New DAC with measurements!

[ojg]

Schematic is now up on the website as a pdf file.

Some of the component values may be slightly different from what I ended up using, but it should be mostly accurate.

Happy reading!

 

[thadude2]

Hello Olj,

Thanks a bunch and much appreciated!

 

[ojg]

I have now replaced the OPA627 with AD825 as I/V converter. In my latest tests AD's $2 op-amp beats BB's $12 op-amp on every account! (And yes that includes the subjective listening tests!)

Have a look for yourself at the project website.

I recommend everyone on this forum to throw out their OPA627's!

(/me ducks and puts on flameproof suit....)

As a sidenote, I listened again to the DSotM track I mentioned before, and could not find the section with the annoying sound. In fact the old cliche is true, I forgot to listen to the 'sound' and started enjoying the music instead. Proof enough for me.

 

[Bricolo]

just a little error

the 3rd IMD graph is called opa627, or it's with the ad825

 

[ojg]

D'oh! Should be fixed now...

 

[jean-paul]

I recommend everyone on this forum to throw out their OPA627's!

Maybe they behave bad just in your DAC ....

 

[JonPike]

Interesting results.. You should try the AD825's with the TDA1541 to see what difference there might be from the 5532's.

Another thing, though possibly harder, would be to try interfacing the 1541 to the DF1704 filter.

I've seen an article (Analog Devices app note AN-207, sorry I don't have a link) on changing the data stream such that a AD DAC could use the SAA7220 filter, it just took a few logic gates.. probably the same could be done to patch the other two together. Too late for me to look into it tonight..

Great to have measured results on a project like this.. I think you've just about inspired me to build something myself.. got a 1541 just sitting around gathering dust.

 

[ojg]

Thanks, but I probably will not experiment more with the TDA1541, I used its measurements as a comparison base for my own DAC.

Good luck with your own project, may I recommend AD1896@192kHz - TDA1541 - AD825, should perform great and requires no glue logic.

I hope you will post your results here when you get it done. I will measure it for free if you send one my way

 

[Terry Demol]

Thanks, but I probably will not experiment more with the TDA1541, I used its measurements as a comparison base for my own DAC.

Good luck with your own project, may I recommend AD1896@192kHz - TDA1541 - AD825, should perform great and requires no glue logic.

I hope you will post your results here when you get it done. I will measure it for free if you send one my way

Hi Ojg,

Why 192k? Can you hear any difference with 1896 at different
SR's?

Cheers,

Terry

 

[ojg]

No I have only tested the AD1896 at 97.6kHz, but the TDA1541 max out at 192kHz (or 176.4kHz?).

You want to use the maximum frequency the DAC can handle to make the analog filter as simple (low-order) as possible. This I believe does make a difference on sound quality.

Cheers!