# SPL meter vs calibrated mic (UMIK-1)



## gpo (Sep 19, 2011)

I am intrigued by a simple thing as "correct" subwoofer level. 

Since last week I own a UMIK-1 mic. Before that I always used a Voltcraft analog SPL meter for years with REW measurements and level settings. The SPL meter is comparable with the older analog Radioshack meters.

Now with the new calibrated UMIK-1 it turns out that after some measurement comparisions between my SPL meter and the UMIK-1, that I have set my subs far too hot when measuring SPL through the UMIK-1 compared to measuring with the SPL meter -->

http://i59.tinypic.com/2e5o00z.jpg

So, I set my subs 10 - 20 dB too hot measured with the UMIK-1, but only a few dB too hot when measuring with the SPL meter. All compared to the one of the front speakers.

Now I finally understand that everybody is saying that Audyssey is doing things wrong in the subwoofer level. I tend to believe now, that audyssey is actually right and that most of us are wrong as we check with an dB meter which is totally incomparable/useless wrt a calibrated mic.

Anyway, if I put my subs down 10-20 dB then there is hardly any bass (especially with music) but it will measure flat.... so I am a bit confused now wrt the definition of a correct subwoofer level or correct bass at all. I should believe the UMIK-1 as it is calibrated, but settings levels with the SPL meter gives me more realistic and punchy bass. I did this for years and now this method looks like it is all wrong....:dontknow:

So, how do other people set their levels if they have a calibrated mic? Do they just run the subs 10 dB hot or so to get some satisfaction in the bass-region?

GPO


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## gpo (Sep 19, 2011)

I am trying to get the picture embedded in this thread, so you don't need to click on links -->










seems not to work for me?? It is there, but it doesn't show up....


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## ntran (Mar 25, 2015)

Just curious if you copied the mic sensitivity data to your calibration file as your cal file, if done by spectrum labs, does not have the mic sensitivity data.

For me, Audyssey set my subs 7dbs hot. Depending on the type of musics you're listening to, you may hear very little bass from your subs


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## gpo (Sep 19, 2011)

ntran said:


> Just curious if you copied the mic sensitivity data to your calibration file as your cal file, if done by spectrum labs, does not have the mic sensitivity data.
> 
> For me, Audyssey set my subs 7dbs hot. Depending on the type of musics you're listening to, you may hear very little bass from your subs


I downloaded the cal file specifically for my UMIK-1 from the minidsp website. It has a "Sens Factor" number included in the header, so I guess I am all set then?

True about the music though; it depends on the music and on the crossover and more things. I mostly use some bass-intensive music (i.e. Massive Attack/Bass Mechanik/Trentemoller) to verify if the subs are ok / not overwhelming or set too low.

GPO


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## gpo (Sep 19, 2011)

ntran said:


> Just curious if you copied the mic sensitivity data to your calibration file as your cal file, if done by spectrum labs, does not have the mic sensitivity data.
> 
> For me, Audyssey set my subs 7dbs hot. Depending on the type of musics you're listening to, you may hear very little bass from your subs


What I mean with "running too hot" is that the measured SPL in the bass is 10 - 20 dB too much compared to the SPL levels in the midrange-frequencies of my main speakers. I think what you mean is that ADSY sets the sublevel to +7 db in the receiver. That's not what I mean.... 

Looking at the chart, one might think my subs are overpowering the sound. In reality it sounds quite ok and in balance. So, that is why have some difficulties with the readings I get from the UMIK-1 measurements.

Also other HT-people are not complaining about bass being too much in my place. Only the wife is complaining (sometimes).... :devil:

GPO


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## AudiocRaver (Jun 6, 2012)

Personal preference is such a big factor here. Most home cinemas I have seen measurements for are tuned with the bass & subwoofers hot, 5 to 8 dB is very common where a lot of music is listened to on the system, and more like 10 to 15 dB where only movies are played.

The Equal Loudness Contours in the 2003 ISO standard show us that the ear is much less sensitive to low frequencies than even the old Fletcher-Munson curves showed us. The average ear is around 20 dB less sensitive at 40 Hz than at 1 kHz. But music is handled differently from test sine waves in the brain at those frequencies. A bass guitar's lowest note does not need that kind of boost to sound true because the ear hears all of its frequencies as an integrated sound and judges its volume by the strength of all of the harmonics together. If boosted 20 dB at 40 Hz in a music system, those low bass guitar notes would sound outrageously loud to most listeners. To me - I listen mainly to music on my system - a 5 dB boost seems like too much, and 1 to 2 dB gives an enjoyable extra solidness to the bottom end without becoming overbearing. But I am on the conservative end of the scale, no doubt.

The kind of music makes a difference, too. My system is used for rock, instrumental, some bluegrass, electronica, and it needs to sound true with acoustical instruments. Listeners who lean more to electronica, hiphop, & dubstep might want a lot more bass.

With home theater, those low frequencies are used more for impact sounds and it is more difficult to judge the rightness of those SPL levels, so 10 to 15 dB of boost at 40 Hz might seem reasonable.

There is really no right answer, other than what you like to hear - and can get away with in your environment.:R


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