Reference Level

Thomasjclark45

I am new to this forum, and I have some questions that Im sure many of you could help me with. I have just upgraded from my Sony V333ES 5.1 to an Onkyo TX-NR609. I let the Audyssey calibrate my system which made it sound 10 time better than without it. The main question that I have is about the reference level.. From what I understand from the manual is that the system calibrates at a level of 82db, which is what the soundtrack was mixed at. Is this correct? Does this take into consideration room size and reverb? Will this take into consideration whether or not my speakers can handle it? Is this the same volume that you would hear in a theater? My receiver alows for absolute and relative volume settings from what I understand it just changes the numeric display from -82db/+18db to 0-99. Does this have any effects on the sound/volume? or is it mearly for people who prefer an acending volume instead of decending decible count? Other questions that I have is the EQ settings. I found that the Audyssey DSX EQ setting sounds better than the THX setting from what I have listened to. Will this change if I am watching a THX Movie? And what about DTS? It seems that all 3 allow for my Front Height channels. Should I change these when going from one movie to another? I would like to learn all I can about home theater audio, but it seams that by the time I learn one thing, the technology changes.
Thanks for your help

kuntasensei

Reference level = peaks of 105dB from the main channels and 115dB from the low frequency effects channel. The relative volume setting shows level in terms of how far below reference you are. For instance, if you are at -20dB, that means your system will roughly peak at 85dB in the main channels and 95dB LFE. It really doesn't matter which volume setting you use.

There is no setting for movies marked as THX, as this is just a specification that they comply with. Some THX-branded movies are pre-compensated for near-field listening (i.e. your room instead of one the size of a theater), which means they have a slight rolloff of the highs to compensate. Unfortunately, this can often cascade with the rolloff that Audyssey does, meaning those pre-compensated movies can sound more dull because of this. Fortunately, that's mostly limited to DVD soundtracks and shouldn't be an issue with Blu-rays.

The listening mode you use is up to you. Pick whichever sounds best. If you want to use height channels, use either DPL-IIz Height or Audyssey DSX. Both should be able to be applied on top of Dolby Digital and DTS tracks.

shawn474

Best way to calibrate IMO is by using an SPL meter. The Audyssey is easy and convenient, but the best way to do it is maually. I would try it and see it what you think. I have always used 90dB as my calibrating point, but people use different levels. It has made a HUGE difference for me in the past.

kuntasensei

Newer iterations of Audyssey do a pretty good job of adjusting to reference levels, but shawn's right in that it never hurts to double-check it with a SPL meter after equalization.

And people don't use different levels, as that would defeat the purpose of setting to a known reference. If you're using the internal tones in your AVR, they should show as 75dB on a SPL meter when properly set to reference because the internal tones are generated at -30dB. If you're using an external source for test tones, the level you should set depends on the source. For instance, if the calibration disc says it should read 75dB, set volume to 0 and then adjust channel trims until all channels are at 75dB. (Make sure you disable DynamicEQ before you try to calibrate with any test disc.)

For the most part, it doesn't matter what you calibrate to if you don't care that 0 on the relative scale = reference level. However, if you're using Audyssey's DynamicEQ, its performance is heavily dependent upon 0 equaling reference level because it adjusts the surround presence and dialogue gradually as you get further below reference (so at reference level/0, Dynamic EQ is performing no alteration of the sound, whereas at any point below that, it gradually adjusts for listening at below reference in a smaller space).

In my opinion, 90dB is too high for level calibration as you risk damaging your speakers (and your hearing) with extended measurements. It also plays the test tone at loud enough a level to potentially excite frequencies in your room that can throw off your readings. Best to stick to either the 75dB internal tones when using a SPL meter, as it is loud enough to calibrate for average dialogue levels but not so loud that you're throwing off the readings with any reflections/reinforcements caused by the room itself. Not saying that shawn is wrong... because ultimately, whatever works best for you is RIGHT, because it's your system. But as far as accurate calibration goes, there is a proper standard.

shawn474

kuntasensei wrote: »

Newer iterations of Audyssey do a pretty good job of adjusting to reference levels, but shawn's right in that it never hurts to double-check it with a SPL meter after equalization.

And people don't use different levels, as that would defeat the purpose of setting to a known reference. If you're using the internal tones in your AVR, they should show as 75dB on a SPL meter when properly set to reference because the internal tones are generated at -30dB. If you're using an external source for test tones, the level you should set depends on the source. For instance, if the calibration disc says it should read 75dB, set volume to 0 and then adjust channel trims until all channels are at 75dB. (Make sure you disable DynamicEQ before you try to calibrate with any test disc.)

For the most part, it doesn't matter what you calibrate to if you don't care that 0 on the relative scale = reference level. However, if you're using Audyssey's DynamicEQ, its performance is heavily dependent upon 0 equaling reference level because it adjusts the surround presence and dialogue gradually as you get further below reference (so at reference level/0, Dynamic EQ is performing no alteration of the sound, whereas at any point below that, it gradually adjusts for listening at below reference in a smaller space).

In my opinion, 90dB is too high for level calibration as you risk damaging your speakers (and your hearing) with extended measurements. It also plays the test tone at loud enough a level to potentially excite frequencies in your room that can throw off your readings. Best to stick to either the 75dB internal tones when using a SPL meter, as it is loud enough to calibrate for average dialogue levels but not so loud that you're throwing off the readings with any reflections/reinforcements caused by the room itself. Not saying that shawn is wrong... because ultimately, whatever works best for you is RIGHT, because it's your system. But as far as accurate calibration goes, there is a proper standard.

Nice post, I just learned something. Maybe now I will listen to my wife when she says, "That's way too loud!!!!!" I thought 90dB was reference level, but your explanation makes total sense to me.

Tour2ma

^Agree... both posts were extremely well written...

Welcome to the Forum, Tjc45...

kuntasensei wrote: »

Newer iterations of Audyssey do a pretty good job of adjusting to reference levels, but shawn's right in that it never hurts to double-check it with a SPL meter after equalization.

Agree that they've gotten better, but (and I'm just catching up with the latest auto-cal routines) from what I've learned so far Audyssey's MultEQ XT and XT32 are their top technologies. Is one of these the routine the DX product uses?

kuntasensei wrote: »

It also plays the test tone at loud enough a level to potentially excite frequencies in your room that can throw off your readings.

Agree on the 75 dB cal level, because it is the standard, but I don't know what you mean when you say "excite frequencies".

kuntasensei

Tour2ma wrote: »

Agree that they've gotten better, but (and I'm just catching up with the latest auto-cal routines) from what I've learned so far Audyssey's MultEQ XT and XT32 are their top technologies. Is one of these the routine the DX product uses?

DX product? You mean DSX? DSX is Audyssey's method of creating height or width channels from existing material. It also tweaks the surrounds a bit to integrate them together better. It isn't another method of auto-EQ like MultEQ.

Tour2ma wrote: »

Agree on the 75 dB cal level, because it is the standard, but I don't know what you mean when you say "excite frequencies".

For example, if you have storm windows, they're particularly bad at resonating, especially at high levels of sound. Same with drywall... or cabinet doors... etc. With normal listening material, the effects are negligible because loud bursts are transient in nature and limited in frequency range. But if you play noise tones loud enough, the resonating of that window/wall/cabinet could provide an artificial boost, throwing off what your SPL meter would read and leaving you with an unbalanced system. A 75dB tone, on the other hand, isn't typically loud enough to cause a problem with your readings from the room itself, so you're just reading the speaker's output. Audyssey's MultEQ, on the other hand, looks for these room-induced issues and EQ's around them before setting the level.

Thomasjclark45

Thanks guys for your help. I guess what it boils down to is that I should buy an SPL meter. I think that I finally understand what the reference level is. I was never one to review forums but this year when I upgraded I spent days on end reviewing posts and reviews on many items, which has helped me understand more about home theater than I ever knew, so now I'll be spending more time envolved in these forums trying to educate myself. Thanks to these posts I feel that I have made a decent purchase given the amount of money I had to spend. No if someone could tell me how to find equipment for free that would be awesome.
Thanks everyone.

tonyb

We may get a tad technical around here from time to time but really HT is pretty easy to do. Let your ears guide you on your tweeking, not everything is written in stone.

Now, music reproduction is where everyone gets their shorts all twisted. Enjoy.

kuntasensei

tonyb wrote: »

We may get a tad technical around here from time to time but really HT is pretty easy to do. Let your ears guide you on your tweeking, not everything is written in stone.

Now, music reproduction is where everyone gets their shorts all twisted. Enjoy.

+1. Reference level is a starting point. Ultimately, it's your system and you're the one who has to be happy with it, so let your ears be your guide. Don't be afraid to bump up the center or surrounds if you think it's unbalanced. Always tweak things to your liking.