Speaker/Room calibration

[jpv]

NorthStar,
At this point it is all about test tones, math and measurement. Without it there is no music. Why else would we be here. The test run by REW is very short only a few seconds long. I am sure most you have heard sweeps before, these are no different.
Jacks point is as you run thru the changes you should be listening for drop out and peaks in the sound. Just listening to music will not show the short comings in the speaker, room, position and settings.
On thing I have done it use the freq. generator to sweep slowly thru the range and listen for rattles, and buzzes a certain freq causes. And yes at the end of all this you will have music that is clean, powerful, and balanced.
John

 

[jpv]

Hi Bruce,
Can you do the bass filter 50 to 100 in small steps. I am looking to see what happen between 50 and 80 Hz. I want to see here that flattens out.
Also can you show a full range. The 200hz looks higher then normal. Be sure to calibrate the REW SPL meter to the external SPL meter. If you are just doing subs calibates use the sub signal. We are doing full range so use the full range speaker signal to calibate 75 db to.
If you can attach your MDAT. It's easier to see thru REW.

Are we going for as flat as possible 20 to 20K?

 

[Bruce B]

Bass Filter settings

50Hz = Green
60Hz = Blue
70Hz = Orange
80Hz = Red
90Hz = Magenta
100Hz = Black

.mdat file can be downloaded HERE

 

[Bruce B]

Full Spectrum without and with smoothing

 

[RBFC]

Bruce,

Can you hear the 3 dips at 40, 130, and 3000 Hz? How about the peaks at 70, 200, & 650? 4500- 15,000 looks remarkable!

I'm looking at ~73dB as the reference value for comparison...

Lee

 

[Bruce B]

Bruce,

Can you hear the 3 dips at 40, 130, and 3000 Hz? How about the peaks at 70, 200, & 650? 4500- 15,000 looks remarkable!

I'm looking at ~73dB as the reference value for comparison...

Lee

I know that 40 and 130 were giving me problems in some of my mastering. I could tell that by taking the material to other reference systems and would have to compensate. The 70 and 200Hz wasn't too bad. I have a couple pieces of analog equipment that I ran the signal through to tame those peaks.

Yes, the ultimate goal is to have a ruler flat (or somewhat close) to where if I made an adjustment to the client's project, I was doing it because the music needed it and wasn't compensating for the room/speakers.

I know the room is capable of it because I saw the graphs on Bob Hodas' Sim3 system. I did have 2 Wilson WatchDogs in here though!

 

[NorthStar]

Wow, pretty good so far Bruce!

From my viewpoint, only two small dips:
1. In the low bass region, at 40Hz.
2. And in the most critical presence region, at 3kHz.

* The small 125Hz droop in the lower end is more of a room effect's exaggeration, but also indicates the system's sensitivity to room interaction with placement. ...From the speaker drivers closer to the floor, I think.

Other than that, quite easily manageable (correctable peaks).

Bruce, what is your opinion on that last graph, and from listening to music you know well?
{I feel weird saying & asking that to an expert.}

Bob

 

[jpv]

Bruce, Thanks for posting the MDAT. I looks like the 70hz bass filter gives the flats results but lowers the area further up. Can you lower the x-over point on the mids. I looks like that rolls off at 200Hz.
Is it possibe to move the speakers around. I'd like to see how that effects the FR. I am looking to see that position gives the smoothest FR. Leave the mic here you would normally sit.
Can the polarty of the subs be reversed and can the two subs on each speaker be adjusted independently/
John

 

[Bruce B]

Thanks John... I moved the speakers last night. Same position side to side but about 6" further from front wall into the room. They are at 67" now from front of speaker to front wall.

Subs within the speaker can not be independently adjusted. No polarity adjustment either, unless you go inside and rewire. I'll shoot the room again this afternoon.

 

[Bruce B]

Out of the above Bass Filter settings, I decided to choose the 80Hz configuration. I then shot the room again today with the new speaker position and the Bass filter at 80. The old position is the red tracing and the new position is the green tracing. I see by moving the speakers, the null at 123Hz is all but gone!

 

[rbbert]

I realize I'm pointing out a theoretical problem, but if your room's effective length is 22' (264")' then 67" is almost exactly 1/4 of the way into the room. That will clearly excite some room nodes, which may not necessarily be bad, but I have to wonder if moving the speakers back from their original position, rather then forward, might be better? Thus from ~60" back to ~53-54" rather than forward to 67"? The unknown (for me, at least) is what if anything all the bass trapping does to alter the "effective" length of the room.

 

[Bruce B]

The speakers were originally set up by Evolution Acoustics at 53" from the front wall. I moved them out to 60" and shot the room. Then today, I moved them out to 67". According to the EA website, if I followed the "Golden Progression" protocol, then the measurement should be about 70" into the room. The "Rule of Thirds" says they need to be 87" into the room! I am measuring from the actual hard surface front wall and not the front of the bass trap.
Just noticed that my room has the exact proportions of the Cardas Golden Cuboid.

 

[NorthStar]

Hi Bruce,

53" from the midrange driver's voice coil to the front wall seems to be a pretty good distance (1/5).

Two other distances that could also work are: 58.5", and 75".

 

[Bruce B]

Hi Bruce,

53" from the midrange driver's voice coil to the front wall seems to be a pretty good distance (1/5).

Two other distances that could also work are: 58.5", and 75".

In Post #19 and #38, the speakers were positioned 53" from the front wall and 36" from the side wall.

Post #67 shows the speakers 72" from front wall and 44.7" from side

Now they are 67" from the front wall and still 44.7" from the side wall.

 

[treitz3]

Just noticed that my room has the exact proportions of the Cardas Golden Cuboid.

Hmmm, then would you at this point consider the Sumiko setup? No pressure at all.....just wondering. Start there, couple the speakers to the room and then start the measurements. Letting your ears decide the end result.

Just a thought, Bruce.

 

[NorthStar]

44.7 " from the side wall is good.
But 67" from the front wall is not the best. 70.5" would be better, I think.

________________________

Here are other great distances you might want to try:

- From the Side wall: 29", 32", or 35".
- From the Front wall: 58.5", 60", 70.5", or 75".

Also, your ears from the rear wall: 75", 87.5", 96", or 105".
And your ears from one of the side walls: 77.5" (I know it is not center, but you can try).

___________________

Bruce, your ears from the floor?
And how high is the center of the lowest driver of your loudspeaker from the floor?

 

[Bruce B]

Hmmm, then would you at this point consider the Sumiko setup? No pressure at all.....just wondering. Start there, couple the speakers to the room and then start the measurements. Letting your ears decide the end result.

Just a thought, Bruce.

Thanks.... a couple of years ago I had a pair of VA Beethovens (or was it Mahler?) in here for audition and went through the Sumiko setup.

44.7 " from the side wall is good.
But 67" from the front wall is not the best. 70.5" would be better, I think.
Bruce, your ears from the floor?
And how high is the center of the lowest driver of your loudspeaker from the floor?

Ear is 47" from floor. Center of lowest driver is 13".

 

[treitz3]

May I kindly suggest you start again with this and then set up your speakers accordingly? It's not like you will lose your money in doing so. The CD's required also have some great tracks within them. This is just a suggestion. I hope for the best with whatever method you choose. I'll chime back in later...

 

[NorthStar]

OK, the lowest driver is fine in relation to the side wall distance; good.

Can you lower your ears to 45.5" from the floor? I think it would be best (that's only 1.5" lower).
- And if you do, don't forget to put the mic at that height as well.

 

[Bruce B]

OK, the lowest driver is fine in relation to the side wall distance; good.
Can you lower your ears to 45.5" from the floor? I think it would be best (that's only 1.5" lower).
- And if you do, don't forget to put the mic at that height as well.

I certainly can.

Just looked at the owners manual and they said it needs to be centered on the tweeter at 37"!

May I kindly suggest you start again with this and then set up your speakers accordingly? It's not like you will lose your money in doing so. The CD's required also have some great tracks within them. This is just a suggestion. I hope for the best with whatever method you choose. I'll chime back in later...

I'll have to wait until I have a "strong" buddy. Speakers weigh ~530lbs ea.!