Ways to convert factory SPDIF signal?

[Sguirrelfeather]

While setting up a buddy's amps, I ran across a weird o-scope reading. Some on here thought the weird signal was distortion. Began testing everything out and the distortion is present all the way through the system.

System is in a 2011 Kia Sorento. Factory HU, factory amp, lines running from amp rear speaker outputs to high side inputs on a JBL amp and subwoofer outputs to a LOC for a monoblock. The distortion is present in all outputs from the amp, regardless of which output I test. This leads me to suspect it is the amp which is bad, having a faulty DAC inside. The amp is supplied signal by a three wire SPDIF connection....I'm guessing two signal wires for front and back, with a common ground.

So, since he doesn't want to try to replace the HU (integrated with the dash in a big way) I was wondering if it would be possible to tie in an rca connector to the SPDIF wires and use an aftermarket DAC to convert over to a 4 channel analog output. Then, plug those into a DSP and go from there.

Possible? Anyone done anything similar?

Click to read more...

 

[Laneyrw 10+ year member]

https://www.parts-express.com/parts-express-dac-digital-to-analog-converter-(51-compatible)--180-999

I just bought one to try out but haven't got around to it yet

 

[Sguirrelfeather]

Yeah, that's basically what I was considering using, but I don't know if car audio uses the same digital signal as home tv/stereo does. That's why I was hoping someone here had. If it works for you, let me know!

 

[Laneyrw 10+ year member]

it will work, google it but you have to get a digital coax cable to go from your device to the input. it looks like an RCA but is different. The issue I have is that this device goes before the factory amp and on some vehicles like min the amp is what produces other interactive sounds.

 

[Sguirrelfeather]

Digital coax? What's the difference?

 

[Laneyrw 10+ year member]

https://www.zzounds.com/item--HOSDRA?siid=185677

This Hosa SPDIF RCA to RCA cable is a true 75-ohm coax for accurate transfer of audio or video data

like the cable wire in your walls are not just regular wire they are coax. its for shielding and ability to send more data/frequencies.

 

[honkyg 10+ year member]

s/pdif (sony/philips digital interface format) is the standard format for the transfer of digital information over short distances by either toslink (fiber optic) or 75 ohm coaxial terminated with rca's and usually designated with the color orange. this format is used mostly in home, a bit in higher end car audio, but ive rarely seen it used in pro audio.

however, the external d-a/c's linked should work if in fact those are s/pdif connections, but with only 3 wires, i would do a bit more research to confirm it's schematic for proper connection.

edit; the s/pdif to rca converters also calls for a 12v rectified to 6v transformer.

 

[Sguirrelfeather]

I had found a schematic showing it labeled as SPDIF. Now that I look at it a bit closer, I realize it might be something different. One is labeled Out-, one is Out+, and third as ground. However, the ground is also shown as shielding the other two (little dashed lines coming from the ground going around the - and +). So would this be a differential twisted pair connection with a shield, or was I right on my first assumption that it's two unbalanced connections?