Subwoofers, Bass, and Transducers > Radio Shack spl meter: Digital vs Analog
Black96Z28's Avatar Black96Z28 04:23 PM 09-25-2010
What are the pros and cons of both of these meters? Witch one is better? Thanks!

DonH50's Avatar DonH50 05:02 PM 09-25-2010
Specs are the same. I prefer having the numerical read-out of the digital, plus it has a bargraph "analog" display for trends. Finally, no meter movement to wear out. However, it primariy comes down to which readout you prefer. Note neither is accurate below 30 Hz. - Don
sholling's Avatar sholling 05:19 PM 09-25-2010
I think these are pretty common correction values.

http://diyaudioprojects.com/Testeq/R...50/33-2050.htm
Bunga99's Avatar Bunga99 10:16 AM 09-26-2010
Maybe someone can shed some light on this. If the correction values are the same for all 3 meters (New Analog, New Digital vs Old Analog) then why such a difference here when used as a microphone:

Look at post 70 and below:
/avs-vb/showt...44#post7683044
Ethan Winer's Avatar Ethan Winer 10:53 AM 09-26-2010
Quote:
Originally Posted by Bunga99 View Post

If the correction values are the same for all 3 meters (New Analog, New Digital vs Old Analog) then why such a difference here when used as a microphone:

How accurate do you need? And for what purpose do you use your SPL meter? I measured two different Radio Shack SPL meters compared to a number of known-accurate microphones:

Comparison of Ten Measuring Microphones

It seems to me that fretting over tiny variations less than 1 or 2 dB is a waste of time, especially considering how badly skewed all rooms are at low frequencies.

--Ethan
pronghorn/az's Avatar pronghorn/az 11:23 AM 09-26-2010
My Radio Shack analog sound meter is at least 12 years old if not older. Nothing has broken on it and I only replaced the battery a couple of times. It helps with everything in my speaker set up. I just used it when I FINALLY hooked up my surrounds after 4 years which helped in setting the surround volumes.

Jeff
DonH50's Avatar DonH50 12:22 PM 09-26-2010
The correction tables are generally for the meter when used as a microphone through the line output. That is, when you take the output from the RS SPL meter into your sound card (or whatever), not when you are looking at the meter itself for readings. The line out is flatter (no weighting).

While there may be differences betwqeen new and old meters, I strongly suspect the variation in most of the published tables is sample-to-sample, not analog vs. digital. As Ethan said, it is not a terribly accurate device. You can spend $200+ and get a more accurate SPL meter*, but it is probably not worth it since with the RS meter into your sound card and correction table many inexpensive software program (e..g REW) will measure your system far more easily than you can. If you just want to use it to match levels, then use the RS SPL meter above about 40 Hz and below 10 kHz or so and you should be fine.

HTH - Don

* A good calibrated meter that has flat response may run $500 to $2000+; a decent measurement mic ~$500 - $1000 (plus preamp and software); and an Audio Precision or Agilent audio test set $25k - $30k. I use an earthworks mic (~$600), inexpensive ($150) m-audio mic preamp, and RPlusD software (~$300 with extras) for my measurements but for setting levels often just grab the RS meter because it is fast and easy.
warlord260's Avatar warlord260 12:58 PM 09-26-2010
I also prefer the digital in ease of use VS the bouncing needle.
mojo_13's Avatar mojo_13 03:16 PM 09-26-2010
I have the digital version and for the little that I use it gets it works great. I don't do anything real in depth but just initial setup of speakers. I also prefer a digital readout compared to a bouncing needle just personally easier for me to read.
spanish68's Avatar spanish68 08:34 PM 09-26-2010
I believe I read a while back that the digital meter's correction values are different than the analog. If I'm not mistaken, they were (add); 3.5db's at 15hz, 2.5db's at 20hz, 1db at 30hz and so on. On the analog correction values, you're adding a lot more db's for the low bass. Is what I said right?
cschang's Avatar cschang 09:20 PM 09-26-2010
I have both.

I like the analog better. The needle reacts faster than the digital display.
pbc's Avatar pbc 06:10 AM 09-27-2010
Quote:
Originally Posted by Ethan Winer View Post

How accurate do you need? And for what purpose do you use your SPL meter? I measured two different Radio Shack SPL meters compared to a number of known-accurate microphones:

Comparison of Ten Measuring Microphones

It seems to me that fretting over tiny variations less than 1 or 2 dB is a waste of time, especially considering how badly skewed all rooms are at low frequencies.

--Ethan

Pretty cool Ethan, did you look at how the mics performed below 20hz?
J_Palmer_Cass's Avatar J_Palmer_Cass 09:20 AM 09-27-2010
Quote:
Originally Posted by DonH50 View Post

The correction tables are generally for the meter when used as a microphone through the line output. That is, when you take the output from the RS SPL meter into your sound card (or whatever), not when you are looking at the meter itself for readings. The line out is flatter (no weighting).




The line output jack of the RS Digital SPL meter (33-2055) is indeed weighted (bandpass filtered). SPL A scale and SPL C scale are applied as selected by the meter weighting scale.

The chart below is a FR sweep of the RS Digital SPL meter with the microphone element removed from the circuit. The accuracy of any individual SPL meter microphone element is an unknow, so a straight C scale compensation factor should be as close as you are going to get with an SPL meter being used as a microphone.

Fast and slow averaging and MAX is not applied to the line output jack signal.


Red is SPL A scale.

Green is SPL C scale.




LL
DonH50's Avatar DonH50 10:06 AM 09-27-2010
Thanks, good to know I was wrong! (Actually, the dealer told me wrongly, and I believed him. Still my bad.) I did notice a significant difference between my reference mic and the RS meter; should have been a clue... - Don
Ethan Winer's Avatar Ethan Winer 12:20 PM 09-27-2010
Quote:
Originally Posted by pbc View Post

Pretty cool Ethan, did you look at how the mics performed below 20hz?

Sorry, No, the speaker we used was the limiting factor. But in the grand scheme of things what matters most is the "speaking range" of bass instruments, which is well above 20 Hz.

--Ethan
stang323's Avatar stang323 02:14 PM 09-27-2010
I have analog and I would think it would be easier to get the average with the needle.
Speedskater's Avatar Speedskater 06:38 PM 09-27-2010
For experienced audio meter readers the analog unit is better. For all others the digital meter is better. It takes lots of practice to read a VU meter scale.
DonH50's Avatar DonH50 06:46 PM 09-27-2010
I am experienced, just old, so it's easier to see the big digital numbers!
cbsmith's Avatar cbsmith 07:03 PM 09-27-2010
Is the analog meter off at low frequencies when looking at the needle as well, or is it just when using the rca output jack? Just wondering if I need to add the correction factor to the needle?
DonH50's Avatar DonH50 07:45 PM 09-27-2010
As has been said, or at least implied, the required correction is the same looking at the meter or using the line out. I was thinking the line out was unweighted, but I was apparently wrong about that.
steven59's Avatar steven59 09:09 AM 01-27-2018
Can we revive this thread? I'm trying to diagnose my hearing using a TIDAL sinewave and my home stereo rated +/- 1db 28-20k. I get room interaction, but as db gets past 4 khz my meter seems to match my hearing as in 12khz is 85 db and most test tones from 50 hz to 4khz fall within 5-10 db past 4khz the meter as my hearing goes down as much as 30 db! if I turn the volume up to the level that the meter reads baseline-80 hz I can hear to 14k but it took about 40% raise in volume to get the meter to see the signal and me to hear it? a realistic analog and kuelsoft phone app both roll off high fq or does the high range need special testing?
DonH50's Avatar DonH50 12:26 PM 01-27-2018
The meter uses C weighting and that rolls off low and high frequencies. If you can afford a UMIK-1 ($75 or ~$100 calibrated by CSL) and REW (free, with a bit of a learning curve) you'll get much more accurate results. Or visit an audiologist.

https://en.wikipedia.org/wiki/A-weighting

HTH - Don
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