Mic position for measurements with Dirac

[LBob]

I'm going to be doing a Dirac trial soon and I'm trying to get organized. I have a couple of questions about positioning the mic when taking measurements:

 

1. I'm using a Umik-1 that is calibrated for 0 degrees so (as I understand it) the mic should be horizontal and point toward the speakers. My question is whether I should keep the mic perpendicular to the plane of the speakers or should I point the mic at a position mid way between the speakers? I'm not sure if it even matters but I'd like to know.

 

2. Based on reading the threads on CA and some reviews, I'm going to do 2 filters. One as "couch" and one as "chair." Doing the couch - literally - would mean that the mic position for some of the measurements would be directly opposite of one speaker (e.g. the mic would be directly across the room from the speaker). Is this a problem? Should I keep the mic inside the speaker position? My speakers are about 6 feet apart. If I went out a meter on either side of the sweet spot I'd actually be outside of the speaker.

 

Thanks in advance for assistance.

[rcohen]

1)

If you use the 0 degree file, you should point the mic between the speakers. Another alternative would be to use a 90 degree file and point the mic straight up or straight down.

You can convert the 0 degree file to a 90 degree file with this utility:

http://www.computeraudiophile.com/f23-dsp-room-correction-and-multi-channel-audio/converting-0-degree-calibration-file-90-degree-file-20505/

 

2)

If you want to optimize for a single seat, use the seat measurement.

If you would like to optimize across the whole couch, use the couch measurement.

The seat measurement will be more precise for a single seat, but the couch measurement will avoid optimizing for the center seat at the expense of the other seats.

This is independent of whether you tow in the speakers. You should tow in the speakers according to your preference. You can search for that and find logic behind whether to tow in and how much. Changing the speaker angles will require new measurements, though.

[LBob]

Thanks. I had actually just found your utility and will try to get a converted file tomorrow. Fingers crossed. It is surprisingly hard to find info on this. I just got a reply from Dirac about the question and they said just point the mic straight up regardless of whether it was calibrated for 0 or 90. I will make two sets of filters one at 0 and one at 90 and see which one I like better.

 

BTW, one silly question from a non-technical person. In your program you use the serial number of the mic. I'm assuming that's just a convention and that any name would work, correct?

[rcohen]

Thanks. I had actually just found your utility and will try to get a converted file tomorrow. Fingers crossed. It is surprisingly hard to find info on this. I just got a reply from Dirac about the question and they said just point the mic straight up regardless of whether it was calibrated for 0 or 90. I will make two sets of filters one at 0 and one at 90 and see which one I like better.

 

BTW, one silly question from a non-technical person. In your program you use the serial number of the mic. I'm assuming that's just a convention and that any name would work, correct?

 

You can use any name you want. The calibration file I had happened to include serial numbers.

 

I would avoid using a 0 degree file with a 90 degree orientation.

Either use the 0 degree file pointed toward the speakers (close enough to 0), or use a 90 degree file with a 90 degree orientation.

The 90 degree file is mainly needed for measuring a surround setup.

I'm not sure what to do when Atmos lands.

[LBob]

Will try the program today. I'm also going to follow your advice with the mic orientation.

 

Out of curiosity, did you use 0 or 90 with Dirac? Atmos? Is that another program?

 

Thanks again for the advice. I'm impressed that you could create a conversion program.

[rcohen]

Will try the program today. I'm also going to follow your advice with the mic orientation.

 

Out of curiosity, did you use 0 or 90 with Dirac? Atmos? Is that another program?

 

Thanks again for the advice. I'm impressed that you could create a conversion program.

I'm using Dirac for two setups. I used 90 degrees for the surround setup. I think I used 0 degree for the stereo setup, since the speakers are pretty close together (near a TV). If stereo speakers are at a large angle to the listening position, 90 degrees is probably better.

 

I was referring to Dolby Atmos, which adds ceiling speakers.

The high frequencies are lower off axis, so the 90 degree files compensate for that.

With ceiling speakers, some of the speakers would be on axis and some would be off axis, so it could get inconsistent.

[LBob]

Well I used your program and got what looks to be a 90 degree calibration file!

 

I think that I will use the 90 first because that's the one that Dirac recommends. I'll compare that to the 0 degree.

 

Thanks again for your help!!!

[onalnincli]

stereo speakers are at a large angle to the listening position, 90 degrees is probably better.