I would like to create a DAC/amp combo for headphone audio. This would be easy enough to do with enough chips and diagrams out there like the PCM1794 chip, which has positive and negative outputs for left and right channels which could be wired to a TRRS or 4-pin mini XLR for a balanced connection. But, I would like to have surround sound headphone technology because the crossfeed, reverb, and delay they implement result in a very natural sounding audio when played through headphones.

One solution is to buy a $30 USB Dolby Digital headphone adapter and strip the DAC board right out of that and wire it in. Simply enough. But I would like a balanced signal as well meaning that when the processed surround sound is converted into audio, it must feed into a + and - output per channel and a DD headphone DAC isn't going to do this.

The idea I came up with is using a NJU26226 chip which is a Dolby Digital headphone processing chip that takes multi-channel audio from a digital source (USB, SPDIF optical or coaxial, etc) and converts it into a 2-channel serial digital output, then this chip could go into a PCM1794 24/192 DAC chip that will take a 2-channel serial input, convert it to an analog signal and has the + and - outputs for L and R channels.

Would this work? Using an NJU26226 and a PCM1794 chip in conjunction to build my own fully balanced Dolby headphone enabled headphone DAC?

 

Anyone?

 

Getting CODEC chips working is very challenging.

Unless you have top-level electronics and software chops, you are in for a very hard road.
just look at the data sheet for the chip, so many registers and signals to contend with, set one little thing wrong and... nothing works.

Beyond the manufacturer's reference designs, you are not going to find much from the DIY community, it's just too hard for most people to be worthwhile, especially when the consumer stuff is so cheap.

It's one of those commodity things that's hard to do but has low perceived value.

 

But having good surround sound audio that works with a high bitrate and a fully balanced system which is important to accurate reproduction of audio is something that doesn't really exist at present and it would be an interesting DAC if possible. The DD chip does seem to output 2 channel serial in a single connection that the DAC chip can read from so they SHOULD be able to work in conjunction with one another as the DD chip decodes the surround sound audio and outputs as a digital signal the DAC can work with.

 

Then by all means - go for it!

You will learn a lot from this project.

 

I did study the datasheets for both chips in question before posting this thread and the outputs of the DD chip look compatible with that of the DAC. Apparently the DD decoder chip itself doesn't create any kind of analog signal and rely on a separate chip for that functionality.