LFE Channel is mute even with 5.1 Surround Project

CinemaPete wrote on 2/21/2013, 6:20 PM
I presume this is the right section since it's related to audio: Has anyone had this situation: I have a project set up in Vegas Pro 12 where the properties for audio are 5.1 surround, and the LFE Filter is active (80 Hz). When I open the Mixing Console panel it shows my front, rear, center and LFE (low frequency effects) channels with their level indicators for a 5.1 setup. When I go to preview the video even though I have only stereo speakers connected to my PC and hear the audio, I can see the levels for all the channels except the LFE channel. Even with the level for the LFE channel set to max, still no output appears in the indicator. However, If I double-click on the Surround Master that appears in the audio track controls for my audio, the Surround Panner window opens and shows a front left and right, center, and rear left and right speakers - but no LFE (the sub-woofer) speaker representation. At the top right of the Panner window is "LFE" and when you mouse over it, it shows "LFE Only". If you click on LFE the previous representation of the 5 surround speakers disappears and only the LFE channel becomes active. If I preview the video and then click on the LFE at the top right of the Panner window suddenly, the LFE channel in the Surround Master panel comes alive and shows audio and I can hear what is being sent to the LFE channel. But if I then click the LFE at the top right of the Sourrond Panner window to show the 5 surround speakers, that disables the LFE channel in the Surround Master panel along with the audio going to the LFE channel. In other words, it seems that the audio for the LFE channel can only be previewed independently and not in combination with the regular 5 surround speakers. Is this normal? Has anyone had this experience?

Comments

ChristoC wrote on 2/21/2013, 7:10 PM
What you are observing is correct - in a surround project, an audio channel's panner has 2 choices = output to surround LRCLsRs only or LFE only
Vegas does not auto-generate LFE stream.
One way to generate your own LFE stream, Insert a Bus in the MIxer; set the bus Panner to 'LFE only', then use the Bus Sends as desired on each Audio Channel to send to this LFE bus; the output of this LFE stream will be band-limited according to the setting for LFE in Project Properties [ see Audio Tab | "Enable low-pass filter on LFE" | Cutoff frequency for low-pass filter (Hz)]. Remember these same frequencies will also be present in the original Channel's feed to the LRCLsRs streams Surround Master; adding a LFE send in the way I described does not create a cross-over in the original signals.
You need to be monitoring what you are doing with a properly setup system in regards to LFE channel otherwise you'll end up in a mess....
Do not mistake LFE for SUB! In film LFE is "Low Freq Effects" channel only.

CinemaPete wrote on 2/22/2013, 10:48 AM
Thank you ChristoC for your detailed reply: Prior to seeing your reply I kind of put 2 and 2 together: The behavior I was seeing was confusing me in terms of getting an LFE output that can be burned along with the rest of the front L/R, rear L/R and center channels which burned OK to my BD but was initially missing the LFE channel. What I wound up doing is to copy my audio track to a lower track and enable that track for LFE only (by enabling the "LFE Only" option in the Panning Window for the track). Once I did that, I was able to see the LFE channel play back along with the rest of the 5 channels and I could hear the LFE channel in the mix. I did set the LFE Filter to 80 Hz so anything below that on my two stereo channels would be sent to the LFE channel. I then burned a test BD and played it back on my 5.1 system and it seems to work perfectly. What I will need to do is try the procedure you described which is new to me since this is my first 5.1 project. You mention that in "film" LFE is "Low Frequency Effects" channel only and I suspected that initially. However, in terms of getting non-film audio (where there are no actual "low frequency effects") below 80 Hz to the LFE channel out to the system it goes to the Sub-Woofer in a 5.1 surround, correct? Is there any difference between the process you described to me to send audio to the LFE channel and what I did? I mean is there a preference or a situation where I would not, or should not, do what I did? Thanks again.
musicvid10 wrote on 2/23/2013, 7:43 AM
Using LFE is usually not necessary, and I get the impression most people don't bother any more.

Pay close attention to what Christo said; we've already got thundering program bass using modern subwoofer technology. LFE is for special effects independent of program audio, and merely sending that to LFE is a waste and will muddy the bass in many cases.
CinemaPete wrote on 2/26/2013, 4:22 PM
Thanks for the input musicvid, will keep all the input I've received in mind !