Why I dislike traditional bass management

[Matthew J Poes]

Ok so I've commented a few times on other threads about the notion that bass management in traditional HT products, a hold over from the THX legacy, is flawed. Based on some good science and some bad science, but ultimately focused on simplicity instead of optimal sound.

The current standard approach to bass management uses true crossovers, meaning there is a symmetric high-pass and low-pass. A 4th order LR low pass for the subwoofer and a 2nd order BW high pass for the mains (that when mixed with a sealed enclosure speaker with an 80hz -3db fs, would yield a 4th order LR high pass acoustically). This made sense if the mains were sitting on top of the subwoofer and/or crossed quite a bit higher. However, when we consider that the length of a period at 100hz is 10ms or 11.4 feet, what sense does it make to use symmetric and steep crossovers. The 80hz standard chosen for THX came from the fact that this was 2 standard deviations below the point at which people could not detect the location of a subwoofer. It was thus believed that this was sufficient to ensure that the majority of people could not detect the subwoofer's location.

Let's start by discussing the benefits to the standard approach, it has merit after all.

Advantages:
-It's easy for most people to understand and utilize, setup is simple, and good results are possible
-The high pass filter on the mains can improve their dynamic range, reduce the load on the main amp, and reduce distortion
-It's simple enough that automated setup algorithms can be made to work successfully with fewer rules to follow. My approach would require predictive modeling of the various scenarios to detect the optimal settings, something not possible a decade or two ago.
-I'm sure many of you will come up with many other benefits, as I said, it has its virtues, so those go here.

Before discussing the specific disadvantages, it's important to look at the limited research conducted here. The one I cite most for this is Earl Geddes, in the early 80's he completed a PhD Dissertation LF's in small rooms. At its core, the paper developed the first complete mathematical model of LF sources in small acoustic spaces along with the inclusion of the effect of boundaries. The models were confirmed through testing, but of course, the advantage of modeling is that we can also test a lot of scenarios that we wouldn't want to test in real life. His conclusions were interesting and cause us to want to draw conclusions in contrast to the traditional bass management approach, as well as the notion of 2-channel full range speakers. First, that there are specific locations that are best for subwoofers, and they are near barriers. Second, that damping on one wall per dimension is all that is needed (but doing both doesn't hurt, it is just not more effective than doubling it on just one side). Third, that bass smoothness was poor with traditional LF sources, such as 2-channel full range speakers or a single subwoofer. In fact, there was a direct correlation to the number of LF sources and bass smoothness. Spreading the LF sources out around the room activated more of the modes in the room causing there to be higher modal density and thus less variation in the peaks and dips. While it didn't necessarily make the response flatter or smoother, it did make it more consistent. We can eq consistent, but we can't eq variable.

Now, this work was theoretical, it did not explicitly test a subwoofer integration method. That didn't happen until 20+ years later with Welti, Toole, etc. at Harman. Their work copied much of the same principles, but in the context of an applicable approach (not that Geddes didn't develop his own, he just didn't publish the subwoofer method itself). Both Geddes and Welti's approaches are more similar than different, which I address in my Geddes Sub video. However, the key difference in Geddes approach, which matters here, is the bass management. Geddes notes that since the more LF sources the better the consistency of the bass, that the mains should be LF sources too. In fact, the modeling even suggested that this was a better scenario than simply adding more subwoofers. Integration and smoothness, as well as consistency, was improved when the mains were operated at full range (that doesn't mean response down to 20hz, just that they didn't have a high pass filter). Geddes also advocates for shallow low pass filters since steep filters don't really benefit us at such low frequencies, but do potentially cause harm in the sense that they increase group delay.

Disadvantages of the traditional approach:
-It neglects the mains as an additional LF source
-It increases group delay
-It can be less spatially robust in both consistency overall and at the integration point
-Speakers have different responses that make the use of asymmetric electrical filters with equal frequency dumb, that only made sense if all speakers were built the way THX indicated.

I think that last point may be one of the most important. Most speakers are ported and most have different port tunings from each other (that is, most speakers aren't tuned to a single common frequency, every speaker is different). Further, the overall response of the speakers varies greatly, so while two speakers could both have a port tuning of 35hz, one may be -6dB at that point and the other +3dB. As such, creating symmetric filters, as the original approach dictated, is impossible. Just like a speaker crossover often uses different slopes and different frequencies between, say, the tweeter and midbass to achieve a flat summed response, so should the subwoofer and mains.

Now remember something else, all speakers have an acoustic highpass. There is no such thing as a speaker with no highpass filter. The enclosure itself (be it ported, sealed, or TL) have a natural highpass. Since the shape of that highpass and its -3dB is different for every speaker, we need flexibility in the tuning of the high pass filters. Both its frequency and slope needs to be adjustable separately from that of the subwoofer low pass. Further, it should be standard on all devices that you simply have no highpass, but that this is unrelated to bass management (directing all bass from all channels to a dedicated bass/LFE channel.

My point with this is not to promote a brand or model, but the notion that bass management should be more flexible. That we hold back the ability to optimize systems with the current approach.

Unfortunately, the misunderstandings around low frequencies in small rooms and the way bass management actually operates leads to so much confusion that I fear there will never be a change.

I am not naive, I don't think most people will want to take the time to study and learn these concepts. Instead, I suspect that our saving grace will be advancements in bass management that will allow more nuanced decision making by the processor. If more LF sources is better, and this improvement is most notable above 50hz, then even fairly robust surround speakers could aid in the improvement of LF seat to seat consistency, smoothness, and bass integration.

Ok what about group delay, what is this business and how serious is it? Well, normally I would say not very important. I mean, the science is thin, but what we have suggests that if the group delay is kept below 1.5 periods, it shouldn't be audible. 100hz period is 10ms, that's a long time for a speaker, it would take a lot to add more than 15ms of groupd delay, right? Well, maybe not. The times are changing, and modern DSP does a lot to screw this up. First, the sub amplifiers now have DSP and DSP itself has overall delay. But a subwoofer is bandwidth limited. What happens when you add a bandwidth limited speaker to the overall system and it has a delay. It becomes group delay.

I will use WinISD to show a series of changes to the natural group delay of a single subwoofer progressing from no added filters to a worse case scenario where someone using the fanciest new DSP powered sub has gone to down with REW, attempting to fill in every little dip with boost EQ, added steep LP filters, etc.

No issues:


Just a low pass filter:


OMG What have you done!


Ok the last one isn't as bad as it could be, but for the sake of argument, after lots of filters, we are at or beyond 1 period across the entire bandwidth. While group delay was generally said to be a non-issue, they weren't thinking it could get this bad!

Now the room itself also gets in the way and so what I'm showing here is still better than reality. Modes add a ton of group delay, and I'll show some real-world examples of this. My point with all this, though, is that we should take steps to not introduce excessive amounts of extra group delay. I've now begun to measure peoples systems reporting more than 100ms of group delay, well over 30ms by 100hz! That isn't good.

Here is a measurement of a good system in room. This wavelet shows what we would want to see in a pretty ideal system. The black line reflects group delay, basically.


This shows a common setup with subwoofers in an ok arrangement. Not terrible, but not as good as above:


And...This shows the OMG what have you done scenario:


I think this is showing what happens when DSP runs wild. The solution is to go back to the DSP in the processor, handling the bass management, and provide the needed facilities to improve bass integration. This will hopefully reduce the reliance on DSP later in the chain (whose delay can't be compensated for if it is not common to all subwoofers) and where often far too much "fix" is applied.

When I setup a system and I "roll my own" bass management, by the time I've completed all of the setup work related to crossover, phase, speaker placement, etc., I only need 1-2 eq filters, and only cut filters. However, that is never possible with bass management the way it is.

 

[Old Onkyo]

Ok so I've commented a few times on other threads about the notion that bass management in traditional HT products, a hold over from the THX legacy, is flawed. Based on some good science and some bad science, but ultimately focused on simplicity instead of optimal sound.
The current standard approach to bass management uses true crossovers, meaning there is a symmetric high-pass and low-pass. A 4th order LR low pass for the subwoofer and a 2nd order BW high pass for the mains (that when mixed with a sealed enclosure speaker with an 80hz -3db fs, would yield a 4th order LR high pass acoustically). This made sense if the mains were sitting on top of the subwoofer and/or crossed quite a bit higher. However, when we consider that the length of a period at 100hz is 10ms or 11.4 feet, what sense does it make to use symmetric and steep crossovers. The 80hz standard chosen for THX came from the fact that this was 2 standard deviations below the point at which people could not detect the location of a subwoofer. It was thus believed that this was sufficient to ensure that the majority of people could not detect the subwoofer's location.
Let's start by discussing the benefits to the standard approach, it has merit after all.
Advantages:
-It's easy for most people to understand and utilize, setup is simple, and good results are possible
-The high pass filter on the mains can improve their dynamic range, reduce the load on the main amp, and reduce distortion
-It's simple enough that automated setup algorithms can be made to work successfully with fewer rules to follow. My approach would require predictive modeling of the various scenarios to detect the optimal settings, something not possible a decade or two ago.
-I'm sure many of you will come up with many other benefits, as I said, it has its virtues, so those go here.
Before discussing the specific disadvantages, it's important to look at the limited research conducted here. The one I cite most for this is Earl Geddes, in the early 80's he completed a PhD Dissertation LF's in small rooms. At its core, the paper developed the first complete mathematical model of LF sources in small acoustic spaces along with the inclusion of the effect of boundaries. The models were confirmed through testing, but of course, the advantage of modeling is that we can also test a lot of scenarios that we wouldn't want to test in real life. His conclusions were interesting and cause us to want to draw conclusions in contrast to the traditional bass management approach, as well as the notion of 2-channel full range speakers. First, that there are specific locations that are best for subwoofers, and they are near barriers. Second, that damping on one wall per dimension is all that is needed (but doing both doesn't hurt, it is just not more effective than doubling it on just one side). Third, that bass smoothness was poor with traditional LF sources, such as 2-channel full range speakers or a single subwoofer. In fact, there was a direct correlation to the number of LF sources and bass smoothness. Spreading the LF sources out around the room activated more of the modes in the room causing there to be higher modal density and thus less variation in the peaks and dips. While it didn't necessarily make the response flatter or smoother, it did make it more consistent. We can eq consistent, but we can't eq variable.
Now, this work was theoretical, it did not explicitly test a subwoofer integration method. That didn't happen until 20+ years later with Welti, Toole, etc. at Harman. Their work copied much of the same principles, but in the context of an applicable approach (not that Geddes didn't develop his own, he just didn't publish the subwoofer method itself). Both Geddes and Welti's approaches are more similar than different, which I address in my Geddes Sub video. However, the key difference in Geddes approach, which matters here, is the bass management. Geddes notes that since the more LF sources the better the consistency of the bass, that the mains should be LF sources too. In fact, the modeling even suggested that this was a better scenario than simply adding more subwoofers. Integration and smoothness, as well as consistency, was improved when the mains were operated at full range (that doesn't mean response down to 20hz, just that they didn't have a high pass filter). Geddes also advocates for shallow low pass filters since steep filters don't really benefit us at such low frequencies, but do potentially cause harm in the sense that they increase group delay.
Disadvantages of the traditional approach:
-It neglects the mains as an additional LF source
-It increases group delay
-It can be less spatially robust in both consistency overall and at the integration point
-Speakers have different responses that make the use of asymmetric electrical filters with equal frequency dumb, that only made sense if all speakers were built the way THX indicated.
I think that last point may be one of the most important. Most speakers are ported and most have different port tunings from each other (that is, most speakers aren't tuned to a single common frequency, every speaker is different). Further, the overall response of the speakers varies greatly, so while two speakers could both have a port tuning of 35hz, one may be -6dB at that point and the other +3dB. As such, creating symmetric filters, as the original approach dictated, is impossible. Just like a speaker crossover often uses different slopes and different frequencies between, say, the tweeter and midbass to achieve a flat summed response, so should the subwoofer and mains.
Now remember something else, all speakers have an acoustic highpass. There is no such thing as a speaker with no highpass filter. The enclosure itself (be it ported, sealed, or TL) have a natural highpass. Since the shape of that highpass and its -3dB is different for every speaker, we need flexibility in the tuning of the high pass filters. Both its frequency and slope needs to be adjustable separately from that of the subwoofer low pass. Further, it should be standard on all devices that you simply have no highpass, but that this is unrelated to bass management (directing all bass from all channels to a dedicated bass/LFE channel.
My point with this is not to promote a brand or model, but the notion that bass management should be more flexible. That we hold back the ability to optimize systems with the current approach.
Unfortunately, the misunderstandings around low frequencies in small rooms and the way bass management actually operates leads to so much confusion that I fear there will never be a change.
I am not naive, I don't think most people will want to take the time to study and learn these concepts. Instead, I suspect that our saving grace will be advancements in bass management that will allow more nuanced decision making by the processor. If more LF sources is better, and this improvement is most notable above 50hz, then even fairly robust surround speakers could aid in the improvement of LF seat to seat consistency, smoothness, and bass integration.
Ok what about group delay, what is this business and how serious is it? Well, normally I would say not very important. I mean, the science is thin, but what we have suggests that if the group delay is kept below 1.5 periods, it shouldn't be audible. 100hz period is 10ms, that's a long time for a speaker, it would take a lot to add more than 15ms of groupd delay, right? Well, maybe not. The times are changing, and modern DSP does a lot to screw this up. First, the sub amplifiers now have DSP and DSP itself has overall delay. But a subwoofer is bandwidth limited. What happens when you add a bandwidth limited speaker to the overall system and it has a delay. It becomes group delay.
I will use WinISD to show a series of changes to the natural group delay of a single subwoofer progressing from no added filters to a worse case scenario where someone using the fanciest new DSP powered sub has gone to down with REW, attempting to fill in every little dip with boost EQ, added steep LP filters, etc.
No issues:
View attachment 27705
Just a low pass filter:
View attachment 27704
OMG What have you done!
View attachment 27703
Ok the last one isn't as bad as it could be, but for the sake of argument, after lots of filters, we are at or beyond 1 period across the entire bandwidth. While group delay was generally said to be a non-issue, they weren't thinking it could get this bad!
Now the room itself also gets in the way and so what I'm showing here is still better than reality. Modes add a ton of group delay, and I'll show some real-world examples of this. My point with all this, though, is that we should take steps to not introduce excessive amounts of extra group delay. I've now begun to measure peoples systems reporting more than 100ms of group delay, well over 30ms by 100hz! That isn't good.
Here is a measurement of a good system in room. This wavelet shows what we would want to see in a pretty ideal system. The black line reflects group delay, basically.
View attachment 27707
This shows a common setup with subwoofers in an ok arrangement. Not terrible, but not as good as above:
View attachment 27706
And...This shows the OMG what have you done scenario:
View attachment 27708
I think this is showing what happens when DSP runs wild. The solution is to go back to the DSP in the processor, handling the bass management, and provide the needed facilities to improve bass integration. This will hopefully reduce the reliance on DSP later in the chain (whose delay can't be compensated for if it is not common to all subwoofers) and where often far too much "fix" is applied.
When I setup a system and I "roll my own" bass management, by the time I've completed all of the setup work related to crossover, phase, speaker placement, etc., I only need 1-2 eq filters, and only cut filters. However, that is never possible with bass management the way it is.

Thanks for the information Matt, I read it ....twice.
Are you suggesting that all speakers in the system process base, and then i run the low pass crossover somewhere below the THX 80?

 

[Matthew J Poes]

Thanks for the information Matt, I read it ....twice.
Are you suggesting that all speakers in the system process base, and then i run the low pass crossover somewhere below the THX 80?

No, actually I didn't really describe what I suggest people do here, just explained what I think is wrong with current approaches and why.

I think that subwoofers and mains should substantially overlap. How low you let the mains play depends on what your mains are and how much amplifier power you have for them. If they are small 5" bookshelf speakers tuned to 100hz, then it probably won't make sense to run them full range. The key is knowing what will cause the mains to overload. If the speaker will distort because it's exceeding xmax, then you need a high-pass filter to protect it. If the speaker is like mine, it will never exceed xmax without exceeding power handling. That kind of speaker doesn't need a high pass filter at all. That may not help much, but basically, if you can share with me what you have for speakers I can probably tell you the best options.

As for the sub frequency, you want as many LF sources operating in different parts of the room as possible, and so if that is true, you want the sub crossover higher. 80hz isn't a bad idea, but it isn't a hard and fast rule. I would say 80 is actually a good place for it. You could try 100hz too. If the sub is near the mains towards the front of the room, that wouldn't be localizable and is beneficial by increasing the number of LF sources that operate in one of the more congested areas for modes.

 

[shadyJ]

Smarter processing would benefit smart users, but it won't benefit someone who doesn't invest any care into setup. They will probably only ever get a single subwoofer, they will not bother to learn where to best position the microphone, nor will they take any care in subwoofer placement for that matter, so the calibration will be pretty messed up, but the good news is that they wouldn't know the difference anyway. They will probably run the sub 10dB hot no matter what.

 

[Matthew J Poes]

Smarter processing would benefit smart users, but it won't benefit someone who doesn't invest any care into setup. They will probably only ever get a single subwoofer, they will not bother to learn where to best position the microphone, nor will they take any care in subwoofer placement for that matter, so the calibration will be pretty messed up, but the good news is that they wouldn't know the difference anyway. They will probably run the sub 10dB hot no matter what.

Then the future of room correction is armed droids! Man cannot be trusted with his own system.

 

[shadyJ]

Then the future of room correction is armed droids! Man cannot be trusted with his own system.

Before we implement widespread room correction, we need to implement widespread personality correction. Man must be made to think and act correctly, but of course only I know what correct behavior and thinking is. It is entirely my responsibility to correct mankind.

 

[Matthew J Poes]

Before we implement widespread room correction, we need to implement widespread personality correction. Man must be made to think and act correctly, but of course only I know what correct behavior and thinking is. It is entirely my responsibility to correct mankind.

now you have gone too far.

 

[ryanosaur]

I'm still catching up to the bus right now, with my new rig. And rather than ask silly questions now, I'd rather learn how to completely f it up before I ask said silly questions.

Thanks Matthew!

 

[viseral audio]

No, actually I didn't really describe what I suggest people do here, just explained what I think is wrong with current approaches and why.

I think that subwoofers and mains should substantially overlap. How low you let the mains play depends on what your mains are and how much amplifier power you have for them. If they are small 5" bookshelf speakers tuned to 100hz, then it probably won't make sense to run them full range. The key is knowing what will cause the mains to overload. If the speaker will distort because it's exceeding xmax, then you need a high-pass filter to protect it. If the speaker is like mine, it will never exceed xmax without exceeding power handling. That kind of speaker doesn't need a high pass filter at all. That may not help much, but basically, if you can share with me what you have for speakers I can probably tell you the best options.

As for the sub frequency, you want as many LF sources operating in different parts of the room as possible, and so if that is true, you want the sub crossover higher. 80hz isn't a bad idea, but it isn't a hard and fast rule. I would say 80 is actually a good place for it. You could try 100hz too. If the sub is near the mains towards the front of the room, that wouldn't be localizable and is beneficial by increasing the number of LF sources that operate in one of the more congested areas for modes.

(for what its worth) the only way I could get the smoothest response even with three subwoofers is to use my front speakers as large to add more low frequency sources, my fronts are very capable there def tech bp2000 with built in 15" powered drivers.the only thing that sucks is Yamaha decided to delete its bass out to both front and subs feature, so to get bass out to subwoofers when front is set to large you have to use extra bass setting and god only knows what there sending to the subs.

 

[Matthew J Poes]

(for what its worth) the only way I could get the smoothest response even with three subwoofers is to use my front speakers as large to add more low frequency sources, my fronts are very capable there def tech bp2000 with built in 15" powered drivers.the only thing that sucks is Yamaha decided to delete its bass out to both front and subs feature, so to get bass out to subwoofers when front is set to large you have to use extra bass setting and god only knows what there sending to the subs.

Sounds like you are confirming my preference. Using the mains as large and subs together.

My Onkyo has the extra bass feature. You can set it so the mains are large and the subs still get bass below a certain crossover frequency. It’s workable but doesn’t redirect LFE.

My preferred method is actually to use the LCR output to an external device to handle bass management but you have to be careful not to aim to mono using anything passive because it kills the channel separation.

Another option is to use an 8 channel soundcard and use a mixer on a computer to handle everything. I recently acquired a Motu 828x for my acoustics work and review measurements. It allows 8 in and 8 out and can do matrix mixing and basic filtering in the included software.

Of course this is all silly. Better would be to allow this level of flexibility in the receiver itself.

 

[viseral audio]

Sounds like you are confirming my preference. Using the mains as large and subs together.

My Onkyo has the extra bass feature. You can set it so the mains are large and the subs still get bass below a certain crossover frequency. It’s workable but doesn’t redirect LFE.

My preferred method is actually to use the LCR output to an external device to handle bass management but you have to be careful not to aim to mono using anything passive because it kills the channel separation.

Another option is to use an 8 channel soundcard and use a mixer on a computer to handle everything. I recently acquired a Motu 828x for my acoustics work and review measurements. It allows 8 in and 8 out and can do matrix mixing and basic filtering in the included software.

Of course this is all silly. Better would be to allow this level of flexibility in the receiver itself.

I totally agree! I just bought a mini dsp 2x4 hd and was gonna use for a pair of subs up front for music and leave one sub in rear hooked to sub out on receiver for lfe

 

[Steve81]

Bass management flexibility is one of the reasons I like my older pre/pro, the Emotiva UMC-200. Its XOs are adjustable by frequency (in 5Hz steps) and slope (12/24dB/octave) per channel group. According to Gene's review, it has an enhanced bass mode similar to that in your Onkyo, but it would redirect LFE as well. The subwoofer channel has a separate XO setting, which makes me wonder if it could overlap their response with the mains (admittedly never tried to see what would happen). My main gripe is only one subwoofer channel; a second would be helpful for setting delays. .

Of course I appreciate "conventional" bass management for advantage #2 on your list:

-The high pass filter on the mains can improve their dynamic range, reduce the load on the main amp, and reduce distortion

Given the overall market's move towards small main speakers with modest low end capability (vs speakers like your Abbeys),it seems like that aspect of bass management isn't liable to go anywhere. Personally, I opt for a 120Hz high pass on my mains to minimize their woofer excursion (and corresponding distortion).

 

[Irvrobinson]

I think that subwoofers and mains should substantially overlap.

I agree, and that's the way my system is set up. (This is a music-only system - no HT.) In my case, the mains are so capable (Revel Salon2s, -3db@23Hz) that I run them full-range and use a single sub just for fill-in of room response dips (using PEQs in the sub amp manually tuned with OmniMic measurements) below 100Hz. The mains are placed for smoothest response above approximately 100Hz, which are about four feet out from the back wall and >6ft from the side walls, and the sub is placed within inches of the back wall. I tried several different ways of setting up the mains and the sub, and experimenting with a second sub, but in the end three bass sources, two unequalized and one compensating for room effects, worked far better than any crossover-based alternative, including alternatives with two subs. But like you say, this strategy requires very bass-capable mains.

I helped a friend set up his system similarly, and it worked well with his KEF R900s, which are good to about 32Hz in-room, though he used two subs (SVS SB4000s). Lucky he did use two subs, because the SB4000s only have three PEQs, but by tuning the subs separately and differently it was like having one sub with six PEQs. Also, we used the low-pass filter set at ~140Hz, because his room was smaller and he had fewer mains placement options, so we needed to fill in a dip in the crucial 100-120Hz range.

I'll never have a primary system without a sub again, but IMO integrating one or more subs with capable main speakers is not easy, and I've never heard a 2.1 or 2.2 system, with a simple crossover below 100Hz that I thought sounded very good. The bass frequencies always seem to sound disjoint with the simple crossover strategy.

 

[highfigh]

Before we implement widespread room correction, we need to implement widespread personality correction. Man must be made to think and act correctly, but of course only I know what correct behavior and thinking is. It is entirely my responsibility to correct mankind.

Not to go too far off the rails, but I would say Man must be made to understand that acting in a civilized manner is more important than thinking correctly- who gets to decide what is 'correct', or 'incorrect'. It's probably easier to define 'civilized'.

 

[highfigh]

Then the future of room correction is armed droids! Man cannot be trusted with his own system.

I have heard some systems that sounded decent with Audyssey but haven't worked much with YPAO, MCACC or the others- I have, however, played with speaker distance settings with/without Audyssey and have made some definite improvements in the sound but I was also using REW at the time, so it was possible to see the changes as well as hear them.

One thing I have never liked is a 0°/180° polarity switch on many subwoofers- that just can't work, unless by coincidence. I have always preferred the continuously-variable control on some subs and it makes placement much easier. It's not perfect, but it is a lot better than an either/or choice.

The key to proper setup, IMO, is for the person/people doing the setup actually understand a bit more than the basic "put it in a corner and the bass will be stronger" model. Unfortunately for many, science and math aren't their strong suit and when the principles of audio & acoustics are mentioned, their eyes glaze over.

One thing I would recommend for anyone who has the equipment that allows adjusting the speaker distance settings, set it to the smallest increment and play with it- it's easy enough to go back to some default distance, but make changes and LISTEN to the differences. I would start by turning the sub off if the main speakers can produce decent energy in the low frequencies, then listen for how the sounds are 'placed' in the stereo soundstage. If the listener moves their head and the sound changes, it means the room/furnishings are affecting the sound and something needs to be done about it but it also comes with this- the room's affects won't necessarily be fixed by using some algorithm in a program. Sometimes, treatment and fiddling with speaker placement is needed. It made a huge difference in my room and at this point, I'm not even using my subwoofer or any electronic equalization.

I would also say that there's far too much attention paid to hitting the lowest frequencies. It's not practical or affordable for most and it annoys people outside of the listening room. If the last part isn't a concern, go ahead. IMO, great response from about 40Hz through the mid-bass and in the midrange are more important for music- our mind can fill in the blanks for what may not be as loud or might be missing altogether. For special effects, the low frequencies are more necessary but harder to achieve.

 

[highfigh]

WRT the simple/ignorant approach I mentioned before (put the sub in a corner...), I'm working on a condo where the original system was installed in a wall of cabinets- the TV was in its own enclosure with doors about 18" from the left wall, the sub and left front speaker were over 10' high, sitting on top of the cabinet above the TV. The center channel speaker was in its own little cubby hole over the TV, the right front was on top of the cabinets to the right of the fireplace in the center of the wall, probably 15' away. The rear speakers are about 12' high, on the back walls. Basically a prototype for bad sound.

I'm not even going to try to make that sound good- I'm using a large LCR sound bar under the larger new TV and I'll make do with the rears- they aren't so interested in surround that a perfect soundstage is terribly important, but with his hearing issues, a more coherent front is more important.

 

[shadyJ]

who gets to decide what is 'correct', or 'incorrect'.

It's OK, I am here now. I will be the arbiter of Correct Thinking. I will lead mankind to a new golden age. But first, we must cleanse humanity of the False Thinkers. It will be a bloody process, but it is necessary.

 

[Irvrobinson]

It's OK, I am here now. I will be the arbiter of Correct Thinking. I will lead mankind to a new golden age. But first, we must cleanse humanity of the False Thinkers. It will be a bloody process, but it is necessary.

I guess this is your brain on drugs...

 

[Matthew J Poes]

I guess this is your brain on drugs...

@shadyJ does this sometimes. As far as I know he doesn’t own any guns so we should be safe.

In all seriousness James, sometimes when you go off, I can’t tell if this is just silliness or a very subtle tease at the notion that there is some right and wrong in audio. We’ve had these discussions before and somehow it always ends with the enslavement of humanity. I just want more flexible bass management.

 

[Matthew J Poes]

WRT the simple/ignorant approach I mentioned before (put the sub in a corner...), I'm working on a condo where the original system was installed in a wall of cabinets- the TV was in its own enclosure with doors about 18" from the left wall, the sub and left front speaker were over 10' high, sitting on top of the cabinet above the TV. The center channel speaker was in its own little cubby hole over the TV, the right front was on top of the cabinets to the right of the fireplace in the center of the wall, probably 15' away. The rear speakers are about 12' high, on the back walls. Basically a prototype for bad sound.

I'm not even going to try to make that sound good- I'm using a large LCR sound bar under the larger new TV and I'll make do with the rears- they aren't so interested in surround that a perfect soundstage is terribly important, but with his hearing issues, a more coherent front is more important.

I do think we need some sort of simple and advanced. Maybe a dual menu approach like Windows uses.

I also have heard reports that most people not only don’t understand this stuff, they fail to adjust the settings or utilize the autocorrection at all. I was talking to a guy who makes purchasing decisions for features on a popular line of receivers, and he told me that room correction is a tough call. If you go by the marketing data, it only sells in concept. Most people who say they want it don’t use it, and many of the remaining who do use it, do so incorrectly.

Maybe Alexa can help.