I was just reading Alan's article regarding sub setup, in the new monthly newsletter. Below is a section from that article. Has anyone experimented with this type of crossover setting? As most of you know, we normally encourage people to leave the sub on bypass mode and let the receiver manage the LFE. I plan to try this tonight when I get home.
"On the rear panel of the subwoofer, set the volume control to the mid-point or a bit less, and turn the subwoofer’s own crossover control to Bypass (if it has a bypass setting) or to its maximum rotation. Note: If a user wants to experiment and set the subwoofer's crossover at the same frequency as the receiver's crossover, better integration of the subwoofer may be achieved. Experiments at Axiom have shown that with the EP400/500/600 subs, it's advantageous to do so because of the brick-wall algorithms in the DSP circuits."
I breezed thru the newsletter and missed that part.. thx for calling my attention to it Randy! I'm gonna give that a try.
Exerimenting now with Diana Krall Live in Paris and the song "Deed I Do". The upright bass is killer, hmmm, is it better, not sure yet.
I'll give it a shot. Ever since I redid the living room and moved my system to the opposite wall, I've noticed the bass isn't as seamless as it used to be. I just wish I knew what the un-modifiable crossover on my needs-to-be-replaced Onkyo TX-DS575 is....
Im looking forward to both your thoughts, if it seems to sound better I may have to try it also.
Okay Randy, I got home and hadn't read the newsletter, but after seeing this I immediately fired up The Planets and listened for about a half hour, both from my normal seat and right at the EP500, switching between 60,80,100Hz and bypass. Since you also have the Mehta Planets, you might check the passage beginning about 4:19 into Mars and a minute or so forward. This seems to reduce the upper bass fullness a bit, but I don't view that as an improvement, since it isn't bloated or otherwise unsatisfactory on bypass.
Curious what Alan's "brickwall" reference meant in more detail. The receiver that I use with the M22/EP500 setup has the usual 24dB/octave rolloff on the sub, which is generally suggested for getting good blending around the crossover.
too late to really test it tonight. I did set the crossover to 80Hz, though. If it sounds wrong, I'll raise it a bit. My receiver's xover may be as high as 100Hz. Who knows.
John, I will try the planets tomorrow night. It is to late tonight as the kids are in bed.
I also wish Alan would expand on his article.
My reciever conforms to the standard 24dB/octave rolloff, unless you let it do the THX setup (all xover 80Hz) in which case it employs a less steep 12dB/octave rolloff. This may be similar in other receivers that do THX processing. I really don't have any opinion if this is better or not.
I have several views on this topic having tried out many crossover configurations and looked at their impact on FR and artifacts near the crossover point on the EP subs but before posting my thoughts I would like more information as well.
Hi sirquack,
I will expand on this when Ian returns to the Axiom plant (10 days) and I visit and get some listening-test time.
The comments were added to the article on the suggestion of Ian Colquhoun and Tom Cumberland, who designed the filters in the DSP circuits in the amplifier.
I know it contradicts the conventional wisdom that one should avoid "cascading" of crossovers, but I was assured that it's worth experimenting with and that, depending on the AV receiver or AV processor's bass management, it may produce a smoother transition. I'm not sure I hear any difference in my own installation so far.
Regards,
Thanks Alan, I look forward to your input.
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That's what SHE said.
Look out, folks, Peter's about.
I'm glad we are a bunch of comedians around here, versus a bunch of grammaredians.
Usually when I tweak crossovers its with an eye to the SMS real time display so I can see its effect on FR. Blending the sub/speakers to achieve flat FR on either side of the crossover point depends on various factors such as slope of the low pass filters , phase, level etc. The conventional wisdom about not having two low pass filters in tandem is that it plays havoc with phase at the crossover point and can cause irregularities in FR at and near the crossover frequency. Having a brickwall filter like we have in the EP subs also means a discontinuity in sub's response above the crossover point compared to the more typical 24db sloping Linkwitz-Riley 4th Order low pass filters you find in most other subs.
That brickwall filter works well if the sub is level matched to the speakers, you are not running the sub hot and if the speakers have flat FR. Room acoustics not withstanding. As we all know Axiom speakers are engineered to linear FR. However most people (not me) like running their subs 3-5db hot so that alone will mean a discontinuity in FR at the crossover point because of the DSP brickwall low pass. Also depending on the processor filter it may or may not introduce phase anomolies or possibly intermodulation distortion.
Perhaps there is something about the DSP chip that avoids the usual problems with using two low pass filters? Conceptually I can see why it could work but only when the sub and linear speakers are level matched and the processor low pass filter doesn't cause phase problems. Anyway, I'm looking forward to some clarification on this one.
I would expect that the DSP filters in the Axiom subs and receivers are implemented using finite impulse response filters. This method avoids phase distortion.
How does running the sub hot create a discontinuity in frequency response?
It doesn't if the receiver crossover is set lower than 100hz and the sub is left in bypass since you continue to get output above the receiver crossover point and below 100hz. Setting the processor crossover at 100hz or more, means no rolloff just the brickwall response at the sub. There is no output above the brickwall DSP low pass filter unlike the typical rolloff you see with fourth order filters. You can see the steep clifflike drop in amplitude from the FR graphs.
So running the sub hot and crossing at 100hz or close to it means a steep drop in response at or slightly above 100hz, a discontiuity in overall FR if you will depending on how hot you run the sub above the speaker level. Its less of an issue the lower you cross and not a factor at 80hz receiver crossover having a 24db slope with the sub crossover bypassed. However, it is an issue as you cross closer to the 100hz brickwall because, except for some nominal port resonance, their is no output above 100hz.
Discontinuity in response may be a problem if you are trying to blend small speakers that are rolling off above 100hz because there is no output coming from the sub to fill in above 100hz. A firmware revision which raises the low pass brickwall to 120hz will mean more of the output from the sub above the receiver crossover point. In addition higher crossovers help when blending two way speakers or bookshelf monitors.
Thanks to those of you that have brought up this issue.
I too would like to see an increase of the brick wall to 120 Hz or more. Today's receivers are increasingly flexible and allow a wide range of crossover frequencies. Of course this is assuming that the FR of the EP500 above 100 Hz is good enough to allow for this.
It would be interesting to hear from Axiom concerning the reasons for designing the brick wall at 100 Hz. I am guessing it relates to the standard of setting all crossovers at 80 Hz. However, the 80 Hz crossover is not always appropriate.
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I was just reading Alan's article regarding sub setup, in the new monthly newsletter. Below is a section from that article. Has anyone experimented with this type of crossover setting? As most of you know, we normally encourage people to leave the sub on bypass mode and let the receiver manage the LFE. I plan to try this tonight when I get home.
"On the rear panel of the subwoofer, set the volume control to the mid-point or a bit less, and turn the subwoofer’s own crossover control to Bypass (if it has a bypass setting) or to its maximum rotation. Note: If a user wants to experiment and set the subwoofer's crossover at the same frequency as the receiver's crossover, better integration of the subwoofer may be achieved. Experiments at Axiom have shown that with the EP400/500/600 subs, it's advantageous to do so because of the brick-wall algorithms in the DSP circuits."
I have the EP500 set to bypass, but the volume is only at 7 or 7:30 - any more and it completely dominates. Even so, it's almost track by track dependent for xover. I have however found that by setting my pre-pro to 90 Hz, I get a more balanced sound and can run more music with a small setting for the mains. With the xover set at 60 it was really punchy.
Scott
Alan,
Just curious if there is an update on this topic? I assume Ian and Amie are back from their vacation?
Sirquack,
They are. Ian is planning on weighing in on this subject tomorrow (Friday) morning, which may mean 3:00 a.m.
Regards,
Awesome,
I know Ian is an early bird, maybe I'll login when I'm letting the dog out at 4am.
Heh. I'd actually call 3am a
late bird -- at least that's how I most often experience the hour.
Very good point.
Those nights don't happen as much anymore now that I have a family unit. Heck, I think I'm going to watch the movie Raising Arizona, ha ha lol.
Looks like I am bit late with this post. Last winter I put a 3rd EP600 into my system in the back of the room and I started playing around with the x-over setting. I found quite a positive difference to the performance if I set the EP600 x-overs to 80 Hz; which is where I had processor x-over set for the center and surrounds. The low pass x-over in the processor is rated at 24 db per octave, which is reasonably steep, but the x-over in the EP600 sub is a “brick wall” IIR filter. So at 80Hz the sub is playing full volume but by 96 Hz it is 24 db down. I think it is worth checking this out; it would be interesting to hear if anyone experiences the same positive results to the performance that I had.
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Heh. I'd actually call 3am a late bird -- at least that's how I most often experience the hour.
That's my usual bedtime, 5 days a week and up around 7AM as my youngest son seems to feel I have slept long enough. Still working on his clock reading skills.
Thanks Ian,
I will experiment some more with various movies and music. Of course, I only have one 600 in my setup. So far I think I have noticed an improvment with both the 600 and Denon 2805 set to 80hz.....I have all speakers set to small, including the 80's. Do you have the 80's set to small?
Randy
This is an interesting thread. I have a couple questions that I never felt satisfied with.
Given EP500's sharp fall off of frequency-response at 100 Hz, setting the crossover in my receiver at 120 Hz would cause me to loose everything between 100 and 120 Hz. Is that correct? If this is the case then I would think one is limited to setting the receiver crossover to 80 Hz or less.
Also, what is the difference between setting the EP500's crossover to 100 Hz or to bypass? The EP500 stops everything above 100 Hz. I don't see what you would gain with the bypass setting.
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Given EP500's sharp fall off of frequency-response at 100 Hz, setting the crossover in my receiver at 120 Hz would cause me to loose everything between 100 and 120 Hz. Is that correct? If this is the case then I would think one is limited to setting the receiver crossover to 80 Hz or less.
Theoretically, you would lose everything (you'd be down about 96% which is pretty close to everything). But you may have a peak in your room acoustics as well that may compensate for this loss.
You could set your receiver cross-over to 100Hz instead of 80 Hz.
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Also, what is the difference between setting the EP500's crossover to 100 Hz or to bypass? The EP500 stops everything above 100 Hz. I don't see what you would gain with the bypass setting.
There's no discernable difference if your room is acoustically large for a frequency of 120 Hz (greater than 10'x10'x10'). If your room is smaller however, the frequencies above 100Hz, although attenuated by the natural response of the EP500, would get amplified by the response of the room. I think the same effect would take place if you had a wall within 10' or less of the listening position.
Since my impressions with music(portions of The Planets)were as given in my previous reply here, I decided to check frequencies more precisely, by using a test-tone disc rather than music. First, the very sharp cutoff above 100Hz, regardless of whether the sub crossover was set to bypass(which ordinarily on a sub would permit frequencies above 100Hz to be heard), was confirmed as being present(this was with the receiver crossover set to 200Hz, so as to not affect the result).
Then, with my usual 80Hz crossover set on the receiver(with the M22s set "Small", of course)the difference between the bypass setting and setting the crossover on the sub itself to 80Hz was that an 89Hz tone, for example, was significantly weaker with the 80Hz setting. This was as expected, since the combination of the 80Hz rolloff done on the sub by the receiver(24dB/octave)and the sharper cut made by the sub itself made the net M22/EP500 response weaker in that area than it was with the receiver crossover alone in effect.
So, as was said before, I didn't observe any benefit from the sharper sub cutoff. I'd imagine that if there was a room resonance in the 90Hz area that the weaker sub response would aggravate it less.
sirquack
I do have my M80s set to small but I have the x-over in the processor set to 40 Hz for the front channel.
Good Morning JohnK. It gets a bit fuzzy at 3:50am; is it a late Friday night or an early Saturday morning.
To pick up on my earlier point about room response and its relevance to this issue, you can see the difference between an 80Hz and 40Hz receiver cross-over for my room right
here. The blue trace is with a x-over of 40Hz while the red is 80Hz. You can see that the 80Hz setting has pulled up two nulls at around 78Hz and 90Hz. I've used a 40Hz setting for music because it sounds less "boomy" but after running the 80Hz test, I think the boominess is a result of having my LFE gain turned up too high( Yes Randy...still too high
). I haven't quite figured out yet why these two nulls are ocurring in my room. Other nulls are ocurring due to comb filtering as a result of a wall located about 10 feet behind my listening position.
I'm bound and determined to smooth out my room response without using "artificial" sound treatment
.
Mojo,
The way to solve this room thing is to add a second sub-woofer; hence the 3rd one going into my room. Four is sort of magic number to eliminate all of the room affects in even the most difficult rooms.
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Four is sort of magic number to eliminate all of the room affects in even the most difficult rooms.
I bet Mark Johnson is whipping out his credit card right now. 
Just out of curiosity, I know you can use a Y adapter for two subs, but how would you hook up four?
Hi Ian,
I've tried a second sub in three different locations, with various cross-overs (on the receiver and sub), gains and phases. The results were disappointing and I have the graphs to prove it
. With some configurations I had cancellations resulting in dips where none existed before and with other configurations, there was no practical difference.
The second sub used was my old 150W RMS Sony that has a -3dB point at 28Hz. I'd be more than willing to experiment with three more EP600s if you'd care to share
.
I also mapped my room response with the three doors shown below opened. The result was a new big dip below 100 Hz and no practical difference between 100Hz and 300 Hz.
BTW, I am now very happy with my room response below 100Hz. The 80Hz setting in my Denon fixed that. Above 100 Hz, my room response with 2.1 (blue trace) still needs work but with multi-channel (red trace), it's acceptable. BTW, the red trace has a Denon cut-off of 80Hz while the blue trace has a cut-off of 40Hz. The 80 Hz cut-off has eliminated the dips at 75Hz and 90Hz and the multi-channel has almost eliminated the 25Hz band-width comb-filtering as a result of the back wall. As I said before, I am very determined to correct this room without artificial treatments.
Two Y-adapters in series with one
.
Homedad, you can daisy chain your subs by using the line-out of one sub to the line-in of the next, and so on.
Mojo, you need treatments, simple as that.
Your walls/corners are totaly bare. Just play your test tones from your denon, and then walk to any corner in your room and see the results of the spl meter.
Randy,
I don't listen to my system while sitting in a corner
. There is one sweet spot in my house my friend. And it's all mine
. And if it's flat and tight in that one spot, I'm one happy camper.
Yes but treating the room correctly affects the overall response of the entire room, not just the corners.
This graph shows by just adding the two superchunk bass traps in my front two corners, how it affected my primary listening position, the mic never moved.
Here is the last time I used RoomEQ Wizard when I had m60's and an ep500. This graph is taken from the primary position with two front corner bass traps, side first reflection panels, and ceiling first reflection panels.
I wonder how a system like Audyssey using several mic positions would effect the total room response, I don't have graphs, but it sure helped my room, it would be an interesting comparison.
Randy,
Do you have the ability to remove your side reflection panels? I'd be curious to hear if your perception of spaciousness increases with them removed. I want to be very careful as I don't want to have a dead-sounding room. Right now, the sound in my room has a very good sense of spatiousness and imaging. And I expect the imaging to improve once I treat the ceiling.
A flat response in the room is one goal. Correct imaging and control of reflections for spatiousness is another.
I'm curious about Audyssey myself. When I get a receiver equipped with auto-EQ, I plan on focusing it only on my sweet spot. That way, I should get the optimum results.
If you get the time, can you do that and let us know your opinion of multi-zone EQ vs. "sweet-spot EQ"?
My side panels can easily be removed as they are hanging with picture frame wire and are not that heavy. It is very hard to deaden a room unless you cover the entire walls/ceilings with treatments.
Treating the first reflection points improves the overall sound as your not hearing the same sound arriving at your ears at different times, just the direct sound.
If you try the clap test, my guess is that you will hear an echo of your clap off the walls.
People think acoustic panels are only designed for recording studios, this could not be further from the truth.
Once I added my FRZ panels I immediately noticed the clarity of the music was more accurate and detailed. I've proved this with Blind listening test where I've had users listen to the same songs right after the other. In between songs I would either remove or add my panels and they would tell wich version of various songs sounded better. The majority of the time they picked the song with panels added.
Mojo
Your room sweep is looking better at the higher crossover compared to the first graph you posted but eliminating that 50hz peak is where you should focus your effort. It is likely making your bass sound boomier than normal. You may want to consider an equalizer to tame that peak. I currently use a Velodyne SMS for that problem but have had good experiences with the less expensive Behringer Feedback Destroyer DSP1124P.
As for those pesky nulls, don't even think about Audessey equalization or any equalization for that matter. Room treatments are your only viaable option. Its normal to be concerned about aesthetics or WAF when it comes to treatments but properly done they can actually accent room decor. I'd start with the easy stuff, bass traps in the corners. Keep posting those graphs its neat to see your progress.
Oh yeah, the other suggestion: get a properly placed second 500 and don't look back. That relatively whimpy Sony sub won't cut it for what you are trying to accomplish.
My rec room is definitely more lively than other rooms in my house. No question about that. And yes, the clap test does indeed reveal this. However, I don't think it's too lively as evidenced by my reverb time below.
Regarding the treatment of the first reflection points, I agree that the ceiling and floors should definitely be treated. And perhaps the laterals need to be treated for some rooms but the question is "how much treatment?". I say perhaps because if you have your speakers toed in "severely" and they are far enough from the side walls, then you may not have anything to worry about.
The lateral reflections give rise to a sense of spatiousness. Of course if they are too live, that's not good either. In my room, with the amount of toe-in from the fronts and the distances to the side-walls, I calculated that I am getting the right amount of spatiousness. And my ears tell me so too. The ceiling area between me and my M80s however is another matter and I need to take care of that right away.
Come to think of it, if you listen to all of your audio in multi-channel, you may want to add "a lot" of treatment to your room since you don't need to rely on any reflections for ambience.
After I finish this project, I'll be able to write a thesis on room acoustics
.
Hi Jake,
Those are good points about the sub (I have a 600 BTW) and the 50 Hz peak. Thanks. I'm still not sure about artificial room treatments though. And yes, I've been thinking about Velodyne and Behringer.
I'm posting this stuff 'cause I think it's interesting and it might help others too. Thanks for reading.
Randy, looking at your graphs, I may just have to buy a few bass traps. Before I do, does anyone know of anything I can use to simulate them?
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If you get the time, can you do that and let us know your opinion of multi-zone EQ vs. "sweet-spot EQ"?
My experience with the Audessey vs. the single spot EQ, is you still get your main sweet spot with the Audessey but you also get 4 or 5 other positions around the room that sound almost as good. With the old system the family would have to pry me out of the center couch sweet spot, now I can sit anywhere in the room and not feel I'm missing anything. It probably doesn't do much for room response but it does make it much more enjoyable when you can sit in other locations and still have great sound.
Mojo,
Items to simulate, that is a good question. It might be hard to find something with the exact absorbtion as 703. Lets seeee....hmmm
maybe a bunch of bean bags stuffed in corners, or a bunch of thick removable seat cusions from a couch stradleing the corners, or you could go to a local home improvement store and buy some roles of insulation (in plastic bags) and just stack them in the corners from floor to ceiling. When your done you could return them since you didn't open the bag and you would have a receipt. I'm sure there is something else you could try, maybe lean some roles of unused carpeting up in the corners left over from when you carpeted your house.
John, I understand your opinion about "auto setup" from receivers, but have you actualy used Audyssey? I agree with you on past versions, but I have really read a lot of good reviews and feedback that this truely is a different animal from previous products.
Audyssey company actually says that it is not a replacement for room treatments, but when combined gives you unbelievable results.
The insulation idea is a good one.
As for carpet, it just so happened that the one we liked was the most expensive one in town. I could have purchased three more EP600s if it wasn't for the carpet
. So, I bought just enough carpet to do the least amount of damage to my wallet and ended up with a 3'X6' patch left after install.
sleeping bags, pillows, ha ha my mind is brain storming ideas.
Do you still have that patch?
I tried to get a refund for it and they just laughed me out of the store
. So I gave it to my daughter and she cut holes in it for an art project at school.
Ha ha, nice refund attempt. I always have to work up the nerve to try for any kind of refund.
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John, I understand your opinion about "auto setup" from receivers, but have you actualy used Audyssey? I agree with you on past versions, but I have really read a lot of good reviews and feedback that this truely is a different animal from previous products.
Audyssey company actually says that it is not a replacement for room treatments, but when combined gives you unbelievable results.
Hi Randy
My knock is not at Audessey a much as the claims made by AVR manufacturers regarding the benefits of auto-equalization. The complex physics involved pretty well rule out a silver bullet approach but it makes for great marketing.
In room acoustical problems can be categorized into frequency domain and time domain issues. To date most equalizers deal in the frequency domain and not time domain which is why I always urge that equalization be used sparingly and only after all other solutions. Auto-equalization in particular is an imperfect approach to an almost insoluble task.
Fixing combined time domain/FR problems with electronic correction is a tricky proposition. I have never heard one which actually set auto-equalization/delay correctly for subwoofers let alone other speakers. The physics involved make it very difficult for an automated program with limited processing power to do well. Its actually refreshing to buy equalizers (DEQ2496) with auto-programs where the manufactuer(Behringer) specifically warns not to use such programs for frequencies less than 100hz and that better reusults can be obtained with custom settings . To date those issues are best dealt with judicious use of manual equalization, room treatments, bass traps and processor delay. Even my SMS-1 performs best with manual tweaking. The auto-results with SMS-1 and all auto-programs create as many problems as they solve by attempting to boost nulls or cut output at the wrong frequencies. And by doing so make the time domain ringing problems worse by adding excessive equalization.
What Audessey or any auto program is trying to do involves Sweep,Measure, Adjust, Sweep, Measure, Adjust.. a long iterative process involving continuous incremental adjustments in the frequency domain. Anyone who has used sweeps and an equalizer goes through it, the main difference is you are now having to consider more measuremnts at more locations. I've spend several idle afternoons optimizing response across six seats this way using the SMS_1 display and delay on the processor . I very much doubt an auto program could optimize the huge tradeoffs involved as well without a huge dedicated processor. Maybe one day with more powerful chips but not with the current technology inside receivers, which is why I am quite cynical about the claims.
In any of my friends setups which I have looked at the low frequency settings were never right. And after listening to the obvious ringing throughout the room caused by adding too much equalization, I've often suggested my friend's shut off the auto-equalization and get a good cheap simple manual equalizer and just tame the sweet spot.
There are advances on the horizon which do look promising however, by Audessey in fact. They have a new equalizer AS-EQ1 which purportedly deals with equalizing delay times and frequency response simultaneouly using fuzzy logic algorythms. It can be attached to a PC or notebook for the processing pwer needed to do complex iterative calculations, a key tool which is missing in the Denons or Yamahas.
Invariably for now, you will get better results with a simple equalizer when you take the time to manually configure it yourself at the sweet spot...and use sparingly.
Here's more to show that I don't think I need side-wall treatments.
I measured the direct distance from my speakers to my listening position and all of the major reflection distances (see spreadsheet). I then used the reflection coefficients for the materials that caused the reflections and the distance of the reflected path to calculate the reflection SPL. I then figured out the reflection delay. This is all according to the Master Handbook of Acoustics.
I used the attached chart from the book to figure out which reflected paths cause me grief. Grief = echo + imaging effects such as shifting and spreading as opposed to spaciousness.
The only areas that could be cause for alarm are the floor and the ceiling between the listening position and the speakers (shown in yellow on the spreadsheet).
Not sure I would say there is no difference. For one, these are not true bass traps. You need at least 4" thick material like 703 spanning across or filling the corners.
If you look across the entire spectrum I see many nulls that have been improved. Overall, it seems to be a flatter outcome.
Ok, that's what I thought. They're not very good simulations. And yes, you're right. There are some nulls higher up that got knocked up. But the nulls below 100Hz have nothing to do with the "traps". They are purely due to the 80Hz vs. 40Hz cross-over on the Denon.
That could be, but I'd bet if your room was treated properly even those freq's would get better and flatter.
Mojo, since we're on pic mode tonight, thought I'd take a quick snap of some fledgling treatment.
I haven't run any frequency sweeps, but I can tell you those little corner thingies really help tame the echo in here. When I first put all these up, I felt I was in a loony bin cell. Maybe I am. . .
Those tube amps look awesome man.
That's great! Where did you get those traps and how do they install?
Sean,
I noticed in a picture on audiocircle, Klaus was talking on the phone with similar traps in the background. I'm sure they help some, but my research has found that you really need more coverage spanning the corners. Those don't look very wide or thick?
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Where did you get those traps and how do they install?
They are from Eighth Nerve. I got the Response room pack. Hmm, I see they are no longer available. It's been a year and a half, or so. Simple installation--push pins.
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Those tube amps look awesome man.
Thanks, Randy. They sound friggin' awesome, too!
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. . .but my research has found that you really need more coverage spanning the corners. Those don't look very wide or thick?
The corner triangles run about 14" per side. The seams are 45"x7". They aren't thick at all. They are made with one sheet of a posterboard-like panel with some stuffing on the back all covered in cloth. The edges are stitched close. You could probably make these pretty easy.
Yes, a larger size would be better, but I have a very small room and even these "smaller" treatments have a detrimental effect on the perceived spaciousness. In this case, it's a choice of form over function.
In my experience of having small listening rooms, bass builds up in the corners and gets boomy. The corner traps, though small, really help alleviate the low frequency dominance.
I know it ain't much, but it's working for me.
>>If you look across the entire spectrum I see many nulls that have been improved. Overall, it seems to be a flatter outcome.
I'm with Randy on this; the red line looks much better.
I think the "not much difference" impression is an artifact of your vertical scale -- about 20 dB packed into 1/4" of graph. If your graph was normal height I think you would be saying "wow, what a difference !!" instead.
