Do 115 dB peaks on the LFE channel represent what you hear in a movie theater?

Increase your subwoofer gain then recalibrate.

You probably felt the midbass from the mains at the movie theater as well as the 18's they use. A good movie theater has lots of 18's and 15's that go down to 20-25 Hz. Using memory is very hard to do especially that long ago. If you liked the movie theater sound then you can just turn up the sub. What are your settings and did you watch at reference? Just make sure, I know you already said you did.

BTW, was your 115 db's peaks from just reading from a SPL meter or corrected thru a computer?

I believe cinemas hit 120 db's. Try moving the sub in the front.

I have that dvd, I will give it a try at reference level and let you know.

Just wondering during low dialogue parts are you down into the 60s?

Nobody asked the OP what subwoofer he had.

Regarding the AoTC scene; it is and should be very loud in scenes like that. I get over 120db peaks.

I run my mains small (as virtually everyone should). That directs more signal to the sub than just the LFE channel.

Dolby spec calls for peaks of 105db in *each* channel and 115 in the LFE. 5 channels of 105db peak + 115db is not 115db.

I use the rat shack analog meter for SPL measurements.

You mentioned you run your sub trim at lowest (-12). I think it's better to run the sub level at it's midpoint and then adjust the gain on the sub. The way you have it gives you no room to lower the sub level at the receiver. Also, the signal level may be a bit low going to the sub.

And why calibrate flat on the sub? Run it hot if that's what sounds good. Nobody ever said flat was correct for LFE. The dolby setup guide for mixing studios even calls for the sub to be run hot when the monitors (main channels) are run as "small".

The Dolby spec for LFE results in a maximum peak level of 115 dB SPL if your subwoofer is calibrated flat.

The subwoofer output jack provides you with LFE plus redirected bass. The subwoofer output jack signal level with the subwoofer calibrated flat could give you maximum levels of near 121 dB SPL peak (115 dB LFE plus another 6 dB for redirected bass).

I measure my peak SPL level with a RS Digital SPL meter set to fast, MAX, C-Scale. I use the data hold function so the meter will record the peak over a long time period.

I just read from the analog meter. I agree with the other guys, turn the LFE trim up and use the gain on the sub(turn that down). What is your crossover at?

It sounds like you have it right, you just need another sub. I still can't believe your speakers hit 120 db's at these frequencies, that is really good. I would run them small and cross them over as low as the processor allows(maybe 30 Hz).

Lab tests by hi-fi magazines that do thorough reviews show that some AVR's distort the subwoofer signal when the sub trim is set to 0 or higher, thus many folks such as the SVS staff recommend setting your AVR sub trim about 25% of the way up from the bottom so you avoid potential signal distortion yet still have some room for conveniently tweaking the sub level on the fly if program material warrants it. So for example if your AVR sub trim has a range of +/-12, you would ideally set it at about -6 and adjust the gain control on your subwoofer itself during calibration with Avia or whatever pink noise tones you normally use to set speaker levels.

Cheers,
Ross

In another thread OP complained about his submersive clipping so I think he should make sure his gain is high enough as I believe someone else had the same problem which they fixed by increasing the gain on the sub.

Edit: I see OP fixed his clipping problem by doing this.

I would also advise OP to get REW and use his SPL to measure his frequency response in his room as some dips at certain frequencies can certainly take away some of that punch he wants.

So, theoretically speaking, even if you are getting clean output with your trim level at say -1.5, you should increase the gain on the sub, and decrease the trim level?

Wow, that disc had insane LFE.

I hit 120 slow weighted uncorrected

Wife told me to get her some qtips..it made her ears...itchy....

Felt like my whole body was being pummeled..

I found high output LFE throught out the movie... interspersed nicely..the ship noises among the loudest...

+1. You simply may have some nulls at your seating location that are preventing the "full effect." Use REW to be sure.

For what it's worth, EQing my subwoofer was one of the best things I have done. It made a HUGE difference (in a good way) for both movies and music. Don't hesitate to take measurements and EQ the response.

I don't think you need to worry about it if your output is fine, only if you are experiencing clipping. I'm not an expert or anything, I just remember someone doing this on their Submersive and it fixed their clipping issue.

I am about 2 to 3 db hot, using RS meter new analog.

I think that dvd is about 6db hot on the LF....

I have two subs in a 2200 cu ft room an MFW nearfield left, and a Phoenix right side....

btw I run my sub trim at -4 and both subs are at 12 oclock gain..

Thanks for the response.

That's very interesting. Is any of this info online anywhere? My subwoofer seems to chuff a lot less since I turned down the trim on my AVR by 5 dB and turned up the gain accordingly.

I first read of this on the SVS website a few years ago, then saw the lab testing on subwoofer output distortion in various AVR reviews in at least one online a/v mag, so yes this info is online. Check out the SVS subwoofer setup info [note: their site is down at this moment, they have had virus problems recently]. I do not recall which online a/v mag had these thorough lab tests on receivers, you'll need to search but they are there (this was about 3 years ago).

Cheers,
Ross

Not if someone is running their system above THX specs. There is no reason people can not have 120dB peaks period.

I never understood this whole discussion, why don't people just set their system to what THEY like? Who cares what someone else has, does or says should be done?

Of course 120dB peaks at the listening position is LOUD and if he is stting 12 feet back he is doing 130+dBs at 1m

I think it all depends on your room size and equipment as to whether you want louder though you can actually damage hearing if going too far above 120db for long periods. For peaks i don't see a problem if your system handles it.

I think i have finally got my system working right with the new Oppo Blu Ray player i bought but will run a few more tests tomorrow.

During the Attack Of The Clones opening scene the explosion scene at the beginning peaked at 103db on my digital radioshack meter. I have an SVS -PB-12/Plus2 subwoofer and use an SMS-1 for subwoofer management and have things set up fairly flat between 20hz and the 80hz crossover point.

My subwoofer runs 3db higher than the other speakers now and thats the way i want it. I haven't had the chance to watch a full movie yet on my new Oppo as i have been too busy calibrating it for days now. I think i finally got it right.

Anyways for my size of room and the 106inch projection screen i use i think 103db peaks are fine to my ears. Plenty of deep bass and slam.

Incidentally the reference levels say 105db for mains peaks. 115db for subwoofer peaks.

What is the total output peak when combined ? 120db ? Anyone ?

Hi Kain,

The math to figure out potential peak levels and output for given scenes is just a best guess if you don't know the frequency response. The first 7 test signals on the "Acoustic Tests" of the Audio Toolkit DVD are what should be used to set levels, but even here the appropriate subwoofer level is very approximate until you know what the frequency response looks like. Peaks in some ranges will make some scenes louder than others, even if the levels happen to be recorded at very similar loudness but have different frequency content. It is possible to get REW running with your RS meter and a cheap sound card, although a real mic and pre-amp are much preferred. Of course I'll caution that the first time you see real measurements of your room it is generally a bit of a let down, or tells you things you didn't really want to know.