Axiom Home Page Forums General Discussion Home Theater my nightmare,

Thought you might want this....

http://www.surroundassociates.com/spkrcal.html

well if you look well at my message i said dead center of you lisning area... and by this i meant where you sit but in the center not to the right or to the left but at the center of the couch right between the the 2 front mains... i have done extensive testing and if the position the spl meter (level of your head and exactly center in lie with the seakers ) is not perfect than the sound will not be well calabrated .... i use a tripod on my leather couch!! wife non approved... but anyways this works for me !!!

Hi Johnny, sorry for the miss understanding, I read it to be that you meant Dead Center of the room when you said dead center of the listening area.

Sean, I saw this earlier today, and thats what prompted me to call THX and in turn get in contact with one of their certified installers, as some of the things in that article did not seem correct to my understanding.

Wow, there seems to be a lot of confusion about this. Whether to calibrate to 75 or 85db depends on which calibration tones you use and what your listening preferences are.

In the case of Avia, the tones are recorded at 85db on the reference scale. That means to get playback at reference level for movies, you should calibrate your speakers to 85db using these tones.

It's entirely possible that the THX optimode and/or Video Essentials test-tones are recorded at 75db on the reference scale, but I don't know that for sure since I don't really use those. But if that's true, then calibrating with VE at 75db would give you exactly the same results as calibrating to 85db with Avia. That's the whole point of "reference-level", it's a reproducible standard. So the best advice if you want to calibrate to reference level is to follow the instruction that accompany the calibration disc you use. The AVIA disc has very good documentation available from the menus for each test.

Now for many people, particularly in smaller home theaters, full reference level will seem very loud with today's action movies, probably too loud. That's fine, you can always turn the master volume down when watching movies. Theoretically, you are sacrificing some dynamic range by not listening at reference level, but in reality few if any movies use that full 105db of dynamic range. Most of todays action-type movies are mixed loud; the sound level is at the upper end of the dynamic range for most of the movie. Dialog-driven movies aren't going to be as loud but they still probably don't use the full dynamic range.

As for the THX guy who said to use 85db for music and 75db for movies, I think you must have spoken to a clueless marketing guy who didn't know what he was talking about. CD audio does not have a reference standard for volume, that's why volume can (and often does) vary from disc to disc. Maybe DVD-A and SACD have a reference standard, but I don't have either so I couldn't say. But for CD audio there's no such thing.

Hi JohnK,

Well with regards to the 75 vs 85 db standards, I have made a call to a friend of mine in LA this morning who is the recording business, and he has confirmed that the reference level for audio is 85db and that The THX technician, (The guy I spoke to was actually a certified tech, not a marketer)was correct that theater is 75db. I agree with you that they should follow the instructions from the disc that this is what the manufacturer of the disk intended, and has done their work on it based on those measurements. But it also does not mean that it is correct or should be taken as the gospel.

JohnK,

While I think that the debate over 75 vs. 85db will continue to ensue fro some time to come, I think that it is important to note that whatever standard you decide upon, and really there are no rules etched in stone about this as for most people trying to listen to your movie or audio at the reference level of 75 or even 85db will be too loud in any case for them. That the main idea is to set a balanced sound stage for your environment, so if you find that in a small room that even calibrating to 65 or 70bd works for you then so be it. Once you achieve the overall balance that the levels from all the speakers are set to the same level at your listening position the rest of it really is not that important as too whether it was done at 75, 85, 65 or even 70db.

John H., note jkohn= Jeff Kohn.

Hi,

Thanks, sorry for the confusion I did not look too carefully at the name and since I see your name often it just registered in my mind as you.

Okay using the S&V test tone, I was able to calibrate my system at 85db and sounds great. I don't know if this is really the behaviour, but after calibrating at 85db using S&V test tone, I run my receiver internal test tone at same volume level (ref), the SPL record only around 78db. Anyway, I had enough with the calibration, almost every weekend this is what I am doing...so time for me to be contented on my current settings, relax and watch movies, listen to my CDs...hmmm I have 3 movies to watch this week, Scorpion King, Lord of the Rings and Panic Room.....ciao