Anyone used the built-in optical SPDIF on a Mac?

goldtop

I just noticed that my old I7 iMac has built-in optical SPDIF! Hidden in the 3.5mm sockets. Seems a lot of Macs do, and using this weird little 3.5mm-to-TOSlink cable - https://www.ebay.co.uk/itm/Black-Audio-Cable-Toslink-Plug-To-Mini-Toslink-Optical-3-5mm-Jack-1M-DSURASK/153415671944 - you can hook them up to other optical stuff.

Who knew!? Has anyone here tried it to see if it plays well with other optical SPDIF stuff? 44.1kHz/16-bit? Wondering how low the latency might be with Apple's own low-level OS coding for it.

goldtop

Bumping this for any advice on those TOSlink inputs, but also because I've been experimenting, and...

I've got to say that the quality of the Mac's built-in analogue inputs and outputs is not at all shabby for Garageband-level songwriting. I dusted off an unused analogue mixer from The Big Cupboard of Stuff and just plugged it directly into this old (2008) iMac's audio sockets, using some cheapo 3.5mm stereo adaptors.

I'd expected to hear distracting levels of noise, or to pay a significant penalty with latency, but not to my ear. Pleasantly surprised, as my current point-of-reference is a Fireface UFX.

octatonic

I haven't but I've used the s/pdif output on the cheesegrater Mac Pro quite a lot.

Latency was 'ok but not great'- I forget exactly what, I suspect around 8-10ms.

goldtop

Thanks. I'm not sure whether to trust Logic's latency reporting, but I might give the TOSlink a go if I can hook something up.

octatonic

goldtop said:

Thanks. I'm not sure whether to trust Logic's latency reporting, but I might give the TOSlink a go if I can hook something up.

Logic is fairly accurate.
There is a way you can verify.

1. Use an IO plugin on a hardware insert and 'ping' it which will give you latency in samples.
2. Set up a send to an output that is recorded back in on an input and then manually drag by samples so they line back up, counting the sample displacement.

It is crazy that in Pro Tools option 2 is the only way to work out hardware latency. In 2019.

octatonic

oh and when you get latency in samples, divide the sample rate by that and multiply by 1000 to get the latency in ms.