diyparadise

Geez, I have not been updating the site for a while but that doesn't mean I'm missing in action. It's just that I have been busy...

... busy with so many things! Over the last few months, have done a lot of cooking, baking, have carried out lots of home improvement projects (to word it nicely, I fixed a couple of water leaking issues in the house), built a few wooden racks, trellis for the garden... and lots more. Err, sounds like I have been domesticated!

Anyway, out of sight does not mean out of mind. I still listen to music, I still build stuffs. It's just that the way monica is at the moment, there isn't much we could do now. I mean we could carry out some modifications here and there, but these likely will only result in incremental improvements. As I'm no cable lover, I want big jumps in sonics! Not teeny weeny, "let's listen to it AB again if we could detect a difference".

But even for a 16 bit DAC chip, TDA1545 is still very capable today, as shown in this Old but Gold article.  Feed it higher sampled material and it won't disappoint you, as long as it's 16 bit. Hey, it can even take in 384kHz sampled material! As explained in the article, you need higher sampled material, not more bits.

But these days, the marketing folks have you believe you need 24 bit. In fact, there are also 32 bit DACs. So 16 bit is no longer in vogue. Makes you feel like your digital system is not complete if you have "less bits". It's like you feel inadequate without the latest Ipad or Iphone. Damn those marketing folks!

To be honest, while 24 bit is touted as "better", more attention got to be paid to the power supply as noise could easily overwhelm the last few bits. [Why aren't more folks talking about this?] Many years ago, the late John Camille did a presentation at a Vacuum State of the Art Conference meet on the subject of noise and shared this excellent info which I have taken the liberty to show here.

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Note that unless your system noise is way below 100uV, at best you could only hear up to 16 bit (more likely worse!) even though you are using your state of the art 24 bit or 32 bit DAC.

Note that even Mr Camille says >23 bit is GOD's DOMAIN.

That said, I'm no match for the marketing crowd!

So if you can't beat the crowd, join them right? So I have a look at 24 bit DACs. Most do not interest me. The ones that do interest me cost too much. I simply can't justify spending >USD30 for a DAC chip [later though, my perspective has changed somewhat].

However couple months ago, CKL on the forum pointed this 6moons review of the TotalDac.  As I just glanced through, I thought it was using industrial DAC chips for audio purpose [yeah, stupid me]. It was only later when I reread the review, I realized it's a discrete DAC! Built using ladder resistors! Interesting!

I did some more reading and got some help here. Sonic Illusion's Tom Browne has been a great help. His page here has sufficient info for you to whip up your own discrete DAC but like all things audio, the devil is in the details. Tom is also working on his production discrete DAC - Sunrise, so you have off-the-shelf options other than the TotalDac.

Alright, after all this talk, so did I get one working? Here's my mock up.

Obviously, it's quite messy! Still, the concept works. From a 1kHz WAV file, I could scope out a 1kHz sine wave at the DAC.  Nice! Note that Black Crow as shown above, is not used at all.

Next step, is to make it stereo and solve a few more other problems before we have a stereo DAC. Long way to go but it's a start!