Home Theater Calibration

[Chip]

Ok guy's,

Like i've seen Andrew start threads on topics like "HDTV" and asks eveyone who inputs to start from the beginning and explain things on a topic so novices can understand, here's a question and discussion i'd like to start:

How do i properly calibrate my system?

I bought an SPL meter and also have Avia Guide To Home Theater. Assume i have no clue but, decent gear (and i do! 8O ).




Chip Engle


"Concrete ain't a spectator sport"


<a href="http://www.htguide.com/bilder/index.cfm?fuseaction=arkivbilder&userid=0&selected userid=336" target="_blank">My HT

[David Meek]

Chip,

The Avia disc will step you through the basics of audio and video set-up. I recommend that first, you watch it all the way through to familiarize yourself with the steps and the terminology. Then go back through it, trying the adjustments as specified. One suggestion: write down the values of any settings BEFORE you change them on your receiver or pre/pro. That way, you can get back to square one if necessary. Don't worry, the first time it may be a little daunting, but tinkering gets to be second nature after a few times.




David - HTGuide flunky
Our "Theater"
Our DVDs on DVD Tracker

[Andrew Pratt]

Good topic Chip

Basically the goal in calibrating our systems is two fold, one is obviously to get a ballenced sound so that no one speaker is louder then another, the second is to set a reference level. I'll talk about these in turn so lets start with ballencing the channels. There's really two ways to do this one being to use the internal test tones in the receiver/pre amp and your trusty SPL meter to make sure that each channel all reads the same volume. The second is to use a special calibration DVD such as Avia guide to home theater (Avia) or Video Essentials (VE)...what these two discs offer is that take into account any small effects the DVD player brings to the mix plus they provide you with a reference level against what the mixing engineers use when creating the mix for DVD's. Okay so now we know that its pretty easy to set all the levels to the same volume with our SPL meter and the test tones from either the receiver or better yet Avia or VE but how loud should they be? Well this is were the reference levels come into play. On the Avia DVD the tones are recorded so that when you play them back at 85 dB you are at the same volume as the audio engineers. For VE its 75dB but that's only because they were recorded at a lower volume..the end result though is identical between VE and Avia so either one will give you the proper volume. There's a couple of different ways people set their reference level depending on the gear they own. Basically manufacturers use either a positive integer or a negative db scale for their volume display. Usually the ones with the negative dB scale allow you to set the display to zero then calibrate all the channels to 85 dB using Avia. This would mean that when you turn the volume up to zero you are now playing back the DVD at the same volume it was mixed at...now for some this might be way to loud but that's ok..what it also does is provide the rest of us with a reference to how loud you were listening to something. For example lets say you were commenting on a something you heard in a sound track and you said your volume display said -75dB we'd all know you were about 10dB lower then reference level...its a frame of reference. For those receivers that use a positive integer volume display try and pick a number that makes sense and go from there. For my Rotel I use 85 since its easy to remember but you can use any number that works for you.

Of course one of the benefits of using Avia or VE is that these discs also have the ability to calibrate your video as well so they are a very good investment to get the most out of your equipment. I've used both VE and Avia and personally I prefer Avia for its easy of use and of course its available here or on Amazon

[Chip]

Thanks David & Andrew,

I'm going too, once again, try this. I've had the Avia disc in on more than one occasion trying too figure it out.




Chip Engle


"Concrete ain't a spectator sport"


<a href="http://www.htguide.com/bilder/index.cfm?fuseaction=arkivbilder&userid=0&selected userid=336" target="_blank">My HT

[David Meek]

Chip,

Another option if you aren't comfortable with the Avia disc, is to try the Video Essentials DVD. It's similar, but different in approach and may be preferrable. I have both and I'm more comfortable with VE.




David - HTGuide flunky
Our "Theater"
Our DVDs on DVD Tracker

[Chip]

David,

Thanks for the suggestion with Video Essentials. I think i may try it . Hopefully, it'll click for me. I just haven't been able to understand this whole calibration thing and it frustrates me.




Chip Engle


"Concrete ain't a spectator sport"


<a href="http://www.htguide.com/bilder/index.cfm?fuseaction=arkivbilder&userid=0&selected userid=336" target="_blank">My HT

[David Meek]

ops: Doh!

In our haste to talk about calibrating, maybe I overlooked one thing - the SPL meter. This is a simple device you can get at Radio Shack for measuring Sound Pressure Levels. It comes in two models, an analog unit which has a meter-type display, and a digital unit which has a numeric readout. I prefer the analog as it's easier for me to read - and it's about $25-29 US, with the digital being a bit pricier.

What you do with it is set it to "C weighting" and "Slow" response, and hold it in the approximate location your head will be in when you are sitting in your prime spot. It'll listen to the tones the calibration disc or your reciever is outputting and show you in decibels how loud each speaker is playing. As Andrew said, for the best effect, you'll want all the speakers set to play the same level, so you'll probably have to adjust the individual volumes on the center and surrounds a bit after setting the mains to the reference level. Again, as Andrew said, the recommended reference level at which you set the volumes will vary from VE to Avia but either is fine.

Hope this helps clarify things a bit.




David - HTGuide flunky
Our "Theater"
Our DVDs on DVD Tracker

[Clive]

Chip, one thing that caught me when doing the calibration was phasing. I noticed that your PSB surrounds are mounted on the walls but it is a good thing to check all your speaker cables to make sure they are all in phase (Blacks to Blacks, Reds to Reds). You may have done this already on the initial setup but I thought I'd mention it because the Guide will take you through a Phasing test.




CLIVE




HEY!! Why buy movie tickets when you can own a Theater?

[Chip]

Thanks Clive,

I believed i did it right when i first installed the speakers however, i just doubled checked and their correct.




Chip Engle


"Concrete ain't a spectator sport"


<a href="http://www.htguide.com/bilder/index.cfm?fuseaction=arkivbilder&userid=0&selected userid=336" target="_blank">My HT