Lots of bass at walls, lack of bass in center of room/listening position


I guess this is relatively common in listening system. Is there any way to smooth this out so I get more bass energy at my listening position? This happens with our without my 2x 18 inch subs. Room is 12 x 16 x 8 ft, speakers 4.5 ft apart on long axis and I am sitting 4.5 feet away. I tried moving back and forward but the entire middle center of the room except near the walls has decreased bass.
Is this a boundary effect or could it be due to bass cancellation effects?
smodtactical
Bass nodes.
All you need is 2 more subs and hours to spend setting them up.
I have a single 12” sub in an open ended approx 15x25 room.  My first location produced bass 20’ away but very little in the listening area.  Moving the sub only a foot and a half, close to a wall ( 4”) and experimenting with forward and side firing (into a corner worked best)  produced smooth response in the listening area.  The sub is across the room from the main speakers (Wireless helped here).  Placement next to the mains seems intuitive but may be just the wrong thing for your room nodes and it’s not necessary if the crossover is set properly.  Good luck!
Your speakers are 4.5 foot apart and your 4.5 feet from the speakers?
That is close to you and close together. WOW!

You are in the wrong place and so are the speakers, it sound like, a bit of humor.  Your in the "cancel zone", if the bass was trapped you would have bass, its the bass bouncing from everywhere to the center (where your at) that's the problem. Cheapest solution move your position.

Correct solution, treat the room as much as you can, place your speakers further from you and wider, get yourself a lot closer to the actual, bass bins, either side of you, or forward of the main speakers, it's a timing issue. Either kill the unused bass or get rid of it, (open the doors on the back wall if you have them). Then you can hear the bass in phase, (correct timing).

Regards
Move speakers about 12” away from wall.

Them sit and listen, move back 6”’s, sit and listen.

Move farther from wall if needed.

Mine are about 11-13” from the wall they are on, I’m 9 feet from them with speakers toed in slightly to my sitting couch position.
I have small woofers, 6-7” drivers, and I get descent bass from mine.
I also put our throw pillows behind the speaker in the corner, which corner speakers tend to sound louder and have more bass than the speaker which is on the wall To the left, it is 10” from a open hallway, staircase, bedrooms. Right speaker is in the corner and has a deeper and louder sound.

I all plays well.
Mess around and have fun!



my speakers are about 9 feet apart, and I sit 9 feet from them, for my small towers, it’s perfect for me.

 Move, listen, move again, pillows, move again, repeat, pour self a dram and get some fav cds, and enjoy the fun.

 Keep us posted!
Imo, had I that room (and it were dedicated) I would not put the system on the long wall, but the short wall, and put the listening chair about 8' away to start. Like so (see my system) 
Your room dimensions are even numbers with common denominators (all divisible by 4...your room was certainly not designed by an acoustics engineer, lol). You’re going to have significant standing waves and bass issues regardless of positioning. Best thing you can do is increase the acoustic space with significant bass trapping. Contact GIK Acoustics and they can help you come up with a custom treatment plan.
Bass traps and possibly 2 subs may be necessary.  Start with the traps.
You may want to give your local guy mitch a call,

https://accuratesound.ca/

Are you doing mostly digital streaming with ROON or JRiver?
If you are doing this for one listener...use your headphones, you will save alot of money. 
Headphones are amazing these days but do not get me to the same level of musical greatness as a great speaker. I say this as someone who sold my amps this week and have nothing to drive my speaker. Just 2 great headphone systems today.
Lots of bass at walls, lack of bass in center of room/listening position
@smodtactical  This is the classic description of a standing wave in the room.

While room treatment will help a little bit, its effect is marginal. You have two solutions both of which will work fine, depending on how you want to handle this.

The first is as others have suggested, move your subs around until you find a location that allows you to hear bass at the listening position. This can be tricky but can be done even with only one sub.

Now if you think you might want to hear the bass properly in any position in the room, then you need to break up the standing waves. The only way to do that (you can't do it with room treatment) is to use multiple subwoofers. You'll need at least 4 to do the job. This type of subwoofer approach is called a 'Distributed Bass Array' and is very effective- with the qualification that none of the subs operate above 80Hz. But its likely that your main speakers go lower than that, so this should be fairly easy. Below 80Hz your ear cannot tell where the bass is coming from- and the harmonics of the bass instruments will make you think that the bass is coming from in front of you.


Two of the subs would be placed in front of you, and the other two placed asymmetrically in the room, with one maybe on one side wall and other other in the rear on the opposite side. You might get better results by putting one of the latter two out of phase with the rest. They can all be fed a mono signal- again, if kept below 80Hz this will work fine. To get bass evenly distributed at all frequencies this is the most elegant approach. There is one subwoofer that is built specifically for this purpose, the Swarm, made by Audiokinesis in Texas.  Good Luck!
Move you listening position closer to a wall boundary.  You may need to be anywhere from inches to 2-3 feet from the wall.
Guys thanks for all the feedback!
I forgot to mention my speakers are Yamaha NS5000 and they are about 1 foot off the wall. As for the separation I know its not ideal but i just don't have much space because I have a door to the left of my left channel and my sub to the right of the right channel.

My right sub is at the front right corner. My left is at the back left corner. Both firing down the long axis. I guess if I had 4 smaller subs I might get a better response than 2 subs. I don't have a ton of space to move my subs around because of other items in the room.

Would changing the firing direction of the subs make a difference since bass waves below 80 as you said are non-directional. I might be able to move one of my subs to a position where it is to the right of the listening position firing at the center of the room. I can't really do a crawl again because of so many other things in my room (it is a bedroom).
And I guess I am kind of stuck with the bass without subs because to fix it there I would have to I am guessing pull my speakers out further which I can't do right now.
The acoustic fields gentlemen says subs in the corners is a big no no by the way.
https://www.youtube.com/watch?v=Gb_yOIuLc_Y
I wonder if diffusers behind my speakers would help? In addition to bass traps. Because I can't pull my speakers out further than a foot off the front wall.
Diffusers work based on wavelength. That's why you see those panels with wood blocks of different sizes at different heights. Each frequency has a wavelength. The higher the frequency the shorter the wavelength. Little blocks of wood can diffuse high treble because the wavelengths are on the order of inches. The low bass you're concerned with is at a wavelength on the order of some tens of feet. Ten to forty or more feet. In order to work your diffuser needs to be at least that big. This is why we have the low bass problem in the first place: even an entire room is small compared to low bass waves!

This is also why bass traps are no solution. They can do something, just not much. The only real solution is a room that is multiples of the lowest bass frequency. A room a hundred or more feet on a side. Think about the phenomenally good bass you have experienced at a rock concert. Because: big room! The next best solution is lots of subs. Each sub still has the same mode problem. But with so many each one puts out less bass, so its mode is small, they are in different places, and together they average out to exceptionally smooth powerful bass.


Miller so in a smaller room you cannot get good bass without subs ?
...so in a smaller room you cannot get good bass without subs ?

Yes you can but you have to work harder at achieving the goal. Your room width is the same as mine and about 3 feet less in length than mine so I know it can be done. To start, get at least one if not both subs out of the corner. A couple folks posted links to videos that show you how to place subs using the crawl method. Try it out, you might be surprised. I use the method referenced by Atmasphere, but you can accomplish this with 2 subs as well, and they don't have to be big subs.
Most speakers don't provide that 'room lock' bass in my room that I hear in shop demos. I can't explain why but I had a pair of speakers on stands I couldn't get any bass from so due to the insanity of this hobby I flipped the stands over, mounted them to the ceiling than mounted the speakers to that and GOT the best bass ever! Why when the speakers were the same distance off the floor as they were off the ceiling and the same distance from the corners did it make such a huge difference? IDK, but it was embarrassing when visitors would bump their heads on them walking by. lol.
Often the best sounding systems by dealers have the speakers in the most unconventional places and if you don't have the freedom to place them where they sound best you're stuck with bass traps and digital eq along with your sub(s).  Nice speakers, seriously wanted to give them a try.
Thanks guys. Interesting anecdote about the speaker flip thing, heh.
Anyway I did some measurements. Both with subs, no subs and at my listening position and at a position that is 3 feet back and 3 feet from the left wall.
www.diabolicaldesign.net/Measure.jpg
Please have a look
See the null ~ 120 Hz ?  Makes me wonder if your speaker/sub polarity is not backwards.  Flip and re-run. 
Miller so in a smaller room you cannot get good bass without subs ?

Correct. And small means small relative to wavelength. Since the the wavelengths of the lowest bass we want are 40 to 50 feet or more (depends how low you want to go) then small is anything less than that. Which means pretty much every room in every house is small. 

Look, its pure physics. Even at much shorter wavelengths we have to be clever with speaker placement and use things like diffusers and absorbers to get a nice smooth response. Exactly the same is true of bass, only the methods used have to be physically bigger on account of the physically longer wave lengths involved. 

Notice when you go to a concert in a large dome or hall the bass is wonderfully deep and uniform no matter where you go in the hall. That's because these spaces are large even relative to low bass waves. The waves have room to run and so when they do reflect off the walls its in different directions and times relative to the wave. 

In a normal room, say 20 ft, the leading edge of the wave bounces off the floor, ceiling, and all four walls even before one complete cycle! The darn thing is coming back and canceling itself sometimes right at the woofer! Think about it. 

But the flip side is if you take all this into account and do it right then you can actually have really fantastic bass even in a small room. You just have to abandon the old false paradigm of one or two subs and embrace the physical realities of long waves and use lots of subs. 

Because there's lots of subs they don't have to be big and powerful. Four or five ten inch subs is way better than one 20" even if the one is ten times as powerful. Because the one will create one powerful set of room modes. Bass will be thunderous but only at certain locations and frequencies. You will fight and struggle to tame this lumpy boomy awful bass. Which will not even go that low, by the way. But the four small subs will create four times as many different modes, each much smaller, so the bass will be smooth, powerful, and go really deep. 

DBA subs don't even have to match. Mine are a combination of three different subs. The bass is to die for.  https://systems.audiogon.com/systems/8367
@erik_squires: I only have a delay knob on my subs (PSA V1800). Is that what I should play with? I don't have polarity or phase controls.
@millercarbon Oh wow different subs? I thought I wouldn't be able to do that. Which subs do you have. Do you find they give you clean bass with your speakers and are fast enough to keep up?

Here are measurements during each sub off and then both on from the listening position:
www.diabolicaldesign.net/subs.jpg
I wonder if diffusers behind my speakers would help? In addition to bass traps. Because I can't pull my speakers out further than a foot off the front wall.

Lets say the diffusers, and traps and everything killed all the reflective problems, you have, what do you have left? 

Only what's coming from the baffle face, even the back side of a dipole would be killed.

So taking what MC said the wave lengths and killing the rest, you can only do a few things. Make a little bass everywhere, very even, very controlled, but everywhere. That's out, can't clutter the floor.

or You could EQ the bass, why? Your killing the reflective excess, so you can increase the actual bass in the seated position. BUT you can't kill all the reflective surfaces, so that's kinds out.

But the bass comes after the mids, and the tweets before the mids, so what do you do? You HAVE to move the speakers. NOT I can only move them this much, there is no other option. If you want to fix the problem..

The bass needs to be closer to you, the mids and highs need to be further away. TIMING.... they (lows mids and highs) need to arrive at your ears, at the same time.

Regards
Delay and phase in reference to a subwoofer are the same thing. Delay in this instance is the more accurate description of what the control is performing.

You have an unconventional listening space which may require an unconventional solution. Try what ever you can think of and see what happens. Aim your subs in different directions, Raise them off the floor, Raise them off the floor at different heights to each other, change the low pass filter setting (crossover point). There could be some cancelation caused by the interaction with the woofer in your mains. Try asymmetrical crossover points. If your speakers have ports try plugging and unplugging in various combinations. I'm sure there are other things you can try all you can do is see what happens.

In my system in a 14 x 10 x 9 room I have one sub sitting right next to the listening position aimed towards the main speakers and another sub almost directly behind that sub and aimed 90 degrees from it.
OP:
In general, your measurements show the two are not integrated. You want the bottom and upper part of this graph to merge completely seamlessly.

I only have a delay knob on my subs (PSA V1800). Is that what I should play with? I don't have polarity or phase controls.

My suggestion:

  1. Minimize the phase setting.
  2. Flip the wiring to the main speakers to compare.
  3. Pick whichever wiring gives better response.
  4. Adjust the phase dial from that point to eliminate null.
  5. Adjust sub level to elimiate step between sub and mains.


Guys thanks for all the suggestions. I will try them and keep tweaking. I did play with the delay of the subs based on what Tom wrote at PSA where he said you should add about 1msec delay for every foot away the sub is from you. So I have 1 sub that is 3 feet away facing me and 1 sub in the back left corner that is 9 feet away so I did adjust that. Can't really tell if that made a big difference though. Maybe slightly better.
But I think Erik is right that the only true way to fix this is to move my speakers around and likely get them more off the front wall. Right now they are about 10 inches off the wall and they probably need to be moved out more.
Here is updated measurements and I zoomed the axis so you can better see the contours.
@audiorusty, interesting idea about the variable crossover points on the subs. That seems cool. The acoustic fields guy also recommended subs at different heights to make things smoother.

www.diabolicaldesign.net/measurefix.jpg
I did play with the delay of the subs based on what Tom wrote at PSA where he said you should add about 1msec delay for every foot away the sub is from you. So I have 1 sub that is 3 feet away facing me and 1 sub in the back left corner that is 9 feet away so I did adjust that. Can't really tell if that made a big difference though.

Of course not. Because he's full of it. The one foot per millisecond is based on being approximately the speed of sound in air. One foot per millisecond.  

There's a couple times this matters. One is side wall reflections. Side wall reflections that arrive within about a 3 to 5 ms window of the direct sound have a very bad effect on imaging. That is why we want our speakers a good 3 feet away from walls. The other time is with movies. If the screen is several feet closer or farther away from you than the speakers then the people talking on screen will be out of synch. That's it. 

This rule of his is not applicable to subs for the simple reason human beings cannot even hear low bass at all, at less than a full wave. Since a 20Hz wave is 1/20th of a second that is 50ms before we even hear it. So when it comes to subwoofer bass you can forget about timing. Its simply not a factor.
Humor me.  Turn the sub off and send me a pic of your mains full-range.
@millercarbon thanks man, I will play with it.
Oh and I forgot to measure the front wall to the front baffle (I was doing to the back of the speaker). My speakers are 28 inches away from the front wall.
I am gonna try to play with the toe, lateral movement and the forward and back movement until I get the low end fuller while retaining the rest of the range. And once I hear something good I'll measure and compare. I think you guys are right in saying placement is the key here.
@erik_squires Its in the picture above called Measurefix. The purple line is with no subs (legend on the top left). I also tried doing 1 or the other sub as well.
Here I did a curve with just mains, no subs and bit more smoothing at 1/12.
http://www.diabolicaldesign.net/nosubs.jpg
Here is another comparison, this time with left sub, 2 subs and no subs and a bit more smoothing (1/12) to make this more clear.
www.diabolicaldesign.net/smooth.jpg
What about running a DSP module just on the subs?  A friend did this with great success.
Look closely at phase between mains and subs. If you don’t have the phase right, it cuts out a hole where they should overlap due to cancellation. This same issue plagued me for a while, and while phase may not be the total solution, it’s a strong cause of “where’s the bass?” I found the lowest bass was dependent on the placement more, while the frequencies near the x-over point were very sensitive to phase. 
Here is another comparison, this time with left sub, 2 subs and no subs and a bit more smoothing (1/12) to make this more clear.


Great pic.  Um, you definitely have complications.  There's an increasing trend from 60 Hz to 1 kHz.  This should be flat or descending.  Also, notice the regular ripple starting at around 6 kHz.  That indicates regular reflections in the mid-treble.

Essentially you have way too much mid bass to mid energy. If this is a highly reflective room that would explain it. Before adding the sub, fix up your mains and room.
BTW, the one thing I don't see evidence for is the need of bass traps.

I know the world will be shocked, but this is not the case here.  What you need is the slope from 1kHz to 10kHz to go further down.  The problem is not, as often the case, that you have too many room modes.  The problem is the relative output from 100 Hz to 1 kHz is far too low relative to the rest, and that is making your system feel like there's way too little bass.

Fix that and you may not even want a sub. :)  As I wrote in my blog:

But wait, you are trying to fix a bass problem right? Well, what if the problem is not too little bass, but too much midrange or treble? A live room will sound much brighter. Reduce that and, like magic, the bass appears like a Spanish galleon emerging from the ocean at low tide.

I had a similar issue.. Solved.. Do you have 3 way tower speakers ? if so, try this.. I first found the perfect toe in.. Then I placed 3/4 in rubber pads underneath the front of my speakers to tilt it back some..  Improved my bass a lot.. Sounds crazy, maybe ? It works for me..  Note that my bass driver sits towards the bottom of the tower.. Good luck.. hope you find a solution
Good thing you are measuring your room/system. Terrible curves unfortunately. I would skip the subs or cross them at 30-40 Hz and use the Roon digital equalisation. Preferably using convolution filters. You seem to have a "loaded" room so I don't think acoustical treatment will give you much help.
Probably I need to keep playing with speaker positioning as you guys are saying. I'll try to keep moving them around. Right now they are 28 inches off the front wall with 10 degree toe in.
You can play with them till the end of time, no amount of moving them around will have the least effect on the underlying physics. Been there. Done that. Found a better way. Don't do that no mo.
OP:
We haven’t discussed your main speakers. What are they and where are they? It is possible they need more rear wall reinforcement. You also, 100% need mid-high frequency damping and dispersion.

If the former is true, moving the speakers towards the rear wall should help reduce the bass-mid imbalance. That is, you should get more bass out of these speakers.

Some one else mentioned Roon. Yes, if you have access to DSP and the other suggestions are not available to try first, this can help, but convolution filters are WAY overboard here. Simple parametric filters will fix everything you have, and not overtax your server.

However, room acoustics are the first place to go. You can’t fix your mid-HF hash with an EQ.

Also, the sub response honestly looks really good.  I was expecting to see a lot more garbage.  This is why I am suggesting that for now, you ignore it, and fix the mains.  That's where your problems are, and there's nothing you can do in the sub to fix this. 
@millercarbon: Ya I am not against a bass array. I would have to get probably 2 more subs and they would have to be smaller, maybe 12s or 14s because I am really running out of space. It would be great though if I could solve this without subs. I wonder if bass traps would allow me to turn my subs up more while still retaining cleaner bass.
@erik_squires : Ya moving the speakers around, forward, back, side to side seems something worth while and free! You mentioned dispersion, do you think dispersion panels behind the speakers would do anything  or be of any value ? My friend is selling two really nice 2 foot x 3 foot wood panels that look extremely well made for $400 usd for the pair.
Hi OP:

Use the tools you have. Move the speakers back to see if you can find a better bass balance. Next, see the tooth like ridges in the high frequency? That’s evidence of regular reflections, possibly even slap echoes.

Yes, diffusion is a great idea, but at $400, I suggest you call GIK Acoustics and see what they could do in your budget. I mean, I am sure these are find diffusors, but for maybe a little more you might be able to get a lot more room treatment from GIK. They have an online service where you can send them pictures and room measurements. I strongly suggest you take advantage of it.

So, this is the order I recommend you work:

  1. Main speaker placement
  2. Room treatment
  3. EQ
  4. Subwoofer

For 3, the Schiit Loki ($149) may be just perfect. Only after you have sorted this out should you spend too much time attempting to integrate your sub.  I can't tell you how much more important 2 is going to be though. 

Again, what speakers are you using though?  This may provide clues.

Best,

E
It would be great though if I could solve this without subs. I wonder if bass traps would allow me to turn my subs up more while still retaining cleaner bass.


So here's how that works. In order to get even bass the conventional way you have to turn the subs up loud enough to bring the drop-offs up to where they sound good. This means having way too much energy at other frequencies. So you try and damp that out with traps.  

But the traps and loud spots are only in certain places, while the excess energy is everywhere in the room. This physical energy excites the walls, the whole room, and physically dissipates over time. Its the dissipation of this energy that smears and muddies bass response. There really is nothing you can do about it. More and more traps leads to more and more EQ and you just never get enough. 

What's funny is everyone knows the last thing you want is to have an overdamped room. A certain amount of acoustic reverb is nice and helps create a sense of spaciousness. Too dead and the room sounds... dead. Yet that is exactly what a lot of these bass trap people are having you do, only with bass instead of midrange and treble. So you don't notice it when you walk in the room the way you would with panels all over the walls that kill the sound. But its the same thing, only lower in frequency. 

You don't need 12" or 14" subs. Those are for when you haven't figured out the answer is more subs and still think its more sub. That "s" makes all the difference in the world. You can easily use 10" subs. I have four of em. Its not how big. Its how many. And where. Dispersed asymmetrically around the room. 

This will cost less, take up less space, and work better than all other options. I really cannot think of a single objection, other than the mental effort required of any new idea.
How are you all connecting multiple subs to your electronics?