20-40hz problem in room. Pease help :(

[Darren-s-88]

Hi guys, i'm not all too clued up with REQ so please be patient

I moved in to a new home 18 months ago and that's where the nightmares began.
The new living room is proving a pain in the a** to get a good sound out of, I've tried multiple subwoofer locations using REW but the response below 40hz is terrible. I currently have a Klipsch R-115SW and considering upgrading to a SVS PB/PC 4000 but don't want to blow the cash if it isn't going to help fix my problem.

I'll attach below the layout of my ground floor, double doors to the kitchen are always open (tried them closed and difference is minimal) door to the hallway generally stays open but closing it does help a little.

measurements taken using multeq xt 32 mic which I read on here somewhere that for bass is pretty accurate give or take 2db. output is connected to bluetooth device as don't have a splitter and the laptop only has 1 3.5mm jack socket. will buy a splitter this week so can connect direct.

Also I'll attach some REW measurements, any help would be much appreciated

 

[highfigh]

Hi guys, i'm not all too clued up with REQ so please be patient

I moved in to a new home 18 months ago and that's where the nightmares began.
The new living room is proving a pain in the a** to get a good sound out of, I've tried multiple subwoofer locations using REW but the response below 40hz is terrible. I currently have a Klipsch R-115SW and considering upgrading to a SVS PB/PC 4000 but don't want to blow the cash if it isn't going to help fix my problem.

I'll attach below the layout of my ground floor, double doors to the kitchen are always open (tried them closed and difference is minimal) door to the hallway generally stays open but closing it does help a little.

measurements taken using multeq xt 32 mic which I read on here somewhere that for bass is pretty accurate give or take 2db. output is connected to bluetooth device as don't have a splitter and the laptop only has 1 3.5mm jack socket. will buy a splitter this week so can connect direct.

Also I'll attach some REW measurements, any help would be much appreciated

Are the room dimensions in millimeters? No problem but if so, it will be difficult to hit 20Hz unless you put the sub(s) in a corner and do some equalization and move the furniture- move the mic when measuring to find the 'sweet spot' and you'll likely find a place where the low frequency response is better.

 

[Darren-s-88]

Are the room dimensions in millimeters? No problem but if so, it will be difficult to hit 20Hz unless you put the sub(s) in a corner and do some equalization and move the furniture- move the mic when measuring to find the 'sweet spot' and you'll likely find a place where the low frequency response is better.

Hi, thanks for the reply.. room dimensions are in metres. I've tried the sub in every corner of the room and more, these were the best 3 result I had. This is direct to the sub with no EQ and at 20hz it's more than 20db below the highest peak, Audyssey does help but still leaves a 12-14db difference. to my ears the 20hz in this room doesn't sound right, if I walk around the house (staircase for one) I get a really good clean sounding 20hz, in the room it sounds as though you hear harmonics more than the actual desired frequency. I really hope i'm missing a trick and this can be fixed.

(EDIT** Sorry yes, measurements on scaled drawing are millimetres)

 

[nathan_h]

I'm very surprised you are not getting better output. The space is large but not THAT large, and that sub is pretty decent.

I am not convinced those Audyssey mics are linear enough to trust and using bluetooth connections is adding additional room for error. So while I understand you may not feel like you have enough bass, I don't know if the measurement is telling us a lot.

Try turning up the volume knob on the sub several steps, then run Audyssey again, and listen. When you run Audyssey, take all your measurements around a single seat. Don't go for a wide set of measurements since that will just result in compromises.

If it is still not enough bass, try turning on Dynamic EQ.

Is it is still not enough bass, go into the TRIM settings on the AVR and turn up the sub by 5db.

If it is still not enough bass, you need to buy a bigger sub. The SVS you mention is a great choice.

 

[highfigh]

Hi, thanks for the reply.. room dimensions are in meters. I've tried the sub in every corner of the room and more, these were the best 3 result I had. This is direct to the sub with no EQ and at 20hz it's more than 20db below the highest peak, Audyssey does help but still leaves a 12-14db difference. to my ears the 20hz in this room doesn't sound right, if I walk around the house (staircase for one) I get a really good clean sounding 20hz, in the room it sounds as though you hear harmonics more than the actual desired frequency. I really hope i'm missing a trick and this can be fixed.

I was looking at the floor plan but in a small room, the lowest frequencies are hard to propagate because their wavelengths are so long.

If you look at sound as a sine wave, the wavelength can be shown to scale if you assume the speed of sound to be a specific length. Since you may not be at sea level for absolute accuracy (the reference for this), you can still use it to come close enough. A wave has points where the energy is at a minimum, maximum and null and these points need to work in three dimensions. Because they interact in 3d, they can interact positively, negatively, or not much at all if they're coinciding at a null- this is called interference and if you're at a spot where negative interference occurs, you won't hear some frequencies as well as you want. All rooms reflect sound at various frequencies, to some degree. Looking at the REW screen shot, if I assume that you're sitting at the point where the head is shown (between the speakers and not close to the sub), I would conclude that the sub needs to be moved closer to the main speakers.

The first thing I would do is move the phase switch to the other position. I don't like a simple switch for this because the problem of woofer cone phase isn't as simple as 'either/or'- it's almost always somewhere between the two, so it's almost always wrong. If possible, a variable control for phase is best, but even better is finding a sub that has a DSP built in. If you can't find one, a passive sub with an amplifier that has a DSP or a separate amp and DSP (like MiniDSP or something similar) is the way to align the speakers and improve the sound.

Remember- not all acoustical issues can be removed through equalization alone, so placement of furnishings can be the next way to help the sound. After that, you would be looking at acoustical treatments.

 

[highfigh]

I'm very surprised you are not getting better output. The space is large but not THAT large, and that sub is pretty decent.

I am not convinced those Audyssey mics are linear enough to trust and using bluetooth connections is adding additional room for error. So while I understand you may not feel like you have enough bass, I don't know if the measurement is telling us a lot.

Try turning up the volume knob on the sub several steps, then run Audyssey again, and listen. When you run Audyssey, take all your measurements around a single seat. Don't go for a wide set of measurements since that will just result in compromises.

If it is still not enough bass, try turning on Dynamic EQ.

Is it is still not enough bass, go into the TRIM settings on the AVR and turn up the sub by 5db.

If it is still not enough bass, you need to buy a bigger sub. The SVS you mention is a great choice.

Doesn't matter if the mic is linear, the software can be tailored to use that mic through calibration, as long as the mic elements are consistent. Think of it as having an equalization curve that replaces missing energy in the same way the RIAA equalization restores low frequencies for recordings on vinyl.

 

[Darren-s-88]

I'm very surprised you are not getting better output. The space is large but not THAT large, and that sub is pretty decent.

I am not convinced those Audyssey mics are linear enough to trust and using bluetooth connections is adding additional room for error. So while I understand you may not feel like you have enough bass, I don't know if the measurement is telling us a lot.

Try turning up the volume knob on the sub several steps, then run Audyssey again, and listen. When you run Audyssey, take all your measurements around a single seat. Don't go for a wide set of measurements since that will just result in compromises.

If it is still not enough bass, try turning on Dynamic EQ.

Is it is still not enough bass, go into the TRIM settings on the AVR and turn up the sub by 5db.

If it is still not enough bass, you need to buy a bigger sub. The SVS you mention is a great choice.

I can achieve a fairly good output by turning up the volume, my problem is how dramatic the spl starts falling below 40hz. I'm trying to achieve a -3db of 20hz for a reasonably flat response but it's proving difficult in this room with the current setup. at my previous home I had a lot of low end room gain, 30hz had to be tamed. I'm experiencing the complete opposite here unfortunately

 

[nathan_h]

Something doesn't compute. Maybe the sub is damaged but that seems unlikely.

The way to get that sub to play well down low and avoid the drop off is to increase the sub level BEFORE running Audyssey. Audyssey will then lower the top end and retain the bump on the lower end, effectively making the roll off less pronounced.

There isn't anything OTHER THAN room size which should create that drop, so it is possible you need a larger sub. But I'd be surprised if you can't do better with that existing sub in that space.

 

[trochetier]

One solution may be to separately equalize the sub. for the desired response. Something like this may work - https://www.daytonaudio.com/product/1664/dsp-lf-low-frequency-dsp-controller

 

[Darren-s-88]

I was looking at the floor plan but in a small room, the lowest frequencies are hard to propagate because their wavelengths are so long.

If you look at sound as a sine wave, the wavelength can be shown to scale if you assume the speed of sound to be a specific length. Since you may not be at sea level for absolute accuracy (the reference for this), you can still use it to come close enough. A wave has points where the energy is at a minimum, maximum and null and these points need to work in three dimensions. Because they interact in 3d, they can interact positively, negatively, or not much at all if they're coinciding at a null- this is called interference and if you're at a spot where negative interference occurs, you won't hear some frequencies as well as you want. All rooms reflect sound at various frequencies, to some degree. Looking at the REW screen shot, if I assume that you're sitting at the point where the head is shown (between the speakers and not close to the sub), I would conclude that the sub needs to be moved closer to the main speakers.

The first thing I would do is move the phase switch to the other position. I don't like a simple switch for this because the problem of woofer cone phase isn't as simple as 'either/or'- it's almost always somewhere between the two, so it's almost always wrong. If possible, a variable control for phase is best, but even better is finding a sub that has a DSP built in. If you can't find one, a passive sub with an amplifier that has a DSP or a separate amp and DSP (like MiniDSP or something similar) is the way to align the speakers and improve the sound.

Remember- not all acoustical issues can be removed through equalization alone, so placement of furnishings can be the next way to help the sound. After that, you would be looking at acoustical treatments.

The 3 measurements attached to the post were the best 3 I got from around 20 different sub positionings. I'm familiar with peaks and nulls, just that normally they're specific frequencies where as this time there's a huge roll off below 40hz. The green line on that graph is the sub in the listening position.

at my old house I never had this issue with the same setup, room wasn't all that different but obviously different enough I had huge peaks to tame at 30hz and 20hz was reproduced nicely. I had a null at 50hz in the old house which a nearfield subwoofer solved quite well.

Maybe time to go down the SVS root and hope the dsp can help, I just have a bad feeling the room is the biggest cause of this problem.

 

[nathan_h]

Other than via ENORMOUS SIZE a room cannot cause a uniform drop off in output. Your room doesn't seem that big and your sub doesn't seem that weak. Maybe it is size in which case a beefier sub is a simple (costly) fix.

If room SHAPE is an issue you would see grossly uneven response with peaks and dips, not a nice flat linear down trend like your measurement suggests.

You've got enough DSP in the Audyssey system to get much better results if you have enough output in the sub for the room size. So the reason to get a new sub would be shear output, not more DSP. (Though of course more DSP would allow further modification once you solve your output problem.)

 

[William Lemmerhirt]

The 3 measurements attached to the post were the best 3 I got from around 20 different sub positionings. I'm familiar with peaks and nulls, just that normally they're specific frequencies where as this time there's a huge roll off below 40hz. The green line on that graph is the sub in the listening position.

at my old house I never had this issue with the same setup, room wasn't all that different but obviously different enough I had huge peaks to tame at 30hz and 20hz was reproduced nicely. I had a null at 50hz in the old house which a nearfield subwoofer solved quite well.

Maybe time to go down the SVS root and hope the dsp can help, I just have a bad feeling the room is the biggest cause of this problem.

Did you measure the FR at the old house with an audyssey mic? I wouldn’t trust one myself since REW doesn’t have a cal file and who knows what the mic roll off is, and a UMIK-1 is a lot cheaper than buying a PB4k. I believe the pb4k is definitely a better sub, but something is weird here.

 

[Pogre]

Did you measure the FR at the old house with an audyssey mic? I wouldn’t trust one myself since REW doesn’t have a cal file and who knows what the mic roll off is, and a UMIK-1 is a lot cheaper than buying a PB4k. I believe the pb4k is definitely a better sub, but something is weird here.

I agree. If using an Audyssey mic with REW all bets are off. I don't think I'd trust that even just to ballpark it. If accurate tho, it almost looks to me like there's some kind of filtering going on there. I'd double check everything. Maybe even full reset with REW, sub and the avr.

 

[Pogre]

How is the bass response on the north or south parts of the room in your diagram? Looks like your couch is currently along the west wall right now, yes? If it's better then we know it's probably not a subwoofer or setting problem. It could be a big null at your mlp in that room. I have spots like that.

 

[TLS Guy]

The response you got is how I would expect it to look. You have three problems, though too of them are related.

The first is that the speakers are along the long axis of the room and not the short axis. That is always a problem and to be avoided if possible. That accounts for the cancellation dip.

Your other problem is the open stairway and bass leakage. That leads to the next problem, that you sub is too small.

Bass leakage is a big issue for cone loudspeakers in the bass. That is especially true of sealed subs, and too a large extent ported ones. You can only correct it with more power, or stopping the bass leakage. Although this is where a transmission line sub has a huge advantage, as pipes can couple and pressurise huge spaces evenly. Our great room is huge, with two corridors coming off it, and an open stairway, yet I can pressurize it to 20 Hz with only a 10" driver that does not even break a sweat.

So the poor bass pressurization can be solved with brute force or guile.

 

[Darren-s-88]

Did you measure the FR at the old house with an audyssey mic? I wouldn’t trust one myself since REW doesn’t have a cal file and who knows what the mic roll off is, and a UMIK-1 is a lot cheaper than buying a PB4k. I believe the pb4k is definitely a better sub, but something is weird here.

I didn't unfortunately, didn't get in to REW until the move. Previously measured with an SPL meter at the old house and the difference was just as audible as it was measurable which is what led me to REW. The UMIK-1 definitely sounds like the next move.

 

[Darren-s-88]

How is the bass response on the north or south parts of the room in your diagram? Looks like your couch is currently along the west wall right now, yes? If it's better then we know it's probably not a subwoofer or setting problem. It could be a big null at your mlp in that room. I have spots like that.

There's no great response anywhere around the room, doors open or closed which I find strange.

 

[Pogre]

The response you got is how I would expect it to look. You have three problems, though too of them are related.

The first is that the speakers are along the long axis of the room and not the short axis. That is always a problem and to be avoided if possible. That accounts for the cancellation dip.

This is my suspicion as well, which is why I asked if he has better bass in the north or south sides of the room. I didn't consider the open stairway because it looks like there are doors he can close for that, right?

 

[Darren-s-88]

The response you got is how I would expect it to look. You have three problems, though too of them are related.

The first is that the speakers are along the long axis of the room and not the short axis. That is always a problem and to be avoided if possible. That accounts for the cancellation dip.

Your other problem is the open stairway and bass leakage. That leads to the next problem, that you sub is too small.

Bass leakage is a big issue for cone loudspeakers in the bass. That is especially true of sealed subs, and too a large extent ported ones. You can only correct it with more power, or stopping the bass leakage. Although this is where a transmission line sub has a huge advantage, as pipes can couple and pressurise huge spaces evenly. Our great room is huge, with two corridors coming off it, and an open stairway, yet I can pressurize it to 20 Hz with only a 10" driver that does not even break a sweat.

So the poor bass pressurization can be solved with brute force or guile.

Unfortunately in this room there's no option to move the mains, sub has a few options but where the TV is, is the only real option.

The door to the staircase can be closed and does help the low end by a few db but nothing spectacular, in fact leaving it open an inch or 2 produces the best results. I've tried closing all doors, leaving one open, 2 open and so on.. nothing fixes the issue

 

[Darren-s-88]

After a run of Audysssey, these were the results. however any slight adjustment to levels afterwards and I get a HUGE null between 80-100hz which is another problem I've been battling with. I assume it's some kind of phase issue with the mains. I'll do a few more runs tomorrow and get the graphs up