Some useful research on EX1 audio to share.

craftech wrote on 3/16/2009, 12:39 PM

After running into some audio input problems with my EX1 I looked all over the internet for some useful tips. I wanted to share the summary of what I found:

You can't use most field mixers with the Line Input. The expected levels don't match. Use the Mic Input and set it to external. Then you have to watch out for your settings due to the limiters and adjust the Trim in the menu depending upon what you are recording. Here are the most useful quotes I found:

I have conducted extensive testing of a variety of video cameras and the EX1 is the only one that rivals dedicated studio hardware recording equipment, both on frequency response and signal-to-noise ratio.

.......and then there was this one:

I’ve done some recording out in the field with the PMW-EX1 and have made some observations about the gain staging setup used internal to the camera and how to set the attenuators to achieve the best dynamic range out of the camera.

Hope this helps.

John

Comments

farss wrote on 3/16/2009, 2:47 PM

Thanks for the research John.

I'm not 100% convinced that there's not something more complex with the EX going on. Based on both sample files other have sent to me and my own experience there seems to be a frequency dependant effect going on as well and I have no explaination for it.

Low frequency sounds at low levels can be clipped whilst mid frequencies remain pristine. I've had this happen to me. The 32' stop on a pipe organ would cause bad clipping and sound quite distorted, a bar or two later with the orchestra and organ going full tilt no problem. Even shooting close ups of the organist right under the pipes with a SPL high enough to make me feel quite drunk the recording was pristine.

I've had plans in the back of my head for a long time to do some detailed tests using a tone generator however I don't really need to deal with the problem for my own benefit as I almost always record double head at 24bits and use the EX audio only for sync. I had hoped someone else would do some detailed testing but maybe it's time for me to step up to the plate. I initialy had high hopes for the XDCAM EX codec as it uses PCM audio. It would be good if these issues were well and truly nailed down as we should be able to get very good quality audio out of the EX.

I do agree with what's said above, the issues seem to have something to do with analogue limiting, the low frequency clipping I noted does not look like digital clipping which is why initialy I didn't see it on the waveforms.

Bob.

craftech wrote on 3/16/2009, 3:05 PM

Bob,

Two different people (quoted above) have come to the conclusion that a setting of "5" on the level setting wheels should not be exceeded. That is irrespective of the Trim settings in the menu. Have you followed that rule? I read somewhere that a setting of "5" equals a setting of 0 dB.

John

farss wrote on 3/16/2009, 3:23 PM

I haven't followed that rule so far as I haven't had any need to!
Having said that it does sound like good advice and I've not read anyone question it so my advice would be to stick with it.

Reason I and probably others initially would have been wary of leaving a lot of headroom is if you do that with HDV's mpeg audio you can get muddy and artifacted quieter passages so the general rule of thumb with HDV cameras is to record as hot as possible. With the XDCAM codec this should not be an issue at all so I need to adjust my thinking. Of course with the EX I spend most of my time thinking "Is this in focus??" and leave the Edirol in set and forget mode.

Bob.

Serena wrote on 3/17/2009, 11:52 PM

My initial thought was that there may be use for my old Beachtek passive attenuator (modified for xlr outputs) but this seems doubtful. I think I might default to a mixer and always have the edirol in the audio recording loop. That can be monitored.

Serena wrote on 3/18/2009, 12:13 AM

I see that Basspig has tested again with upgraded firmware and is much happier with the audio http://dvxuser.com/V6/showthread.php?t=162666Basspig latest[/link]

farss wrote on 3/18/2009, 12:40 AM

His results are more in line with my experience since my firmware was upgraded. Feeding +8dBm with pot at 10, input switched to line I could not get it to clip, obviously the limiters are doing their job.

I don't know if I'm so thrilled by the crosstalk performance and I also noted that when I was feeding tone into one channel and using the other channel to record notes on what I was doing. It wouldn't be a problem with feeding a stereo signal however with dual mono you might need to be careful.

Bob.