I took some measures ...

[antipop]

Originally Posted by GIK Acoustics

Antipop, could you upload the .mdat file?

You can get it from here :
http://db.tt/Qtm9Ggt9

[GIK Acoustics]

Antipop,

I've included a view of the waterfall graphs which give us some important information about the decay of sound in the room.

You can see some major resonances all through 30-60 Hz. These are pretty difficult areas to treat, especially 30 Hz, but probably don't bother you too much. The decay for 30 Hz is over a full second and a half! Thats the time it takes for it to get down to -40dB below the direct sound. You could hear this by playing a 30 Hz sine wave in REW's signal generator (you might want to glue everything down before the room rattles apart). When you stop the signal, you can hear that it isn't a direct cutoff. The other modal resonance in the lower range do this as well. Like I said, at 30 Hz, it shouldn't matter too much for most styles of music. But resonance at 70 Hz and above affects most music quite a bit.

From 100 Hz to 300 Hz there's still quite a bit of decay that could be cut down as well. Is there currently any treatment in the room?

[antipop]

Originally Posted by GIK Acoustics

Antipop,

I've included a view of the waterfall graphs which give us some important information about the decay of sound in the room.

You can see some major resonances all through 30-60 Hz. These are pretty difficult areas to treat, especially 30 Hz, but probably don't bother you too much. The decay for 30 Hz is over a full second and a half! Thats the time it takes for it to get down to -40dB below the direct sound. You could hear this by playing a 30 Hz sine wave in REW's signal generator (you might want to glue everything down before the room rattles apart). When you stop the signal, you can hear that it isn't a direct cutoff. The other modal resonance in the lower range do this as well. Like I said, at 30 Hz, it shouldn't matter too much for most styles of music. But resonance at 70 Hz and above affects most music quite a bit.

From 100 Hz to 300 Hz there's still quite a bit of decay that could be cut down as well. Is there currently any treatment in the room?

Wow that is awesome. Thank you so much

There is absolutely no treatment. Right now I'm using a Behringer DEQ2496 to actively correct some flaws but I'd love to go beyond that though I have no clue how to proceed.

That is a view of the living room. As you can see I have little room for maneuver

[GaryProtein]

Yesterday I was playing with the REW software and apparently did something to lose my REW settings and spent a long time tonight finding them again so I could make a graph, but I finally got them back and did a few tracings.

Measurements were made from my listening chair about 21-22 feet from the speakers.


Green = L+R together
Magenta = L only
Blue = R only


The volume remained constant throughout. The Green L+R is, as you would expect a little higher in volume than L or R alone. I was pleasantly surprised to find the room response of the LEFT and RIGHT channels were so similar.

Frequency sweeps are from 5 (FIVE) Hz to 20 kHz. Gotta get the bottom octaves! I was afraid to go any lower because tonight was the first time I ever put sine waves through the system. As I get more familiar with the software I'll do more tests and go lower.






Thank you to everyone who posted links for software, hardware and tutorials!

[GIK Acoustics]

Originally Posted by antipop

Wow that is awesome. Thank you so much

There is absolutely no treatment. Right now I'm using a Behringer DEQ2496 to actively correct some flaws but I'd love to go beyond that though I have no clue how to proceed.

That is a view of the living room. As you can see I have little room for maneuver

Nice looking room!

If you've noticed in the measurements, you can see that you don't have low frequency symmetry. The left and right channels have some similar peaks, but there are a few that one speaker has that the other doesn't. This is due to placement in your room. That would be almost impossible to fix without moving your position in the room, though, so we'll likely have to live with it.

The active EQ doesn't seem to do a whole lot. EQ systems can't remove resonance (as resonance happens over time, not just at the same instant the speakers play sound) but should help to even out the frequency response more than it is. You might want to do some tests with and without the EQ to see if you can tune it a bit better. I don't have much advice here as I don't have experience with active correction EQs but I think you could get a bit more even of a response with it.

Treating the front corners in the room with thick traps would definitely help with some of those lower resonances, and while it won't completely clean up the image, would give a lot sharper transients particularly in the low end. Separation of kick drum & bass would likely be instantly obvious.

The room looks quite "live" - that is, a lot of reflections and ambiance in the space. If you enjoy a live feel to the room you could treat your reflection points with diffusion so that you're breaking up harmful first reflections without removing the ambiance from the room. Of course, a few absorption panels would be beneficial as well, preference just overrules here.

What does the rest of the space look like? Open concept room?

[GIK Acoustics]

Originally Posted by GaryProtein

Measurements were made from my listening chair about 21-22 feet from the speakers.


Green = L+R together
Magenta = L only
Blue = R only


The volume remained constant throughout. The Green L+R is, as you would expect a little higher in volume than L or R alone. I was pleasantly surprised to find the room response of the LEFT and RIGHT channels were so similar.

Frequency sweeps are from 5 (FIVE) Hz to 20 kHz. Gotta get the bottom octaves! I was afraid to go any lower because tonight was the first time I ever put sine waves through the system. As I get more familiar with the software I'll do more tests and go lower.

Gary,

You probably shouldn't need to do measurement under 5 Hz. Not to incorrectly judge your equipment but 5 Hz would take tens of thousands of watts to drive - I hardly doubt your speakers can put out such a frequency. A 5 Hz tone has a full wavelength of over 200 feet. Also, a microphone doesn't usually capture below 20 or 30 Hz. It'll show something down that low in the measurements, but it won't be an accurate reading so it shouldn't matter. You can take measurements from 20 Hz and up. You should look at your graphs with a more limited range. No need to show all the empty space

You might see some comb filtering in the high end when you take measurements of both speakers. Nothing to worry, this just means your microphone isn't exactly between the two speakers so the sound just arrives milliseconds earlier from one of the speakers. Typically, we look at modes when you measure with two speakers, so usually a 2 speaker (or two speaker and a sub) measurement is viewed from 20 Hz to maybe 200 Hz. Full range graphs is better to have for separate speakers (though the low end in those graphs is important too - just like antipop's room, you can see each speaker has a much different interaction with the boundaries due to placement. Looking at the low frequencies of each separate speaker confirms this as well )

You can post the .mdats here as well if you like, but your posts sounds like you wish to get the hang of measurement more first.
There are loads of uses for measurements, and you can find out much more information from them than one might think! On the other hand, getting caught up with measurements of a room sometimes detracts from the listening experience.

[antipop]

Originally Posted by GIK Acoustics

Nice looking room!

If you've noticed in the measurements, you can see that you don't have low frequency symmetry. The left and right channels have some similar peaks, but there are a few that one speaker has that the other doesn't. This is due to placement in your room. That would be almost impossible to fix without moving your position in the room, though, so we'll likely have to live with it.

Thank you Alexander.

I was expecting not to have a symmetry with the placement I had. So I'm using active EQ to try to mitigate some of the issue here but I will have to live with it.

Originally Posted by GIK Acoustics

The active EQ doesn't seem to do a whole lot. EQ systems can't remove resonance (as resonance happens over time, not just at the same instant the speakers play sound) but should help to even out the frequency response more than it is. You might want to do some tests with and without the EQ to see if you can tune it a bit better. I don't have much advice here as I don't have experience with active correction EQs but I think you could get a bit more even of a response with it.

I need to take some measures with the EQ on to see what kind of results I can get. I'll try to do that this weekend.

Originally Posted by GIK Acoustics

Treating the front corners in the room with thick traps would definitely help with some of those lower resonances, and while it won't completely clean up the image, would give a lot sharper transients particularly in the low end. Separation of kick drum & bass would likely be instantly obvious.

The room looks quite "live" - that is, a lot of reflections and ambiance in the space. If you enjoy a live feel to the room you could treat your reflection points with diffusion so that you're breaking up harmful first reflections without removing the ambiance from the room. Of course, a few absorption panels would be beneficial as well, preference just overrules here.

So it could be helpful to put some bass trap in the corners ? What products do you recommand (GIK of course ). I could also add a plant behind each speaker if that helps

I honestly don't know which I would prefer, though I feel like I would like it more less lively. I have already planned to put some curtain on the right to kill the reflection on the window. On the left, I don't know if the sofa is enough or if I need panels on top of it.

Also, I'm looking for a larger carpet (but I'm very specific ) but the glass table will stay. I don't know what I can do on the ceiling without looking like it's coming from a spaceship

Originally Posted by GIK Acoustics

What does the rest of the space look like? Open concept room?

On the left of the room, there is a small place with a dining table (1,2m large and 3m long). I took the picture from the double door leading to the room and behind it there is a square hallway with the front door (1.5m deep)

[GaryProtein]

Hi Alexander, when I was doing the sweeps, I started out at 20 Hz, then tried 10 Hz. The graph stayed pretty flat, and my curiosity was killing me, so I went down in one hertz increments until I got to 5 Hz and stopped there. I could feel when the vibration started and a little higher in frequency the entire room (about 6000 cubic feet) was literally shaking. I couldn't do anything about the empty space on the graph. When I did the measurement capture in the REW software, what you see is exactly how the graph came out. I used the software feature to show the three measurements on the same graph. Next time I can have them on separate graphs.


The volume of the test sweeps were not far from the ballpark for regular listening, and the IRS-V has a servo amplifier for the woofer and I was told by the amplifier designer that it could go down almost to DC. The woofer amps will put out 2000 watts each, so driving the 5 Hz wave wasn't a problem. When I tri-amped the system, I spoke with the amplifier designer because I would no longer be using the original Infinity active crossover that bi-amped the system, as I would be switching to the PassLabs to tri-amp it and wanted to know if there was anything that I should be aware of in the process. The designer told me to be careful because the Infinity crossover had a low frequency limit to prevent the servo amp from extending down to DC, which he said the woofers, amp and servo could do, but would obviously be very bad for the system.


I have three microphones, the Behringer, AudioControl and the one that comes with the MEN220. I will try them all. With regard to comb filtering, I set the graphs at 1/12 octave smoothing because there are twelve notes in the chromatic scale and I felt a room frequency response with a resolution of one note would be meaningful in the realm of listening to music.


When I set up my system, I don't get over-involved with measurements. It was most recently refined about a year and a half ago almost entirely by ear by myself and my flutist daughter who plays in orchestras and knows what real live music sounds like. We both listened and dialed it in. Having active crossovers and a tri-amped system greatly helped. (Don't tell Nelson Pass I have light pencil marks on the XVR1 crossover faceplates showing the dial positions.) When my daughter and I both finished, we demoed it for each other. Our settings were not identical, but both agreed they were very close to each others and we could accept each others settings. I don't move stuff around or tweak much at all, so there will have to be something really new on the market to make me change what I already have.

[antipop]

Originally Posted by GaryProtein

Hi Alexander, when I was doing the sweeps, I started out at 20 Hz, then tried 10 Hz. The graph stayed pretty flat, and my curiosity was killing me, so I went down in one hertz increments until I got to 5 Hz and stopped there. I could feel when the vibration started and a little higher in frequency the entire room (about 6000 cubic feet) was literally shaking. I couldn't do anything about the empty space on the graph. When I did the measurement capture in the REW software, what you see is exactly how the graph came out. I used the software feature to show the three measurements on the same graph. Next time I can have them on separate graphs.

Gary, you can zoom on the graph. Use the box with the 4 arrows on the top right of the graph to set the correct axis We can better understand the measure with a bigger graph

Your post is really good and you have a great system. I'm very envious

[GIK Acoustics]

Originally Posted by antipop

So it could be helpful to put some bass trap in the corners ? What products do you recommand (GIK of course ). I could also add a plant behind each speaker if that helps

I honestly don't know which I would prefer, though I feel like I would like it more less lively. I have already planned to put some curtain on the right to kill the reflection on the window. On the left, I don't know if the sofa is enough or if I need panels on top of it.

Yes, bass traps in the corners work really well (for a couple reasons, actually). To keep it simple, bass traps simply absorb the most low end in corners.
Considering your placement in the room, first reflection panels would probably need to be on stands since there is an open space to the left and window to the right.
I imagine these few steps along with the curtain would make a big difference in the ambiance of the room, so I would recommend going that route and seeing how it suits you. Of course, you may want/need more (and the graphs show sub bass treatment is really needed, so you might want to look into tuned traps for certain problems)

Originally Posted by GaryProtein

Hi Alexander, when I was doing the sweeps, I started out at 20 Hz, then tried 10 Hz. The graph stayed pretty flat, and my curiosity was killing me, so I went down in one hertz increments until I got to 5 Hz and stopped there. I could feel when the vibration started and a little higher in frequency the entire room (about 6000 cubic feet) was literally shaking. I couldn't do anything about the empty space on the graph. When I did the measurement capture in the REW software, what you see is exactly how the graph came out. I used the software feature to show the three measurements on the same graph. Next time I can have them on separate graphs.

The volume of the test sweeps were not far from the ballpark for regular listening, and the IRS-V has a servo amplifier for the woofer and I was told by the amplifier designer that it could go down almost to DC. The woofer amps will put out 2000 watts each, so driving the 5 Hz wave wasn't a problem. When I tri-amped the system, I spoke with the amplifier designer because I would no longer be using the original Infinity active crossover that bi-amped the system, as I would be switching to the PassLabs to tri-amp it and wanted to know if there was anything that I should be aware of in the process. The designer told me to be careful because the Infinity crossover had a low frequency limit to prevent the servo amp from extending down to DC, which he said the woofers, amp and servo could do, but would obviously be very bad for the system.

Perhaps I was being more doubtful than necessary then! However, I will still emphasize that microphones have a hard time capturing 30 Hz, let alone something 3 octaves lower, so I wouldn't expect true results (regardless if they look good or not).

Typically, you will want to run your sweeps quite loud to get the noise floor down. Of course, they don't have to limit the amps or anything silly, but uncomfortably loud while within the systems limits are best for accurate decay readings. Also, doing more sweeps can help limit the s/n ratio as well.

Originally Posted by GaryProtein

I have three microphones, the Behringer, AudioControl and the one that comes with the MEN220. I will try them all. With regard to comb filtering, I set the graphs at 1/12 octave smoothing because there are twelve notes in the chromatic scale and I felt a room frequency response with a resolution of one note would be meaningful in the realm of listening to music.

Yes, this is a 'realistic' view to take, especially when viewing high freq (or full spectrum) measurements. However, I do recommend looking at frequencies under 300 Hz with no smoothing as you can uncover some nulls relating to SBIR that would otherwise be hidden with such vague resolution. Of course, if you're trying to deduce information from them, you really want to see the measurements in the worst (best) way possible, if that makes sense. With higher frequencies though, we obviously cannot hear a difference between 1/200th of a note at 2k so it makes sense to smooth.

The comb filtering is just a byproduct you may or may not see when measuring two speakers. I just want to make people aware of it so they aren't thinking their speakers are messed up or anything

However, if you see comb filtering with just one speaker and not two, its typically a sign of first reflections being untreated. Depending on your distance from the speakers, this could actually end up lower in frequency than you'd expect.

Originally Posted by GaryProtein

When I set up my system, I don't get over-involved with measurements. It was most recently refined about a year and a half ago almost entirely by ear by myself and my flutist daughter who plays in orchestras and knows what real live music sounds like. We both listened and dialed it in. Having active crossovers and a tri-amped system greatly helped. (Don't tell Nelson Pass I have light pencil marks on the XVR1 crossover faceplates showing the dial positions.) When my daughter and I both finished, we demoed it for each other. Our settings were not identical, but both agreed they were very close to each others and we could accept each others settings. I don't move stuff around or tweak much at all, so there will have to be something really new on the market to make me change what I already have.

Excellent.