calibration of your theater sound system

[JSt0rm]

WHY:

Calibrating your speaker system and having a baseline volume to watch movies with will ensure a constant pleasurable experience that is close to the director, sound designer and mixers intentions.

All movies are mixed in rooms that have been calibrated and balanced by Dolby. This is called an x-curve and is something you wont really have to deal with. You can get close to a real experience by making sure all of your speakers are hitting your listening position at the same db rating.

WHAT YOU NEED

so you will need a spl reader. I cheat a lot and use a db meter on the iphone called decibel.

http://www.gadgetfrontier.com/apps/decibel

or you can use this meter from radio shake

http://www.radioshack.com/product/in...ductId=2103667

You will also need the ability to play pink noise through your speakers. I use this pink noise and so does dolby

http://www.thedubstage.com/files/Dolby Pink @ -20dbfs.aif

HOW YOU DO IT:

Now most large mix rooms are calibrated at 85db. This is too loud for you! My edit bay is calibrated at 73db. This is how you do it.

Play pink noise through each channel of the audio system one at a time. You must make sure that there is no digital attenuation of the pink noise from your source this is to ensure that the pink noises average is -20dbfs (-20db below digital 0). you may need to change the source to the different inputs on your reciever if you are unable to play the pink noise through all inputs. Or for simplicity you can use the built in pink noise generator (its different and i recommend spending the time to do it right)

1. Starting with the left speaker adjust the volume of the receiver or amp to make it so that the spl meter reads 73db (or 75 or 76 or 78 or 80 or 82 depending on the size of your room) AT the normal listening position.

2. Move on to the center channel speaker and work your way to the right, right surround, left surround and subwoofer. Use the decibel meter and adjust the individual gain of each channel so that it reads 73db.

You now have all the speakers at the same volume at your listening position and movies will sound close to how they should sound and its not hard at all. Make a mental note of the volume of the reciever and always start movies at this volume. Every film should play at a comfortable volume with very little need to change the volume. Loud passages will be loud quiet ones will be quiet and it will all be as the sound team intended.

 

[Number1]

What's wrong with the calibration systems like Audysey and others that come built in, into every 5.1 receivers on the market?

 

[JSt0rm]

What's wrong with the calibration systems like Audysey and others that come built in, into every 5.1 receivers on the market?

I've never used it but I would say there is nothing "wrong" with it.

The dolby pink noise with spl meter combo will give you the closest you can get to what a Dolby tuned room has.

I have calibration software on my jbl lsr4300 series speakers. I've found I prefer to do it myself with the Dolby pink.

 

[bobdole369]

This relies on the iPhones microphone being calibrated, or at least a known value. It is not, thus any calibration is piss-poor at best.

You need a setup like this to properly tune a theater:

Audyssey stuff is for noobs and self installers.

http://www.behringer.com/EN/Products/ECM8000.aspx

Of course you then need a way to supply phantom power, the xlr cords, etc into a mixer, that then goes into your laptop or PC, which has also been calibrated, you input into a program like Room EQ Wizard the curve supplied from when your mic was last calibrated.
http://www.curtpalme.com/forum/viewtopic.php?t=10808

Then you tune your impulse and gated responses to bursts of noise with an equalizer (to prevent echo and constructive/destructive reflections). Ideally you end up with a flatline at 0db. This is the true purpose of equalization, as it is not meant for you to adjust the way it sounds by ear. You should set your EQ and let it be, never to be touched again.

Some people take it way too far and do weird shit like put foam blocks in corners and treat specific locs with fabrics. It took me over a day to get my line with under 5db of variance 20-20khz. Its "good enough" lol.

 

[JSt0rm]

This relies on the iPhones microphone being calibrated, or at least a known value. It is not, thus any calibration is piss-poor at best.

My point is to calibrate the speakers to themselves in relation to the sitting position. If the iphone microphone is flawed then it will be equally flawed across the board.

Getting into waterfall projections of reflections and room nodes is beyond what I was offering here.

This is a fairly quick and easy way to ensure that the speakers are outputting the correct spl without going into the more esoteric stuff.

 

[s44]

Congratulations, you've reinvented a wheel that's now free on every AVR. (And miles less sophisticated than Audyssey, Trinnov, ARC...)

 

[JSt0rm]

Congratulations, you've reinvented a wheel that's now free on every AVR. (And miles less sophisticated than Audyssey, Trinnov, ARC...)

I didn't invent anything. This is one of the steps I do before I cut sound effects on the movies you watch.