Room issue questions

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Danny Richie

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Re: Room issue questions
« Reply #20 on: 20 Aug 2018, 02:13 am »
You can EQ some of it out with the servo amp, but it is best to try and solve it first.

mlundy57

Re: Room issue questions
« Reply #21 on: 20 Aug 2018, 03:51 am »
You can EQ some of it out with the servo amp, but it is best to try and solve it first.

Solving it is going to be the thing. I’m already using the sub’s PEQ to bring down a peak at 40Hz.

Since the drivers are easily playing these frequencies it is definitely a cancellation effect in the room. But knowing what it is and figuring out how to fix it in this room are two different things.

Tomorrow I will remove the bass traps from behind the speakers and see if that helps.

nrenter

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Re: Room issue questions
« Reply #22 on: 20 Aug 2018, 04:19 am »
I’d make sure the acoustical centers are on the intersections the 1/5th and 1/7th division of the room. Then, rather than try to move the speakers around, try shooting the room response +- 1 foot from your current listening position.

That’s a lot of subwoofer for that small of a room.

HAL

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Re: Room issue questions
« Reply #23 on: 20 Aug 2018, 08:00 pm »
Mike,
Do you have a nearfield measurement of one servo woofer as a comparison? 

mlundy57

Re: Room issue questions
« Reply #24 on: 21 Aug 2018, 03:16 pm »
Mike,
Do you have a nearfield measurement of one servo woofer as a comparison?

Rich,

No I don't.  However, the midwoofers should be covering this range without any help from the subs.

Mike

mlundy57

Re: Room issue questions
« Reply #25 on: 21 Aug 2018, 03:24 pm »
I did some more moving. I pushed the speaker back until the baffle of the NX-Otica section was 3' from the front wall. At this point the dip was gone.

The green line is the NX-Otica section by itself




The gold line is the sub by itself. I adjusted the crossover point until the gold line crossed the green line about 6dB down (at 60Hz).

You would think the two would couple at this point and when played together the dip at 60Hz would go away. However, this is not what happened. When I played both together, the dip at 60Hz got 2dB worse.

Mike

Danny Richie

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Re: Room issue questions
« Reply #26 on: 21 Aug 2018, 03:29 pm »
Quote
You would think the two would couple at this point and when played together the dip at 60Hz would go away. However, this is not what happened. When I played both together, the dip at 60Hz got 2dB worse.

Now start adjusting the phase control and the dipped area should go away.

mlundy57

Re: Room issue questions
« Reply #27 on: 21 Aug 2018, 03:32 pm »
Now start adjusting the phase control and the dipped area should go away.

Ahhh, I never really understood how/when to use the phase control to change the measurements. I'll get on that this evening

Thanks

Mike

mlundy57

Re: Room issue questions
« Reply #28 on: 21 Aug 2018, 07:01 pm »
Now start adjusting the phase control and the dipped area should go away.

Here is what I have after experimenting with different phase settings:

The Green line is the Otica by itself.  The Purple line is the sub by itself.   The Red line is both together



Tyson

Re: Room issue questions
« Reply #29 on: 21 Aug 2018, 07:04 pm »
Seems like the Ottica has a hump right at the bottom of it's response.  You might try swapping the speakers so the wings are on the outside of the speakers instead of the inside of the speakers.  I'm thinking the way they are now might be causing a "bass cavity" or "bass tunnel" with the side walls that's causing that bump in response you see at the very bottom.

mlundy57

Re: Room issue questions
« Reply #30 on: 21 Aug 2018, 11:34 pm »
Seems like the Ottica has a hump right at the bottom of it's response.  You might try swapping the speakers so the wings are on the outside of the speakers instead of the inside of the speakers.  I'm thinking the way they are now might be causing a "bass cavity" or "bass tunnel" with the side walls that's causing that bump in response you see at the very bottom.

I'm not sure they will image properly with the large wings on the outside. One thing about the graphs is that they have 2dB graduations. that makes the changes more exaggerated than they would appear with 5dB gradations.

mlundy57

Re: Room issue questions
« Reply #31 on: 21 Aug 2018, 11:49 pm »
Once I got the left speaker to the above point I worked on the right speaker. Once I got it as close as I could I disconnected the computer and rechecked the center image. It was now off to the right.

I recentered the image then reconnected the computer and shot new measurements. They were now off so I readjusted the speakers. I was able to get the right speaker to an in room response of plus or minus 4dB. This graph has 1dB gradations.





The right wasn't quite as good. It was plus or minus 6dB. This graph has 2dB gradations.




Both together came in at plus or minus 4dB. Also 2dB gradations.




Mike

Tyson

Re: Room issue questions
« Reply #32 on: 21 Aug 2018, 11:59 pm »
Once I got the left speaker to the above point I worked on the right speaker. Once I got it as close as I could I disconnected the computer and rechecked the center image. It was now off to the right.

I recentered the image then reconnected the computer and shot new measurements. They were now off so I readjusted the speakers. I was able to get the right speaker to an in room response of plus or minus 4dB. This graph has 1dB gradations.





The right wasn't quite as good. It was plus or minus 6dB. This graph has 2dB gradations.




Both together came in at plus or minus 4dB. Also 2dB gradations.




Mike

That's a damn fine result!  Nice work :thumb:

poseidonsvoice

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Re: Room issue questions
« Reply #33 on: 22 Aug 2018, 12:07 am »
Mike,

Definitely looks like improvement.

Do you mind (for each speaker individually):

1. Removing all smoothing (or 1/48th octave).
2. Only showing 20Hz to 400 Hz (changing horizontal axis).
3. Changing vertical axis to 5dB increments.
4. And thus, changing vertical range to 50 dB.

I suspect, things are a lot flatter in your bass/midbass than they look.

Thanks,
Anand.

mlundy57

Re: Room issue questions
« Reply #34 on: 22 Aug 2018, 01:14 am »
That's a damn fine result!  Nice work :thumb:

Tyson,

Thanks

Mike,

Definitely looks like improvement.

Do you mind (for each speaker individually):

1. Removing all smoothing (or 1/48th octave).
2. Only showing 20Hz to 400 Hz (changing horizontal axis).
3. Changing vertical axis to 5dB increments.
4. And thus, changing vertical range to 50 dB.

I suspect, things are a lot flatter in your bass/midbass than they look.

Thanks,
Anand.

Anand,

I have all the measurements saved so I can do that later this week.

I have learned a number of lessons during this. One of the two biggest is that farther out into the room isn’t always better, even with OB speakers. It depends on the depth of the room. In this case I started with Otica baffles 50” into the room but had to push them back to 36” to get away from the canceling effect around 150Hz.

The other biggie was the proper use of the phase control with the measurements. MY GAWD these things sound Good!! They are better than I have ever heard them, even at LSAF.

Before Steppenwolf, Uriah Heep, CCR, etc sounded good but they didn’t’t get your toes tapping (if those don’t get your toes tapping something’s wrong). Now they have me almost dancing in my chair  :D

The final movement of Mahler’s 8th, from its ethereal whispers to its layering and rising voices to its final crescendo is something else.  Pipe organs too.

I’ve always known these were great speakers but they have shown me a side of themselves I haven’t experienced before.

Mike

poseidonsvoice

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Re: Room issue questions
« Reply #35 on: 22 Aug 2018, 01:47 am »
Mike,

Happy for you.

But 1 thing is for sure. Without taking measurements one would never know and therefore I would encourage others to do the same.

Best,

Anand.

Captainhemo

Re: Room issue questions
« Reply #36 on: 22 Aug 2018, 05:19 am »
Looks pretty  darn good in-room  Mike  :)

jay

Tyson

Re: Room issue questions
« Reply #37 on: 22 Aug 2018, 04:40 pm »
The other thing you can do - now that you know where your biggest bass hump still resides, you can buy a bass trap from GIK Acoustics that's "tuned" specifically to deal with that frequency.  IME its better to deal with room modes like that acoustically instead of electronically (ie, with an EQ). 

Folsom

Re: Room issue questions
« Reply #38 on: 23 Aug 2018, 02:23 am »
Dont be afraid to land phase somewhere not on a 90° interval. The best phase is rarely that incrementally found.

What is the space between the speakers?

mlundy57

Re: Room issue questions
« Reply #39 on: 26 Aug 2018, 07:12 pm »
Mike,

Definitely looks like improvement.

Do you mind (for each speaker individually):

1. Removing all smoothing (or 1/48th octave).
2. Only showing 20Hz to 400 Hz (changing horizontal axis).
3. Changing vertical axis to 5dB increments.
4. And thus, changing vertical range to 50 dB.

I suspect, things are a lot flatter in your bass/midbass than they look.

Thanks,
Anand.

Anand,

Here are the graphs with those parameters: (in REW the graphs are showing 5dB segments with a 50dB range but when I capture the image it converts them to 10dB segments. I don't know why or how to get the JPEG to be in 5dB segments.) Figured it out, I had to change the save resolution to 1,095 in REW.

Left Speaker






Right Speaker







and both speakers






Mike