Total bass suck out at 40hz

Good work! If you play with the phase of the rear (or side) subs you might be able to kill that slight 40Hz peak too.

A little bit of an update, I added a fourth sub to the room. I now have very audible bass from approximately 26 hz up. The fourth sub was not as big a jump as going from two to three but it is an improvement. I now a a slight peak at 40 hz instead of no sound at all but overall the results are vastly better than what I had before. Thanks, to all who chimed in with actual advise, Allen (Mizike).

Three cheers for rvnye2! Isn't that something? People just do not realize what happens to an anechoically flat loudspeaker when you put it in a room. Millercarbon would vomit if he could see how his system measured. Actually everyone would. +- 10 dB peaks and valleys is par for the course. That is twice or half as loud! Whatever you think the degradation in your signal might be converting it to 24/192 digital the improvement made by digitally equalizing and timing your system drastically out weights it. You see this comment time and time again in reviews of the best room control units over the years. It reminds me of when cycling was moving from manual to syncro shifting back in the late 80s. "Real cyclists don't need syncro!"

When I figure out how to photograph my computer I will display measurements of ESLs in a 16 X 30 X 8 foot room along with pictures of the system.

I've had some pretty nice systems throughout my lifetime.  When COVID struck and I had some time at home I decided to get a digital sound processor.  I fiddled for weeks and tri-amped my speakers with a relatively cheap Rotel 6 channel SS amp.  I got a microphone and some software to record the frequency response.  WOW, what a learning experience!  There were a lot of peaks and valleys in the frequency response.  I did some correction with the DSP, and did a time delay to align the speaker drivers.  Adjusted the location of speakers in the room, and did some room treatment.  The results were incredible.  This is the best sounding system I've ever had.  And I can still tweak it to sound better.

Before you spend $2K on those speaker cables, think about measuring your frequency response and making adjustments to get it flatter.

no matter what you think tony1954, I could not possibly care less what you think. If you feel you're so much better than me, please feel free to explore options for where you can take it, and what you can do with it. 

@millercarbon
No matter what you think, arrogance is not an positive attribute.If the rest of us are beneath you, please feel free to explore other options.

Could one of the speaker cables be reversed?

try putting the subs on the wall behind your listening position and have them fire looking towards the fronts. Reverse the polarty on them and you will get a smoother response than you now are getting.

Yes sir, I actually know why it works, I was being a wee bit facetious, thanks for you thoughts.(Giddy with delight)

who would have thought that it would be so absolutely awesome. I don't know why it works but it dang sure does.

Actually the explanation for why is posted above. And also explains why the 4th will help too- but beyond that is a vastly diminishing return. Glad you're getting it sorted out!

Ok, time for an update. First off I spent some time moving the two subs I had around. I finally got some bass output at 40hz but it was 12-13 db down from the rest of the band. I ordered some Y cables from Blue Jean and they came today. I have a big ass HSU 15" sub for HT use that I moved to the far end of my long room. I put it in the corner, 4" from the side wall and 10" from the back wall facing into the back wall.(by back wall I mean behind my chair 24', very long room). Holly smokes Batman, who would have thought that it would be so absolutely awesome. I don't know why it works but it dang sure does. I have full artriculate base output from 20hz up through 60hz. I have all the crossovers set @ 55hz. The volume went WAY down on the two Rythmik subs the HSU matches them at approximately 1/3 volume. It's so good I can't believe a forth subs will make it better.(I'm getting one anyway just to be sure) I forgot to say one "front" sub I placed on a extra heavy duty steel & wood table 34" off the floor straight behind the left speaker facing into the left corner about 2.5 feet out. Could not be any happier with the results.Thanks again to everyone that gave tips and tricks and real advise, sincerely, Allen.

Thanks for your input, greatly appreciated. I am running two subs, seams like more is the next step.

I have audible base to below 30 hz, just none at 40. My room is long and narrow, equipment is set up on narrow wall. 14' x 38'.

@mizike   The phenomena you are dealing with is called a Standing Wave. When the bass comes out of your speakers, before you can even hear it (the ear can't hear anything until the entire waveform has passed by it), its bounced off of the wall behind you and your listening chair is positioned such that its out of phase with the incoming waveform at 40Hz.


You can do room treatment and also electronic room correction using some really sophisticated software, but you won't have much impact on the standing wave.


What room correction does is actively figure out how the room deviates from flat and equalizes it. the problem is no matter how much power you put out at 40Hz it will get cancelled, so room correction won't work.


Room treatment is the idea of installing bass traps to prevent the energy bouncing around. The problem here is that as the bass notes change, the places where the incoming and reflected wave energies combine and re-enforce (rather than cancel) changes, so unless your bass traps can move around dynamically with the music, this won't work either.

But running multiple subs does (this is the distributed bass array you've been hearing about on this thread). By running multiple subs you are able to break up the standing waves, and thus have even bass throughout the room.


People on this thread have been talking about nodes, nulls and modes- these are references to the behavior of standing waves. I'm only putting this post up so you know how these terms relate to what you are experiencing. Good Luck!

At a speed of sound of ca 330m/sec, a 40 Hz wave length estimates at ca. 8.3 m, half wave = 4.15 m, pretty close to 14 feet.
I.e., you experience a text book suck out (cancellation of half wave by reflected half wave of opposite amplitude).
As others have stated, move the subs around, asymmetrically.
Good luck!

I do have them set up symmetrically I will try that first. I was thinking the swarm is the way to go. Just not sure how to implement more subs with long cable runs. Is 30' of single ended cable on a sub a bad thing? Random is better, this is what I am getting mostly.
Symmetry is death for bass. All symmetry does is ensure even more modes and suckouts. What you want is asymmetry, so the modes are all different frequencies and locations. More subs helps even more with this. More subs also means each one has to put out less total volume, because they all add together. This further smooths out response.

Long runs are no problem at all. Wire quality is much less important with subs. We just aren't that sensitive to fine differences in low bass the way we are with midrange and treble. Biggest problem guys have is getting their minds around just how different low bass is and how important it is to treat it completely differently than everything else. 

My DBA is four subs driven by 2 Dayton amps, and a 5th powered Talon Roc sub. You can easily hook them up in a chain one to the next around the room. https://systems.audiogon.com/systems/8367#&gid=1&pid=10 My one pre-out goes to the Daytons, then from one Dayton to the Talon Roc. You could go from pre amp to sub to sub, etc around the room. 

Start with one near each corner facing the wall, with each one a different distance from each corner. Its so simple when you do it you will be shocked that there's so few telling you about this. Its totally the way to go. Everyone knows it. They just won't admit it. 

The only frequency response chart I could find for the NS-1000M inexplicably stopped at 200 Hz, but according to that chart the NS-1000M starts to roll off at approximately 630 Hz with 200 Hz being approximately 6db lower. According to Hifi News test figures 53 Hz is another 6db down from 200 Hz which leads me to believe that 40 Hz is rolled off even further.

The selected setting on the F12's low pass filter should be either, the 3 or 6db down point of that filter so when combined with the natural rolloff point of the main speaker makes a kind of quasi crossover.

It might be worth a try setting the low pass filter at say 80 Hz and then adjusting it back to see if there is any improvement in your 40 Hz output.  

Wow lots of really good stuff.
before you ran your test did you notice anything wrong. I believe its
a null in your speaker crossovers.
or room acoustics, your speaker cables play a big part in your system as well. I doubt your speakers will reach 20hz nor would you hear it. But you should feel it, 
Even if you move them around you’ll lose some else. Do you use a line conditioner? Do you use an equalizer ?Many factors come into play, Put all your test equipment away, and use the best test equipment there is, your ears. Enjoy your music! GT
alien tweek audio

Is the test tone playing at 40hz or is it a dead track? Try another speaker.

If the file is good, then check to see if your woofer is moving at 40 hz. 
This is why I always measure frequency decades one foot from each speaker before I measure at the listening position.

Yes mijostyn, I have come to that conclusion as well. I do think I will build a platform for one of them just to try that and see what it does. I can tell a definite volume gain while playing test tone by just leaning forward and down so I tend to agree with your thoughts on moving closer. A little more like near field listening.

Mizike, it is not uncommon to have room modes and boundary effects combine resulting in nulls of 30 dB or so.  That pretty much constitutes a total suck out, as you put it.   I assumed you have 8 ft ceilings and put your room dimensions into the amroc room calculator.  You have 4 axial and tangential room modes between 40 and 50 Hz.  Those will be broad bands and will merge into on another, resulting in a deeper null.  It's possible you have boundary cancelations due to speaker and listening position adding to this problem.  If you google Speaker Boundary Interference Response, you will find SBIR calculators that will help you figure out if speaker position is adding to the problem.  You have gotten a lot of good advice above, but I suggest you approach this systematically.   Also, you must be aware that you can't just improve the 40 Hz null without impacting other frequencies.   What you want is not the flattest 40 Hz response.  What you want is the flattest response from 20 Hz up to about 150- 300 Hz.  If you decrease your 40 Hz null by 20 db but create a null of equal magnitude at a different frequency, what have you accomplished?  So as you work on improving the 40Hz null, pay close attention to what else is going on at other frequencies.

First, optimize the positioning of your Yamaha mains with the subs turned off. Without explaining why, I would try you speakers placed with the center of the drivers 34" from the side walls.   Because your room is atypically long, an optimal distance from the front wall and an optimal seating distance from the rear wall won't be practical.  You are going to have to play around with this.

Second, optimize your seating position.   I would advise not placing your seating position in the center of the room.  16 ft or closer to the front wall, or else 23 ft or further from the front wall will probably work best for you.  Once you optimize the seating position, move the speakers again a moderate distance forward and back, and make sure they are still placed optimally.

Third, optimize sub placement.  Asymmetric placement is best.  If you set your crossover at 80Hz, you won't need to worry about loss of image or time related aberrations.   If it were me, I'd try at least one of the subs elevated off the floor, perhaps as much as 4 ft. Try one in a front corner, then try it centered between the speakers.   Try a sub along a side wall out as far from the front wall as you can get. 

I encourage everyone who gets into this to think about investing the time required to learn to use and interpret REW.  The ability to rapidly run full spectrum sweeps makes room optimization and speaker placement much easier once you get past the frustration of getting started. 

Mizike, leave everything as it is for now. Have you measured at different points in the room? It sounds like you are measuring in a null. Putting subs next to your sofa might be great for Movies but really bad for Hi Fi.
Subs in corners is alway a good idea as long as you can match them in time and phase with the satellites which without digital bass management you can not. So, with a point source system the best way to set up two subs is against the wall between the satellites on a radius from your listening position. This means that all speaker are the exact same distance from the listening position. Assuming none of your equipment inverts phase you should be pretty close. You will still have node issues in the room. The easiest way to deal with this is by moving your listening position forwards or backwards to a position were the bass sounds best.
without room control that will be the best you can do unless you are ready to add two more subs. I would keep them on the same radius but against the side walls. Hope this helps  🥴

I do not have enough cable to place subs at my listening chair. My room is very long at 38' only 14' wide. I bought a pair DL Labs sub cables here on the Gon at 12' each, also hampered by outlet locations. 

I wonder how many have actually done any of the stuff they recommend. I did the sub crawl. Subs wound up right back where they were, along the walls, asymmetrically different distances from the corners. Tim did the crawl, his are in the corners, same thing. Its no big mystery. Bass is ALWAYS strongest in these locations! 

Want good bass? Put a sub near each corner. 

We now return you to your regularly scheduled missing the point comments. 

Sub crawl. Put one sub exactly at your listening position. Play the 40 hz tone on continuous repeat. Get down on your hands and knees, and carefully cover the whole of the listening area--some kind of grid pattern is good so you know where you’ve been. Mark any spots where you can actually hear the tone. Hopefully there will at least two. Move the two subs to the marked positions, and return to your listening position to check result.

I have just went through the entire range of phase adjustment, moving the nob three clicks at a time and playing test tones up to 60hz. Above 60 nothing really changes no matter what I do.I have made the mode better but it is still there, down 8/9db from 30hs and 5/6db from 50hz. (i have some loss of volume at 50hz as well, although not nearly as much) I do notice a definite gain if I move my head and/or meter forward and down towards the floor. Maybe I should just get a much shorter chair. Or consider building a platform for one or both subs. 

Regarding phase, there are a several ways to adjust. Here are the two I think are best. In each one, you run ONE speaker and its associated sub at a time:

1. Put a mic at the main listening position (MLP), run a sweep, and analyze with something like REW. Move the phase control to get the smoothest frequency response (FR) around the xover frequency. This is the most direct and reliable way, in my opinion.

2. Sit at MLP, having reversed speaker leads of the main to put it out of phase. Play a tone at the exact xover frequency. Adjust phase control to give the best null at that frequency. (Remember to put the speaker back into phase when done!) This is the best way when you don't have the measurement equipment for method 1.

Any phase adjustment depends on positions of main speaker, sub, and listener. If you move anything significantly, it will change, so needs to be redone.

Hope that helps.

They do have continuously variable phase controls. I;m not sure what to try there, I guess trial and error. I have spent the last hour or so just moving them around randomly and re-testing. I have gotten audible base in the 40hz range but it is still down 13db from the 30hz tone. So do I have a peak or a null? I have 90db at 30hz and 89 at 20. The 30 hz tone is clearly audible the 20 not so much but I can feel it well. Back down to play with the phase control and see what that does. I'll be back up later to see if there are any more suggestions. And thanks to everyone who has tried to help, I really appreciate it, Allen. (AKA Mizike)

A 40 Hz null is typical of a room node, as noted. Here’s what worked in my room, where I use two subs and had a 43 Hz null. I moved the subs, measuring at each position. Putting furniture glides ("supersliders" under the feet helps with moving.) The position where the bass null was minimal put the subs behind the listener, near the rear corners.

I agree with others that a distributed bass array of at least 4 subs is a great solution, but I didn’t have room for that.

I also agree that asymmetrical positioning of the subs can help, but I wanted to keep them symmetrical and running in stereo.

The Allison effect (floor bounce cancellation) was mentioned; my impression is, it is typically higher in frequency (100-300 Hz).

SBIR suckout at 40 Hz might be a factor with speakers 7 ft from a boundary, more so for speakers 7 ft from several boundaries.

Oh, one other thing . . . do the subs have continuously variable phase controls, and have you adjusted them for smoothest FR? That can be an important step in many cases. As can be changing the xover frequency, especially if running the mains full range.

I hope that helps.

Are you saying that wherever you're standing or sitting within the room, there's no 40Hz.  Have you tried the subwoofer crawl (Google for details)?

Try a 30’ Blue Jeans cable - pretty good shields/ quality for not a lot of $$ the RF and other trash in the system will determine if you can get away w 30’

Three EZ yep natural roll off still yields some energy into the room and just as significant load on your amp

I do have them set up symmetrically I will try that first. I was thinking the swarm is the way to go. Just not sure how to implement more subs with long cable runs. Is 30' of single ended cable on a sub a bad thing? Random is better, this is what I am getting mostly. 

Except we can get there with one word: mode

Thanks for pointing out the Qobuz test tones.  I found it interesting that I can hear my speakers at 20Hz despite they are only spec'd down to 25Hz.  Perhaps that's common.  Apparently 15KHz is the top of my hearing range.

Based on the measurement I sent them, REL actually said the solution isn’t more subs, but to get the main speakers positioned correctly.

Sad to see so many who have been here long enough to tell the OP exactly what is going on, and yet they don't. I don't get it. What explains this reluctance to learn?

mizike, this is very common. Bass frequencies bounce around the room, canceling and reinforcing at different points depending on the frequency, room dimensions, and speaker locations. All you can do is move them around trying to find locations that are less lumpy. Symmetrical locations are worst, because they'll double up the cancellation and reinforcement. As you noticed there's bass lower than 40, just none at 40. Move them around you will probably be able to get bass at 40, but then none at 30.

The solution is more subs. This is what everyone here knows but shamefully is keeping from you. Do a search for Distributed Bass Array, DBA, or Swarm subwoofer system. That is the answer. None of the other stuff they're talking about is anywhere near as good. And they know it.

2+2=4

mizike,
Yes, I'm referring to moving the main speakers closer to the wall behind the speakers. I plan on moving them in small increments and taking measurements to see if moving them helps eliminate the 40hz suck out.

ricred1, are you talking about main speaker placement or sub placement? I am thinking you mean the main speakers need to be closer to the back wall.

I am testing with the subs playing, and yes I have good audible bass to about 25hz, just nothing with the 40hz tone playing.

Mizike, is there anything below 40 Hz? If not then that is just were your speakers run out of gas. Very few speakers make it below that. If you want to go lower you will have to cross over to subs.

mizike,
I had a guy measure my room using REW Room EQ Wizard. He said, "my speakers have real bass output down to 22hz in my room, but I have a 40hz suck out." I have dual REL G1 MK2 subs. My room is treated with GIK products. I sent the measurements to REL and they told me the suck out is the result of speaker placement and I should move them closer to the front wall. I plan to start experimenting with speaker placement in the next couple of days.

I have audible base to below 30 hz, just none at 40. My room is long and narrow, equipment is set up on narrow wall. 14' x 38'. I will try moving the subs around some. I do not have real long cables so that may be a problem. I was reluctant to get super long cables. I always thought the shorter the better with single ended cabling. 

40 hz, is the sub set higher than 40 hz. Set it to 40 or below, and place it.
2 sources of 40 hz in the wrong place, comb, cancel, suck out, whatever you want to call it.

Maybe, kinda, sorta?

Regards

Vandertones ( a free download ) are calibrated for the RS analog meter - do yourself a favor and use those.

post the results, do one channel then the other, then combined.

note Vandertones are on typical room mode centers not octaves,

welcome to rare air an audiogon poster with and using an spl meter - u are light years ahead

The problem is when you have your subs placed symmetrically.

My suggestion is, put 1 sub in your listening location, then measure where the bass is best.  When you find htat, put the sub there.  Problem solved.

Also,  the imm-6 from Dayton does a better job than the RS SPL meter.  Around $20.  Use it with Audio Tools on Android.

https://amzn.to/35VgIKJ

Most speakers with dynamic woofers will have the best bass (flattest) by placement against the front wall. And the worst farther out into the room. This is the "Allison Effect" - discovered by noted audio engineer Roy Allison.

Try moving the NS1000's right against the front wall. I assume they are on stands so your ear level is about the middle of the cabinets. Play the 40hz tone and start listening near-field at around six feet. Move back gradually until the 40hz tone starts to diminish. That will be the best listening spot for bass.