# Do you think S/PDIF is an old tech?



## CDWaterloo (Jul 18, 2008)

I am going to record with an AD/DA device direct into my computer. I think using the spdif output of my effects processor is a good idea since it does not need to convert digital to audio. but some of my friends told me it is an old technology and does not worth buying a long spdif cable, instead I should use the regular instrument input of DAW. so what do you think?


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## hollowbody (Jan 15, 2008)

There's nothing wrong with SPDIF at all. It all depends on which D/A converter is better. If the D/A in your effects processor is superior to the one in your DAW, then yes, let it do the converting and send an analogue signal to your DAW. If your DAW has the better converter, then by all means, send it a digital signal and let it process.

FWIW - higher bit depth and wavelength don't necessarily mean a better D/A. There are lots of crappy 24bit/192khz converters. You just have to A/B them and see which you prefer.


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## Pneumonic (Feb 14, 2008)

Not sure if this is helpful wrt your question but I come from the audio world and SPDIF, as well as AES/EBU protocols, is a topic near and dear to the heart of myself and most any of my audiophile friends.

SPDIF/AES/EBU are all horrendously designed interfaces for use with the transmission of digital signals. The reason being, these interfaces combines the clock and audio coding onto the same signal forcing the receiver in question to recover the clock from this signal as well as extract the audio data. 

Now this function turns out to be a non-trivial task and one that, despite the best intentions of engineers to react in an attempt to correct inherent design flaws with these interfaces, always leaves the recovered clock contaminated with signal correlated jitter artifacts. Yes, even with re-clockers that employ ASRC. and PLL. It is well known fact that jitter degrades sound quality considerably so adding jitter due to interface connections is an unwanted outcome if sound quality is important. 

Ideally, the best thing is to avoid SPDIF/AES/EBU altogether when dealing with any audio transmission that involves clock recovery. Unfortunately, these protocols are still in rampant use today so it's tough to find capable alternatives. But there are alternatives. 

One much alternative is firewire of which more products are becoming available. Better yet is TCPIP (ie Ethernet) but the audio/recording industry has been dragging their feet on this one. BTW, USB is also a poor interface for digital audio transmission.


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## Guest (Aug 23, 2009)

Pnuemonic: a very informative post. I always though SPDIF was asynchronous, being that it was one wire. Or handshake driven at least. Very interesting read.


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## CDWaterloo (Jul 18, 2008)

Thanks for the info. I've heard the same thing about spdif from my friends as well. So the best thing for right now is to buy an audio interface with a firewire output. Can you recommend a specific recording interface? What about PreSonus Firebox or TC Electronic Konnekt 6?


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## Pneumonic (Feb 14, 2008)

Your welcome fellas.

One other point I'd like to make is that when it comes to DAC's and ADC's (A/D/A converters) there are only a handful of manufacturers (AKM, Burr-Brown, Analog Devices, Wolfson, Crystal, and maybe a couple more) that make the key chipsets inside the A/D/A units. While some people believe there are sonic differences in these different chipsets most people believe that what sets one A/D/A apart from the other is the quality of the power supply, the quality of the analogue output stage and the accuracy of the clock circuitry. IOW, the name of the A/D/A in use is pretty much irrelevant in terms of sound quality. 

CDW, I would go firewire if at all possible. If only to improve the latency of the unit in question (versus USB). Any jitter benefit is added bonus. 

I really don't have any specific recommendations other than to say that I own a Metric Halo ULN-2 unit which I use as a standalone DAC in my main home audio system (I have yet to record with it) and it's an excellent sounding unit. It's MAC based however and quite costly but, relative to other ultra expensive audiophile DAC's, it's a huge bargain. For firewire units under $400 I'd grab the one with the most neutral sounding mic input circuitry and I'd be most interested in ensuring that it does native (not upsampled) 24/96 recording/playback.


- Kerry


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