Earlier this week - we ran a series of tests for a specific project that would be using the DIVA 5 audio recorder with multiple cameras, all needing to have matching TC.
Previously, in our build 15 tests, we found an sync offset so we were anxious to re-test. Here's some notes from our test - I'll break it up over a few posts.
Also, Deanan had sent us prototype 16G CF cards for the Offhollywood team to try to break (we couldn't - and yes, we hammered hard) - so, we thought we would throw that into the mix and shoot takes 9 minutes + with head and tail slates 4K RC36 2:1 + 16x9 to CF.
First, the DIVA, DB and audio cables:
Never worked with the Diva. I called up one of our favorite sound department guys - Brian Miklas - and asked him to come over and play.
Peter Schneider co-owner of Gotham Sound was kind enough to make a "house call" and bring the Diva 5 over and give us all a "Diva for Dummies". If you don't know Gotham Sound, you should. They are the best of the best - the sell and rent gear and provide support to the A-List and Indies alike.
One thing we discovered back when audio appeared on the Red - was that RED's line level input was based on a the philosophy that "line" is voltage based and 0dB Tone is 0.775V RMS - this is the "line is line" philosophy.
The problem with that is, the voltage output of various mixers is going to be slightly different - and folks that send line to HD cameras are just use to sending -20bd tone - check the level on the camera, ADJUST THE LINE LEVEL ON THE CAMERA to match - and go. On the RED, you can't adjust line level input.
We also discovered in earlier tests, when you send a -20db tone to Line on the RED it over-modulates. The cables sent by RED were padded -4db - but our tests indicated what was needed to "nail" -20db tone in - so that it was -20db when extracted - was in fact much closer to -10db.
i am not an audio expert by any means (be nice fellow experts!) - but I know I would rather be UNDER than OVER - and in the real world of field recording - working with only a -4db pad on the Red means you stand a very good chance of over-modulating.
We had Gotham make us -10db pads which we have using on almost all of our shoots.
Now, the funny thing here is - ZAXCOM (makers of the DIVA) have the same exact thinking as RED. The LINE output of the Diva, is in fact, -10db compared to typical recording devices.
So, the first thing we did, was send -20db tone to the RED with NON-PADDED cables. And, as expected, dead on.