Is Tone Board Non Over Sampling/NOS DAC or no?


#1

I’m interested to know - is Khadas Tone Board Non Over Sampling/NOS DAC ?

If it isn’t, what is the internal operating frequency of Tone Board when used as DAC in HiFi system without VIM ?

Thanks


#2

Anyone, please.

Thanks in advance.


#3

I’m not an audio / DAC expert. However, by pulling up the specs for the ES9038Q2M, it does have a 7 preset oversampling filter (that can be bypassed, apparently). The Tone Board uses the ES9038Q2M, this means it’s likely not a NOS-DAC.


#4

Hi,

I found that data too and came to the same presumption as you have but i need to know for sure is the oversampling filter bypassed in Tone Board or not.

If Tone board is manufactured and engineered in Khadas, isn’t there someone who knows for sure answer to the question from thread title ?

I and many more of us would appreciate the answer that should have been included in Tone board specs from the begining.

Thanks, for answer, in advance.


#5

I’m interested to know - is Khadas Tone Board Non Over Sampling/NOS DAC ?

  • The signal coming from the XMOS is fed directly into the ES9038Q2M, and emerges unchanged as from before: Over-Sampling-Filter is bypassed on the Tone Board.

If it isn’t, what is the internal operating frequency of Tone Board when used as DAC in HiFi system without VIM ?

  • Could you clarify what you mean by this? @terry will attempt to answer your question.

#6

Other part of the question makes sense only if Tone Board was oversampling DAC (which it isn’t as you’ve established).

Thank you very much for your answer. I’m very pleased to know that Tone Board is a NOS DAC.


#7

Are you certain the oversampling is bypassed? The datasheet claims that data should be 8x upsampled externally if osf_bypass is set, although that might be more of a recommendation. Is there any oversampling done in XMOS or the driver (in exclusive mode)?

My understanding is that setting osf_bypass disables impulse response filtering (e.g. brick wall, minimum phase, apodizing) although I am not entirely clear on what the datasheet means by “sourcing data directly into to the IIR filter.” It would be great to have firmware variants that allow selecting between the different impulse response modes. There is much debate in the audio community over which filter is best, with NOS being one of the more disputed options especially at low sampling rates (although it may make sense with such a modern otherwise near-perfect DAC, I’m not an expert).

Thanks