Room Treatment Question, lost the lowest bass notes.

Don't know from bass room modes.
Nodes can be overcome by
1 Bass traps up the wazoo with one or 2 well places subs. Use REW for that.
2 Moving speakers and or seat until balanced at listening position
OR
3 Abandon all hope of using the room for anything besides A/V. Get out your wallet and hire a home decorator to find a place for 4 subwoofers. Probably in lieu of seating.,

Honestly, it hardly matters which sub you use. I have three different types in my room. https://systems.audiogon.com/systems/8367 They all work together perfectly, and blend seamlessly with the mains.

The problem with EQ is you can only get it flat by putting more bass into the room. Bass energy takes time to dissipate in the room. Putting more bass into the room with EQ always results in slower muddier bass. So then you have to remove the extra bass with bass traps. When instead you could use multiple subs. Because there are more each one can put out less bass. It all adds up to the correct amount of bass. Its smooth because they're in different locations, greatly reducing the amplitude of the modes. Its just a way more elegant and effective solution all the way around.

+1 millercarbon

     It's also very important to realize that equalizers and automatic room correction programs and gear are not nearly as effective as multiple subs are at improving bass performance in a given room.
     Room correction (mics to measure room bass frequency response,  parametric equalization to adjust the bass  and amps to adjust bass output) is very effective at reducing the bass level of bass peaks in the room, since these bass level reductions at specific bass frequencies result in reduced overall bass amplifier power demands, but room correction is much less effective at increasing the bass level of bass dips in the room, since these bass level increases result in increased overall bass amplifier power demands, and bass amplifier power is limited.   
     In other words, automatic room correction has the unlimited ability to correct bass peaks and a limited ability to correct bass dips and nulls. It's also important to note that automatic room correction is going to optimize the bass at a single position, usually at the listening seat where the mic is placed to measure frequency response, which actually causes the bass response to be worse at other spots in the room and uneven in the room overall.  
     The beauty and elegance of utilizing multiple subs as a bass solution, is that it is based on the scientifically proven and reliable principles of how humans actually perceive bass sounds and tones in normal, smaller, domestic-sized rooms containing room boundaries (floor, ceiling and walls).  For example,utilizing the following scientifically proven and reliable principles or facts:

1.  Humans generally cannot localize bass sound tones at frequencies below about 80 Hz.  This means we're unable to determine where a bass sound tone is specifically originating from if its frequency is below about 80 Hz and we perceive all of these bass sound tones as mono, and we're unable to perceive bass tones in stereo below this 80 Hz frequency threshold.
2.  Humans don't even perceive sound at all until our ears detect a full-cycle sound wave, the brain processes it and then creates a perception of a sound tone at the detected amplitude,frequency, tone and pitch.
3.  Full cycle bass sound waves are omnidirectional and extremely long (a very deep 20 Hz sound wave is 56' long), full cycle treble sound waves are highly directional and quite short (a 20,000 Hz very high 20,000 Hz sound wave is a fraction of an inch long).  The length of full cycle sound waves are proportional to their frequencies; the lower the sound tone frequency the longer the full cycle sound wave and the higher the sound tone frequency the shorter the full cycle sound wave. 
4.  All sound waves radiate outward, the long bass soundwaves in an omnidirectional pattern and the much shorter midrange and treble sound waves in a highly directional pattern, and continue on their outward path until they are absorbed or diffused by acoustic treatments, run out of energy and decay, encounter a room boundary (floor, ceiling and walls) and are reflected and redirected in a new direction or collide with another sound wave travelling within the room.
5.  Since the main speakers and subs are continuously launching new soundwaves into the room, and all these soundwaves are constantly being reflected off of room boundaries (floor, ceiling and walls), sound waves inevitably collide or crash into each other. Whenever these soundwaves collide with each other, what's termed a "room mode" is created in the room at the specific spot in the room that the collision occurred.
6.  When the shorter and highly directional midrange and treble sound waves collide with another soundwave, depending on the angles of the collisions, the room modes created are typically perceived as a midrange or treble 'peak' (overemphasis), a midrange or treble 'dip' (attenuation) or a 'null' (midrange or treble cancellation or absence).  If these midrange and treble room modes are left uncontrolled by acoustic room treatments/panels, they are typically perceived as an 'airy' or spacious' quality.  However, these midrange and treble sound waves are also more easily controlled with strategically placed absorbing and diffusing acoustic room treatments/panels that reduce midrange and treble room modes at the designated listening position.
7,  When the longer and omnidirectional bass sound waves collide with another sound wave, depending on the angles of the collisions, the room modes created are typically perceived as a bass peak, a bass dip or a bass null/cancellation/absence.  However, these bass sound waves are much more difficult to control with strategically placed absorbing room treatment acoustic panels and traps, which often results in bass room modes at the designated listening position and elsewhere in the room.
      Finally,  I've reached the point, in this essay of a post, where it's appropriate to explain why and how utilizing multiple subs as a bass solution is such a beautiful and elegant solution:
     I've already detailed why bass acoustic room treatments and bass room correction software and gear are insufficient and poor bass solutions.  The beauty of multiple subs as a bass solution stems from the fact that it doesn't try to reduce the number of bass modes in the room, but rather and counterintuitively, its goal is to increase the number of bass room modes in the room.  The solution relies on the facts that bass is cumulative in a room  and, when multiple bass room modes exist in a room, our brains react and process this sonic chaos by summing and averaging the bass by frequency and creating a perception that the bass is powerful, solid, fast, smooth, detailed, dynamic and natural. 
     These multisub benefits begin to be realized, at a single designated listening position, with as few as a pair of properly positioned and configured subs.  
    Utilizing 3-4 subs, positioned in an asymmetrical distributed bass array (DBA) manner and optimally configured, results in even further enhancements to these multisub benefits along with extending them throughout the entire room, not just at a single designated listening position, and even better blending of its near state of the art bass performance with virtually any brand, model and type of main speakers.
     I believe this qualifies the 3-4 sub DBA concept as a beautiful and elegant bass system solution.  I can also personally and definitively state that the 4-sub DBA system works like a charm in my room and combo 2-ch music and 5.4 HT surround sound system. 

Tim

Your #6, when my room was brand new and empty, literally just one chair and the stereo on the floor, no room treatment at all, the bare walls created obvious modes at every frequency. There was a test CD with tones and some frequencies you could hear the dips and peaks dramatically come and go as you move around, sometimes in a foot or less. We don't notice this because most rooms are nowhere near so empty, and everything in a room either absorbs or reflects and scatters. So usually we only notice the modes with bass. But they're everywhere.

Hello millercarbon,

     Yes, exactly!  The negative sound quality effects of the combination, of highly directional midrange and treble sound waves constantly being  reflected off of hard and untreated room boundaries (floor, ceiling and walls) in an empty room,  are definitely numerous and obvious but it's also an excellent teaching tool.  
    As I think you're aware, until about 6 months ago I had zero room treatments in my room.  The odd part was I didn't notice any obvious negative sq effects in any part of the audible sound frequency spectrum without them.  The bass was near state of the art in my room with my 4-sub Audio Kinesis Debra DBA system without any bass traps or panels of any type.  The only semblance of bass room treatments in my room were fairly thick wall to wall carpeting and some well cushioned leather chairs and a sofa. 
      I even considered the midrange, treble and stereo imaging sq to be very good at my listening seat using a pair of large, 6'x2', 3-way  Magnepan 2.7QR dipole speakers with no absorbing or diffusing acoustic panels in the room at all.  I believe having my panels positioned over 4' away from the front wall, 2' away from the side walls, along with their being dipole speakers with a figure-8 radiation pattern, were probably responsible for them performing so well in my room sans room treatments.
     But I knew from online reading/research and audio forums, as well as having my room analyzed by GIK Acoustics, that adding the $3,500 worth of various room treatments that GIK recommended would likely be a very good investment.  I was most concerned that the suggested stacked bass traps in all 4 room corners, and the numerous other bass trap panels in the room, might negatively effecting the extremely good bass performance in my room.  But GIK and Duke convinced me that these bass room treatments would do no harm and probably only serve to improve bass performance. 
     So about 6 months ago, I bought the full $3,500 complement of GIK recommended room treatments and had them installed in my room. 
     What were my overall impressions of the sq effects of having all of these fairly extensive room treatments installed in my room?
     Well, the bass still sounds spectacularly good in my room but I don't think it's actually been improved with the added bass room panels and traps.  Sometimes I perceive the bass as sounding especially detailed, 3 dimensional, effortless or just plain amazingly natural and realistic on music or even tv programs and commercials.  But then I recall numerous times, prior to having any bass room treatments installed, that I noticed very similar bass perceptions.  I can definitely state with certainty, however, that Duke and GIK were correct and I don't believe the additional bass room treatments caused any negative effects to the bass sq in my room.
     On the other hand, the approximately 20 added absorption and diffusion panels in my room have had a profound positive effect on the midrange, treble and stereo imaging performance performance in my room at my designated listening position/seat. 
      I believe for the first time that my entire system has been optimized over the entire audible spectrum, from top to bottom while prior I perceived the bass performance only as being optimized and superior to the performance of the rest of the audio spectrum.  Overall, everything sounds very well balanced and a few degrees higher in sound quality.

Later,
Tim