Buffalo II

[regiregi22]

Having a REAL microprocessor in that interface, possibilities can reach the sky...

[Bunpei]

Originally Posted by glt

I suppose if you send 44.1K material at 8X re-sampled, this would correspond to 352.8K (which you plan to support). With 32bit per channel I2S, this corresponds to a clock of 22.5792 MHz.

As all of you may know already, the great ES9018 DAC chip on Buffalo DAC is doing this partially as usual. The Buffalo DAC default setting employs "Over sampling mode ( 8x )". Hence, 44.1 k 16 bit materials are internally re-sampled to 352.8 kHz.
For a true 352.8 kHz /24 bit file, internal sampling rate is 352.8 kHz x 8 = 2.8224 MHz!

[Joshua_G]

Is there a way to cancel oversampling with ES9018 DAC chip?

[Russ White]

Hi Bunpei,

I think you are confusing two features. If you turn off the OSF the chip does work better if you input PCM at 8X the original sample rate. Here ESS is assuming you likely used an external digital OSF that outputs at 8X FS. The OSF rate and the final sample rate are not exactly the same.

In the best performance mode, all sample rates in are internally asynchronously re-sampled to rate that is independent of the source sample rate. That rate is set by the master clock alone.

It very true that prior to jitter reduction the supplied sample rate is run through the 8X OSF .

So it is true to say that ay one point the sample rate is 8X FS, after that it is even higher.

[Russ White]

Originally Posted by Joshua_G

Is there a way to cancel oversampling with ES9018 DAC chip?

Yes you can disable the OSF.

[Joshua_G]

Originally Posted by Russ White

Yes you can disable the OSF.

How can it be done on Buffalo II?

[Russ White]

Originally Posted by Joshua_G

How can it be done on Buffalo II?

Set the correct register via I2C.

We do not recommend nor supply firmware for that configuration, but it is not at all hard to do.

We may consider providing firmware for that application if there is a big enough demand, but I caution that the performance of the DAC is very much compromised in my experience in this mode.

[Joshua_G]

With a proper firmware, will it be possible to switch between oversampling and NOS modes?

[Bunpei]

Originally Posted by Joshua_G

With a proper firmware, will it be possible to switch between oversampling and NOS modes?

In the case of SDTran192, its recent firmware has capability of outputting I2C commands to set ES9018 registers on Buffalo II. The firmware switches the oversampling filter mode file by file depending on its sampling rate. For 352.8 kHz/ 24 bit: No over sampling, and for other sampling rates: Over sampling.

[Joshua_G]

Originally Posted by Bunpei

In the case of SDTran192, its recent firmware has capability of outputting I2C commands to set ES9018 registers on Buffalo II. The firmware switches the oversampling filter mode file by file depending on its sampling rate. For 352.8 kHz/ 24 bit: No over sampling, and for other sampling rates: Over sampling.

Can the user choose manually between oversampling and NOS, regardless of the file's rate?