Expensive but very cool cable for monitoring audio.

Vimeo member Dennis O’Clair produced a fun video showing how you can monitor audio straight from your T2i 550D while you record using a cable he helped developed called the Sescom DSLR-550D-HOCF.

I thought that was pretty cool you could actually monitor what you are recording in realtime with your DSLR since this was not even possible until Magic Lantern came out a few months ago for the T2i. Actually, I am not sure why I am so excited since my camcorder has been able to do this for years, but since Canon didn’t design this to be a video camera, hey I guess it is pretty cool!

You can create this cable yourself if you like but it can become a mess of cords and since several cables are in the mix you have more points of failure so this is an elegant solution for people like myself.

You might be saying to yourself, “Hey Dave that is cool, but why not skip this and just use a Zoom H4n?” My answer is I am very lazy in post, I hate adding additional steps to the post production process if I don’t have to, and importing more files and sync them is just a time sink I would rather skip if it is a project I can do so.

At close to $40 it’s definitely on the pricey side, but Dennis tells us why:

The cable is expensive to manufacture because the USB mini AV out cable is a unique Canon cable. Sescom uses original Canon cables in the manufacturing process. Unfortunately, at this time there are no other supplier of the USB mini connector.

My first question is where in the audio chain are we monitoring? Is it just before it hits A/D converter or is it even better and after the recording and it coming off some sort of virtual “playback head”. I seriously doubt the later.

I was rather disappointed that when I played back a recording that I could no longer hear the audio anymore out of the headphones. I’m sure this is no fault of the cable but more of a function of the firmware itself.


In order to make this work you will need the following:

Within Magic Lantern – Under the ‘Audio’ menu:

  • Turn AGC off (optional)
  • Input to “external stereo”
  • Loopback to “On”
  • Raise the Output volume as desired
  • Monitoring-USB to “On”
  • Put the USB cable in ***AFTER*** you make these changes to the audio menu and you have the camera ON (if you plug in the USB before you turn it on the LCD screen will not turn on.

Headphone Recommendations

Since the volume to the headphones is pretty low you will want to get low impedance headphones that are mostly closed and not open air type.

Audio Technica ATH-M50.  Impedance: 38 Ohms  $159

Sony MDR-7506.  Impedance: 63 Ohms  $99

Sennheiser HD280 Pro.  Impedance: 64 Ohms  $99


The build quality on this cable looks excellent just like their AGC hack cable I reviewed last year. Overall I really like this cable, just wish I could hear on playback.

Two see products used in this video check out my gear page.


  • Was just thinking today about how nice it would be to have headphone monitoring. Now I know what I’m buying next time I get paid, thanks for the tip!

  • Hey Dave,

    Great info-thanks. Can you can you clarify something. If this really a solve for the monitoring issue? You said you listened on the little speaker. What did that mean? Also, not one to assume so I thought I’d ask, will it work with my Canon 60d?


  • @Mike the little speaker I am referring to is the one on the camera body. I don’t think Magic Lantern works on the 60d from what I know.

  • Dave, first off, thanks for the great work! I’ve had my T2i for a couple weeks now, and been playing with Magic Lantern on there. Last night I discovered, by accident actually, that you CAN monitor playback through headphones instead of the small camera speaker.

    I had the same settings you specified above (Loopback on, USB monitoring on, Output volume at 0db), but instead of the Sescom cable, I just used an RCA female to mini jack stereo female adapter that I had sitting around.

    It’s the same as this item here .

    I just plugged the supplied canon A/V cable into this adapter, and then my headphones right into it, and I was able to monitor in LiveView, recording, and playback.

    Don’t know if it’s the cable or some other setting I used by accident. I’m using the 3/22/11 version of ML, don’t know if that makes a difference either.

  • I’m sure it is not the cable. It seems every different ML build has different features, menu settings, etc. I’m going to update to the newer version like Chris has.

  • @Renier
    The canon cable has extra pins that are not in those headphone usb cables or normal usb cables

  • Hi Dave! Just curious, can you describe what lens and lighting you used for your b-roll of the guy from Free Rental Site? Looks really nice.

  • @Doug:

    No your not alone, I’m missing that feature as well.


    In the video it loos like you’re hearing the sound that your rode mic is giving to the T2i, don’t you?

    Because I just can’t get it to work that way. I made my own sescom-cable and followed your instructions (except for the loopback setting which I’m missing right now), but I am not able to monitor the sound that my rode is giving the cam. It’s either the sound from the internal mic that I’m able to monitor (even though I set ML to “external stereo”), or I’m hearing nothing. But when I’m hearing nothing the rode is giving me sound, according to the audio meters… it’s just not going to my headphone somehow. I assume it’s a ML bug in the release that I’m using.

    Which ML-version are you using Dave? Have you some kind of a workaround for that problem, or is it totally new to you?

    Has somebody else experienced this issue?

    I’d appreciate some help from u guys, thanks in advance.

  • @Sven I am using magiclantern-2011Mar10.550d.fw109.AudioMon.gui-tweaks.alex. I am going to upgrade soon so I will see what happens to the menus.

  • @Dave:

    Thank you very much, I just tried the ML-vesion your using and it works just fine. I was using the latest build before, it seems that this problem is a bug…

  • Dave, Does this cable eliminate the noise for the auto feature of the t21? I purchased the cables that you showed, but this one would be more attractive. Please advise

  • Hi Dave,

    I’m just starting to get set up w/
    audio monitoring on the T2i w/ the
    latest ML. I ordered the Sescom cable.
    IYO, which set of headphones would you go
    with from the ones you mentioned above,
    the Audio Technica, Sony, or Sennheiser?



  • Are there any I.strutting available how to update the magic lantern firmware…? Mine has a lit of freezes when looking back through photos or videos which I made on the t2i body itself….is this normal?

  • Hey, I don’t think telling you this on your post Monitor Realtime T2i 550D Audio While You Record is the right place but I couldn’t find a contact form in your somewhat cluttered theme (sorry). My readers used to tell me the same so I switched over to a new theme, you should check it out on this website. I’ve only gotten compliments ever since. Regards, Skola gitare

  • @Dave, does Chris’ way work? I don’t really want to buy the cable, if it doesn’t work.
    If you haven’t tried, then no big deal, but if you have it’d help me to know.

    PS if i buy a rode mic, I’ll probably buy it from B&H to support you!

  • Hey Dave, I was wondering how the comments worked on your site. Do I have to check back to the site on the exact page to see your reply, or do you email me or something?

    Thanks again for all the videos, they really helped me, and will continue to. 😀