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Creating an S/PDIF connection would save the (Hifi-wise and otherwise) wobbly conversion via USB, or via mini display port (or even via AVB over ethernet) to my high-end external DAC (coax-in only).
It seems many laptops actually do have it somewhere:
http://www.hardwaresecrets.com/everythin...
Many thanks for your ideas & rgArts
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Apple uses a custom DAC chip which does not offer S/PDIF services.
The best way to gain Hi Def audio is to use an external USB DAC like this one: AudioEngine D3
I think you're over-focusing on jitter here, we are talking about the output side of things here correct?
You talk about laptop power supply as a jitter source, it would create noise not jitter. But to be fully truthful here unless you have a very dirty AC power noise won't be an issue (hint: use a UPS or good surge suppressor).
The USB cable and the DAC won't create timing issues as there is no reference point for a timing issue. The timing is more a factor of the computers ability to process Vs the signal going across the USB cable. Yes, the signal will be delayed across the USB port and the conversion process within the DAC is that the timing you are concerned with? You can't really alter it.
In our studio I think we are using an Antelope A/D Converter (I don't remember the model) for our audio recording for presentations with a Mac Pro (the newer generation). The audio is then saved on a Thunderbolt based SSD RAID system (we also do video editing on it). Once created we play it back across a D1-24-Bit-DAC to the studios speakers.
In any case you can encounter jitter from the analog inputs going into the A/D converter and if the converter does not offer a digital optical output the signal here as it enters your system. Is that the area of your concern? The input side of the A/D conversion? Vs the D/A output side?
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Tx Dan! Besides USB-out, MBA offers mini-display port-out and AVB over ethernet-out.
Am I right in that mini-display port (=PCI express) and AVB-ethernet produce less polluted (clock- and power-wise) digital outs, than USB?
USB is much more common and thus cheaper in terms of cables and converters, but if jitter is my prime concern?
There is no jitter within a digital signal realm (USB or Ethernet). MiniDisplay is a bit different here as not all versions support digital audio (depending on the systems age). You can encounter dropouts or mis-sync if the signal is disrupted (just like your HD TV signal).
Jitter is mostly an analog issue, so the ability of the DAC to convert a given signal could be an issue. Within digital signaling the error correction of the protocols correct any jitter issues that might popup.
Can you explain what you are planning on doing here. I might be able to guide you if I fully understood what you were doing.
Thanks much for your thoughts Dan!
- As to digital jitter:
so Laptop's USB power supply, its USB cable and plug to DAC cannot cause timing differences above the audible threshold of 100 ps? Or do you mean that as long as Laptop is DAC's slave, the DAC's clock will clean it all up?
- As to audio over MiniDisplay:
thanks for checking! MBA luckily does support it since late 2010.
- As to the DAC:
That's a recent (2015) and rather high-end box (Sugden), so I hope that it would add more to the solution than the problem.
- As to my plan:
I try to ensure the shortest, and cleanest, digital audio (Hi Res) signal path from Laptop to to DAC (only: digital coax in).
Now that MBA doesn't allow for direct S/PDIF, my remaining options would be:
(1) USB,
(2) minidisplay port (PCI/ thunderbolt),
(3) AVB over ethernet.
All of these three would imply the right cable to a converter box/ interface with coax-out towards the DAC. Where USB seems ubiquitous, the other two appear more exotic and/ or expensive. What would you think is wise? knd rgArts
You talk about coax digital audio why are you going that way? I would recommend digital optical (TOSLINK) as it's a cleaner signal. Less likely to pickup noise or have a sync issue between the channels.
Coax:
Why? Just because I need to feed my digital audio into my DAC, which only has coax-in.
So at some point I am looking at a conversion (from USB/thunderbolt/AVB/HDMI-Arc) into coax.
TOSlink:
I agree that technology has its pros, but also its cons, eg: tends being capped to 24/92 where coax reaches 24/192.
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digital coax:
why? just because it's the only way into my HiFi DAC. So I need to convert the digital audio file at some point from USB, minidisplay port or hdmi into digital coax.
TOSlink:
seems to have such pros indeed but also its cons; for one, it tends to be capped to 24/92 where coax goes up to 24/192.
da Arthur