There’s A Fiber Optic Connection Built Into Every Mac

Posted on by Larry

[ This article was first published in the April, 2010, issue of
Larry’s Final Cut Studio Newsletter. Click here to subscribe. ]


Did you know there’s a fiber optic connnection built into every Mac?

Nope, I didn’t either. I didn’t discover it until we started our technical preparation for NAB this year.. It’s called TOSlink.

TOSlink is a fiber optic connection.
(Image courtesy of Hustvedt.)

According to Wikipedia, “TOSLINK or Optical Cable is a standardized optical fiber connection system. Its most common use is in consumer audio equipment (via a “digital optical” socket), where it carries a digital audio stream between components such as MiniDisc and CD players and DAT recorders.”

TOSlink was originally created by Toshiba to connect their CD players. Basically, it transmits digital signals between devices using fiber optic cables. And, as you can see below, it uses a square plug to connect to the gear.

TOSlink connector.

NOTE: S/PDIF optical and TOSlink are two words that mean the same thing.

I learned about this in talking with Wayne La Farr, product specialist for Aphex. We were setting up the studio gear for our NAB coverage and I was planning on outputting the final signal as analog from the 320D Compellor into the streaming server. Wayne suggested I use a digital signal.

However, as I was streaming from an Intel iMac, I didn’t think I had S/PDIF optical connections. At this point, Wayne told me that I was wrong – they were just hidden.

Because we would be running cables in a high traffic area, we decided to use AES copper cable — it looks like standard XLR mic cable, but manufactured to higher standards — from the audio rack to the streaming server. This was a distance of about 20 feet. Then, we would convert the AES signals to TOSlink and connect them into the back of the iMac.

HOSA AES/EBU to TOSlink converter.

The conversion is done using the Hosa S/PDIF Optical to AES/EBU Digital Audio Interface. That converts the digital signals carried over copper wire to digital signals carried over fibre.

We added a short length of fiber optic cable to go from the Hosa to the back of the Mac. This created a fully-digital signal path from final signal processing in the Compellor to broadcast — IF we could get it into the Mac.

And here is where the magic occurred.

Adapters that allow fiber optic signals into a Mac.

The Microphone In and Headset Out ports of ALL Macs support BOTH optical and copper signals (digital and analog). If you plug in standard audio plugs, the ports become analog. However, there’s a special TOSlink adapter that turns a standard 1/8-inch miniplug into a hollow tube that light shines through. Plug this into ANY Mac and the port switches from analog to digital.

Poof! Audio quality into your Mac as high as 24-bit, 96 kHz!

Very cool.

The only problem I had was that the system worked great during our initial setup in the office. But once we got to NAB, it kept dropping the signal. We would start recording and in less than 45 seconds, the signal would drop out.

Whether this was due to a bad power supply, bad mini-plug converter, or bad Hosa unit, we did not have the time to diagnose. We instantly dropped back into analog so that we wouldn’t miss deadlines.

However, this technology has the potential to be very cool and worth exploring. If I have a similar opportunity, I’ll buy the gear with a money-back guarantee a couple weeks before I need it to be sure everything is working properly.

Because when it was working, it sounded GREAT! I just wish we could have figured out how to get it to work more reliably.

 


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13 Responses to There’s A Fiber Optic Connection Built Into Every Mac

  1. Andrew says:

    Hi Larry,
    I found your article about the Mac’s Fiber Optic connection whilst searching for the best way to transfer recordings from my Minidisc to my Mac.

    I have:
    – the Minidisc player
    – the recordings on the discs
    – the fiber optic cable
    – a Mac with the optic jack

    The Minidiscs are the old original variety – they can’t be loaded and viewed on the Mac as files – it’s a real time transfer process.

    Using Garageband I have successfully recorded the Minidisc content to my Mac via the Fiber optic cable

    What I’m wondering is – by using the fiber optic cable, I am actually recording with any greater quality than if I were to use analog cables….?

    • Christopher Morley says:

      Hi Andrew –

      I have just found your comment of December 9 2012 to Larry. I too have been transferring Minidiscs in in the same way, using Garageband.

      Since the content of a minidisc is always digital, to transfer in the digital domain to the Mac should always be preferable, in order to avoid D/A and then A/D conversion. There is a snag, however!

      All my minidiscs are from radio broadcasts; some are from FM (analog) and the others from DAB (digital). Those from FM will transfer via optic cable – but those from DAB are not recognized by the Mac and will therefore not transfer digitally. This seems to be a consequence of the “Serial Copy Management System”, which is incorporated into minidisc recorders to prevent digital re-recording of copyrighted digital material (e.g. CD’s). Non-copyrighted sources such as DAB seem to have got caught up in this.

      Any ideas on how to get around this would be most welcome…in the meantime I could transfer via the analog line-out from my minidisc player, but would rather not do so in case there is a solution.

  2. Brian says:

    Hi Larry,
    So, do you know what the digital audio output Spec is?
    is it possible to output 4 discrete channels of audio? I’d like to use the optical out in conjunction with Ableton Live and an Edirol FA-66 audio interface that has an optical in (in the shape of a toslink connector).
    thanks for your insight.
    Brian

  3. tobto says:

    hi –
    thanks for useful info! I like to connect my TC Konnekt24D optical out to iMac via TOSLink. iMac sees the signal but I can”t hear it. No signal in Garageband, no in Logic. What I missed?

    Thank you!

    • Larry says:

      Tobto:

      You’ll also need to change your System Preferences > Audio settings to Digital In. The sad news is that Apple is moving away from TOSlink on their newer gear. When I asked them, they told me that “most professionals” preferred USB-connected devices.

      Larry

  4. H Munster says:

    I still use my minidisc recorder to make stereo archives of garageband and logic projects. An easy quick way to do a mix down and listen to on my stereo. Plus minidiscs are just too cool. It works great, sometimes have some clock sync issues which require a reconnect in audio settings.

  5. Dave says:

    Hi Larry
    wonder if you can help me i am recording my old vinyl records from a mixer to my pc i was using a rca to usb converter, But i now have a new mixer djm900 which has a rca digital output and have a iMac, but no optical connector .
    what type of lead do i require
    regards Dave

    • Larry says:

      Dave:

      Apple discontinued optical connecters a few years ago. Sigh…

      So, now, you’d need a converter from your mixer to USB. Given how prevalent USB is in the audio industry, the manufacturer of your mixer may have one already.

      Larry

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