Help calibrating SUB in REW

E

Erus1982

Audioholic Intern
Hello all. I recently bought an SVS PB 2000 pro to go along with my B&W685 speakers (5.1, single sub). This is my first true subwoofer so even uncalibrated it sounds powerful to me. So, I bought a UMIK-1 mic and made some measures and tried to get a flatter response with the sub internal PEQ (3bands).

no aud-raw.jpg
1) With no Audyssey, no EQ

aud-raw.jpg
3) This is enabling Audyssey after running XT calibration on Denon (don't have XT32, only XT). I first tried to get a flatter response with sub PEQ and then to run Audyssey but results were ugly. So I decided to first run Audyssey to get it somewhat calibrated and use SVS PEQ afterwards to fix it.

final-200hz.jpg
3) This is what I could get by using SVS PEQ after running Audyssey.

final-xover 80hz.jpg
4) This is when I change the crossover from 250hz to 80 hz (which I use). Is this normal?

Sorry for this wall of images, but I have a few questions.

A) Is the 3rd graph considered improved and somewhat acceptable for the subwoofer response?
B) Why I get those nulls at 50hz and after, when I simply change my crossover to 80hz?
C) Although REW SPL meter shows that subwoofer and speaker are on the same 75db, watching movies has anemic bass. When I used my mobile spl meter to measure test tones from AVR I saw that subwoofer was 70db so I raised it 5-6db. Now it sounds good. Which spl meter do I trust?
D) I can feel a lot of low bass but mid bass feels less than before I calibrate the sub. Is this normal? Has this something to do with the 4th graph?

Again, I am sorry for being so novice but If anyone has the time to check those graphs and give me a hint would be much appreciated.

Thank you!
 
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TheWarrior

TheWarrior

Audioholic Ninja
Is this a big and open living room?

Is the mic positioned where your ears would be? And pointed to the ceiling?

Where is the sub in relation to your seat? What other positions are available for it?
 
E

Erus1982

Audioholic Intern
Is this a big and open living room?

Is the mic positioned where your ears would be? And pointed to the ceiling?

Where is the sub in relation to your seat? What other positions are available for it?
3FAC02D1-7E41-4655-81E9-3B4325D40D33.jpeg

Red circles are speakers and green is subwoofer which is around 1.10meters away from the right corner. Position is a bit limited.
Yes, mic was at ear level pointing at the ceiling. As you can see, I have a 2seated couch opposite to my tv and a 3seated at the side. I meaused the MLP at the left seat of the 2seated couch. Would it be better to measure and set the MLP where the green X mark is? That would create a perfect equilateral triangle with front speakers and X. I wont sit at X though, I will sit either left or right side which would be around a foot off. Would this be better?
 
TheWarrior

TheWarrior

Audioholic Ninja
Measure from where you sit. Bass can vary wildly seat to seat. The goal is to minimize those peaks and dips with placement, and then DSP.

Can you move the subwoofer to the other side of the TV? Or even along that left side partial wall?
 
E

Erus1982

Audioholic Intern
Measure from where you sit. Bass can vary wildly seat to seat. The goal is to minimize those peaks and dips with placement, and then DSP.

Can you move the subwoofer to the other side of the TV? Or even along that left side partial wall?
I moved the sub to the other side of tv and I took a measure and I got many dips as well. Left partial wall is not an option. So better to set a MLP a seat instead of the X middle mark?
 
TheWarrior

TheWarrior

Audioholic Ninja
I moved the sub to the other side of tv and I took a measure and I got many dips as well. Left partial wall is not an option. So better to set a MLP a seat instead of the X middle mark?

Sorry, been busy!

Yes, you want to take measurements from where ears will be located.

Bass wavelengths can measure 50 or more feet in diameter. So when you try to produce bass sound waves in an enclosed space, those waves bounce off the all the walls and ceilings and floors etc and you create a series of high and low sound pressure zones - if you're seated near the edge of the wave you likely see a peak in the measurement, or if you're seated in the middle of the sound wave it will measure as a dip - either way, those peaks and dips are called Room Modes. They are a reaction of sound waves bouncing off boundaries of similar size.

This gets extremely complicated, but I am trying to convey a sense of how difficult it can be to achieve smooth bass response in any room. One sub can be positioned and then programmed to potentially satisfy one set of ears, particularly in open rooms like yours and mine too. Some people hear good results with REW's DSP programs, or Audyssey, or YPAO or any other room 'correction' software. And some of us do not.

Depending on far you want to go with this, you may be looking at multiple subs in the future. Cool!

Don't want to deal with all this? Cool! Then stop using REW and just move the sub around where you can, use a SPL meter from the same seat, each time you move a the sub, to make sure you are getting the same sound level from the sub as you are from the rest of the speakers. Listen to some familiar bass heavy media, and let your ears decide what sounds best!
 
E

Erus1982

Audioholic Intern
Hello again, thanks for helping me out. I managed to find a better position for front speakers /sub, at least I got better measurements so it was an improvement. Allow me to post the results and I would appreciate a last comment whether they are now acceptable enough :)
no aud.jpg

Above is without Audyssey or PEQ

aud.jpg

Above is with Audyssey EQ applied and crossover with front speakers/sub set at 80hz. No sub PEQ applied yet.

final.jpg

This one is my final curve. Audyssey EQ on, SvS internal PEQ applied. Crossover again at 80hz.
I applied sub's PEQ to drop the 3 spikes: 21hz -4db q6 / 33hz -4db q4.1 / 43hz -4.5db q10. The 78hz spike isn't dropping with EQ.

If there's no trouble I would like to ask 2-3 questions,
1) Is my final curve now good enough? Considering I have no room treatment.
Do the adjustments I made seem correct?

2) Should I leave alone the 21hz? If I don't apply any EQ there I might have some more db but a bit larger dip at the 23hz.

3) When I used REW's internal SPL to measure the subwoofer (sub cal) I measured 75d (same as speakers). I then raised it to 78db to get a bit more ooph. The thing is that when I checked with the AVR test tones, the subwoofer measured 72db instead of 78db from REW. Which one do I trust?

Thanks a lot!
George
 
TheWarrior

TheWarrior

Audioholic Ninja
Hello again, thanks for helping me out. I managed to find a better position for front speakers /sub, at least I got better measurements so it was an improvement. Allow me to post the results and I would appreciate a last comment whether they are now acceptable enough :)
View attachment 48901
Above is without Audyssey or PEQ

View attachment 48899
Above is with Audyssey EQ applied and crossover with front speakers/sub set at 80hz. No sub PEQ applied yet.

View attachment 48900
This one is my final curve. Audyssey EQ on, SvS internal PEQ applied. Crossover again at 80hz.
I applied sub's PEQ to drop the 3 spikes: 21hz -4db q6 / 33hz -4db q4.1 / 43hz -4.5db q10. The 78hz spike isn't dropping with EQ.

If there's no trouble I would like to ask 2-3 questions,
1) Is my final curve now good enough? Considering I have no room treatment.
Do the adjustments I made seem correct?

2) Should I leave alone the 21hz? If I don't apply any EQ there I might have some more db but a bit larger dip at the 23hz.

3) When I used REW's internal SPL to measure the subwoofer (sub cal) I measured 75d (same as speakers). I then raised it to 78db to get a bit more ooph. The thing is that when I checked with the AVR test tones, the subwoofer measured 72db instead of 78db from REW. Which one do I trust?

Thanks a lot!
George
The opening to dining room - to the right of the opening there is a rectangle with an incomplete circle - what is that? Computer desk?

Also, to the left of that same opening, there is a black rectangle (and more in other places) what is that?
 
E

Erus1982

Audioholic Intern
The opening to dining room - to the right of the opening there is a rectangle with an incomplete circle - what is that? Computer desk?

Also, to the left of that same opening, there is a black rectangle (and more in other places) what is that?
The renctagle with the incomplete circle is a fireplace. The other rectangle is supposed to be a small desk but its not there actually atm
 
TheWarrior

TheWarrior

Audioholic Ninja
The renctagle with the incomplete circle is a fireplace. The other rectangle is supposed to be a small desk but its not there actually atm
If you have a bunch of pillows or other big fluffy THICK things, perhaps try placing them around that entry to the table - DO NOT place them where they would be a fire hazard. ;)

My thought is that opening is the cause of the 23hz dip. You would need to re-run Audyssey, but I would try measuring again with and without Audyssey. If the pillows work, you should see that dip, rise.

Additionally, absorption may also be needed on the farthest wall behind the couch, right where it says 3.25m. I suspect that wall interaction is your 40 hz dip.

An important note when dealing with bass issues... start at the Bottom! Room Mode calculations are also logarithmic, so every time sound bounces off another wall, the frequency doubles. So if we solve some issues down low, they should start to alleviate issues higher up in frequency.
 
E

Erus1982

Audioholic Intern
If you have a bunch of pillows or other big fluffy THICK things, perhaps try placing them around that entry to the table - DO NOT place them where they would be a fire hazard. ;)

My thought is that opening is the cause of the 23hz dip. You would need to re-run Audyssey, but I would try measuring again with and without Audyssey. If the pillows work, you should see that dip, rise.

Additionally, absorption may also be needed on the farthest wall behind the couch, right where it says 3.25m. I suspect that wall interaction is your 40 hz dip.

An important note when dealing with bass issues... start at the Bottom! Room Mode calculations are also logarithmic, so every time sound bounces off another wall, the frequency doubles. So if we solve some issues down low, they should start to alleviate issues higher up in frequency.
Thanks for replying. I didnt understand where exactly to put the pillows, could you draw it for me please? Also, why should I put pillows and see the dip going away if I am going to remove them afterwards?
Could I try add some db and try to fix that 23hz dip?
 
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TheWarrior

TheWarrior

Audioholic Ninja
Thanks for replying. I didnt understand where exactly to put the pillows, could you draw it for me please? Also, why should I put pillows and see the dip going away if I am going to remove them afterwards?
Could I try add some db and try to fix that 23hz dip?
The pillows could verify a measured improvement, but your ears would be a deciding factor. The pillows become furniture, FULL book cases, or other items that add similar sound absorbing mass to that specific location, in normal use.

It looks like Audyssey was able to raise the dip more than 6dB. That's beyond 100% increase in power at that frequency. It could be damaging to the amps to raise that further with any more DSP. It is certainly a room induced issue, and that also means any other rooms that the space with sound equipment, is open to.

Hopefully a good stack of pillows, blankets, whatever, around that opening will limit the amount of energy leaving the room, and reducing the interference of the room mode created between the wall that says 6.2m and the far wall 4.78m. Is that a sliding glass door? You can also hide absorption materials behind valences/drapes over those doors.

See what I mean? It gets complicated. And then more subs get added, and then level matching and phase issues get added. I love this stuff, honestly. It's just math and then you can do acoustic measurements to verify - assuming the measurements were taken properly - vertical mic and all...
 
L

latapx

Audioholic Intern
Can the sub be placed behind the couch near your rear right speaker? Placement in the room can make a HUGE difference. Have you tried the "subwoofer crawl" yet?
 
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