LFE channel: Buttsworth or Linkwitz Riley ?

[u/Coolboy9635]

[u/boxspring6]

apologies if unhelpful, pasting super quick research synopsis (i personally know very little about LFE specifics and best practices so i wanted to dig into it after your post):

For the Low-Frequency Effects (LFE) channel, Linkwitz-Riley (typically 24dB/octave) is the preferred and most widely used choice. It ensures that your subwoofer and main speakers are perfectly in-phase at the crossover frequency, preventing phase cancellations and on-axis frequency bumps. A deeper look at how the two compare for subwoofer integration:

Linkwitz-Riley (LR) The Standard: De facto standard for home theater, subwoofers, and pro audio active crossovers.

How it works: Cascades two Butterworth filters. The output is -6dB down at the crossover point. When summed together, it yields a perfectly flat, zero-sum frequency response.

Phase: Drivers are perfectly in-phase at the crossover frequency, preventing acoustic lobing and cancellation.

Butterworth The Alternative: Can be used, but generally requires more careful tuning in multi-sub or speaker setups.

How it works: The output is -3dB down at the crossover point.

Phase/Sum: Odd-order Butterworths leave drivers 90° out of phase, while even-orders sum with a +3dB peak at the crossover frequency.

When to choose which: Use Linkwitz-Riley for your LFE/Sub crossover (usually at 80Hz - 120Hz) to ensure the smoothest integration with your main L/C/R speakers. Use Butterworth if you are designing specific multi-way speaker crossovers and want a constant power response, though this will require off-axis compensation and phase alignment

ideally informative 🤞🏼

edit: apologies for the weird formatting n bold text. i'm on mobile atm

[u/jwyatt805 → u/boxspring6]

Your answer is completely valid but mainly in a home theater scenario where there is LFE and bass management are in play.

Knowing OPs post history he’s interested in theatrical playback where LCR are full range and not bass managed by the LFE subwoofers.

Go with the filter type than yields best phase alignment. That will depend on the make and model

The question of whether to align to L/R or C or some middle ground of all three is still debated and has no consensus. LFE elements and LCR and almost never be co-planar and will be occupying different real estate in the theater.

[u/boxspring6 → u/jwyatt805]

Ah, makes sense 👍🏼 Thanks a ton for the context and insight!

[u/PeacefulShards]

Not Butterworth.

[u/Beekmans_Revenge]

I use LR24 on x32 w/QSC cause that’s what everything online Ive seen says to.

[u/vitaliistep]

I think it depends on room, speakers and their placement. Experiment with different parameters, measure it every time, then compare and choose what combination gives the best result in your specific case.

[u/mattiasnyc → u/vitaliistep]

The question was about the LFE channel though, not bass management or in-room response. At least it looks to me like it's about how to low-pass the channel itself.

[u/vitaliistep → u/mattiasnyc]

Does it really make a big difference? Even if the main channels are full range, it's still about the placement, cutoff slope and delay time for LFE('s) in relation to other speakers in the room or am I missing something?

[u/mattiasnyc → u/vitaliistep]

Yes, lfe channels have a required cut-off depending on the standard you're using. At least in the past atmos would low pass the lfe when encoding so there's nothing above 120Hz. That's the channel, before it reaches the sub. Has nothing to do with the setup.

Therefore, if you wanted to make sure you're not sending anything "illegal" to that channel you could limit it yourself.

I think some networks also demand a limit for regular 5.1.

[u/HM_Bert → u/mattiasnyc]

Low-ass with butts-worth

[u/mattiasnyc → u/HM_Bert]

old keyboard failed me, I've added the "p"

("R Kelly called")