SPDIF to USB conversion question

[Mr. Swordfish]

I've asked this question a number of other places, without hearing a good answer. Hoping maybe someone here has some insight:

Older digital gear used coax/RCA to emit digital signals using the SPDIF format. (there was also AES/EBU that used XLR, but that's another discussion). That's largely been replaced with an optical implementation of SPDIF, toslink.

The thing is, to get audio into the computer, the standard is a USB connector. And it's not easy to find a coax SPDIF-to-USB converter. Anybody know why that is?

You can get an optical tos-link SPDIF to USB from HiFime for about $50. Or many many inexpensive options for USB to coax SPDIF for even less. But coax SPDIF-to-USB converters seem to be as rare as hen's teeth.

So, I'm wondering if there's a reason for this. Is it just lack of consumer demand, or is there some technical or legal reason?

I know this has previously been discussed here and here, but I've still not heard a good answer.

(BTW, I've been transferring old DAT tapes via the SPDIF output of a Tascam DA-30 using the M Track Plus that I bought years ago to convert to USB. When the Tascam stopped working about a month ago, I borrowed a more recent vintage Sony, which only had optical SPDIF and had to buy an optical SPDIF to USB, which fortunately is readily available. This re-ignited the question, which I suppose is mostly academic.)

 

[kyuu]

I'm not sure there is a good answer. Optical SPDIF just seems to have become the defacto standard over coaxial. It provides galvanic isolation and works well, so there's no real downside. Annoying if you have a device that only supports coaxial SPDIF, but that's largely legacy devices at this point.

 

[gwing]

Well, the best way to get a co-ax spdif signal into a PC is probably to have said coax connector on your PC , if necessary via a soundcard

There clearly isn't any technical reason why you can't have a coax to USB converter as there seem to be multiple coax to optical converters available which you could combine with your optical to usb converter and anyone could put the two devices together in one box.

 

[Power Pop 23]

I too would like to move some DAT's from a coaxial SPDIF output to a USB input (of a Mac mini).

Is it a fool's errand to convert the coaxial SPDIF output to an Optical SPDIF so that I can then make use of an Optical to USB converter from HiFiMe ?

 

[gwing]

Not a fools errand if it does what you want and you want to work around a Mac's limitations. Maybe worth getting a bidirectional coax/optical converter so that it's more versatile.

Or maybe a raspberry pi with a coax spdif input hat so you can connect directly without messing about with either USB or multiple transport conversions.

 

[DVDdoug]

Is it a fool's errand to convert the coaxial SPDIF output to an Optical SPDIF

That should work perfectly.

So, I'm wondering if there's a reason for this. Is it just lack of consumer demand, or is there some technical or legal reason?

I assume it's just consumer demand.

 

[Mr. Swordfish]

I too would like to move some DAT's from a coaxial SPDIF output to a USB input (of a Mac mini).

Is it a fool's errand to convert the coaxial SPDIF output to an Optical SPDIF so that I can then make use of an Optical to USB converter from HiFiMe ?

It never even occurred to me to convert coax to optical so that it could be converted to USB. It's just a stream of ones and zeroes, so it should work flawlessly. Assuming it works at all, but I would imagine it does.

 

[Vincent Kars]

There are DDC's (Digital to Digital Converters) that convert any digital audio into another: https://www.mutec-net.com/product_mc12plus.php#data

 

[lini]

M-Audio used to offer a pretty neat SPDIF converter box, the CO2. Iirc, the CO2 sports transformer-based isolation and three operation modes: Bidirectional optical <-> electrical, electrical -> optical with electrical pass-through and optical -> electrical with optical pass-through. And due to the pass-through function it can also be used as a repeater.

Greetings from Munich!

Manfred / lini

 

[phofman]

E.g. https://www.aliexpress.com/item/1005004127457820.html ?

 

[TheKoC]

Many Pro-Audiointerfaces have SPDIF digital in/out, although optical is more common then electrical, so you might need to look at "pricier" models.
The cheapest I found in a quick search on the Thoman-Website is the ESI U24XL at about 80 Euros.

 

[gwing]

I'm not to sure about flawless as it isn't a question of just passing a pure data stream between digital devices but each spdif conversion stage is going to have to extract the timing info and regenerate so jitter would build up, unless we are talking more than simple devices and pass it though a sample rate converter or something that fully regenerates the data stream.

It'll probably be good enough though

 

[phofman]

IIUC the OP wants to capture the stream to a computer, so the timing (clock jitter etc.) is not important.