Rat Shack SPL meter - so we are all on the same page...

[kenratboy]

...we use 'A' when we are talking about SPL, correct? 'C' seems to inflate the numbers (this mode uses a lot more bass, where as 'A' has like a 1000 Hz. hi-pass, correct?)

In 'A' and fast, my 'threshold' is peaks at 100-105 dB. and ~90 dB. sustained - after that, it kinda gets annoying (not even fun, just painfully loud - I am not making up for any hearing loss, so I am sure that has something to do with it).

[sfogg]

"'C' seems to inflate the numbers (this mode uses a lot more bass, where as 'A' has like a 1000 Hz. hi-pass, correct?)"

Actually 'C' weighting still rolls off the numbers in the bass range too, just not nearly as sharply as 'A' weighting.

Most people use 'C' weighting for things like channel balancing and such if they don't have a flat measuring option. Which the R/S meter doesn't have.

To get good comparions between people you really need to use a standard. Lots of test CDs have a 1kHz -20dB sine wave on them. Measure that on 'C' weighting at your normal listening level and that will give you a good comparison to someone else. That will also tell you what your peaks are since it would be 20dB louder then the -20dB signal.

Shawn

[Spkrdctr]

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On 5/10/2005 2:02:48 PM kenratboy wrote:

...we use 'A' when we are talking about SPL, correct? 'C' seems to inflate the numbers (this mode uses a lot more bass, where as 'A' has like a 1000 Hz. hi-pass, correct?)

In 'A' and fast, my 'threshold' is peaks at 100-105 dB. and ~90 dB. sustained - after that, it kinda gets annoying (not even fun, just painfully loud - I am not making up for any hearing loss, so I am sure that has something to do with it).

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Ken, is that 100-105 at hour seating position? If it is, you are listening very, very loudly! I find my average level is in the high 70's with peaks up into the high 80's max. This saves on my hearing. It is good that you have the spl meter. It will allow you to realize when you are over 90 db at your seating position, and causing hearing damage. Please try to stay under 90 for your average, if you have very short term peaks into the 90s that is ok, you will thank me when your 50!

[kenratboy]

At seating position (like 6 feet away )

Those numbers are the MAX I could listen at, above that is WAY too loud. I would probably want my peaks around 90 dB. max.

I don't like loud music, but I love clean, dynamic sound.

[mbajner]

info on using the RS SPL meter

http://www.audioholics.com/techtips/setup/avhardware/audiovideosetup2.php

[WMcD]

The C range is the most flat and is intended for testing like you're doing.

The A range matches the ear-brain's lack of sensitivity to bass at low levels, per the Fletcher-M? curve. I think the hearing protection people let factories get away with higher bass (because it is not heard). So lots of bass doesn't show up on the A setting.

BTW I find 80 dB to be pretty loud on continuous tones.

Gil

Gil

[Seadog]

Gil is correct about the "A" weighting for industrial noise measurement. The OSHA standards that I have seen are based on dBA. For example 90 dBA continuous for an 8-hour day.

The "C" wieghting should be more applicable for music applications.

[colterphoto1]

Fletcher-Munson is the loudness contour curve based on the human ear's lack of sensitivity to lower and very high frequencies at lower volumes. That is what the 'loudness' button on your receiver does, is boost those frequencies. Same with the switch on the db meter.

Remember to take measurements with the meter stand mounted if you can, just handling can induce sound that is recorded by it, and your body will have an effect on room nodes if it is blocking reflected sound. I believe for close measurements, you're supposed to hold the meter at RIGHT ANGLES to the source for accurate measurements, not pointed directly at the source.

M