KillerDac > General Information
feeding I2S from a computer into a KillerDAC
rab:
Hi all, last week i bought an EXAU2I USB to I2S interface board to play with. This board does galvanic isolation and includes a FIFO reclocker for jitter reduction.
So the first thing I discovered before hooking it up is that it always outputs 32-bit data, even when sending 16-bit data (i.e., the data word is followed by a padding word of all zeros). There was some discussion on the diyaudio forum in 2011 about whether this would be a showstopper for the TDA1541A, with the conclusion that it "should work". However, as far as I can tell, nobody has actually tried it until now.
Much to my relief, it works. At present, I am using a late 2009 mac mini with SSD and 8GB RAM, serving audio from a NAS. As far as software is concerned, my initial testing has been limited to squeezeplay and VLC, but i have now installed a trial version of Audirvana Plus and i may also trial Amarra.
OK, so that's the background; here's my question.
In a recent telephone discussion with zenelectro, he mentioned that although the TDA1541A is limited to 16-bit data, it should in theory work with clock rates up to 4 x 44.1 kHz = 176.4 kHz in NOS mode, because it was designed to support 4x oversampling.
In a fit of blind optimism, I generated a 16-bit 88.2kHz audio file and tried to play it with my killerdac. No sound.
Now i confess up front that i have not looked at all into whether this is expected behaviour and/or what would be required to play higher sampling rates, but my guess is that the clock driving the DAC chip in the killerdac is probably fixed at 44.1kHz and some switching logic will be required to reduce the division of the (crystal) clock frequency by a factor of 2 or 4, as appropriate.
Does anyone know the answer?
- richard
kajak12:
Ask zenelectro
enjoy your journey
zenelectro:
--- Quote from: rab on August 21, 2013, 10:10:09 PM ---Hi all, last week i bought an EXAU2I USB to I2S interface board to play with. This board does galvanic isolation and includes a FIFO reclocker for jitter reduction.
So the first thing I discovered before hooking it up is that it always outputs 32-bit data, even when sending 16-bit data (i.e., the data word is followed by a padding word of all zeros). There was some discussion on the diyaudio forum in 2011 about whether this would be a showstopper for the TDA1541A, with the conclusion that it "should work". However, as far as I can tell, nobody has actually tried it until now.
Much to my relief, it works. At present, I am using a late 2009 mac mini with SSD and 8GB RAM, serving audio from a NAS. As far as software is concerned, my initial testing has been limited to squeezeplay and VLC, but i have now installed a trial version of Audirvana Plus and i may also trial Amarra.
OK, so that's the background; here's my question.
In a recent telephone discussion with zenelectro, he mentioned that although the TDA1541A is limited to 16-bit data, it should in theory work with clock rates up to 4 x 44.1 kHz = 176.4 kHz in NOS mode, because it was designed to support 4x oversampling.
In a fit of blind optimism, I generated a 16-bit 88.2kHz audio file and tried to play it with my killerdac. No sound.
Now i confess up front that i have not looked at all into whether this is expected behaviour and/or what would be required to play higher sampling rates, but my guess is that the clock driving the DAC chip in the killerdac is probably fixed at 44.1kHz and some switching logic will be required to reduce the division of the (crystal) clock frequency by a factor of 2 or 4, as appropriate.
Does anyone know the answer?
- richard
--- End quote ---
Hi Richard,
There are a few possibilities but I think you should get someone to check the integrity of the 88.2k I2S signal.
There are certain timing requirements for I2S and there are also a few different I2S flavours.
I'll check the exa website for some info on their product tomorrow.
cheers
Terry
stevenvalve:
I have tried many different transports, including Computer audio, now I am listening to the digital out of a DVD player straight into the DAC, all my music DVD video's work with the DAC. But what is the sampling rate of these DVD,s.
rab:
--- Quote from: stevenvalve on August 22, 2013, 06:35:22 PM ---all my music DVD video's work with the DAC. But what is the sampling rate of these DVD,s.
--- End quote ---
I would think that depends on how the DVD player is configured... it might be setup to output 16/44.1 on S/PDIF. Also, remember i am using I2S, not S/PDIF.
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