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Aligning Subwoofer Phase with AutoCal

reckless-erik, modified 12 Years ago.

Aligning Subwoofer Phase with AutoCal

Youngling Posts: 4 Join Date: 9/16/09 Recent Posts
I am a little confused as to how to do this correctly! I have a 5.1 system setup with 5x8250As and an 7270A Sub. In the autocal setup routine to adjust the phase relationship of the sub to the rest of the system you are asked to input channel and loudspeaker. I make the assumption that the loudspeaker I choose should be the one that reproduces the centre channel. But what should the channel field be set to? Centre or LFE? :?

Nick
ilkka-rissanen, modified 12 Years ago.

Re: Aligning Subwoofer Phase with AutoCal

Yoda Posts: 2564 Join Date: 3/23/09 Recent Posts
Hi Nick,

You should set both channel and loudspeaker to read the physical loudspeaker you wish to calibrate the subwoofer's phase with. Normally this means the centre speaker or either one of the main speakers (L or R). Depending on the acoustics and system placement in the room, different speaker may give slightly better result. But usually centre speaker should be used.

The reason for separate channel and loudspeaker settings is the fact that one could use multiple speakers to reproduce the same channel, therefore needing to choose which speaker the phase should be calibrated with.

Hopefully this helps! :)
reckless-erik, modified 12 Years ago.

Re: Aligning Subwoofer Phase with AutoCal

Youngling Posts: 4 Join Date: 9/16/09 Recent Posts
Thanks Ilkka,

Your answer really helped. One other thing. It is fairly straight forward to use the pink noise generator to set the reference levels for each speaker but in the GLM there are both pink and sine wave gen for the sub woofer. Which one is best to use? What should I set the ref spl level as?

Thanks Nick
ilkka-rissanen, modified 12 Years ago.

Re: Aligning Subwoofer Phase with AutoCal

Yoda Posts: 2564 Join Date: 3/23/09 Recent Posts
I'm not sure if I follow you? You shouldn't need to calibrate each speaker/subwoofer individually if you are using the AutoCal for calibration. It automatically calibrates SPL for each speaker and matches them with each other.

You can set the global reference monitoring level from "Setup -> Calibrate Reference Level".

1. Place an SPL meter to the listening position (use C-weighting and Slow setting)
2. Set the main level slider to 0 dB in the GLM (maximum)
3. Go to "Setup - > Calibrate Reference Level" and select centre speaker (L or R if C not available) and enable the test tone
4. See the SPL meter and enter the value measured to the box
5. Tick "Enable reference level" and click "OK"

Now you can see the reference monitoring level on the main page. You can see it varying with the main level slider. It is your responsibility to set it where you want it, but typically Dolby specifications recommend ~80 - 85 dB.
reckless-erik, modified 12 Years ago.

Re: Aligning Subwoofer Phase with AutoCal

Youngling Posts: 4 Join Date: 9/16/09 Recent Posts
Thank you Ilkka