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  #1  
Old 07-19-2006, 02:50 AM
RenderBot RenderBot is offline
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Default SPL Meters: Quality vs. Savings

So my nostalgically stylish/retro approved Radio Shack analog SPL meter (ok, ok, its just old...) went deaf today. So it's time to buy a new SPL meter and thought I'd consult the DUC to get some opinions on what all of you think about the the different SPL meters out there and whether the difference in price is justified.

The only considerable when comparing spec sheets is an SPL meter's own max SPL. Most offer the same weighting options and operate in the same general Freq. Range.

So what about accuracy. Does accuracy account for a significant enough amount to matter? And how can a consumer measure determine the difference in accuracy from one meter to the next. Dolby makes a point to mention that,
Quote:
The most readily available units in the US are from Radio Shack, as shown in Figure 2-20. These units are also very
inexpensive. Because the concern for level relative to each channel is usually greater than that for
absolute level, the accuracy of this meter is sufficient. For greater accuracy, there are more
expensive meters. It is recommended that an inexpensive meter be left in the control room for
quick calibration checks.~Dolby
You've also got to consider that with as many Radio Shack meters as there are in circulation, having one must have its advantages. They're the NS-10 of SPL meters. Being that they're practically a standard, does this make it more accurate thanks to its widespread use? Unless of course Radio Shack's meter reading vary from one another as well.

In the end I'll probably end up buying another Radio Shack Star Trek Taser meter, but I just thought I'd post it to find out what others think and because I've always wondered if there were significant differences in quality out there.

Cheers,
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Old 07-19-2006, 06:42 AM
georgia georgia is offline
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Default Re: SPL Meters: Quality vs. Savings

I have purchased probably 10 SPL quality meters from varying companies in my career... EVERY SINGLE ONE was not calibrated when I got it. DO NOT open up box and expect the meter to be accurate. Get the meter calibrated or calibrate it yourself.. Good meters come with a complete description in the manual on how to calibrate your meter... I've purchased a lot of Radio shack meters in a pinch on the road or at a work site in various cities and countries. These are far the worst for calibration.. They work moderatly well for the basics once calibrated.


cheers
geo
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Old 07-19-2006, 08:29 AM
Richard Fairbanks Richard Fairbanks is offline
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Default Re: SPL Meters: Quality vs. Savings

I have been researching this a bit recently. RS meters have two problems, one is the calibration they come with. The more serious problem is that they are not "true RMS" responding. This is not an issue if you use the same thing to calibrate with as to measure with (i.e. full range pink). However, if you calibrate with full range pink and then use filtered pink on your speakers, the meter can show you wrong readings. The same happens if you calibrate with a steady tone (as most calibration devices have), and then use pink noise of any kind.

The analog RS meter I have here shows around 1.5db difference from time to time!

The world seems to be a crap shoot.
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Old 07-20-2006, 01:38 AM
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Default Re: SPL Meters: Quality vs. Savings

Quote:
RS meters have two problems, one is the calibration they come with. The more serious problem is that they are not "true RMS" responding.
Good to know Richard. Thanks alot.

RenderBot
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Old 07-20-2006, 06:36 AM
Richard Fairbanks Richard Fairbanks is offline
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Default Re: SPL Meters: Quality vs. Savings

I like for things to make sense, and for readings taken one way to correlate to readings taken another way. My Ivie RTA does that. My analog RS does not. Don't get me wrong, I would use the RS meter if nothing else was around and it does work well when balancing each speaker's level, but I have this feeling that we should try to get away from RS meters as some sort of standard. They are only supposed to be +- 2 db anyhow, which is a fairly wide window. I know that when I set monitor levels using filtered pink with the RS meter, the speakers end up being about 1.5 db louder than if I use the Ivie. How much inaccuracy is due to frequency response problems and how much due to non-true RMS detection I can't say. Comparing warble tones to pink noise might help answer that. I imagine there may even be a problem with my particular unit. Maybe someone else with access to both an RS meter and a more reliable device can check and report in here.

For my money, I want something I don't have to worry about. I just had the Ivie re-cal'd so I think it is within spec. My next purchase may be a pistonphone so I can KNOW my level measurements are good.
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Old 07-20-2006, 11:25 AM
Noiz2 Noiz2 is offline
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Default Re: SPL Meters: Quality vs. Savings

Richard,
You got me looking and I found something interesting.
http://www.dasdistribution.com/produ...meters1.htm#LM

It looks like the +- 2 dB is pretty standard. The high precision ones I found only got down to the +- 1.5 dB and some of those were in the +$800 range.
But the above looks pretty good and it includes a calibrator.
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Old 07-20-2006, 11:51 AM
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Default Re: SPL Meters: Quality vs. Savings

..if it helps....

here is a link to an article on the Basics of SLM's Sound Level Meters. in it, he talks about the RS meter...

SOUND LEVEL METER BASICS
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Old 07-20-2006, 04:09 PM
RenderBot RenderBot is offline
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Default Re: SPL Meters: Quality vs. Savings

Quote:
I have this feeling that we should try to get away from RS meters as some sort of standard.
I agree so long as it's an affordable option. Not to sound thrifty, but it really shouldn't be something that costs someone more than a couple hundred dollars AT THE MOST. There is deifinitely a sense of inaccuracy when I use a RS spl meter and I don't like that feeling. And there's more to a good meter than simply it's range of accuracy in dB. In particular response and exactly how and what a meter reads. I know, you're thinking, "duh... sound pressure levels", but The other ongoing thread posted by Richard Fairbanks regarding perceived loudness and room size is a perfect example. Will varying meters provide varied readings in usch cases? It would be interesting to find out.

I haven't yet read the link Minister sent, but I will.

Thanks for the link Minister.

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Old 07-20-2006, 04:20 PM
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Default Re: SPL Meters: Quality vs. Savings

Minister,
I used your link:
http://www.prosoundweb.com/studyhall.../slm/slm.shtml

and put it on the "Room Calibration for Film and TV" Stickey.

Thanks!
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Old 07-20-2006, 04:25 PM
Richard Fairbanks Richard Fairbanks is offline
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Default Re: SPL Meters: Quality vs. Savings

Pretty well written article! I am a little surprised that the author insists that A-weighted measurements are the best for sound systems. I guess he is thinking about public venues. In our world, C-weighted measurements are the ONLY ones to use when setting up monitor playback levels.

Noiz2,
Those look interesting. We shouldn't forget that calibrators have a deviation, too. The one that comes as part of the set has a +- .8db variance, when new. Others are more like +-.3, pistonphones even better. Whatever the calibrator's possible error, that gets added onto your meter's accuracy, or should I say subtracted? Whatever, the whole thing is a crap shoot, like the article says, when you're thinking about a single reading. I got on this kick a while back because I've been wondering how much these stupid little meters have been screwing with us! With a +-2 db window, when new, what's to say that an actual 85dbC pink noise playback cannot read 87 on your meter yet read 83 on mine? If we both set our rooms up according to our meters, our playback levels would be 4 db different. That is too much! It just makes me wonder, when Frank talks about sound level perceptions from room to room, how much is perceptual and how much is some cheapo spl meter?

Anyway, I've had too much time on my hands to think about stuff like this, I guess.
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