5.1 decoder

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soundNERD

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Joined 2003
electronet.dyndns.org
Hi,

I currently have a 100Wx2 Kenwood amp powering 2 front and 2 rear speakers. It distorts easily, and goes into protect mode with too much bass. I would like to upgrade to surround sound, and of course build the amp myself. I plan on using 2 sets of 2 lm3886 bridged for the two main channels, and 1 lm3886 for the rear speakers and the center channel. My sub is in progress right now and will use 4 lm3886 in B/P mode to get 300W into a 4-ohm speaker. Now, I need to find a way to decode the surround sound from the red and white analog wires from the dvd player. I would like to use optical or coax connection to make it easier, but all I could find was a 2-channel coax decoder from www.sound.au and was told a few months ago by people on this site that it wouldn't even work for dvds since dvds output digitally in 5.1channel mode, not 2 channel mode.

Is it possible (and simple) to build a decoder? If chips are required, they have to be something I can solder (a DIP would be great). I was going to build the 2 channel one and see how it works, then when the samples arrived, I noticed that they were tiny SIP chips.

Thanks for the help, Mike
 
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koolscooby

Member
Joined 2003
bradleyehughes.com
Yes, Cirrus makes a 5.1 decoder chip, check out the CS492x series chips, i got a sample 492[something], not arrived yet, but i only requested it a week ago, and those things take time.. :) good luck, and i'd like to know of any progress ;) (thinking of building a digital decoder into my pre-amp, and emulating 2 channel sources into 5.1 etc... :/)
 
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koolscooby

Member
Joined 2003
bradleyehughes.com
soundNERD said:
Now, I need to find a way to decode the surround sound from the red and white analog wires from the dvd player. I would like to use optical or coax connection to make it easier, but all I could find was a 2-channel coax decoder from www.sound.au and was told a few months ago by people on this site that it wouldn't even work for dvds since dvds output digitally in 5.1channel mode, not 2 channel mode.
Click to expand...


ok.... :smash: Red and white wires, referred to RCA, are two channels of audio, red is right [correct me if i'm wrong :xeye: ], and white is left... you *will* need coax/optical input of sorts... unfortunately i believe the Cirrus chip i'm getting is in a big pain in the a** package :mad:, its a sqaure chip, IIRC, i forget the name, is it SSIP? ... i think its 4sidesX10 contacts per each, 40 total pins, not sure though....and i hope its not surface mount or i'll be really bummed... but anyway, www.cirrus.com... good luck! :) (btw i'll let you guys know when i recieve my chip ;)) also, dont get scared just because of a surface mount or non-dip chip :)... make a simple pcb that has terminals (pin headers) for each pin down along the side if you would like to work on it easier ;)..., so you never have to remove the chip, and will have the pin header, and you could even get a IDE connector, which is 40 pin, and carry all of the pins from the chip to another board or prototyping station :) (IE: setup would be, PCB w/ chip attached to a IDE Cable thatp lugs into a prototyping breadboard :)... just my suggestion)
 
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machinow

Member
Joined 2002
SMD Package

Don't want to dissapoin u, but it is Surely SMD - I expect PQFP/TQFP packages. I have no problems soldering down to 0.65mm interlead distance packages, only 0.5mm is a little bit difficult. And you will need a PCB for it, too.
I ordered samples of it, too, and if I have the time and money I can make a PCB for it, and some DAC/ADC's also. Is anybody interested??
Regards :)
 
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osey

Member
Joined 2003
It could be OK. Im fortunate in that where I am I have access to smt/pcb technology so Ive never tried the laser print and peel option.

It might be an idea to see if theres anywhere near you that can offer reflow soldering or a similar technique.

I soldered a o.5mm lead spacing package onto a pcb before, and whilst its certainly possible, you do have to be pretty delicate and be very mindful of the amount of heat you put into the lead. A small heatsink would be a good idea.
 
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koolscooby

Member
Joined 2003
bradleyehughes.com
Re: SMD Package

machinow said:
Don't want to dissapoin u, but it is Surely SMD - I expect PQFP/TQFP packages. I have no problems soldering down to 0.65mm interlead distance packages, only 0.5mm is a little bit difficult. And you will need a PCB for it, too.
I ordered samples of it, too, and if I have the time and money I can make a PCB for it, and some DAC/ADC's also. Is anybody interested??
Regards :)
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Yeah figured, thats fine though that its smd :)... i can deal with it ... i can make a PCB for it, yet again not a problem... You could do that just like they are doing with the Aleph-X Boards.... unelss thats too big of a operation for you(which i can understand ;))
 
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elizard

Member
Joined 2003
How about making a normal 5/6/7 channel pre-amp, and using (if your dvd has them) the pre-outs?
There's a number dvds out there that do 5.1 decoding, unless i'm mistaken.

Then all you'd have to do is simply make a preamp w/ 5 channels (just a normal pre-amp), and then make 5+ separate amps for it.
 
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koolscooby

Member
Joined 2003
bradleyehughes.com
elizard said:
How about making a normal 5/6/7 channel pre-amp, and using (if your dvd has them) the pre-outs?
There's a number dvds out there that do 5.1 decoding, unless i'm mistaken.

Then all you'd have to do is simply make a preamp w/ 5 channels (just a normal pre-amp), and then make 5+ separate amps for it.
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hmmm... no, that defeats the purpose,we [as far as i know] want an optical or coaxial sp/dif connectioon from [insert device here]... but i would like to make it part of a pre-amp.... i just lack the abilities to do so, so i'll bs about it until i know exactly how to do it :)
 
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elizard

Member
Joined 2003
koolscooby said:



hmmm... no, that defeats the purpose,we [as far as i know] want an optical or coaxial sp/dif connectioon from [insert device here]... but i would like to make it part of a pre-amp.... i just lack the abilities to do so, so i'll bs about it until i know exactly how to do it :)
Click to expand...


I guess I misunderstood the original post then. :(

You can't of course using the coax or optical connection with this, but its an alternative to building a separate decoder.
 
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koolscooby

Member
Joined 2003
bradleyehughes.com
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