Bass Management for your Home Theater
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- เผยแพร่เมื่อ 8 ก.พ. 2024
- #hometheater #audioadvice
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Last weekend I used test tones through REW to to find out what frequency my speakers seem to lose SPL and at what frequency I could locate where the bass was coming from. For example I found my rear on wall 6.5” focal speakers started rolling off around 120hz, and the other interesting thing was I could start to locate where sound/bass was coming from at 150-160hz, which is spot on to what anthony grimani said it would be. I ended up setting all my speakers to 130hz and it sounds clean during intense action scenes
Thank you Matt. Eagerly waiting for another pro insight (control room vs HT). Have fun.
There is a pro bass management one coming, as I just send the editor some feedback.
The front speakers look stunning beside the projector screen 😍
Hah, glad you like, but those aren't actually my front speakers. My front speakers are hidden behind the screen. That is a review speaker taking up temporary residence.
Finally got time to watch this, thank you as always 😁. I've still got your Transforming Subwoofers video to watch next (hopefully tomorrow) so looking forward to that 👌
Well thank you! Appreciate you watching these.
Great video. Should try high levelling(speaker level) your mains and center to dedicated subwoofers as well as having subwoofers for lfe. It allows your speakers to run full range for all of your speakers
Thanks!
Thank you
seems like dirac ART completely change the current bass Management and makes achieving your preferred method easier
Could you do a video on an ideal in-room frequency response graph? Assuming 1/6 smoothing, should the graph be flat or slightly higher in the base regions or higher in base/lower in treble, etc?
Matt, in a video Anthony made a point of how bose used their acoustimas system that was convincing to many people with a very high high crossover because it was actually more difficult to recognize the point of bass production than people believe. THX wanted a 80hz cross over because of "detectability" when only one subwoofer was the common set up. Now that we use multiple subwoofers do you think that 4 corner sealed subs could be crossed over much higher (150hz +) with low detectability?
I am also curious to get your take on Erin's Audio Corner recent discussion of "do big speakers sound big."
Interesting video 👍
In my setup I’ve got a 5.2.4 config, subs are FL and RR. Room is about 15.5ft long, 11ft wide, 8.5ft high. MLP is unfortunately about 14” from the rear wall (all solid brick walls).
I always struggled with a dip around 55-65Hz… best measurements for me are x-over at 100hz… but then I improve that dip more by stuffing the ports in my front towers, measures a few db smoother in the dip and sounds less phasey.
I guessed I’m stopping that out of phase region with my tower ports vs my sub ports which you’ve confirmed in the video. No matter how much I play with timings etc I can never get a better alignment with the tower ports open 🤔
Guessing the MLP position isn’t helping either and causing impulses/cancellations from the rear wall to a certain extent.
No I don’t think crossing at 150hz is necessarily a good idea. Multiple subs isn’t going to change the fact that you could localize the subs. Bass usually sounds diffused and around you. Hard to place. But as you go higher it can start to sound like it’s coming from the walls. But the actual LF sound object would be coming from the speakers. Causing a cognitive dissonance issue. Your brain will try to make sense of it, but really it can’t. So I suggest not going too high unless the sub is tied to a speaker. Or near it. Between ~100hz and 200hz bass management needs to be directionally steered in my opinion. Most processors can’t do this. Trinnov is the only one I am aware of that can both do this and summed mono bass. Mosimo products can do 4 quadrant steerable bass but it then doesn’t allow for the benefits of a typical multisub approach.
I’ve never watched it. I don’t know what his take it. I don’t think big speakers sound big. I mentioned in my review of the Polk L800s that they actually sounded like a mini monitor hooked to subs. The midrange and tweeter were not that efficient and so it sounded small. It couldn’t play all that loud.
My view is that a “big” sound comes from the bandwidth, output, and scale is the image. The actual speaker size doesn’t matter. But it’s very hard to make a loud and wide bandwidth speaker that is also small.
If you have only 2 subs and they are near Left respectively Right speaker, you can have XO much higher than 80Hz because when they start to became more localizable they will be aproximately in the same spot as speakers. Not best solution, but still good enough.
Hey Matthew nice video. I have the ONKYO RZ-50 and Dirac Live set the fronts at 70hz.... Should or I can i move them to 80hz without changing the sound or having phasing issues?
Yes of course you can. Give it a shot, may actually restore a little dynamic range. Hard to know without trying it. There is not a huge difference between 70hz and 80hz.
Matt, An online video showed a Perlisten R5M demo room with 2 subs crossed over at 100Hz and just plugged the R5M ports so they crossed over at 80Hz, essentially having an overlap from 80-100Hz with subs and monitors. Is that unique to how they setup the demo room or is that something we could try at home with those speakers and non Perlisten multi-subs? Also, did they keep listeners from localizing the subs by placing them behind the R5Ms?
I can’t speak to what was done. But in many cases something like this works well. The key is how it blends in both the time and phase domain as well as amplitude. Intuitively many assume a broad overlap will cause a bump in the response, but frequently that isn’t the case. It all depends. My suggestion is to use measurments. It really helps. You can figure out the right time alignment and phase alignment. Adjust the level and get it blended.
As for localizing the sub. That should not be an issue with any decent sub below 100hz. If it’s local sizable more work is needed in setting it up. Sometimes if a sub is making mechanical or other in harmonic noises the sub calls attention to itself. Bass itself is largely not readily localizable at 100hz. But sure, placing them behind the speakers would have the benefit of also fooling the brain, as well as ears, as expecting it all to come from the same place.
I’ve gotten good at using Dirac Live and MSO with my two Monolith subs. Only trouble I have is modifying target curves - I can never seem to get it right. Dirac’s new auto curve function helps a lot, but I still wish I had a better idea of what to do to raise the bass levels without being too boomy/muddy at a certain point…
Too much more than +4db at the bottom end (with -1.7db in the upper frequencies), and it looses its clarity even though I still feel like it’s too thin in certain frequencies. Things clean up a little when I taper off the bass a bit below 20hz, but I still feel like my target could be better. The more I mess with it though, the more off it starts to sound.
How do you go about finding the correct target curve?
I’ve listened to you explain it a bit in the past on Audioholics, but I feel like this topic deserves an in depth video on your channel as well - would love to hear more from you on that.
I can do more.
As a quick response, try a ramp shape. When others have researched this, they found that a wedge shaped response is boomy and muddy. So a kind of low shelf was applied. But they never really tried more than 6-8dB. What you can do when you need more bass and it sounds muddy is to keep the level between 50hz and 150hz lower, but then ramp up slowly toward 20hz. Sometimes what you are missing is the lower stuff and you want more of that.
You can also try adjusting the turnover point from whever you have it now to somewhere lower. if it starts at 150hz then move it to 100hz, if it starts at 100hz, move to 80hz, etc. See if that helps. Sometimes even 1-2dB can make a big difference.
Also be sure you don't conflate visceral bass with bass loudness. They can easily be confused in our expectations and you end up turning the bass up too loud to get more vibrations. Vibrations are really a function of the lower bass more than the upper bass, but also a big function of the room.
@@PoesAcoustics I’ll give this all a try. Thanks so much for the advice!
Great video. Love the nodal density comment about using towers down to 35hz as part of the bass equation.
I have a question that Audyssey themselves couldn’t answer. In MultEQ X, if you use the speakers as “full range”, but apply a low frequency cutoff at 35hz for example, if you set the double bass overlap at 80hz, won’t the subs receive the full range signal from the speakers set to full range, less the low frequencies that have been cut off? I.e in this example, won’t the subs only get 80hz - 35hz, if that’s what the rolloff of the speakers was set to in MultEQ X? I really want to try this with my 802d4’s, because I don’t want to neuter my $25k towers, but I want to make sure I’m bass managing the system via maximizing the potential. Thoughts?
I am not sure I understand. How can you run the speakers full range and cut them off at 35hz? When you say cut off, do you mean to apply a high pass filter at 35hz? If so, they are run as small, not large, correct?
@@PoesAcoustics great question.
In MultEQ X, there are three ways to bass manage. 1.) set small/crossover, 2.) set Large and apply a cutoff on the Design Curve page, and 3.) apply a curtain (which isn’t really a filter, it’s more of deciding which frequencies you want to allow EQ to be applied). That is the reason for the question…
@@HiFinest343 ok I understand what you mean now. I am not sure I’ve ever done 3. But my hunch is that everything between 0hz and 80hz or so is sent to the sub. It doesn’t throw away bass between 0 and 35hz.
Crossover is a term when you have a cross over from one driver to another based on a frequency division. Basically symmetry crossovers with no overlap. But you don’t have to do that. So a system that high passes the mains at 35hz while low passing the sub at 80hz is totally acceptable. You just have to manage the extra LF energy between 35hz and 80hz.
Bass management is something else all together. It refers to taking bass from a small speaker and sending it to a bigger speaker like a subwoofer. This also doesn’t have to be symmetry. It can have substantial overlap.
Since exciting the modes in a room through multiple low frequency sources tends to help even things out and create better bass smoothness seat to seat (often in the MLP too), I like having the mains contribute when they can. But sometimes they can only contribute partially and so using high pass filters below the sub crossover can be a good idea if the system can apply a type of double bass.
Doing this does need to be balanced against dynamic range. Lots of speakers can play very low but not loud at those frequencies. And most receivers do not have enough power to push a speaker very loud if it included low frequencies. So powering a tower off a receiver could actually reduce dynamic range rather than increase it. I actually had this happen in one of my older systems. I was powering my Gedlee speakers (95dB sensitivity) off a receiver. I did their version of double bass. The amp would audibly clip during dynamic peaks. I had to apply a highpass to get more output. I eventually added external amps and could again run it full range. The speaker could handle it, the receiver could not.
@@PoesAcoustics thank you for the detailed response. In my case, I have a similar setup to what you guys muscled through at Gene’s living room with MultEQ X. I have an 8805A pre/pro, with a Michi S5 amplifier driving 802d4 towers in a large, open concept family room. Both subs are at the front of the wall, one corner loaded one not (and there’s a 7dB difference between the two due to boundary gain, crazy).
Would love to see more tutorials on how to optimize a pair of large ported towers with sealed subs, exactly what you and Gene talked through with the AV10 MultEQ X video, but going into detail on how you achieved a linear response and time alignment. I also messaged Gene on Patreon about this, hopefully y’all can accommodate! Thanks Matt!!
The blending of Ported speakers with subs has been on my mind.
The logic of having both the subs and the towers be ported also hasn’t been sotting well with me, as I consider that the port resonances are typically placed on the bottom end of the operating range.
Meaning that there’s port effects where on the tower side where it crosses-over, but not on the sub side as it crosses over at the top of it’s range.
Naturally the Q width of the ports operation is relevant here.
If the towers perform well down to 35hz with a port, and the Q of the sub’s port is wide enough to encompass 35hz then I think they would blend well with the crossover set to 35hz. But that same equipment pairing, set to crossover at 80hz may have both sub and tower crossing over outside their port’s Q. Which may also blend well since they are outside the port range. But if the crossover activates the port resonance of one but not the other, it may be problematic
So I’m thinking in order to pair subs and towers well and determine optimal crossovers, we would need to think in terms of the Q width of the port resonances.
I’m curious how these thoughts find you and how you think about blending ported or non ported equipment. I’m tempted to go in a port-less direction next upgrade cycle for a little more even order harmonics. But I currently have a ported set of towers with no sub, and have been thinking about how to choose a sub with the my existing tower’s port resonances in mind. With a slight aversion to plugging them.
You shouldn’t cross the towers that low. Better to cross them over at something like 80hx which is well above their operating range.
Ports are used on smaller speakers to help extend the max SPL at 80hz. Ascendo has some speakers like that. Those require a little extra effort to blend but it can be done. The key is to actually pay attention to both phase and timing so that the group delay rise blends correctly with the subs.
@@PoesAcoustics Thanks Matt I appreciate it, I’ll remember to think more about about the group delay and not just the phase.
Hopefully we’ll see the emergence of more manufacturers sharing these details for easy cross comparisons. I’m tired of living in the dark, not even knowing the Q of my ports! The measurements you guys do at Audioholics really goes a long way in informing these decisions. And your insights here on your own channel are also fire! Good stuff!
Interesting enough, Dirac ART basically does away with bassmanagement as it has traditionally been done? What happens in that case?
That’s essentially true but bass management is still a thing. Speakers can’t suddenly run full range. ART is a means of dealing with modes. Not dynamic range. Bass management is about dynamic range. So you need both. But ART works differently and so how you think about it is different. I’ll cover this more directly in the future.
Hello. Lfe has brickwall of 120hz. Im using full active config with all speakers to bass mgmnt @80hz. To do this i need to LPF thr subs at 80hz as well. Do i miss a lot in term of lfe content ?
First, LFE is not brickwalled. LFE has a crossover like any other channel. On the Trinnov, you can actually choose filter type, slope, and frequency. It doesn't even have to be 120hz. It could be 150hz. In my system, I have it set to L-R 4th order at 120hz.
The crossover point for bass management is unrelated to the crossover point of the LFE. Normally the LFE defaults to 120hz and its often L-R 4th order. Ultimately up to you. I wouldn't cross an LFE at 80hz, but again, remember that is a different setting from the bass management frequency.
Why do REL subwoofers (even the HT series) like doing full range on speakers? Are there any phase issues that are better if speakers are set to large/full range instead of doing bass management? Love to know your thoughts. Thanks!
Let's start by not assuming that what REL does is the right thing to do. That is there approach, I don't agree with it. They've never produced any reports that support that their approach is valid or better. Merely that they feel it sounds better and anechdotely hear that from their customers (and realistically, all companies can make similar claims).
There are a lot of reasons to believe that their approach is not better. Welti's own published work is enough to begin to question their approach because their multi-sub approach ties a speaker channel to a subwoofer. Which means if you have multiple subs around the room, typically they are not fed a mono channel. Their approach appears to be about sending a channel specific to each sub location and then remixing LFE. I believe such an approach is likely to yield poor seat to seat uniformity.
Now...if the question is can you have full range speakers run full range (as in without crossovers) and mix in suibs, sure. But getting that to blend well and work right can be tricky and often requires sophisticated DSP to make work. Simply using line level inputs rarely yields better results. But I've been a proponent of this concept for a long time when the speakers can handle it. My old speakers, the Gedlee's, could handle 1000 watts RMS, could handle a full range operation because the enclosure was so small for the woofer that short of boosting the bass, it was not possible to exceed xmax. Meaning that the speaker didn't need bass management for dynamic range. However, the speaker naturally rolled off at a 2nd order starting around 100hz, with a -3dB point of 80hz.
@@PoesAcoustics thanks for the insight!!
My crossover is 67hz because my subs have a peak much higher that's masked better with a lower crossover...
That happens from time to time but really is a sign that the subwoofers need to be bettered. The benefit of the higher crossover point is that it increases the bandwidth of the area in which you get the higher SPL and the improved smoothness. Remember that the area at which you need to hit 115dB is from 20hz to 120hz or more. It's the LFE max output and so by crossing the subwoofer at 67hz (I assume you have adjusted the LFE crossover too) you are limiting your dynamic range for hte LFE channel too. If not, then something else to keep in mind, the resonance you are trying to avoid is being activated by the LFE channel. You may want to address the resonance.
i dont really know who this video is for. a novice would not fully understand everything you are referencing. and an enthousiast who does understand you most likely knows most of this. i learned all of this from your series over at Audioholics, although lengthy, they were much better imho.
I thought it was good and I think it's totally fine to repeat things that have been presented elsewhere. I appreciate having a more concise version and now we know his current thoughts on the subject.