putting decent D/A's in there.

Another alternative is to use one of the commercial Windows DVD players that support decoding + send the signals to whichever ports you have available.

Yet another alternative is to purchase say one of the higher end Sony processors and modify it. They contain lots of kit + DSP's etc. Now that I am thinking about it again, perhaps one of the cheapes surround sound receivers would be even better, just clean out all the amps etc. so you have room for modification.

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Old 13th January 2002, 05:53 PM   #15
bytefx is offline bytefx
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Wow! Talk about luck. This is the exact subject I logged on for. I'm really looking for a DIY 5.1 decoder/preamp but can go with one of each. Looks like the most feasible way is buy a used decoder then build/find a 5.1 preamp. But I have seen used all-in-one's on the net from reasonably reliable sources. Problem was they were discontinued models. Still waiting for the spec shets from the original builders to be sure they have the right features.
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Old 6th February 2002, 04:11 PM   #16
dwk123 is offline dwk123
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This topic has gone a bit stale, but the only open DD decoder that I'm aware of is at liba52.sourceforge.net. AC3 only, and reports on quality aren't the most encouraging, but at least it's an implementation that you can look at and play with. Mostly targeted at Linux DVD players, but should be relatively portable.

If you can get any boards/chips then it's obviously a great way to go, but I wouldn't hold out much hope. Any legit manufacturer will likely clam up if you aren't a Dolby licencee.
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Old 6th February 2002, 06:21 PM   #17
tiroth is offline tiroth  United States
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Has anyone talked to Dolby about licensing? They have info available on their site, and since at least one college project recieved a gratis license it seems within the realm of possibility that they would grant a license for "educational" purposes.

After all, I doubt anyone here is looking to develop a commercial decoder.
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Old 14th February 2002, 02:56 PM   #18
Helix is offline Helix  United Kingdom
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i think that s what i will do, build a hi end dac (2channel) 5.1 pre-amp (with 6 bosoz of course!) complete with 6 boards of relays and resistors for volume and then get a hi end player which has audio outs. that way u can switch between the audio ins (5 channel) from DVD or computer or whatever, or the digital ins (2 channel) for CD, TV and MD.

Complete 5.1 channel sound from signle ended design, nice, but big!
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Old 1st June 2002, 12:23 PM   #19
bimbla is offline bimbla
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Default DIY Decoder

Forget about getting a single piece of Decoder IC.

Best way is to design one in analog domain.

Try Center, Surround and Sub-Woofer configuration.

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Old 1st June 2002, 04:10 PM   #20
tiroth is offline tiroth  United States
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It is possible to obtain the ICs one-off. But not the code.

I don't think analog matrix decoding is really that worthwhile...it is an interesting project, but doesn't come near to matching the impact of discrete (at least for theater).
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