Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz - Page 31 - diyAudio
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Old 29th August 2014, 08:13 AM   #301
esgigt is offline esgigt  Netherlands
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Originally Posted by soekris View Post
Press ALT and type 155 for lowercase and 157 for uppercase . You might also need code page 865 loaded as IBM originally forgot the Danish and , they had the other ones , , , , they then added the nordic code page 865.... Have no clue if it's needed on windows....
Wrong code page
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Old 29th August 2014, 10:06 AM   #302
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Originally Posted by soekris View Post
The inputs goes into a FPGA, so I could in principle add any format. But why ? Everything seems to be I2S nowadays....
In fact i have a CD MARANTZ CD5004 and the audio format seems to be RIGHT JUSTIFIED 16 bits ...

The actual DAC ( CD 5004 ) settings is RIGHT JUSTIFIED 16 bits ...
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Old 29th August 2014, 10:54 AM   #303
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@Sergelisses
I2S is 2's complement MSB first fixed format, word length is not fixed.
The DAC used in Marantz CD5004 is the Cirrus Logic CS4392, that accepts I2S format (see the datasheet), either PCM format.
I have no idea which format was used from Marantz to connect the transport to the DAC, it depends on the setting of some pins of the DAC chip.

@ Soekris
I wonder how you can reach 24 bit accuracy with such these resistors tolerance.
As you are an engineer, you know that with 0.01% tolerance you can reach not more than 12/13 bit accuracy.
And I have not considered the thermal drift, supposing since the resistors are identical they have the same drift (but it's not so): to reach 16 bit accuracy you need 5ppm resistors or better.
Finally I have not considered also the RDSon of the 595s, that affects the accuracy.
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Old 29th August 2014, 11:16 AM   #304
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Originally Posted by andrea_mori View Post
@Sergelisses
I2S is 2's complement MSB first fixed format, word length is not fixed.
The DAC used in Marantz CD5004 is the Cirrus Logic CS4392, that accepts I2S format (see the datasheet), either PCM format.
I have no idea which format was used from Marantz to connect the transport to the DAC, it depends on the setting of some pins of the DAC chip.
If you look at the CS4392 in the CD5004 the format settings is RIGHT justified 16 bits

Serge
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Old 29th August 2014, 12:08 PM   #305
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Originally Posted by Sergelisses View Post
If you look at the CS4392 in the CD5004 the format settings is RIGHT justified 16 bits

Serge
So it's not I2S format.
If you want use the transport of the Marantz to feed Soekris's Dac you have to use S/PDIF (I see the Marantz provides optical and coaxial digital output).
As an alternative, you can get I2S signal directly from the decoder chip TC94A70FG inside the device.
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Old 29th August 2014, 12:18 PM   #306
soekris is offline soekris  Denmark
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Quote:
Originally Posted by andrea_mori View Post
@Sergelisses
I2S is 2's complement MSB first fixed format, word length is not fixed.
The DAC used in Marantz CD5004 is the Cirrus Logic CS4392, that accepts I2S format (see the datasheet), either PCM format.
I have no idea which format was used from Marantz to connect the transport to the DAC, it depends on the setting of some pins of the DAC chip.

@ Soekris
I wonder how you can reach 24 bit accuracy with such these resistors tolerance.
As you are an engineer, you know that with 0.01% tolerance you can reach not more than 12/13 bit accuracy.
And I have not considered the thermal drift, supposing since the resistors are identical they have the same drift (but it's not so): to reach 16 bit accuracy you need 5ppm resistors or better.
Finally I have not considered also the RDSon of the 595s, that affects the accuracy.
You might want to read though the whole thread, some of my posts contain more tech info, see t.ex. post #34 and #67:
Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
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Old 29th August 2014, 01:57 PM   #307
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Originally Posted by soekris View Post
You might want to read though the whole thread, some of my posts contain more tech info, see t.ex. post #34 and #67:
Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
Also with sign magnitude format, 33R RDSon means 7-8 bit accuracy, not 12 bit.
Am I wrong?
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Old 29th August 2014, 03:55 PM   #308
soekris is offline soekris  Denmark
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Originally Posted by andrea_mori View Post
Also with sign magnitude format, 33R RDSon means 7-8 bit accuracy, not 12 bit.
Am I wrong?
Yes, you're wrong. As I said in post #34, there has been compensated for the driver output impedance, which btw is ~13R.

And please read up on Sign Magnitude DAC principles....
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Old 29th August 2014, 03:55 PM   #309
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... and to reach 24 bit accuracy with sign magnitude you need 2 * 23 bit ladder network accuracy.
I have re-read your posts, but I have not understood how you solve the problem of accuracy.
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Old 29th August 2014, 03:57 PM   #310
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Originally Posted by soekris View Post
Yes, you're wrong. As I said in post #34, there has been compensated for the driver output impedance, which btw is ~13R.

And please read up on Sign Magnitude DAC principles....
That's means 8-9 bit accuracy.
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