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Dealing with subwoofer Nulls

Hi @auxinput,

You wrote:

... I have a question on the Bag End. Have you actually used the Bag End E-Traps? I have a pretty good room and do not have any major bass ringing. However, I do have a huge hole around 80hz where bass just falls out (this is a room node where I’m sitting). The Double-Bass Array (DBA) configuration that is popular in Germany would probably solve my problem, but it is just not practical for me to do in my room. I have looked at general broadband absorption, Helmholtz resonators, membrane panels from GIK, etc. I tried a pair of GIK full Soffit bass traps, but I didn’t like them -- they seemed to suck all the life/excitement out of the room. I am curious about the flex-range limiter panel on their monster bass traps and the tuned membrane. I haven’t yet looked into spending money on this problem (maybe next year). My initial thoughts were to try the flex-range-limiter option. However, this Bag End E-Trap looks really effective. There is one review where the user was able to restore a big dip in the bass area. Other feedback indicates the Bag End cannot restore big dips - it can only reduce bass peaks/ringing. Do you have any experience with this? ...

You actaully can make nulls manageable with a bass trap or active devices. I do not have personal experience with the Bag End.

I will say that I think your problem with the bass traps was your EQ didn’t go far enough. :) Usually users try to go for flat, when they should go for a declining response, about 1-1.5 dB per octave.

Before going with a second sub, have you tried inverting the sub and your chair? :) Here are the steps I recommend:

1. Put the bass traps back in
2. Place the sub where you listen, then use a measurement microphone to scout possible locations. Wherever the sub’s output is most full and even is the best place to put the sub.
3. EQ the sub so that it has a dropping response from 16-20 Hz. Approximately 1-2 dB/octave will be your ideal.

Best,


Erik
erik_squires
auxinput
1,538 posts
 
Oh, I also built an adjustable Helmholtz resonator.  It had a very minor effect on the bass and I didn't see the benefit in my situation.  The Helmholtz cabinet also cause a lot of blair/harshness in the upper mids highs (probably due to high frequency refraction off the corners of the cabinet).
auxinput
1,538 posts
 
When I was moving subs around, I tried all different combinations.  Subs in the middle of the room, subs 1/3 way into the room, subs next to my sitting position, subs in opposing diagonal corners, subs firing upwards, subs firing backwards, subs in the back of the room.  They still were best in the front corners firing forward.
geoffkait's avatar
geoffkait
14,147 posts
 
 
auxinput
Oh, I also built an adjustable Helmholtz resonator. It had a very minor effect on the bass and I didn't see the benefit in my situation. The Helmholtz cabinet also cause a lot of blair/harshness in the upper mids highs (probably due to high frequency refraction off the corners of the cabinet).

I built a Helmholtz resonator to address a standing wave of about 70 Hz in one corner of the room. The Helmholtz resonator was about 15 feet long. It was a folded S shape resonator, about 8" diameter with medium size nozzle on one end, the other end sealed. White PVC pipe, straight sections and elbows. Purple PVC sealant and PVC cement. Worked great.

erik_squires OP
5,268 posts
 
Hi everyone,

I'm not sure if it's clear, but the key to bass traps is that they work in combination with EQ. Not either or.

Also, I'm not sure if you meant to say it this way or not but it sounds like you placed your subs symmetrically. They probably benefit most from being assymetrically placed. Assuming one of them is near ideal, but you still suffer the 80 Hz null, try the idea of putting the second one in the listening location, and try to find the place where it produces the most fill at 80 Hz. It may be that it works best next to or behind your listening location even. :)

Best,

Erik
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