SPL Meter to Set Levels; Question re: Sub

msg
msg Posts: 10,020
Do any of you use an SPL meter to setup your speaker levels?

Where do you normally like the sub's level in relation to the mains/front output level?

I've seen some say +3dB on the sub in comparison to the fronts, and thought I read something a while back saying up to +6dB, but that sounds like a lot.


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I just got an SPL meter from Amazon a couple of months back, and have been playing around with a bit lately. I didn't really know what to do with it at first, and it sat around for a few weeks. I ended up using it a couple of weeks ago to test functionality of a couple of pieces of gear I was having some trouble with, but having a difficult time confirming by ear

Using an SPL meter for a quantifiable metric for comparison works a little better than changing around a bunch of stuff and trying to remember how it sounded minutes earlier.

Another neat thing I just used it for was to the see the difference in a track's overall SPL output when the sub was out of phase. With the sub out of phase, the sound for a track dropped by almost exactly 3dB for the room, according to the meter. It's neat to actually see the difference.

I don't fully understand the difference/relationship between intensity and loudness. I saw that +3dB has twice the sound energy/intensity/power, but it takes +10dB to be twice as loud.

What does +3dB mean in plain terms?

Here are a couple of articles I was reading:
https://pulsarinstruments.com/en/post/understanding-3db-rule
http://www.sounddeadsteel.com/what-is-a-decibel.html
I disabled signatures.

Comments

  • F1nut
    F1nut Posts: 50,554
    It is said that for someone to notice a change in the volume level it must change by 3dB. I strongly disagree with that.

    It is also said an increase of 3dB in volume takes twice the power. I generally agree with that.

    Let's say your speaker is 90dB efficient @1 watt/1 meter. Therefore,
    90dB -1 watt
    93dB -2 watts
    96dB - 4 watts
    99dB - 8 watts
    102dB - 16 watts
    105dB - 32 watts
    108dB - 64 watts
    111dB - 132 watts
    114dB - 264 watts
    117dB - 528 watts
    120dB - 1056 watts
    Political Correctness'.........defined

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    President of Club Polk

  • Gardenstater
    Gardenstater Posts: 4,468
    I have only used an app on my Android phone to set the R and L channel levels the same by playing mono recorded songs with the phone centered between the midrange and the tweeter and exactly 1 ft from the baffle. Play the song, record the max. dB level and then move the phone to the other speaker and repeat. Worked pretty well even though it may take a few iterations to get it dialed in.

    Another alternative would be to use an online tone generator generating pink noise but that's pretty monotonous and harsh to listen to at normal listening levels and I haven't tried that method yet.

    PS: I made a support for the phone that holds it in precise orientation to each speaker and attaches to the speaker stand.
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Onkyo A-8017 integrated
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • delkal
    delkal Posts: 764
    edited August 2020
    Spl meters are a big time saver when setting up a home theater. Even the free apps that work with your phone. Just hold the meter where you listen and toggle thru the speakers adjusting as you go. You just need to to get them to the same number not the specified test tone level. Of course you can do a just as good (or better) job by ear but to get you dialed in a meter is easier. I checked my system that I first tuned by ear and the fronts and center were dead on but the rears were off. Probably due to psychology and comparing sounds in the front where you can focus and something behind you.

    For subs I only do it by ear. I don't trust that my free cellphone app is accurate with low frequencies.