Fixing below 500Hz

[sharock]

I posted this in the measurements sharing thread, however, I was looking for some specific advice on if it's possible to improve my FR below ~400Hz in my living room. Ideally, as cheaply as possible (I do lust after D&D 8c or Genelec Ones) and without too much room treatment since I don't have the space or 'partner acceptance factor' budget.

The room is 5m x 3m with the speakers, sub and TV positioned along the 5m wall facing a sofa. I can take a photo later if it helps, but the position is not very changeable due to lack of space. At best, I can maybe move the speakers forwards or backwards relative to the front wall but too far back would put them behind the TV (which I assume is even worse for the FR) and too forward means they'll be in the middle of the room. Right now they are level with the front of the TV unit with no toe-in. I'd need to measure the actual distance from front wall.

NAD C658 > Elac Navis ARF-51, SVS SB4000
REW MMM, 1/6 smoothing, after Dirac Live correction to the default target curve.

The specific area that looks quite bad to me is between 150-400Hz. Is this SBIR? I'm actually crossing over the sub quite high at 120Hz as other frequencies tested (60, 80, 100, 150Hz) seem to make things far worse. I have even tried a second sub (SB1000 Pro) but without proper bass management it made below 100Hz even worse! Could some absorption directly behind the speakers help?

Thanks for any thoughts or advice!

 

[Dj7675]

I posted this in the measurements sharing thread, however, I was looking for some specific advice on if it's possible to improve my FR below ~400Hz in my living room. Ideally, as cheaply as possible (I do lust after D&D 8c or Genelec Ones) and without too much room treatment since I don't have the space or 'partner acceptance factor' budget.

The room is 5m x 3m with the speakers, sub and TV positioned along the 5m wall facing a sofa. I can take a photo later if it helps, but the position is not very changeable due to lack of space. At best, I can maybe move the speakers forwards or backwards relative to the front wall but too far back would put them behind the TV (which I assume is even worse for the FR) and too forward means they'll be in the middle of the room. Right now they are level with the front of the TV unit with no toe-in. I'd need to measure the actual distance from front wall.

NAD C658 > Elac Navis ARF-51, SVS SB4000
REW MMM, 1/6 smoothing, after Dirac Live correction to the default target curve.

The specific area that looks quite bad to me is between 150-400Hz. Is this SBIR? I'm actually crossing over the sub quite high at 120Hz as other frequencies tested (60, 80, 100, 150Hz) seem to make things far worse. I have even tried a second sub (SB1000 Pro) but without proper bass management it made below 100Hz even worse! Could some absorption directly behind the speakers help?

View attachment 182527

Thanks for any thoughts or advice!

Just a couple comments..
-How does it sound to you? Can you measure in a different place (either forward or back) that doesn’t have that issue there? Does it sound better?
-What does your before measurement look like?
-Adding some 4 inch rock wool or oc703 fiberglass behind the speakers would be an inexpensive test. Or changing the distance from the wall your speakers are to see if the issue changes
-EQ/DSP is a strange thing. I have on some occasions gotten things that looked perfect on a graph, but didn’t sound right. Always go with your ears with EQ.
-I had a similiar issue in my HT that was SBIR. When I tried to flatten it out it didn’t sound good, so I leave it alone since it sounds fine.
With SBIR there are online calculators where you put in your distance to the speakers and the distance of your speakers from your front wall, that should help figure it out

 

[Kvalsvoll]

The specific area that looks quite bad to me is between 150-400Hz.

Usually is so.

But you should worry more about what happens in the time domain, this frequency response only show a symptom of the real problem.

Unfortunately there is no quick-fix. Better speakers can improve things, but to get this to a high performance level, acoustic treatment is necessary.

 

[ldarieut]

That doesn’t look bad at all for a in room fr . Maybe you should look at other curves for Dirac, like Toole or b&k. The standard one sound bland.

 

[Dj7675]

I posted this in the measurements sharing thread, however, I was looking for some specific advice on if it's possible to improve my FR below ~400Hz in my living room. Ideally, as cheaply as possible (I do lust after D&D 8c or Genelec Ones) and without too much room treatment since I don't have the space or 'partner acceptance factor' budget.

The room is 5m x 3m with the speakers, sub and TV positioned along the 5m wall facing a sofa. I can take a photo later if it helps, but the position is not very changeable due to lack of space. At best, I can maybe move the speakers forwards or backwards relative to the front wall but too far back would put them behind the TV (which I assume is even worse for the FR) and too forward means they'll be in the middle of the room. Right now they are level with the front of the TV unit with no toe-in. I'd need to measure the actual distance from front wall.

NAD C658 > Elac Navis ARF-51, SVS SB4000
REW MMM, 1/6 smoothing, after Dirac Live correction to the default target curve.

The specific area that looks quite bad to me is between 150-400Hz. Is this SBIR? I'm actually crossing over the sub quite high at 120Hz as other frequencies tested (60, 80, 100, 150Hz) seem to make things far worse. I have even tried a second sub (SB1000 Pro) but without proper bass management it made below 100Hz even worse! Could some absorption directly behind the speakers help?

View attachment 182527

Thanks for any thoughts or advice!

-Also, I don't know if you have experimented with partial (say under 500hz) vs full range with a room curve. Some interesting comments by Floyd Toole regarding "room curves" LINK

That doesn’t look bad at all for a in room fr . Maybe you should look at other curves for Dirac, like Toole or b&k. The standard one sound bland.

It looks like a pretty good boost to me... looks like around an 8dB increase from 20hz to 10K.

 

[sharock]

Thank you for the replies.

I'm a bit busy this weekend but will try to find some time to measure the uncorrected FR and reply directly to some of the comments.

 

[DJBonoBobo]

In my case this area was affected by placing absorbers behind the speakers at the front wall (look: https://www.audiosciencereview.com/...n-a-small-room-subs-ma1-absorbers-avaa.27288/)

It is possible the TV plays an important role in this area, too.

I your case i would also think about the back wall, because i guess your LP is close to the back wall?

Your measurement looks not bad, but it´s difficult to see because 1/6 is too much smoothing. Better use var smoothing.

 

[Hipper]

You could move your speakers temporarily to your listening position then move the out of the way when not in use.

 

[sharock]

Here are some measurements with and without Dirac correction, var smoothing.

The speakers are about 63cm out from the front wall and could be moved back another 20cm at which point they'd be level with the TV.

You could move your speakers temporarily to your listening position then move the out of the way when not in use.

They are 20kg towers so a bit annoying to move around constantly!

But you should worry more about what happens in the time domain, this frequency response only show a symptom of the real problem.

I'm not sure how I'd go about checking this?

Just a couple comments..
-How does it sound to you? Can you measure in a different place (either forward or back) that doesn’t have that issue there? Does it sound better?
-What does your before measurement look like?
-Adding some 4 inch rock wool or oc703 fiberglass behind the speakers would be an inexpensive test. Or changing the distance from the wall your speakers are to see if the issue changes
-EQ/DSP is a strange thing. I have on some occasions gotten things that looked perfect on a graph, but didn’t sound right. Always go with your ears with EQ.
-I had a similiar issue in my HT that was SBIR. When I tried to flatten it out it didn’t sound good, so I leave it alone since it sounds fine.
With SBIR there are online calculators where you put in your distance to the speakers and the distance of your speakers from your front wall, that should help
figure it out
-Also, I don't know if you have experimented with partial (say under 500hz) vs full range with a room curve. Some interesting comments by Floyd Toole regarding "room curves" LINK

It sounds decent enough to me, but surely I'm missing something with that suckout in the upper bass and lower mids? The uncorrected FR above 500Hz looks a bit uneven too so that's why I've opted for a full range Dirac.

 

[Kvalsvoll]

I'm not sure how I'd go about checking this?

In REW, many ways to do this; Decay, Waterfall, Spectrogram. Decay is often useful for a quick look.

Frequency and time are sort of mixed-up when the sound has left the electric wires and enters the mechanical and acoustic parts in the speaker, and then eventually enters a room with reflections. Sound is very easy and simple before that happens, and very complex and difficult after.

The graph you see in a frequency response plot is only a picture of what is really going on, what is displayed depends on the time window you view. The response shown in the frequency graph uses a very long window, so it shows what happens if the speaker plays a continuous signal.

I had a thread somewhere here, with some examples where I try to explain how to view this, with 2 different speakers measured, they have a similar frequency response, but they sound very different. Looking at what happens in the time domain shows that these differences can indeed be measured. But be careful, if you find that thread, because some people got angry over this.

 

[Tangband]

I posted this in the measurements sharing thread, however, I was looking for some specific advice on if it's possible to improve my FR below ~400Hz in my living room. Ideally, as cheaply as possible (I do lust after D&D 8c or Genelec Ones) and without too much room treatment since I don't have the space or 'partner acceptance factor' budget.

The room is 5m x 3m with the speakers, sub and TV positioned along the 5m wall facing a sofa. I can take a photo later if it helps, but the position is not very changeable due to lack of space. At best, I can maybe move the speakers forwards or backwards relative to the front wall but too far back would put them behind the TV (which I assume is even worse for the FR) and too forward means they'll be in the middle of the room. Right now they are level with the front of the TV unit with no toe-in. I'd need to measure the actual distance from front wall.

NAD C658 > Elac Navis ARF-51, SVS SB4000
REW MMM, 1/6 smoothing, after Dirac Live correction to the default target curve.

The specific area that looks quite bad to me is between 150-400Hz. Is this SBIR? I'm actually crossing over the sub quite high at 120Hz as other frequencies tested (60, 80, 100, 150Hz) seem to make things far worse. I have even tried a second sub (SB1000 Pro) but without proper bass management it made below 100Hz even worse! Could some absorption directly behind the speakers help?

View attachment 182527

Thanks for any thoughts or advice!

My advice for you is to maximize the quality of the digital source in the beginning of the chain . It dont need to be expensive at all.
This way you will somewhat clean up any boominess in the bass and you will experience a better articulation of the recorded music . If you use a Windows computer as a source , use ASIO to a dac or Foobar as player because the Windows internal player really sucks .

As for the loudspeakers …. Dirac or GLM are only good if you have a really bad room or if youre forced to do a poorly setup for your loudspeakers .
Every correction you do in the analog or digital domain are gonna be slightly worse overall to the sound . There is no such thing as a transparent digital room correction .

SBIR is real , but in my opinion much less disturbing than having reflections from the tweeter to a nearby wall and such , or a bad digital source, - that will really ruin the sound .

Trying to tame SBIR with thick damping material on the wall behind the loudspeaker will make the sound worse in some way , better in some . But no clear advantage , because the stereosystem is flawed and needs some reflective help from the back wall to make the 2 channel illusion bigger .

The sound gets much clearer if the loudspeakers are free from walls , more than 100 cm soundtravel from the baffle . That means about 50 cm or more from the loudspeaker baffle to the back wall .

Try it - listen, and you will hear that the sound gets more unclear if the speakers placement are against the wall .

But first - optimise the digital signal from the source and turn Dirac off .

Edit : I have made thousands of measurements and the mic at listening position is very different to what the ear/brain hears . Dont trust full range measurements from longer distances than 5 ms soundtravel , ie 1,7 metres because of the precedence and HAAS effect .

Read about it here :

Precedence effect - Wikipedia

en.m.wikipedia.org

 

[Tangband]

Edit : a 5.1 or 7.1 system dont need any help from the reflections from the walls to compensate for the flawed 2 channel stereo system, you can with a 5.1 cinema setup have much more damping material on the walls and the sound will be better.

This is not the case with an optimal sounding 2-channel setup.