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Is this the best I can get? Do I now supplement with EQ for Main Monitors?
Old 2nd September 2019
  #1
Gear Maniac
Is this the best I can get? Do I now supplement with EQ for Main Monitors?

Over the past several weeks I've been experimenting with different layouts and have ended up on what I believe is the best that I can get.

With that being said, I still have some problematic ranges. I'm looking for any advice on how to nail down specifics, and whether EQ is a valid option at this stage.

I have some extreme nulls around 300, 500 and 700. I have tried moving the monitors as close as physically possible (about 8.5 inches) and the the frequency response was actually better in the current position vs. closer.

I tried moving and rotating the phase of the sub, and the current results indicate the best I was able to achieve to-date.

Thank you in advance!


EDIT:

Stereo KH120a + 805 sub.
Room L / W / H: 230" x 180" x 85" to 120"
X-Over @ 80hz (internal via 805 sub).

Sub Positioning:
57" from front wall.
13.75" from left wall.
7.5" from ground.

Mains Positioning:
16" from front wall.
53" from side walls.
48" from ground.
74" L/R spread

Listening Position:
73.5" to each L/R monitor.

Treatment:
Soffit Traps @ front corners.
Tri-traps @ rear corners.
244 @ first side wall reflection points.
242 @ ceiling reflection point.
244 @ rear wall.
MBT's @ front center wall stacked 2 deep.
DC2 diffusors @ rear wall and rear ceiling (nearest drum kit)

Room Construction:
2 layers drywall + green glue (side walls + ceiling)
Concrete slab + wood laminate
4 windows (2 front wall + 2 left side wall)
2 doors (2 right side wall)
Ceiling (as noted above) is tapered from 85" to 120" front to back.

EDIT #2: Updated REW measurements to include Sub only, L only, and R only measurements. Removed old file.
Attached Thumbnails
Is this the best I can get?  Do I now supplement with EQ for Main Monitors?-20190902_072650.jpg   Is this the best I can get?  Do I now supplement with EQ for Main Monitors?-20190902_072830.jpg   Is this the best I can get?  Do I now supplement with EQ for Main Monitors?-20190902_072834.jpg   Is this the best I can get?  Do I now supplement with EQ for Main Monitors?-20190902_072841.jpg   Is this the best I can get?  Do I now supplement with EQ for Main Monitors?-20190902_072849.jpg  

Is this the best I can get?  Do I now supplement with EQ for Main Monitors?-20190902_072857.jpg   Is this the best I can get?  Do I now supplement with EQ for Main Monitors?-20190902_072903.jpg  
Attached Files
File Type: mdat SleepyStudios-2019-09-07-3PM.mdat (13.91 MB, 5 views)

Last edited by formula428; 2nd September 2019 at 03:37 PM.. Reason: added more info.
Old 2nd September 2019
  #2
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You’re gonna have to give more detail about your room dimensions, current treatment, the speaker and listener positions you have tried etc.
Old 2nd September 2019
  #3
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akebrake's Avatar
 

Quote:
Originally Posted by explorer View Post
You’re gonna have to give more detail about your room dimensions, current treatment, the speaker and listener positions you have tried etc.
It's in the mdat if you take a closer look
Old 2nd September 2019
  #4
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Synthpark's Avatar
Quote:
Originally Posted by formula428 View Post
I have some extreme nulls around 300, 500 and 700. I have tried moving the monitors as close as physically possible (about 8.5 inches) and the the frequency response was actually better in the current position vs. closer.
I see more severe problems with your low end below 40 Hz, and 150 Hz, the rest is quite ok, a little weak at 200-400 Hz, but not critical. The 700 Hz is very narrow. The overall sound in der mids/heights is too dry for my taste, slats could help. Measurement without table, right? cheers.
Attached Thumbnails
Is this the best I can get?  Do I now supplement with EQ for Main Monitors?-fg.jpg  
Old 2nd September 2019
  #5
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Quote:
Originally Posted by akebrake View Post
It's in the mdat if you take a closer look
You got me. I didn’t open the mdat before replying.
Old 2nd September 2019
  #6
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Quote:
Originally Posted by explorer View Post
You got me. I didn’t open the mdat before replying.
But you’re partly right...
(I just happened to find it)

We still need a lot more information about the room.
Shape, what kind of walls, ceiling, floor. (concrete, wood, ply...) Carpet on floor, openings, windows, wardrobes lockers etc.

Best
Old 2nd September 2019
  #7
Gear Maniac
Quote:
Originally Posted by Synthpark View Post
I see more severe problems with your low end below 40 Hz, and 150 Hz, the rest is quite ok, a little weak at 200-400 Hz, but not critical. The 700 Hz is very narrow. The overall sound in der mids/heights is too dry for my taste, slats could help. Measurement without table, right? cheers.
With table. But it really didn't change that much without when I tried it. I can move and retest if you'd like.

Slats - like some type of large diffuser? Could that go in front of the existing absorption? Right now I have large 244's covering nearly all the side wall and 100% of the rear wall. This was done because the left side wall is almost all windows (hard reflections) and the right wall has 2 doors. The rear is a drum kit, and I wanted to deaden the space.

I also have some 244's with the range limiter. I can switch the first reflection points to be with RL instead of full range. I will try and get back with update.

How would I go about fixing sub 40hz and 150?
Old 2nd September 2019
  #8
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Quote:
Originally Posted by formula428 View Post
With table. But it really didn't change that much without when I tried it. I can move and retest if you'd like.

Slats - like some type of large diffuser? Could that go in front of the existing absorption? Right now I have large 244's covering nearly all the side wall and 100% of the rear wall. This was done because the left side wall is almost all windows (hard reflections) and the right wall has 2 doors. The rear is a drum kit, and I wanted to deaden the space.

I also have some 244's with the range limiter. I can switch the first reflection points to be with RL instead of full range. I will try and get back with update.

How would I go about fixing sub 40hz and 150?
Wow, with table! Mids look very flat above 800 Hz. How did you manage to avoid any comb filtering by the table? I am really struggling with mine currently, it creates a dip at 900 Hz and a bump at 3k. Maybe a photo would be nice.

The treatment problems often start below 40-50 Hz where commercial bass traps stop to work (unless a company offers something special, like mbakustik here in Germany). There are a couple of solutions. DIY could consist in building some helmholtz absorbers for the lowest range, or membrane (which is not as easy). I got rid of problems like this by having the sub under my table, avoiding exciting the (1,0,0) mode too much. Or you simply use a highpass filter. I would keep an eye on the group delay.
Old 2nd September 2019
  #9
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You can always supplement your treatment with Sonarworks, it can take you a long way if you've treated your room at all.
Old 2nd September 2019
  #10
nms
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Quote:
Originally Posted by formula428 View Post
I also have some 244's with the range limiter. I can switch the first reflection points to be with RL instead of full range.
Don't do this. First reflection points should be absorptive.

Quote:
Originally Posted by damnfractals View Post
You can always supplement your treatment with Sonarworks, it can take you a long way if you've treated your room at all.
Not a good idea to use Sonarworks to try fixing room problems. If you decide to use it, any room correction is best applied lightly.
Old 2nd September 2019
  #11
Gear Maniac
I've added pictures in the first post, and more description about the room.
Old 2nd September 2019
  #12
Gear Maniac
Quote:
Originally Posted by nms View Post
Don't do this. First reflection points should be absorptive.

Not a good idea to use Sonarworks to try fixing room problems. If you decide to use it, any room correction is best applied lightly.
Okay - noted about the absorption. They are supposed to be absorption below 400 and gain reflectivity above 400.

Sonarworks was a consideration, and I'd only use it to reduce the sub-40hz and tame the 150 bump.
Old 2nd September 2019
  #13
Gear Maniac
Quote:
Originally Posted by Synthpark View Post
Wow, with table! Mids look very flat above 800 Hz. How did you manage to avoid any comb filtering by the table?
I spread out the mains such that only the corners of the table are the direct path to mic and listening position. I do have to sit back about 1.5 feet away from desk when critical listening. The table is also 100% real wood (not sure if that matters).
Old 2nd September 2019
  #14
Here for the gear
 

Quote:
Originally Posted by nms View Post
Don't do this. First reflection points should be absorptive.

Not a good idea to use Sonarworks to try fixing room problems. If you decide to use it, any room correction is best applied lightly.
Exactly why I said 'supplement', often it will be a more realistic (money wise) way to get better results than rebuilding the entire room. It will obviously do nothing for your decay times, but the response can be improved quite a bit and it, of course works best as the last touch not as a main fix.
Old 3rd September 2019
  #15
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akebrake's Avatar
 

Quote:
Originally Posted by formula428 View Post
I've added pictures in the first post, and more description about the room.
Thanks! Looks like a lot of boxes, instruments etc are placed on the floor. They will certainly reflect sound above say 200 Hz. Especially those fairly close to the speakers or mic.

I plotted some measurements from the first mdat as an example.(reference)
Pic 1. L& R +sub overlaid. 30-40 Hz are strong.
If 150 Hz is "strong" or 50-100 are ”weak” is up to debate.

Pic 2. Waterfall.(L+sub) Red arrows (my marks) show that ”something” happens in the first trace of the plot. This is a REW default plot with long IR window (0.5 s) which gives high resolution in frequency. The yellow arrows mark resonances which might be drums or other resonating objects.

Pic 3 Is a Spectrogram Wavelet plot. (L+sub)
E.g. a waterfall (”seen from above”) but with peak normalized and a Frequency Dependent Window used. E.g. IR window gradually shortens towards higher frequencies. Also: Linear (%) amplitude scale which means the first 12dB or so is ”favourised”. A lot of detail shows up like the black blobs (”SBIR- holes”) at diferent times.

Pic 4. A Wavelet with a longer time scale. Also normalized but with log amplitude and a -20 dB floor. Used to compare decaytime of modes which can be difficult to estimate on a WF plot. The 30 Hz mode decays a lot slower than the higher frequencies.

That’s what it looks like IMHO.
What it sounds like and what you like to improve is up to you.

Best
Attached Thumbnails
Is this the best I can get?  Do I now supplement with EQ for Main Monitors?-l-r-sub-ovly-2sept.jpg   Is this the best I can get?  Do I now supplement with EQ for Main Monitors?-l-sub-2-sept.jpg   Is this the best I can get?  Do I now supplement with EQ for Main Monitors?-l-sub-wave-lin.jpg   Is this the best I can get?  Do I now supplement with EQ for Main Monitors?-l-sub-wave-20db-2sept.jpg  
Old 3rd September 2019
  #16
Gear Maniac
Quote:
Originally Posted by akebrake View Post
Thanks! Looks like a lot of boxes, instruments etc are placed on the floor. They will certainly reflect sound above say 200 Hz. Especially those fairly close to the speakers or mic.

I plotted some measurements from the first mdat as an example.(reference)
Pic 1. L& R +sub overlaid. 30-40 Hz are strong.
If 150 Hz is "strong" or 50-100 are ”weak” is up to debate.

Pic 2. Waterfall.(L+sub) Red arrows (my marks) show that ”something” happens in the first trace of the plot. This is a REW default plot with long IR window (0.5 s) which gives high resolution in frequency. The yellow arrows mark resonances which might be drums or other resonating objects.

Pic 3 Is a Spectrogram Wavelet plot. (L+sub)
E.g. a waterfall (”seen from above”) but with peak normalized and a Frequency Dependent Window used. E.g. IR window gradually shortens towards higher frequencies. Also: Linear (%) amplitude scale which means the first 12dB or so is ”favourised”. A lot of detail shows up like the black blobs (”SBIR- holes”) at diferent times.

Pic 4. A Wavelet with a longer time scale. Also normalized but with log amplitude and a -20 dB floor. Used to compare decaytime of modes which can be difficult to estimate on a WF plot. The 30 Hz mode decays a lot slower than the higher frequencies.

That’s what it looks like IMHO.
What it sounds like and what you like to improve is up to you.

Best
Thanks for pointing out some of the REW tools and how to read them. The measurements certainly coincide with the sound - 30hz is very strong indeed. Sounds cool if I was watching a movie, but not so great for critical mixing. Would definitely want to tame that low end.

For the sbir holes, can I "find them" by using their durations? Same with the resonances, I would be curious to know where they are coming from. Some items during critical mixing I could remove from the room.
Old 3rd September 2019
  #17
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Quote:
For the sbir holes, can I "find them" by using their durations?
Yes you can! Well, not their duration really, but rather by using the frequency. SBIR comes from one source only: the distance between the speaker and the walls(s). Those "hole" or "dips" are caused by sound waves going out from the speaker hitting a wall, bouncing back the way they came, then interfering with themselves as they get back to the speaker again, causing phase cancellation at some frequencies. The front wall is normally the biggest culprit here, but it could also be caused by the rear wall or the side walls. It's fairly easy to figure out if you know the frequency: divide that by the speed of sound, divide that answer by 4, and that's the distance that is causing the null. Get out your tape measure and measure from the front face of the speaker to find which wall is the culprit. Stated more simply: if you know the frequency then divide that by 86 and that's the distance in meters.

Quote:
Same with the resonances,
Those are most likely modal resonances, and once again they are caused by the walls... but this time it's not related to the speaker: only the walls. For every wavelength that fits in exactly between two room boundaries, there is one such resonance. Those are called "axial modes", because they occur along the three principles axes of the room: Front to back, left to right, and ceiling to floor. There are also resonances that involve four such boundaries, and those are called "tangential" modes, and there are others that involve all six boundaries, and those are called "oblique" modes. The axials are pretty much always the biggest ones, the lowest in frequency, and the hardest to treat. You could find them all by using pen and paper to do al the math, but there's a much easier way. Use one of these Room Ratio calculators to figure out the response of your room:

http://www.bobgolds.com/Mode/RoomModes.htm
https://amcoustics.com/tools/amroc

Both of those are very good. Just enter the dimensions of your room, and they do all the hard work for you. They give you tons of other information, in addition to just the axial modal frequencies, and all of that is useful in understanding the acoustic response of your room.

- Stuart -
Old 3rd September 2019
  #18
Gear Maniac
Quote:
Originally Posted by Soundman2020 View Post
Yes you can! Well, not their duration really, but rather by using the frequency. SBIR comes from one source only: the distance between the speaker and the walls(s). Those "hole" or "dips" are caused by sound waves going out from the speaker hitting a wall, bouncing back the way they came, then interfering with themselves as they get back to the speaker again, causing phase cancellation at some frequencies. The front wall is normally the biggest culprit here, but it could also be caused by the rear wall or the side walls. It's fairly easy to figure out if you know the frequency: divide that by the speed of sound, divide that answer by 4, and that's the distance that is causing the null. Get out your tape measure and measure from the front face of the speaker to find which wall is the culprit. Stated more simply: if you know the frequency then divide that by 86 and that's the distance in meters.

Those are most likely modal resonances, and once again they are caused by the walls... but this time it's not related to the speaker: only the walls. For every wavelength that fits in exactly between two room boundaries, there is one such resonance. Those are called "axial modes", because they occur along the three principles axes of the room: Front to back, left to right, and ceiling to floor. There are also resonances that involve four such boundaries, and those are called "tangential" modes, and there are others that involve all six boundaries, and those are called "oblique" modes. The axials are pretty much always the biggest ones, the lowest in frequency, and the hardest to treat. You could find them all by using pen and paper to do al the math, but there's a much easier way. Use one of these Room Ratio calculators to figure out the response of your room:

http://www.bobgolds.com/Mode/RoomModes.htm
https://amcoustics.com/tools/amroc

Both of those are very good. Just enter the dimensions of your room, and they do all the hard work for you. They give you tons of other information, in addition to just the axial modal frequencies, and all of that is useful in understanding the acoustic response of your room.

- Stuart -
Looking at the following:
16" from driver to front wall = 211hz
53" from driver to near side wall = 63hz
127" from driver to far wall = 27hz
212" from driver to rear wall = 16hz

Do those numbers seem correct? If so, not seeing any being a dip in the freq response. Is it possible I just lucked out?

Also, how do you evaluate a room with a sloped ceiling? Goes from 85" to 120", about a 9.25° angle from listening position (front wall) to drums (rear wall).
Old 5th September 2019
  #19
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In addition to Stuarts Modal Tutorial I like to add that the Modal frequencies
are inserted as coloured bars along the x-scale in the graphs in post 15.
Red= Axial Length, Grn= Width and Blue=Hight (estimated)

As I understand it, your Sub is located to the left in the room some 57” (1.4m) from the front wall. Like in the REW Room Sim pic?
(I don’t know how Room Sim looks in your REW 5.16 version)

Is this the best I can get?  Do I now supplement with EQ for Main Monitors?-sim-l-sub-.jpg

One can watch how calculated Room-modes and First Reflections (roughly) correlate with measured results and what happens to the Frequency Response when you:

1. Insert /change room dimensions (e.g. ceiling hight)
Swap between ft/ meter.
2. Move speakers around (L-R-Up-Down-Front-Back)
3. Move listener (L-R-Up-Down-Front-Back)
4. Add (average) absorption to individual boundaries.
5. Add one or more subs. Move Subs.
6. Change X-over frequency, Polarity, Time align and more...

Quite educational IMHO.

Before one can say too much how to improve FR & Decay (from the first measured results) I like to see a couple of new measurements:
Left KH120 alone & R alone and Sub only.

Best

BTW How did you find the current speaker positions?


Quote:
Originally Posted by formula428 View Post
...
Also, how do you evaluate a room with a sloped ceiling? Goes from 85" to 120", about a 9.25° angle from listening position (front wall) to drums (rear wall).
RE Hight dimension. A sloped ceiling adds uncertiness obviously. Move mic and measure what happens. (Another tutorial )
Attached Thumbnails
Is this the best I can get?  Do I now supplement with EQ for Main Monitors?-sim-l-sub-.jpg   Is this the best I can get?  Do I now supplement with EQ for Main Monitors?-sim-r-sub.jpg  
Old 5th September 2019
  #20
Gear Maniac
Quote:
Originally Posted by akebrake View Post
In addition to Stuarts Modal Tutorial I like to add that the Modal frequencies
are inserted as coloured bars along the x-scale in the graphs in post 15.
Red= Axial Length, Grn= Width and Blue=Hight (estimated)

As I understand it, your Sub is located to the left in the room some 57” (1.4m) from the front wall. Like in the REW Room Sim pic?
(I don’t know how Room Sim looks in your REW 5.16 version)



One can watch how calculated Room-modes and First Reflections (roughly) correlate with measured results and what happens to the Frequency Response when you:

1. Insert /change room dimensions (e.g. ceiling hight)
Swap between ft/ meter.
2. Move speakers around (L-R-Up-Down-Front-Back)
3. Move listener (L-R-Up-Down-Front-Back)
4. Add (average) absorption to individual boundaries.
5. Add one or more subs. Move Subs.
6. Change X-over frequency, Polarity, Time align and more...

Quite educational IMHO.

Before one can say too much how to improve FR & Decay (from the first measured results) I like to see a couple of new measurements:
Left KH120 alone & R alone and Sub only.

Best

BTW How did you find the current speaker positions?




RE Hight dimension. A sloped ceiling adds uncertiness obviously. Move mic and measure what happens. (Another tutorial )
I can get those measurements later today for you.

Question: How would I estimate absorption coefficients in the software?

How I got my current speaker positions:

The L/R I had moved around several times. Started a little wider, about 84" (and roughly 1/4 width of room from side walls) and slowly moved together. I also started at this distance away from front wall. I mixed all the way from 16" to 11.5 to 8.5 and the measurements got worse. Took off the stands, got worse. Resumed with existing setup. Always kept at ear height, 48".

Sub was at reduced gain to balance 30hz.
Was centered and under table. Massive dip in 40hz. Moved to 1/4 length and closest to side wall. Dip shifted to 60hz, but still large. Turned gain up to 0 (to match mains) and dip was better but now had bump at 30. Rotated phase and ended up with 45° as best (from 0, 45, 90, 135, 180).
Old 7th September 2019
  #21
Gear Maniac
Updated the file to include only sub, only L, and only R (as well as the previous measurements).
Old 4 weeks ago
  #22
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akebrake's Avatar
 

Real Time positioning

Quote:
Originally Posted by formula428 View Post
Updated the file to include only sub, only L, and only R (as well as the previous measurements).
Thanks for the mdat! Sorry for my late reply...
After a lot of plotting and thinking () I suggest you try a couple of things.

1. Clear the front area from larger objects.

2. Concentrate on the mains and watch if you can improve positioning.
See this LINK /posts by the great Boggy who sadly died a couple of days ago.
Speaker placement methods

3. Use Pink PN & RTA in REW and move Left KH 120 speaker by hand while
watching in Real Time ! (almost) what happens to the low end. No sub yet.
”Get the bass right”
E.g. Move dips upwards in frequency as much as possible.

4. I don’t know what your (REW 5.16) Generator and RTA window looks like. (5.19 set up example below)

Note: I used Custom freq range like 25-500Hz
Less tiring and will save tweeter & ears.

Best.
Attached Thumbnails
Is this the best I can get?  Do I now supplement with EQ for Main Monitors?-spkr-pos-rta-tst.jpg  

Last edited by akebrake; 4 weeks ago at 02:06 PM.. Reason: Pic added
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