Jump to content

Arri Alexa audio


Philip Perkins

Recommended Posts

We ran some tests on the newly-enabled audio recording aspect of the Arri Alexa today.  I'm happy to report that they did a MUCH better job on sound than RED did.  The Alexa allows a pretty wide range of trimming of the each channel of input levels (separately), using the whole height of the display in that mode.  (I was able to trim up a -10 input to nominal level, for instance.)  The audio output is similarly precise to set (or can be switched to a fixed level mode).  When you go back to the "home screen" there is a small audio meter above the TC display--good for a confidence check.  The audio plays out the TRS mini jack in E- to E and record--the sound was good but the level isn't tremendous--low in fact even when turned all the way up.  The audio (in record and e- to e) also plays out the HDSDI output, and puts little level meters on the screen (but off the image, one in each corner of the monitor).  With this firmware the picture will playback on the camera....without audio.  We listened to a comparison of the same audio recorded on my 744 from the same mixer through my studio monitors--I felt like the camera audio was a little thinner and lacking in midrange detail, but certainly as good as what I recall high-end Sony and Pana cameras sounding like, and quieter than lesser cameras like EX, HVX-200 etc.  The audio connector (5 pin female) is in an odd place by the lens at the front of the camera--Chater Camera in Berkeley (where I tested) was thinking of building an extension cable that brought the audio inputs and output to the rear of the camera.  We haven't decided if a Neutrik-type right angle 5 pin would be better or more in the way than a Switchcraft A5M there (but fortunately 5 pin xlrs are pretty easy to solder).

phil p

Link to comment
Share on other sites

Here's a basic audio input cable for the Alexa I made for a friend who has the Alexa with the audio revision. The included directions are somewhat tongue in cheek as he's not very audio savy. I'm planning to get with him later this week and check out the camera for audio. My next venture will be to bring the audio in/outs to a Sound Devices multipin connector that would attach to an SD multipin input.

post-21-130815093756_thumb.jpg

Link to comment
Share on other sites

So far the camera folks sort of want a cable that remotes the A3Fs away from the front of the camera, along with the audio output/return.  I made one like that pictured above but they weren't happy with all those XLRS banging around the front of the camera.

I agree that the best solution is a custom fan for the end of a multipin snake.

phil p

Link to comment
Share on other sites

So far the camera folks sort of want a cable that remotes the A3Fs away from the front of the camera, along with the audio output/return.  I made one like that pictured above but they weren't happy with all those XLRS banging around the front of the camera.

I agree that the best solution is a custom fan for the end of a multipin snake.

phil p

The cable assembly in the picture is 20" long end to end so the input XLR's will hang about 18" down from the body. How much of an issue is the line level only inputs be for wireless hops and where could the receivers be comfortably placed?

Eric

Link to comment
Share on other sites

Nice diagram.  Since I've noted in the past that you are normally a grammatically-aware and syntax-aware person, I hasten to point out that "carry's" means "carry is" when what you no doubt intended is "carries." <g>

John B., CAS

Yeah I know it's wrong and it's caused me many sleepless nights ;-)). Mia Culpa.

Eric

Link to comment
Share on other sites

Go's worrying as well as Carry about her signals and Eric's sleeplessness?

Worry not though there's a society dedicated to helping us -

http://www.apostrophe.org.uk/

http://www.apostrophe.org.uk/examples_1.htm

Thank's for the link's.  Well all rest better now.  (Sorry, sometimes the rebel in me takes over.)

John B., CAS

Link to comment
Share on other sites

Is there anything special about the pin-outs of the 5 pin XLR?  I have a couple 5 pin connectors that I use for stereo mics, thou I wonder if the pin configuration might be different.  A google seach on this info didn't reveal too much of anything.

thanks,

-greg-

When I spoke to Eric recently he said it was the standard 5 pin xlr wiring

Link to comment
Share on other sites

This is what I know to be standard wiring.  Is this what the Alexa is using?

5 Pin       

pin 1 shield 

pin 2 Left channel + 

pin 3 Left channel - 

pin 4 Right channel + 

pin 5 Right channel -

That's the pinout that was confirmed in another thread.  The pieces are sitting in the "to do" section of my workbench waiting for proper motivation.

Link to comment
Share on other sites

Thanks John and Jim.  Another question.  In the video it looks like there is a green mini return to the left of the 5pin.  Is that correct?  Is that the only audio return?

Thanks,

Andy

Yes and no. AFAIK the green mini is the only audio only output. There is another output that has audio & video but uses a video connector of some kind. There's a lot of tech details on the Arri site under the Alexa tab.

Eric

Link to comment
Share on other sites

  • 4 months later...

Hello All,

I wanted to make up a few input cables for the alexa for myself, I know the pin configuration, but my question is does everyone connect their shield to their shell on each xlr.

I noticed on the assembly I was using recently that, all 3 shells were connected to the shield.

On all my xlrs for years I havent connected the shield to shell and I haven't had an issue.

I guess I should just connect shield to shell and be done with it,,,,,,,

But I would like to know on your guys alexa cables are your shields all jumped to the shells....

I just want to write shield to shell a few more times.

shield to shells

shield to shells

shield to shells

Thanks,

JEff

Link to comment
Share on other sites

" does everyone connect their shield to their shell on each xlr. "

I can safely say: NO.

I suspect most do not, and some do only on one sex, or the other!

this question has been often discussed, and never resolved completely.

I carry standard pin-1 ground lifts, and I also carry a couple of "shell lifts" (as well as isolation transformers) for circumstances when I must hook yp to someone else's cables and have a ground loop issue.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...