subwoofer placement and measurements

[JD1]

hello all, I have a 1961 1s arendal sub and I have a .mdat for the fs response the first positions I did using MMM method on a microphone stand using random pink noise, the remaining positions I did using sweeps, room is 23 m2 + 4.85 m2 with a 2.56 meter height.

I would like some help figuring out the best position for the subwoofer and eq with limited to 3 bands unless I also use Wiim Ultra which has another 10 bands which I was going to use for the speakers, any suggestions about measurements would also be welcomed, I tried my best to keep them somewhat constant (not moving mic for sweeps, somewhat linear -dbfs, mic pointed at ceiling using 90º cal file (beyerdynamic MM1).

I know the cardinal system in the picture is wrong but I already typed the measurements that way , sorry for anyone with OCD.

I think FINAL POS SWEEP (even though it's behind LP) seems the best but I can be wrong (subwoofer positions 3 or 4.mdat)

lpf crossover at 160 hz with 24 db slope, MMM measurements (first 8 (pos 1 to 4)) have an F, facing back of the room (which = S in sweep measurements).


Thank you for all and any help.

Best regards,

 

[OCA]

If this is a stereo system place the sub at the front wall between the speakers or else you will have shifted center image with any crossover above 60Hz. If this is a surround set up, place it where it has the maximum overall output and then then filter out the peaks with DRC.

 

[sigbergaudio]

Not necessarily so, the sub can be many other places than between the speaker with a crossover up to 80-100hz without a problematic center image.

 

[OCA]

Not necessarily so, the sub can be many other places than between the speaker with a crossover up to 80-100hz without a problematic center image.

I'm aware that view is prevalent, but it's not what I've experienced with my single sub placed slightly to the left between the mains. There's a slight but persistent shift at 80hz which disappears at 60hz. The AVR has no xover between 60 and 80 so can't say where exactly it starts to localize.

 

[sigbergaudio]

I'm aware that view is prevalent, but it's not what I've experienced with my single sub placed slightly to the left between the mains. There's a slight but persistent shift at 80hz which disappears at 60hz. The AVR has no xover between 60 and 80 so can't say where exactly it starts to localize.

Your experience is your own of course.

 

[JD1]

Not necessarily so, the sub can be many other places than between the speaker with a crossover up to 80-100hz without a problematic center image.

I was aiming for 80 to 90 hz xo because it is behind, aswell as since the kef r5 meta start to play flat at that range (anechoic response). Atm still waiting for speakers (pair), as it will be a stereo, however I did try with the TV (lg g5) and I do feel it will integrate well with speakers at that spot since the bass does feel like it's coming from tv. I do notice something slightly but also the levels aren't really matched as it is going to sub via sub out and from tv to ultra via toslink.

I wanted to try hdmi (easier to balance volume) but tv doesn't have hdmi + tv speakers option, only toslink + tv speakers.

I can put it at the front (POS 1/2/3/4) however room modes seem worse than FINAL POS SWEEP measurement. Between speakers would be POS 2 and 3.

But I'm no expert so sorry for so many measurements, however I wanted to have as much data as possible, I am thinking of doing pos 1-4 with sweeps aswell so I can confirm.

Mic (beyerdynamic MM 1 via focusrite 2i2 gen 3 using loopback cable) is SPL calibrated using external SPL calibration device.

 

[OCA]

I've recently checked actual R3 measurements and they had 12dB/oct roll off at 66Hz. I'd think R5 should ideally be crossed even lower.

 

[JD1]

anyone willing to suggest EQ from 3 to 5 bands?

MMM goes lower in db for some reason.?

 

[JD1]

so between postion 4 (red) and current position which one seems best (ERB smoothing)?

position 4 is front right side of room

final position is back left side of room

position 4 seems a tad bit worse however it would be near speakers (also alot worse with no smoothing) im only interested until 80 hz mostly.

however both behind and front are about the same distance from listening position, also posting 1/48 smoothing.

is using ERB smoothing the way to eq and check room?

 

[Keith_W]

I gave up when I downloaded 2 MDAT's and had no idea what I was looking at. Your diagram does not explain any of those positions. Nobody knows what "position 2" or "position 5" or any of these things are. And there are more than 50 measurements to look at, this is why nobody is looking at these measurements. So let's forget all those measurements, they are useless and don't tell us anything.

To be clear, this is what you need to do:

Step 1: place your subwoofer properly by doing the subwoofer crawl or using another method. There are many schemes and theoretical ideals for subwoofer placement, but for one subwoofer the "crawl" is the most reliable method.
Step 2: once your subs are dialled in, take measurements and EQ the result to flat.

How to do the subwoofer crawl (or you can google for instructions or look for a video on youtube):

1. Place your subwoofer at your listening position on a stool or a short table. The subwoofer should be approximately at ear height. If you are off by a foot, it's fine. Do not move it.
2. Use REW to play pink noise through your subwoofer. Turn on REW's RTA.
3. With your mic mounted on a boom (or duct taped to a long stick), walk around your room and try to find the best position for your sub. Don't forget that subs don't need to be placed on the floor, sometimes elevating the sub will give you better results. What you want is a placement that will give you as many peaks as possible with the fewest dips. Peaks are better than dips since they can be EQ'ed out.
4. When you have found a good position for your subwoofer, place it there.
5. Return the mic to the listening position and take a final sweep to confirm.

If you have a PROPER mic tripod, you can do sweeps instead of pink noise + RTA.

 

[JD1]

does this look okay ?

right side front of room target 75 db with 6 eq bands.

1/6 smoothing and no smoothing.

I intend to cross it at 70 hz or 65.

 

[JD1]

or is left back position better ?

both positions .mdat measurements attached with eq and without.

 

[Keith_W]

You should decide for yourself which is better. This is how I do it.

1. Apply 1/6 smoothing to all measurements.
2. In "All SPL", display one measurement. This one is "Position 2 Sweep".

3. Display another measurement. This is Position 2 vs. Position 5. Clearly, Position 5 is better because it's flatter and has fewer dips.

4. Since we reject Position 2, unclick it to remove it from the display.

5. Proceed with the next measurement, this one is "Position 5" vs. "Position 5 N". Clearly "Position 5" is better since the bass does not fall off as steep and it's a little bit more flat.
6. "Position 5 N" is rejected, so unclick it to remove it.
7. Continue until you have examined all your measurements. Every time you see a better measurement, reject the worse measurement. That way you will eventually find the best looking measurement.

 

[JD1]

So using 1/6 smoothing is not a bad way, I was kind of unsure if one should use 1/6 although it resembles more what we hear, like ERB.

Thanks for all the help and tips, I'm actually going with position "4" right front corner for now as it seems to sound the best with EQ, by the way does rattling of let's say a door affect thd shown or is that exclusive to the driver ? I mean Mics are dumb therefor don't distinguish but I've seen various thd values from the sweeps and I doubt it's the driver.

 

[janbth]

So using 1/6 smoothing is not a bad way, I was kind of unsure if one should use 1/6 although it resembles more what we hear, like ERB.

If you are interested in the bass region, use Var smoothing, or no smoothing. (Var has no smoothing up to 100 Hz, if I remember correctly.) This will show you how the resonance peaks from room modes actually look. If you intend to use a measurement to compute PEQ filters, you *must* use no smoothing (or Var), otherwise the computed width (Q value) will be wrong.

 

[JD1]

Not able to select max q to use with rew is kind of nasty I mean it's either max 5 q (untick allow narrow filters below 200 hz) or it goes up to 50, wiim ultra allows for max q of 24, rew wants a peq band with a 30 q value, why is there no way to tell rew max q value can be 24

Hmmm OK disabling the auto eq on that band, setting it to 24 and optimise gain and q and frequencies might be a work around

 

[OCA]

Not able to select max q to use with rew is kind of nasty I mean it's either max 5 q (untick allow narrow filters below 200 hz) or it goes up to 50, wiim ultra allows for max q of 24, rew wants a peq band with a 30 q value, why is there no way to tell rew max q value can be 24

Hmmm OK disabling the auto eq on that band, setting it to 24 and optimise gain and q and frequencies might be a work around

 

[JD1]

View attachment 467237

Oh there is configurable PEQ in model , thanks I thought it applied only with a manufacturer selected

 

[JD1]

Another question which is probably better done in wiim forums but rew doesn't give a q for high shelf and low shelf however in wiim home HS and LS filters do have a Q for selection I guess this doesn't apply for HS and LS filters even if Q is given in wiim home eq page?

 

[OCA]

Another question which is probably better done in wiim forums but rew doesn't give a q for high shelf and low shelf however in wiim home HS and LS filters do have a Q for selection I guess this doesn't apply for HS and LS filters even if Q is given in wiim home eq page?

Configurable PEQ only works with custom peaking filters AFAIK but you can set shelving filters with any Q value manually: