Old but Gold

Digital audio has come a long way. From the introduction of compact disc to today’s high resolution media, we have indeed covered lots of bytes, err miles. Bearing this in mind, how does a “vintage” DAC chip of circa 1993 fare in today’s high rez media?



Charles Altman from Altman Micro Machines explains what is more important for digital audio is the sampling rate of our media rather than number of bits. Have a read on his page. Don’t worry, I’ll wait.


Thanks for coming back.

So the higher the sampling rate, the better it is for our “signal reconstruction”. Hey, that’s what a DAC does basically.

So how about some real life example? How does Monica’s TDA1545A cope with higher sampled material.

And thus, I began my experiment.

But I hit a snag. Apparently, high resolution test tones are not easily available. 44.1/16 versions abound but not higher rez. Fortunately, you could create your own high rez wave files by using Linear Tech’s excellent LTSpice.

I also have a bigger problem in that I don’t have a media capable of high resolution. For the sake of you dear readers, I have to spend money… [another excuse to buy!] and I bought a John Kenny modified I2S Hiface module.


i2s monica beside vintage oscilloscope


The signal path is now… Mac Mini -> jkenny I2S Hiface -> I2S Monica. Software is Channel D’s Pure Music Player and music library is via iTunes.


Oh yeah, did I mention I built a new I2S Monica as well?

Did I mention I had to haul the whole Mac Mini setup to the listening hall?


All this done [phew!], began feeding test tones. Please note that these test tones are created using the described sampling frequency. Note that no software/hardware upsamping nor over sampling is performed at all.


44.1kHz sampled

1kHz sine wave

1khz sine wave. 44.1khz sampling

10kHz sine wave.

10kHz sine wave. 44.1khz sampling

16kHz sine wave

16kHz sine wave. 44.1khz sampling


As you could see above, 10kHz above, the DAC is struggling to reconstruct the sine waves.


96kHz sampled

1kHz sine wave

1khz sine wave. 96khz sampling

10kHz sine wave.

10kHz sine wave. 96khz sampling

16kHz sine wave

16kHz sine wave. 96khz sampling


10kHz is still decent but 16kHz is a stretch…


192kHz sampled

1kHz sine wave

1khz sine wave. 192khz sampling

10kHz sine wave.

10kHz sine wave. 192khz sampling

16kHz sine wave

16kHz sine wave. 192khz sampling


Wow! 16kHz is no problem here!


So what does all this tell me?

The problem of digital audio is not in the equipment. It is in the material. We just need higher sampled data to begin with.


If fed high resolution material, our “vintage” DAC chip is far from an old clunker. It is still capable of reconstructing the signals properly.


In other words, Old is Gold.  ha ha!



  1. jkenny May 27, 2011
  2. yeo May 28, 2011
  3. jkenny May 28, 2011
  4. yeo May 28, 2011
  5. jkenny May 28, 2011
  6. yeo May 29, 2011
  7. charlyb July 10, 2011
  8. yeo July 10, 2011
  9. charlyb July 12, 2011
  10. yeo July 12, 2011
  11. Jochen Lanz October 17, 2011
  12. Charles January 13, 2012
  13. yeo January 13, 2012
  14. Chris October 28, 2012
  15. yeo October 30, 2012
  16. Dimiter November 9, 2016

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