Reference level

tpeter

I was at hometheaterforum and they all talk about playing their movies at reference volume. What exactly is reference volume? HOW lOUD?

TheGrayGhost

When the audio is recorded at reference level (0dB) on a DVD the sound system should produce a sound pressure level reading of 115dB for the LFE and 105dB for all other frequencies.

Very few home theater sound systems are able to reproduce this level for the bass.

tpeter

So would you just need a really great sub? Or an all around total package like a great sub with a great amp?

organ

You need a really good sub to hit 115db especially for 20hz. A lot of subs usually start roll off around 40 to 30hz. I wouldn't recommend watching your movies at reference levels all the time if you want to keep your hearing.

Maurice

scottvamp

I built my HT specificly for reference levels but not all movies play at that level. Some movies I will watch at these level but not all. It is great to show off on demo material and have the "muscle" when u want it. Even if you have the "equipment" - room acoustics and proper setup really come into play to get reference quality sound levels.
2cents:)

organ

Hey scottvamp, are you the one with the PSW1200?

How is it for music and movies? What mains, center surrounds do you own to go with it? I almost got one when it first came out but didn't make enough money from my summer job and went with the PSW650. It's too bad the sub is discontinued because it was one of the 3 subs polk had that could reach 20hz(others were PSW150 and PSW200).

Maurice

Dr. Spec

GrayGhost hit it on the bean. Those SPL reference numbers are from Dolby Labs.

Here's how to get close to approximating "reference level" from your HT system:

1) Get yourself a properly calibrated SPL meter.

2) Use the test tones on the receiver, or a calibration DVD. The DVD is supposedly better, but both methods are acceptable and WAY better than calibrating by ear. Note, the following is for the 75dB tone method - I know one DVD test disc requires 85 dB instead, but you get the idea.

3) Set all the individual speaker volume controls on the receiver to 0. Set the sub volume control to -5.

4) Play the center channel test tone and measure the SPL AT your listening position.

5) Adjust the Master volume on the receiver until the test tone for the center channel speaker is showing 75 dB on the SPL meter.

6) DON'T touch the Master volume ANYMORE, and write down the Master volume setting.

7) Switch to the test tones for the mains and surrounds and adjust the individual speaker volume controls on the receiver (NOT the Master volume) until they also read 75 dB at the listening position.

8) Switch to the sub test tone and adjust the plate amp volume control AT THE SUB (NOT the receiver Master volume, and NOT the receiver sub volume, which should be left at -5) until the SPL meter reads about 75 dB at the listening position. If you like your bass a bit on the hot side, adjust the sub amp volume control until you hit 78 dB at the listening position. The bass tone will fluctuate some on the SPL meter, so try to take an average.

Your system is now properly calibrated, and the Master volume setting you wrote down will get you pretty close to reference level SPL peaks for both surround sound and bass.

Be warned, some DVDs are recorded on the "hot" side (LOTR-FOTR comes to mind) and will actually be louder than reference at this volume setting - use your judgement. Also, most (actually nearly all) subs cannot take true reference volume level playback without bottoming out or otherwise destroying themselves. Exercise caution and work your way up the Master volume scale on playback. If anything sounds like it is straining or distorting, or bottoming, back off immediately and accept the fact that your system cannot deliver reference SPL at the listening position.

I usually listen to my HT system at between 5 and 10 dB UNDER reference. At 10dB under reference on the Master volume control, I have hit 110 dB bass peaks at the listening position on LOTR-FOTR. That shows you how "hot" this DVD is mastered. At 6 dB under reference, I have hit 112 dB bass peaks at the listening position on The Haunting in DTS.

This is probably pushing the clean limits of my sub and I would be a fool to increase the volume another 6dB to try true reference listening on The Haunting - that would equate to 118 dB peaks at the listening position.

BTW, a 112 dB bass peak at the listening position 12 feet from the sub corresponds to approximately a 124 dB peak 1 meter from the sub. That shows you why it is so hard to hit true reference in a regular sized HT room with just one sub, even a really powerful one. Your PSW650 does not have nearly that kind of output capability (the PSW1200 DOES, though) so be careful when working up in volume.

Doc

tpeter

Your PSW650 does not have nearly that kind of output capability (the PSW1200 DOES, though) so be careful when working up in volume.

Doc [/B]

I was thinking about getting the SUb that you have,The SVS PC+
This your saying hits reference levels with ease?

scottvamp

Organ, yes I have the PSW1200. It does sound great with music and movies. It is clean, loud and low. I have had it for about two years now and it has worked flawlessly. No problems at all. When I first saw this sub when I got involved on the polk site. It was being showcased and even had a seperate page dedicated to this monster. I knew that I had to have it. Ordered it from Cruchfield and they had to freight it to me. Took less than a week. I also have a Bosten Acoustic VR500 sub in the rear.
For mains I have rt1000's as mains and a cs400 for the center. Here is my 6.1 set up on the showcase. Though things have changed a little - now have to rows of seating with the rear couch elevated about a foot. Better front stage appearence and center raised about a foot.
Garage HomeTheater

scottvamp

Dr. Spec, very interesting sound cal. setup - very detailed. I have never had it explained this way. I believe I will try out your system to see how my volume will differ. I have heard though that at setup the spl on the sub should be hitting 105db. But I am sure at DVD bass peaks it will be quite abit higher. But I like the bass man. Thanks - Scott

Dr. Spec

Tpeter:

The PC+ will NOT hit reference levels with "ease". Reference level is measured AT THE LISTENING POSITION. It depends on how big your room is in cubic feet, how many openings are there to other rooms, how close you are to the sub, etc.

There are very few single subs that can hit clean 115 dB peaks at the listening position. The PC+ MIGHT be able to do it in my HT room, but I don't want to try - it's kinda expensive and I don't want to destroy it. Twin PC+ (or better yet twin Ultra's) WOULD hit reference levels in my HT room - with ease. Twin subs in the same location adds 6 dB of additional volume.

Scott: I have never heard of any calibration where the sub hits 105 dB. That is very extreme. Trust me on this one - if you follow the calibration described above, and run your sub(s) about 3dB "hot" (i.e., 78 dB on the test tones at the listening position) you WILL hit over 112+ dB peaks at your seat at or even slightly BELOW your "Master" volume setting on your receiver. Try it out and get back to us and post the results.

Doc

JediCowboy

Originally posted by Dr. Spec
I know one DVD test disc requires 85 dB instead,

Would this be the Avia DVD?

Dr. Spec

Can't remember for sure - anyone else? I think you are correct - maybe a check on the internet website will help............

JediCowboy

Originally posted by Dr. Spec
Can't remember for sure - anyone else? I think you are correct - maybe a check on the internet website will help............

Yes it is. I borrowed one this afternoon and used it this evening. It suggested to set the levels to a reference of 85 dB, or 75 dB for those that prefer somethign not as drastic. This DVD is amazing. I've already put my own copy on order.

Previously I callibrated my system according to the Denon 3802 Reference tones to a level of 75 dB. At that time my levels were:

Front Left: +1dB
Center: +2dB
Front Right: +1dB
Right Surround: +3dB
Left Surround: +3dB
Subwoofer: +0dB, Level at 7+

After using the Avia DVD and DrSpec's suggestions I calibrated the system to a level of 85 dB and my settings are:

Front Left: -3dB
Center: -2dB
Front Right: -2dB
Right Surround: -1dB
Left Surround: +0dB
Subwoofer: -5dB, Level at 7 +

It sounds much cleaner and an annoying hiss that has been bothering me for weeks seems to be gone, or at least minimized.

The things I've tried so far can be played up to about +5 dB from reference level before I start hearing the hiss. Was my probelm just that I had my previous settings too high and the internal calibration was just throwing me off?

And you had it right about LOTR being "hot." With these levels and the master volume at -10 dB the SPLs are at 103 db in places ("You shall not pass!"). And its still clear when I put the master volume at 0. Just had to try it

Thanks DrSpec!

tpeter

I just got that Avia Disk and havent used it yet but i will soon. One question, I know it plays its own pink noise from the DVD to make adjustments but I can only change my speaker levels by going into my receiver and playing there test tones. Im not sure if there is a way on the Onkyo 797 to change speaker levels while im listening to the avia disk.

Also if you went up higher to 85db wouldnt you speaker levels have gone up not down from 75dbs?
Thanks

JediCowboy

Originally posted by tpeter
I just got that Avia Disk and havent used it yet but i will soon. One question, I know it plays its own pink noise from the DVD to make adjustments but I can only change my speaker levels by going into my receiver and playing there test tones. Im not sure if there is a way on the Onkyo 797 to change speaker levels while im listening to the avia disk.

Also if you went up higher to 85db wouldnt you speaker levels have gone up not down from 75dbs?
Thanks

I just went through that little puzzle myself with my Denon. What I did was set the Master Volume to 0 dB while the Avia Pink noise was playing. Then the Denon let me adjust the levels using just the remote and without going into the OSD setup. I can press the Pause/Enter key on the remote and adjust the levels on the fly without the OSD or internal pink reference noise. It displayed the levels on the receiver LED. I had to squint to see it from where I was, and it involved a bit of button pushing on the remote (switching back and forth from DVD to AMP), but it worked. I'd check your user manual for your receiver and see if there is something similar.

I have no idea why my levels were +X dB when I calibrated it to 75 dB with the internal program and to -X dB when I did it to 85 dB with the Avia DVD. Someone more knowlegeable than I will have to answer that but it works.

scottvamp

It sounds much cleaner

JediCowboy, I am going to go through Dr. Specs process tomorrow.
I'm not sure if I can adjusts gains either on my Onkyo while my cal. disc is playing but if not I will use the internal pink noise to do so.
But the simple theory is exactly what you have come up with----
there are going to be less positive on the individual gains and more master volume than I currently use. Your gains went from all positive to all negative.
Less gain my equal cleaner sound. You have proved what I thought the outcome would be. I wonder if Dr. Specs set up is going to improve my sound. I will let you guys know tomorrow.

JediCowboy

Originally posted by scottvamp
I'm not sure if I can adjusts gains either on my Onkyo while my cal. disc is playing but if not I will use the internal pink noise to do so.
But the simple theory is exactly what you have come up with----

I just did the emperical proof; Someone else needs to give us the reason But I'm guessing you're right, the hiss was from the positive gains.

As far as adjusting from the reference disk, you can still do it I believe, but the process will be a pain. I'm guessing that you could set the Master volume to 0 dB, play the Avia tones and note your SPL. Then switch to the calibration menu and guess which way and how much you need to adjust the gain while ignoring the actual level given by the Onkyo reference. Then switch back to the Avia DVD and check your setting on the meter. And over and over until you get it right for each speaker.

Granted, not the easiest way, but you will be able to avoid the internal tones in this manner.

And as a final note, when I now play the Denon internal test tones at 0 dB, they register around 70 - 73 dB on the SPL meter. According to the Denon manual these should be registering at 75 dB, where I had them before. Go figure. I didn't make any adjustments from here, but just looked at it out of curiosity. I'm leaving my system calibrated to the DVD, not the internal tones.

jeberhart

I wasn't ever going to say anything about this on any post here or elsewhere, but this thread has prompted me. Plus, I'm logging post after post tonight. Guess I'm in a chatty mood.

But with all this talk about reference levels, I wanted to warn everybody out there: Be careful. Not of damaging your subs, but of damaging your ears.

Three years ago, I developed chronic tinnitus, or severe ringing in the ears, as a result of years of noise exposure. Granted, it wasn't always home stereo stuff. I played electric guitar, worked in home construction, and generally did some other things (rock concerts come to mind) that contributed to this.

Once it starts, it usually doesn't go away. I'll have to live with this the rest of my life. I've been treated for it with a controversial protocol called Tinnitus Retraining Therapy that worked for me, but all that means is that I was trained, over a period of 18 months, not to pay attention to the noise in my head.

My tinnitus has been measured at 42 decibels in my left ear and 41 in my right. Some people have it much worse. Still, some days it sounds as if I have a combination of a jet engine and a whistling teakettle in my ears.

Thanks to my treatment, I can now enjoy music again -- even music at a fairly robust volume. But for a long time I couldn't. I had hyperacusis at first, in which the body's audio system basically just turns up the gain until everything, even people's voices, sound painfully loud.

There's one way to avoid this: Be sensible.

Hitting peaks of 115 decibels is not only beyond the capabilities of most home systems -- it's also edging into the danger zone as far as hearing damage and tinnitus goes. I have an SPL meter, and I've done all the calibrations people talk about. I also bothered one day to figure out how loud I like everything. And the fact is that once I start hitting levels of 95 to 100 DBs on the peaks, I can't take anymore. Of course it's much more dangerous to be exposed to that kind of noise at sustained levels. Jets taking off can produce 120 to 130 decibels. That's why those guys directing traffic on the runways all wear hearing protection. It isn't optional for them. It's mandatory. On the new International Space Station, they had to work to get constant sound levels down from the 65 DB or so that they had to begin with -- fans running, etc., and the station proved to be noisier than they thought. Even at 65 db sustained, hearing damage can result.

I'm not trying to rain on anyone's parade. Just be careful out there. Give your ears rest periods. Sustained exposure seems to be a problem.

I'm also convinced that home systems are not the biggest danger. In-ear headphones sold with some portable CD players can really do you harm if used to excess.

But the single most damaging thing is probably the modern rock concert. When Cream and the Allmans played the Fillmores 30 years ago, their gear and setups were ridiculously underpowered. Now sound reinforcement is a science, and it can go too far. Anyone who sits in the front half of a hall at a contemporaneous rock show without wearing earplugs is in danger of suffering permanent hearing loss or tinnitus, even with only one such exposure.

OK, end of sermon. Hell, I just bought a second sub. But with some of my listening now, I'm roaming the house, doing chores, etc. When I'm actually in the same room with my system, I try to be aware of what I'm doing. Here's the reason: I already have tinnitus. Fortunately, my doctors tell me my hearing loss is almost immeasurable -- no more than what you'd expect for a 41-year-old. And most of it is in the frequencies above 12 khz. But there's one thing I definitely don't want: Being deaf, plus having this internal noise in my head. Don't think I could take that, so I'm preserving what I have. I hope you'll all try to do the same.

HBombToo

Thanks jeberhart, Well said and I agree with you.
The Wife Acceptance Factor has prevented me from overdoing it so I guess there are some Pro's the "WAF".

Regards
HBomb

Dr. Spec

Agreed - I use hearing protection for everything - at work on the production floor, at home using power tools and mowing the lawn, target practice (double up with plugs and muffs) even while hunting with a handgun or a field shotgun (plugs only).

The other thing to consider is that the ear is less sensitive and cannot be damaged as much, by deep bass at high amplitude. We can all sit there and marvel at a 25 Hz tone at 110 dB and it doesn't hurt our ears. Try that same tone at 3 kHz and everyone is running for cover.

The average SPL of my HT during reference playback is MUCH less than 90 dB in the critical 500-8kHz spectrum. There are the occasional loud peaks to 95 dB or so, but it is the bass peaks that really move the SPL meter into the 105-110 dB range. They are transient and low in frequency so I don't worry too much about them.

Overall though - I am a huge proponent of hearing protection - once you lose it, you can't get it back.

Doc

jeberhart

All,

Doc made an excellent point that I left out: High frequencies do seem to pose their own special risks. And it's interesting, too, that hearing loss usually manifests itself first as loss in the high frequencies, while the ear's detection of lows takes longer to damage. One hearing specialist told me part of the reason for that seems to be due to the spiral structure of the inner ear, where the cilia are -- apparently the low frequencies don't penetrate that sensitive chamber as easily. From the little I know about acoustics and sound transmission, it sounded right to me. Also, the doc in that practice who treated my tinnitus started nodding his head when I added to my list of sins the fact that I'd played trumpet for many years in school. Soprano brass instruments, he said, can be very damaging. Always knew I shoulda played tuba instead.

kberg

Just saw this earlier post and the reference level calibration information provided by Dr. Spec - thanks Dr. Spec! One question for you (Dr. Spec) or anyone else that may know the answer...

When using the calibration instructions, am I correct in my understanding that the receiver bass and treble controls be set to zero for calibration purposes, and be left at zero?

Thanks,

Kevin

Dr. Spec

For digital 5.1 playback via a DVD, my receiver totally disables the bass and treble controls.

I think this is common, but maybe some other guys can verify.

Also, I have an updated definition for "reference level": 105 dB peaks from any surround channel, 115 dB peaks from the LFE channel, and if you set your speaks to small and let the sub handle that bass also, this becomes 121 dB peaks from the LFE channel. All measured at the listening position.

Doc

faster100

I just wanted to mention from the few post above about hearing problems, I to believe i have tinnitus but have never been diagnosed. about 4 years ago i purchased a hand gun and decided to go shot it for awhile, No ear protection, so stupid of me!! Well for about a week it was so loud the ringing was driving me mad literally and i couldn't hear normal at all. well since then 4 years have passed and i still have ringing in my ears, at night laying in bed sometimes when its dead silent my ears ring like crazy. I hate myself for doing this to myself and since have gotten used to it, But no more relaxing silent nights... Its ringing for me for life i guess, I still like the music somewhat loud, One time i remember breaking up some wood with my foot on the steps type thing trying to clean up some and when i stepped onto the thin wood and it snapped. My ears went into ring overdrive, waaaaaaaaaaaaaa i was like damm!! so i have to be careful of sudden loud noises.. anyways alittle off topic but along the above posters idea.

danger boy

faster100, thanks for the information. it is so important to wear ear protection when doing anything. I now take ear plugs to all concerts i attend. Tonight, i'm going to a Cher concert.. with Cyndi Lauper as the opening act. While i don't think Cher or Cyndi will be all that loud.. i will keep a pair of ear plugs close by. I got to a lot of concerts, but ear protection is a must now. I do have some hearing loss from when i was a child.. in my right ear. i can't afford to lose any more.

Dr. Spec

I touched off my .44 Magnum long barrel wheel gun ONCE this season without hearing protection during deer season.

I always wear plugs when I hunt with it but this time I was getting up to take a leak and I almost stepped on a wounded deer that someone else had failed to track and finish off. It jumped up and hobbled away, and instinctively I drew a bead on it at 50 yards when it stopped and touched it off - man what a mistake. My ears rang for 2 days - what a GD cannon than thing is!

As a rule, I ALWAYS use plugs AND muffs at the range, and always use plugs for everything like mowing, or power tools, etc.

I agree with everyone - be conservative, wear the plugs and muffs whenever you can - how can we appreciate our superior Polk speakers when we're deaf?

Doc

Soccerplyr

My onkyo 595 remote lets me adjust the outputs while listen to something, then resets to what was done in the setup. The button (I don't remember what it is called but will post when I get home)on the remote is next to the menu button just below the blue button in the middle. Once I did the setup (with the dvd) I just wrote down the numbers I entered, then with the the built in test noises, entered in the levles I came up with.