# My room waterfall response after lots of work



## hybris (Jan 25, 2009)

Hi, just wanted some general response as to how this looks, I think it SOUNDS really good, and from what I've been reading and comparing it to other waterfalls the ringing / decay seems pretty decent. This is achieved with the natural furniture in the room as well as an Antimode 8033C for the subwoofer, and manually tweaking the standing wave control of my Pioneer receiver for the main/front speakers. The cutoff frequency for the subwoofer is 100hz (to help the main speakers avoid the room mode at around 45hz as much as possible). 

The main room gain is at 45hz and was originally about 10dB.

This is my best effort so far, and I'm really happy with the sound  

The speakers are the B&W 804s and a small XTZ 99W10.16 10" subwoofer is doing the low end. 

Would you consider additional room treatment with this result, or should I be happy with this? :blink: 



















The low end still needs some work, I'm aiming to get a house curve that ends up at about 9dB at 30hz, but the main work has gone into smoothing out the curve and the decay so far.  I haven't decided if I should punish the subwoofer to go that extra mile in the low end, or keep the headroom available instead. This is mainly aimed at music, where the sub 25hz information doesn't matter all that much (some of you will disagree I'm sure) 

EDIT: Looking at the graphs now, maybe I should do something to increase the level between 80 and 100hz slightly.. ?


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## hybris (Jan 25, 2009)

An overlay of before and after scaled out to 600ms shows quite an improvement in ringing. Nothing has been done physically to the room before/after.


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## glaufman (Nov 25, 2007)

A lot of what you call ringing in the before I don't think is ringing at all, but looks much more like extraneous noise in the setup... based on it reaching a point where it doesn't seem to be decaying at all... I'm looking at the big stuff just over 100Hz and just over 120Hz... that being said, it's more usual to see those effects at 60 and/or 120Hz (50/100 in EUR)... How tightly sealed is this room? Is there a chance there are other noise factors at work here, such as HVAC systems?


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## Moonfly (Aug 1, 2008)

glaufman said:


> A lot of what you call ringing in the before I don't think is ringing at all, but looks much more like extraneous noise in the setup... based on it reaching a point where it doesn't seem to be decaying at all... I'm looking at the big stuff just over 100Hz and just over 120Hz... that being said, it's more usual to see those effects at 60 and/or 120Hz (50/100 in EUR)... How tightly sealed is this room? Is there a chance there are other noise factors at work here, such as HVAC systems?


If there was a HVAC system at work, wouldnt it still be in the after waterfall?

Either way, the after response is looking good enough to me, as its all within the 300ms (target) window. I do think that if the response target house cure is aimed at music, then boosting the bottom end is probably not as big an issue as it might be for movies. Music uses the sub 30hz regions much less than movies might, and even then its usually a more gentle use of those frequencies albeit more sustained in some cases. It'll just be a case of being aware of how hard your pushing your kit.

All in all you have a decent smooth low end response I think I would be quite leased with.


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## glaufman (Nov 25, 2007)

Moonfly said:


> If there was a HVAC system at work, wouldnt it still be in the after waterfall?


Not necessarily... HVACs are expected to cycle on/off periodically...


> Either way, the after response is looking good enough to me, as its all within the 300ms (target) window.


No agrument there.
If you're concerned about the small dip around 80-100Hz, since it's within range of the crossover, you might play with the phase control...


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## hybris (Jan 25, 2009)

Hm, I guess some of that from the before waterfall may have been external noise sources. Don't know what it could have been as it is gone now. The room is quite tightly sealed, but I guess it could have been a refrigerator temporarily turning on or something like that? 

I'll do some more work on calibrating today to see if I can further improve the curves.


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## hybris (Jan 25, 2009)

Moonfly said:


> Music uses the sub 30hz regions much less than movies might, and even then its usually a more gentle use of those frequencies albeit more sustained in some cases. It'll just be a case of being aware of how hard your pushing your kit.
> 
> All in all you have a decent smooth low end response I think I would be quite leased with.


Yep, I'm thinking the same thing, so I probably won't push the low end any further. I'm planning on focusing on 80-350hz today, and see where that brings me


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## Moonfly (Aug 1, 2008)

Its worth monitoring the waterfall then, if you cant reproduce the apparent noise in the ringing then I think you can safely right it off as an anomaly caused by 'something'. If it does reappear at some point, you could start looking for what might be causing it, just so you know :T 

Its worth keeping in mind, that you can end up endlessly chasing another 1 percent and go a little insane doing so  :gulp:, I did for a while :R. You have to try find the point at which your efforts arent really gaining you anything more, and try be happy with what you have got. Its just telling your brain its time to forget about it thats the hard thing.


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## atledreier (Mar 2, 2007)

I've stopped lookign so much at curves and started enjoying the sound instead. It took me 20 years to get to this point, but currenty my system is giving me more than ever before!


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## Moonfly (Aug 1, 2008)

EQ'ing certainly helps you get the absolute best from your system, and really helps account for room effects :T


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## atledreier (Mar 2, 2007)

I would never run my system without EQ, but I'm done doing ten setups a day just to get that last 1%, it's not worth it, and it's definetly not audible.


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## hybris (Jan 25, 2009)

I got quite a lot of background noise from the computer/soundcard while measuring, so I ended up doing the measurements at 75dB today anyhow.. (http://www.hometheatershack.com/for...ve-measure-75db.html#post219656#ixzz0b06QThRw)

Redid the calibration of both antimode and my Pioneer receiver, and this time I had the Full Band Phase Control activated on the Pioneer, as I've found the sound to better and more..rhythmic and tidy with this activated in the past. So I'm now running it with this option activated. Seems to work out well. 

Ended up focusing on the 20-100hz area today as well, and managed to increase the overall response somewhat. It was a little bit on the lean side earlier. Got back a bit of the ringing at 45-60hz though, not sure how that happened, or wether it's background noise again (it seem to go on forever). Also measured up to 2khz and the overall decay was around 300ms all the way. 

Here is a graph of the result from last session compared with the end result today (green is from today):


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## hybris (Jan 25, 2009)

atledreier said:


> I would never run my system without EQ, but I'm done doing ten setups a day just to get that last 1%, it's not worth it, and it's definetly not audible.


Hehe, I agree - I prefer listening to music over sweeps any day, and I guess that's what the antimode is about as well, set it and forget it.  But it gets a bit addictive too.. But hopefully 2010 will be more about listening than measuring


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## glaufman (Nov 25, 2007)

I certainly like the most recent FR better in the crossover region... if you like the "house curve" you've dialed into the sub 80Hz then you can leave that... if you want to flatten the crossover region some more, you'll want to start by taking independent scans of the sub, left main, and right main, to begin to see what's causing what. If you want to track down that ringing, you might try playing a single tone at the frequency you see the ringing at, and see if you walk around the room if you hear anything rattling or the like...

I seem to have the opposite problem everyone else does... I leave my setup the same thinking it's the best sounding setup in the world for years until I hear something better or someone points out a flaw I didn't notice, then I fix that and again stop, not realizing just how much further I could go, until someone else points out what they don't like...:coocoo::dumbcrazy::hissyfit:


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## hybris (Jan 25, 2009)

Glaufman - thanks for that advice, now I have to dedicate another day to this stuff. :sweat: :blink:

I just spent a few hours now, using my ears as much as my meter, and I'm pretty satisfied now. But you are probably right that running each speaker independently could help me sort out the crossover area even more. But now it sounds really tight and good. It was a bit bass heavy after yesterdays session, but now I think it sits just about right. 

Red curve was yesterday, green curve is after today. I actually increased the 125hz and 250hz area somewhat on the 10 band EQ in my receiver, as the overall volume between 100-500hz was a bit low. Not sure if that is the actual frequency response of my speakers. Anyhow, that made the peaks a bit bigger between 100 and 200hz, with my current setup I don't have enough EQ power / bands to do anything about that. Perhaps I should reduce 125hz by 1dB or something again. Anyway, it sounds good. :foottap:









Here is 15hz-1500hz smoothed 1/3. 









And here is waterfall of both 20-200hz and 20-1500hz:



















Lots of work but I guess it's worth it. I sure learn a lot about parametric EQs, only wish I had more bands to play with. (but then again - then I'd probably be tweaking for weeks, not days) :R


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## atledreier (Mar 2, 2007)

Just remember that very often you can achieve very much with only a few filters used. Don't go out of your way to EQ every little wiggle on the curve. Move your head 10cm and all that goes out the window.


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## hybris (Jan 25, 2009)

atledreier said:


> Just remember that very often you can achieve very much with only a few filters used. Don't go out of your way to EQ every little wiggle on the curve. Move your head 10cm and all that goes out the window.


Yep, I discovered that when I took a break of about two hours, and then remeasured without actually touching any EQ settings, and got a relatively different result. I don't know if the temperature/humidity in the room changed or whatever. Probably moved the mic a little bit as well. But the result is surprisingly uniform in the bass area even though I move the mic stand around a bit in the couch. 

But yes - getting the overall sound better, and not just measuring to make the curve look its best appears to be a good approach  I paused the EQ process to listen to the result with ears and music a lot today - and the bass response feels much more right than it did yesterday. 

But remember I've only got the antimode (which does its magic without my intervention) and then the three band parametric EQ for the sub channel and three band parametric eq for the mains (the pioneer standing wave control) - so a total of 6 bands for the bass area. So it wasn't about adding 20 different filters, just spending a lot of time trying to get the most out of the few I had (I was surprised how smooth I could get the curve by correctly combining them). 

It was also interesting to see how much effect it had to insert filters for the main channels well below the cutoff frequency. Cutoff frequency is a bit misleading - as it is probably a 12dB filter it's a lot of output from the speakers down in the bass area even though the cutoff frequency is set to 100 hz.


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## atledreier (Mar 2, 2007)

I always save a baseline measurement before I start tinkering, so I can compare to where I am today. The measurements usually vary a bit, but with the baseline I can see if I'm in the ballpark of if something is messed up. Saves me alot of trouble, usually. I once measured and tweaked a whole night ithout realizing all my measurements were worthless due to a fridge.


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## hybris (Jan 25, 2009)

atledreier said:


> I always save a baseline measurement before I start tinkering, so I can compare to where I am today. The measurements usually vary a bit, but with the baseline I can see if I'm in the ballpark of if something is messed up. Saves me alot of trouble, usually. I once measured and tweaked a whole night ithout realizing all my measurements were worthless due to a fridge.


Yep, I store the final result from the last session and use as a baseline the next time I measure. 

By the way, I'm getting a bit annoyed with the fact that REW can only hold 9 measurements at the same time. Seems like an artifical restriction to me. Or have I missed some setting where this can be increased? If not I'd really like that to be increased in the next version


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## Moonfly (Aug 1, 2008)

hybris said:


> By the way, I'm getting a bit annoyed with the fact that REW can only hold 9 measurements at the same time. Seems like an artifical restriction to me. Or have I missed some setting where this can be increased? If not I'd really like that to be increased in the next version


I'll bring it up for you :smashin:. I believe their will be a version 5 at some point.


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## hybris (Jan 25, 2009)

Listening to lots of different music now, this still isn't perfect.. Need another round next year (in January that is).. .. :doh: :nerd:


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## atledreier (Mar 2, 2007)

I've requested more measurements in the past as well. I got a reason for it, just can't remember what it was..  Do a search, you'll probably find it.


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## JohnM (Apr 11, 2006)

hybris said:


> By the way, I'm getting a bit annoyed with the fact that REW can only hold 9 measurements at the same time. Seems like an artifical restriction to me. Or have I missed some setting where this can be increased? If not I'd really like that to be increased in the next version


The internal architecture of V5 has been changed so that it can in principle handle any number of measurements until the host runs out of memory, but from a practical point of view it becomes difficult to distinguish very many measurements, particularly on overlays. What would be a more useful maximum?


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## Moonfly (Aug 1, 2008)

JohnM said:


> The internal architecture of V5 has been changed so that it can in principle handle any number of measurements until the host runs out of memory, but from a practical point of view it becomes difficult to distinguish very many measurements, particularly on overlays. What would be a more useful maximum?


I think ten is a good number, then perhaps the ability to group your blocks of ten to give 100 maximum. Might be asking too much though.


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## atledreier (Mar 2, 2007)

What I would like is some sort of folder structure or grouping. 

I usually work like this:

Do a baseline measurement with front and sub(s)
Do a baseline with fronts only
Do a baseline with sub(s) only.

Then the tweaking begins, with lots of intermediate measurements. Change something, measure, change again, measure and so forth. The measurements rack up pretty quick.
If we could have a group for 'temporary' measurements, separate from the 'proper' ones that was unlimited in number, or at least a pretty high number. I wouldn't be concerned with presentation of these measurements, just that they are easy to access and toggle visibility. Usually don't view all at once anyway, but having them available for comparison with a click of the mouse is a real plus.
Then I arrive at some sort of conclusion, and then I'd like to be able to copy the selected measurements to the 'proper' category before I start a new run of 'temp' measurements when tweaking something else.

Now, I know I can use the realtime display for this 'temp' tweaking, but I like having a reference for comparison. Also, the realime display is just too slow when doing tweaking. This is a technical limitation of course, and nothing anyone can do anything about.

But let's take this to the REW thread, maybe?


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## hybris (Jan 25, 2009)

JohnM said:


> The internal architecture of V5 has been changed so that it can in principle handle any number of measurements until the host runs out of memory, but from a practical point of view it becomes difficult to distinguish very many measurements, particularly on overlays. What would be a more useful maximum?


How about a set of numbered slots, that you could choose from on the screen that comes up when you click the measure button, including a checkbox with "overwrite", so you could remeasure on the same slot, or perhaps switch between two while you're doing lots of measurements. 

The annoying part now is that you have to keep manually deleting measurements in between each measurement. So some clever way to avoid that would rock.


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## hybris (Jan 25, 2009)

Got up early to do some more measurements today before going away to the mountains for new years eve :coocoo:

Was able to extend the low end a bit now and make the bump less obvious. It appears my next task should be measuring all speakers individually and trying to get the crossover area a bit more tidy. 










compared to yesterday (purple is today):









A happy new year to everyone


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## Ricci (May 23, 2007)

I sorta like the one from yesterday better (green). 80-95hz is smoother and the low end is more extended.


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## hybris (Jan 25, 2009)

Ricci said:


> I sorta like the one from yesterday better (green). 80-95hz is smoother and the low end is more extended.


Yes, the crossover area around 80-100hz certainly didn't get any better, I haven't had the time to give that proper focus yet. (I haven't measured all speakers independently, which I suspect that I need to do in order to figure out what is going on) I probably haven't got the EQ available to actively change anything there, so it is slightly random what happens there based on EQ changes elsewhere in the frequncy band. 

When it comes to the low end, the reason why it was more extended the day before was because I had the LIFT25 activated on Antimode (lifting 15-25hz) - but I suspect my XTZ doesn't really appreciate that at higher volumes, and it made the response start to roll off at 45hz. With the new curve I have LIFT35 activated (lifting 25-35hz) which makes the response stay flat longer, but the then rolls of hard at around 25hz. 

To my ears that sounded better, keep in mind that I'm primarily tuning for best response for music, Super low end response for movies are a second priority. But I guess we can conclude that I ideally would require a larger / more powerful subwoofer.


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## Ricci (May 23, 2007)

Well GL. Overall that's not a bad response. Try to get the 70-120hz area as smooth as you can. Looks like maybe a phase or tweak of the distance setting might help. If you can try inverting the polarity of the sub completely first. 180deg. it might fill one of those dips right in.


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## hybris (Jan 25, 2009)

Yes, I'll try the phase on the sub. But I was under the impression that the antimode should handle the phase of the subwoofer, but maybe I'm mistaken?


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## hybris (Jan 25, 2009)

Hi, I've now done individual measurements of front, left and sub in order to help me figure out if there's anything I can do to tidy up the crossover area, but I'm not sure if I see any obvious phase problems or anything like that? 

The crossover is set to 100hz, so I guess the most obvious / interesting thing here is to see that the room mode actually overpowers the filter so the curve doesn't really begin dropping until below 50hz. At first I didn't think the filter was active at all, but when I tested to change it to 80hz it increased even further.

Here is a photo showing how the speakers / sub are placed in the room and in relation to each other. The listening position is about 3.5-4m from the speakers.









Left:








Right:








Sub: 








All three curves:









And here is all curves + when eveything is actually playing together (orange):









Any obvious issues to any individual channel here? I guess the right speaker is responsible for the huge dip at 85-90hz, so not much to do about that without moving it, which isn't really an option.


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## hybris (Jan 25, 2009)

Ricci said:


> Well GL. Overall that's not a bad response. Try to get the 70-120hz area as smooth as you can. Looks like maybe a phase or tweak of the distance setting might help. If you can try inverting the polarity of the sub completely first. 180deg. it might fill one of those dips right in.


I tried inverting the phase, but that didn't seem to go very well: 

(blue is after inverting phase)


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## glaufman (Nov 25, 2007)

Obvious issues? Yes. Obvious solutions? well...
I personally think the swings above 100Hz in your left channel are interesting, as well as the big suckout in your right channel...


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## hybris (Jan 25, 2009)

glaufman said:


> Obvious issues? Yes. Obvious solutions? well...
> I personally think the swings above 100Hz in your left channel are interesting, as well as the big suckout in your right channel...


Guess I have to settle with an interesting frequency response then.  I don't have anything that can resolve them anyhow. Wonder what is causing them.. 

Settled with this (red) curve today (9dB house target curve), green is the previous response. They look quite similar, but the interesting thing here is that I actually deactivated all EQ on the subwoofer channel, this is just Antimode with LIFT35 activated. So I must say Antimode manages to create a quite smooth response. I've also managed to reduce most dips/peaks between 100-200hz a little bit









I guess I won't get much further than this with the equipment / room I have.


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## laser188139 (Sep 19, 2009)

hybris said:


> ...
> Any obvious issues to any individual channel here? I guess the right speaker is responsible for the huge dip at 85-90hz, so not much to do about that without moving it, which isn't really an option.


I have a similar sharp drop-off in my front speaker that is near a corner. And the simplest solution is to choose a crossover frequency above that point, as you have done. If the null is a simple reflection from the corner, with the drivers of the right speaker 1m from the corner, it might not take much, 20cm farther out, to drop the null to 70Hz. You could then try an 80Hz crossover. 



hybris said:


> I tried inverting the phase, but that didn't seem to go very well:
> ...


That matches my experience, that swapping the phase can fix a problem in one place but create a worse problem somewhere else. You have to try them both, though, to see which is better. 



glaufman said:


> Obvious issues? Yes. Obvious solutions? well...
> I personally think the swings above 100Hz in your left channel are interesting, as well as the big suckout in your right channel...


The left is interesting, as Greg writes. Not being near a corner, these may be a combination of multiple reflections off the walls. The frequency is high enough that these might be amenable to some treatment. But so far my wife has vetoed any effort in that direction, so I cannot tell you what works. 

Bill


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## glaufman (Nov 25, 2007)

hybris said:


> Wonder what is causing them..
> I guess I won't get much further than this with the equipment / room I have.


Well, experimentation/analysis could point the way to what's causing them, and then what it would take to smooth them, sometimes placement, or at these frequencies treatments, can make a difference, as Bill said...


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## hybris (Jan 25, 2009)

Hm, is there anything except bass traps that stops 100-200hz? I have very limited options when it comes to placement I'm afraid. Just about the only option would be to move the speakers even closer to the wall..


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## glaufman (Nov 25, 2007)

As usual, it depends. You might have REW "find peaks" and/or post waterfall(s)... that will help determine if the issue is modal or not... 
Assuming you can't move the speaker(s) in question too far, you may be faced with acoustic treatments of one sort or the other. 
Taking another look at the pic, I would think deadening that corner would do you a lot of good, perhaps hidden by the drapes, perhaps even just the front wall behind that speaker... 
As for treatments other than traps, there are Helmholtz reonators, but I don't know much about their effectiveness in over this range... I'm sure Bryan over in the Acoustics section can give you more info...


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## hybris (Jan 25, 2009)

Here is the waterfall for left/right speakers. I'm not 100% sure how to use the find peaks feature. If I set the target range to "subwoofer" he finds a lot of peaks (but I assume that is because the program finds information above the cutoff frequency), but if I set it to full range it found none. 

Left:









Right:


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## glaufman (Nov 25, 2007)

How to set the target is going to depend on the scan on which you want to find peaks... if it's a sub-only scan, use the sub target, if it's sub+mains, use full range target, if mains only, use the bass limited target. Based on the waterfall of the left, those peaks look modal to me. Same thing for the right, althouh it's a little more difficult to tell. Could be that having that speaker in the corner is especially exciting multiple modal influences. Bare in mind that there ARE lots of peaks to be found


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## hybris (Jan 25, 2009)

glaufman said:


> How to set the target is going to depend on the scan on which you want to find peaks... if it's a sub-only scan, use the sub target, if it's sub+mains, use full range target, if mains only, use the bass limited target. Based on the waterfall of the left, those peaks look modal to me. Same thing for the right, althouh it's a little more difficult to tell. Could be that having that speaker in the corner is especially exciting multiple modal influences. Bare in mind that there ARE lots of peaks to be found



Just to be clear, you say the peaks look modal. What are the alternatives if they are not?  What other possible causes to the peaks do we have except room modes? I guess we can rule out phase problems as each speaker was measured individually.


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## glaufman (Nov 25, 2007)

Reflections. To my understanding, if the distance is there to do it, there's not reason a path length difference can't cancel out bass the same way it causes comb filtering in treble. Modes are simply reflections that continue reflecting back and forth between two parallel surfaces (axial modes, specifically... there are also tangential and oblique modes that use more than two surfaces...).


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## hybris (Jan 25, 2009)

glaufman said:


> Reflections. To my understanding, if the distance is there to do it, there's not reason a path length difference can't cancel out bass the same way it causes comb filtering in treble. Modes are simply reflections that continue reflecting back and forth between two parallel surfaces (axial modes, specifically... there are also tangential and oblique modes that use more than two surfaces...).


Aha. So given the correct distance, a reflection can cancel out its source - or actually increase the amplitude.


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## laser188139 (Sep 19, 2009)

hybris said:


> Aha. So given the correct distance, a reflection can cancel out its source - or actually increase the amplitude.


Yes, absolutely. If a reflection comes together with the direct wave at an odd multiple of the half wavelength, it will subtract. If it comes together at an even half wavelength, it will add. (Of course, one can see the same between reflections off different surfaces that arrive over different path lengths.)


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## hybris (Jan 25, 2009)

laser188139 said:


> Yes, absolutely. If a reflection comes together with the direct wave at an odd multiple of the half wavelength, it will subtract. If it comes together at an even half wavelength, it will add. (Of course, one can see the same between reflections off different surfaces that arrive over different path lengths.)


But if that is the case, moving the speakers will probably just move the peaks up or down in frequency, not remove them. So ideally I would require room treatment.. 

My main room mode is at around 46hz. (7.4m?) The length of my living room is approx 7.48m (the speakers are placed along the wall with that length).

The dip of the right speaker is 84hz. (4.05m?).. That doesn't add up to the width of the room or the height. So I guess that might be a reflection as you indicate.

The width of the room is 3.56 which should indicate a peak at 95hz. I do have some peaks around that area, but not very powerful ones.


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## hybris (Jan 25, 2009)

I looked back at the original measurement to compare with today. (unfortunately the original was only up to 150hz). The green graph is with stream direct activated on the pioneer with all DSP bypassed, and no antimode. Crossover 80hz and open bass reflex tubes on the speakers. So that's the actual frequency response in the room (perhaps with the sub running a bit hot). 

The blue response is with Pioneer full band phase control, some manually configured standing wave control on the mains, and antimode. 100hz crossover and closed bass reflex on the speakers (closed box configuration).


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## hybris (Jan 25, 2009)

Looking at the new graphs I wasn't entirely happy with the early bass rolloff in the deep end.
Listening to the system and going back to older measurements before antimode (when using digital EQ through my computer and squeezebox) I confirmed that I had indeed had better response before with the same speakers and sub. 

I was determined to make that happen again, so I changed antimode to LIFT25 and re-tuned all the standing waves filter in the pioneer in order to achieve the deepest possible response while still having a smooth curve mimicking the target curve. 

The response now stays above 75dB until 21.5 hz. :R This is a 10" sub so I think that's quite decent.


Bass response compared to before todays work (green is before):









Compared to a 8dB target curve:


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## hybris (Jan 25, 2009)

Here is current frequency response with Pioneer + antimode correction(red) compared to natural room response (both pioneer and antimode deactivated(green)):









For those of you who find the details interesting on how the red curve is achieved: 

Antimode 8033C is activated with LIFT25. 

The Pioneer is manually configured as follows:

Crossover 100hz.

Subwoofer Standing wave control: 
Band 1 = Frequency: 63hz Q: 2.0 Att: 12dB
Band 2 = Frequency: 78hz Q: 8.0 Att: 7dB
Band 3 = not in use

Main/Front speaker Standing wave control:
Band 1 = Frequency: 120hz Q: 9.8 Att: 9dB
Band 2 = Frequency: 142hz Q: 9,8 Att: 6dB
Band 3 = not in use

Full Band Phase Control is activated.


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## glaufman (Nov 25, 2007)

Why have two of your dips become complete suckouts?


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## hybris (Jan 25, 2009)

Mic was probably moved a little bit from the previous measurements. the 100-200hz area differs alot depending on where in the couch you sit. 

This is three measurements (made during my measurements yesterday) made at three separate spots (left/right/center) that in total is maximum 100cm apart.


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## glaufman (Nov 25, 2007)

Hmmm... Any of those frequencies correspond to room modes?


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## hybris (Jan 25, 2009)

The one moving around at about 100hz is originating from the right speaker, so I guess that is some kind of reflection. The one at 120-125hz I assume is a room mode. The one at around 140hz (large purple that isn't present on green and red I'm not sure about. 

Not sure exactly how I determine every possible room mode. (length between any walls and floor+ceiling?) The room is an open living room + kitchen with a bar that is about 1.5 meters tall and it is also basically L-shaped (the bottom L moving into a small hallway/entry area), so it's kind of a tricky layout 

Here is the apartment and a very crude sketch of how the system is setup. Red = speakers, blue = subwoofer and green box = couch  The distance measurements are approximate and in millimeters.


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## glaufman (Nov 25, 2007)

Yes, I remember discussing your right speaker and it's proximity to the corner... Did you ever try moving it out from the corner a bit? There may be a few other things going on in your room due to the odd shape, proximity to boundaries, and such... if you're thinking reflections (and there's no reason you shouldn't) you'd be looking for points which would give you a path length difference of 5.5-6.5 ft. How far from that speaker is the sub?

John gave us a formula a few days ago for room modes... what's the ceiling height?


> f = (c/2)*sqrt((p/L)^2+(q/W)^2+(r/H)^2) where c = speed of sound, L,W & H are length, width and height (and should use the same length units as the speed) and p,q,r are the mode numbers. For example, for the length modes p = 1,2,3 etc and q=r=0. The lowest frequency corresponds to the 1,0,0 mode.


There may be a few other things going on in your room due to the odd shape, proximity to boundaries, and such... if you're thinking reflections (and there's no reason you shouldn't) you'd be looking for points which would give you a path length difference of 5.5-6.5 ft.


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## hybris (Jan 25, 2009)

glaufman said:


> Yes, I remember discussing your right speaker and it's proximity to the corner... Did you ever try moving it out from the corner a bit? There may be a few other things going on in your room due to the odd shape, proximity to boundaries, and such... if you're thinking reflections (and there's no reason you shouldn't) you'd be looking for points which would give you a path length difference of 5.5-6.5 ft. How far from that speaker is the sub?
> 
> John gave us a formula a few days ago for room modes... what's the ceiling height?


Nope, I'll try shifting the placement of the speaker slightly as well as giving that formula a go. Thanks


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## Wayne A. Pflughaupt (Apr 13, 2006)

hybris said:


> Mic was probably moved a little bit from the previous measurements. the 100-200hz area differs alot depending on where in the couch you sit.


That's perfectly normal, and I highly doubt with program material that you can hear any difference at any location on the couch? A mic doesn't "hear" the same way our ears do. The ears are very forgiving of those narrow peaks and dips.

If I may ask, why the intense concern over what's happening between 100-200 Hz? It's only one of eight octaves above the subwoofer range.

Regards,
Wayne


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## hybris (Jan 25, 2009)

Wayne A. Pflughaupt said:


> That's perfectly normal, and I highly doubt with program material that you can hear any difference at any location on the couch? A mic doesn't "hear" the same way our ears do. The ears are very forgiving of those narrow peaks and dips.
> 
> If I may ask, why the intense concern over what's happening between 100-200 Hz? It's only one of eight octaves above the subwoofer range.
> 
> ...


Hehe, I'm not really all that concerned, but that area is what everyone is commenting when I'm posting the graph (presumably as the 20-100hz area is virtually free of dips and peaks) - so the impression I'm getting is that I ought to work with the crossover area..  

But I think it sounds great, and no I can't hear any difference in the sound on music material when moving around in the couch. So the next logical step would probably be considering some acoustic treatment to make an overall improvement in the area from 1-200hz and upwards instead of a futile attempt at EQing anything much above 100hz.. 

Another reason is that I understand that it is increasingly less effective to use EQ the higher you come in the frequency range. I'm not sure where the magic "limit" is. Lastly, above 200hz I only have 9 fixed range bands available in the pioneer, so there's not a whole lot I could do with EQ even if I wanted to.


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## Wayne A. Pflughaupt (Apr 13, 2006)

hybris said:


> Another reason is that I understand that it is increasingly less effective to use EQ the higher you come in the frequency range. I'm not sure where the magic "limit" is. Lastly, above 200hz I only have 9 fixed range bands available in the pioneer, so there's not a whole lot I could do with EQ even if I wanted to.


On the contrary, EQ can be very effective in the upper frequencies, if called for. It just requires a different approach than the subs. Here’s one thread on the subject that you might find of interest. 

Regards,
Wayne


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## hybris (Jan 25, 2009)

Thanks. Interesting thread.  

I've bought a ECM-6 mic here from the forum a little while back, only need an XLR cable to hook it up to my mic preamp - but I always work so long that the shop is closed. Hopefully I'll get away early enough to buy one soon. Then I'll do a full range measurement and see there are some broad range areas that can be EQed with the filters I have available. The pioneer MCCAC room correction of my receiver does some modifications to the EQ - but I've reset these as it didn't sound better in my ears. We'll see if I'm able to do a better job myself..


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## hybris (Jan 25, 2009)

I figured I could actually plug the mic directly into the preamp (without a cable in between), so just did a quick measurement now, the sub isn't correctly calibrated, hopefully the calibrationfile for the mic is correct at least so the measurement from 200hz-20,000hz is correct. I was unable to include my mic preamp in the loop when making a calibrationfile for the soundcard (I don't have the necessary cables as the input on the preamp mic is XLR) - but hopefully it is relatively flat (M-Audio Audiobuddy). 

If this graph is correct it seems like I should be able to add some broad band filters at 250, 500 and 1khz to make the overall response somewhat flatter. I have a -0.5dB/octave x-curve from 2khz, so the rolloff towards the top is to be expected. The rolloff seems a bit extensive at the very top perhaps, dunno if that could be the mic preamp.

This is 1/3 smoothing.









I'll do some more careful measurements and with the sub correctly calibrated later this week - just wanted to post a full range measurement.


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