5.1 post production - Subwoofer routing and bass management tips

Nuendo
1

I’m a composer and musician, and I have some fairly serious 5.1 sound design projects coming up. I have a lot of experience in film sound, but mostly working in stereo.

I’m considering upgrading my current 2× Neumann KH310 setup to a 5.1 system consisting of:

  • 3× KH310 (LCR, non-DSP)

  • 2× KH120 II (Ls/Rs)

  • 1× KH750 DSP subwoofer

My room is well treated and fully sound-isolated.

For music production, my plan would be to route the left and right channels through the subwoofer. However, for post-production work, I would want the subwoofer to run on a dedicated LFE channel—and this is where I’m unsure.

I’m wondering if it would make sense to connect the subwoofer on its own channel and then use a monitoring preset (in Control Room) to integrate it when mixing music. My concern is whether this approach could lead to inaccurate monitoring or unreliable translation.

The alternative would be to mix music in stereo without the subwoofer and only use the sub for post-production work which is what I’m leaning towards right now.

Does anyone have experience with this kind of setup or any recommendations?

Thanks!

2

Hi, do I understand correctly your description:

Main idea - sub is always an extension for speakers AND is lfe at the same time

Alternative - sub is either an extension for speakers in stereo, OR just lfe itself

?

3

I don’t really see why you wouldn’t be able to do decent bass management in software. Just check the bass manager plugin for what the crossover filters are doing and compare to what the sub’s built-in processing does.

I think you’re basically going to have similar problems no matter what you do, i.e. room placement, adjustment for distance, possibly phase, level and so on. Doesn’t matter much if you’re tweaking that in software or hardware.

Like PMB wrote, I guess the question is if you’re considering using the sub for LFE and for bass management as well - at the same time. I think that it potentially puts some additional stress on the sub in addition to making setting it up a bit more cumbersome since the LFE channel has a level offset and bass management “doesn’t”. It can be done though.

Personally, if I was setting up a new room, I’d do bass management in hardware, or at least outside of my DAWs. That way I get full range regardless of if I’m currently in Pro Tools or Nuendo or just listening to Spotify. And then I’d treat LFE separately. And I’d most likely just get an interface that can get it done since that way it’s also controllable (on/off) in the interface.

4

Hi there!

That is a nice set of speakers!
I believe if you want the subwoofer for music (meaning, your speakers don’t go as low as youd’ like), you probably want it for post too. I know the KH310 can be considered full range without a sub for all practical purposes, but the 120 dosn. Plus using a sub has a very clear advantage in that you can put it wherever the bass is best, which rarely coincides with the best position for your speakers, specially when you have five of them. So if I were you I’d just set it up in a way you can use it for everything.

Now, yes, the Sub needs its own channel so it can be used for the LFE. But If you are going to use the same sub for both LFE and bass management, then it also needs to be fed signals from all your other channels so it can manage bass. For that you are going to need something to take care of routing and processing (crossovers, phase control, possibly delays). I agree with Mattias that you should avoid doing that inside your DAW, for the reasons he specified.

Fortunately there are many alternatives for that. I for one use a combination of RME Totalmix FX and Dirac Live and it works wonderfully.

Totalmix FX takes care of the routing (sending from all 6 channels to both of my subs, with the right levels, with different specs for BM and LFE, and handling the crossovers) and Dirac takes care of frequency and phase correction. I tried Dirac’s Bass Control which can deal with everything at once, but it introduces HUGE amounts of group delay in the bass, so it is unusable. But I find their basic correction very good.

If you have the newer RMEs (UFXII and III, UCXII, 802fs, etc.) you can even ditch Dirac, cause they come with a 9 band eq per output and they can manage delay, which mine (UFX I) doesn’t. I can’t recommend RME enough.

Once you have the processor, a good measurement microfone, a piece of free software called REW and reasonable treatment, integrating the subs is a simple matter of finding the optimal position (there’s plenty on this in Gearspace), setting the levels right so it works a natural extension of your speakes for a full range response, and not a bass boost (of course makee your own “house curve” as you like it.) and adjusting phase and crossover points for each speaker.
Measure in every step of the way and with a little bit of trial and error you’ll get there.

I’m sorry if I went into too basic stuff for you, but I’m not sure what is your level of familiarity with the subject. Feel free to ask any questions!

5

Thank you very much for your detailed responses. Perhaps ideally I would have two subs. One to use with bass management and one on a separate LFE channel… That will be out of my budget for now. I don’t have RME yet, but it does sound very clever.
I guess for now I’ll chose between separate lfe or bass management - unless you have other ideas? Thank you again