Digital or Analog Sound Level Meter? [Archive] - Audio & Video Forums

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russel
08-10-2004, 04:57 AM
I am going to buy a sound level meter from Radio Shack. I noticed that they also sell digital meters. Which one should I buy, the digital or the analog? Is one easier to use when calibrating my system? Is one more accurate than the other? Thanks for any advice you have.

This Guy
08-10-2004, 05:46 AM
Use the analog. It's cheaper and they both have the same microphone so they both have the same accuracy.

-joey

sy_lu
08-10-2004, 09:10 AM
The digital one is easier to use but more expensive and less accurate in the sense that it only display in whole db increment. With the analog version, depends on your skill, you can probably do +/- 0.5 db or better. Despite the short coming, I still got the digital version for the ease of use. You should try the demo units in the store before you buy.

Swerd
08-10-2004, 09:29 AM
Joey is right. Accuracy is determined by the sensor (the microphone in the case of a SPL meter), not by the readout display. Is the speedometer of a car more or less accurate if the dashboard has an analog or digital readout? Not if the speed sensor is the same. Just because you can see the needle of an analog meter moving between marks on the dialface does not mean that the sensor is really capable of making those readings.

sy_lu
08-10-2004, 09:56 AM
Accuracy is determined by the entire system not just a single part. What good does it do if rest of the system can be +/- 0.1 db but the display can only show +/- 1db? In this case, the accuracy of the digital meter is +/- 1 db. It was some time ago when I looked at the analog scale but I think the scale goes down to 0.1 db. This means if rest of meter includes the microphone and electronics is also +/- 0.1db then the accuracy of the meter is +/- 0.1db vs the +/- 1db of the digital meter. If however the system can only be as accurate as +/- 1db then your are right, both the analog and digital unit has the same accuracy but I don't think this is the case.

Bryan
08-10-2004, 10:21 AM
Having used both, IMO the analog meter is the easier of the two to read. At least, for getting initial volume. Unfortunately, with the digital one you need to know the vicinity of the volume you are at for it to be accurate. The analog one you keep turning and it will let you know, be it mid-60s or high 90s. My preference, overall, is the analog one. Digital is nice but analog gets the cake in this area.

mtrycraft
08-10-2004, 09:27 PM
Joey is right. Accuracy is determined by the sensor (the microphone in the case of a SPL meter), not by the readout display. Is the speedometer of a car more or less accurate if the dashboard has an analog or digital readout? Not if the speed sensor is the same. Just because you can see the needle of an analog meter moving between marks on the dialface does not mean that the sensor is really capable of making those readings.


I need to disagree here a bit. The car speedometer is a continuous meter. If the spacing between the whole numbers were wide enough, you could check out its repeatability but not very useful. On a digital meter, it is only whole numbers that can be displayed and it has to flip over at a predetermened round off speed or level. No such case for the continuous meter. The Speedometer converts the cables rotational rpm to the needle on a continual basis.
The sound level meter works in a similar manner. The needle gets a continuous signal and deflects. Because of the markings interpretation between numbers is not very accurate but, if one level matches on a mark it will be repeatable very accurately for all channels.
On a digital meter, you could be at either side of the whole digit determined by the round off number. If it rounds up from .6dB and down from .5dB, the channels can be off .9dB and still read the same whole number.
But, I could be wrong; however, my book has few records in it :D

mtrycraft
08-10-2004, 09:34 PM
Having used both, IMO the analog meter is the easier of the two to read.

Well, that depends what you want it to do. I like both for their own reasons. The digital is great for sound pressure reading where you are not trying to repeat a very small difference. Easy and fast. Those large whole numbers are very easy to read.

Unfortunately, with the digital one you need to know the vicinity of the volume you are at for it to be accurate.

I am not sure I follow you here? ARe you saying that you need to know the level to dial in the range?

The analog one you keep turning and it will let you know, be it mid-60s or high 90s. My preference, overall, is the analog one. Digital is nice but analog gets the cake in this area.

You turn the dial on the digital one just the same. I don;t see this an issue.

skeptic
08-11-2004, 04:16 AM
While analog meters are fun to look at, they have their drawbacks. First there are the ballistics. In the old analog only days, there was a difference between meter balisitics preferred by Europeans and Americans with Americans preferring less damping and tollerating more overshoot especially on VU meters. And they can go out of adjustment and need to be periodically recalibrated. If they are exposed to dust or dirt, their bearings can fail, they can be damaged if they are pegged too hard and having known a guy who did nothing but repair meter movements, you get an appreciation for what's in them. BTW, he had the largest collection of tools for working on small precision instruments I ever saw in my life. He could disassemble a meter movement and completely rebuild it from scratch. Where would someone like that be needed? In the world's largest steel mill.

Personally I like the digital types that have both a digital readout and LED bar display. One thing that is very useful is peak holding and sample and hold. This allows you to see either the peak readout over a given period or the average. Analog meters can be difficult to read precisely because of their inaccuracies near their extremes and their lack of sufficent indication markings. Also because of paralax error unless you view them dead on. I've often had jobs where I had to take lots of field readings of electrical equipment so I am particularly aware of this. One of the most attractive I've ever seen was at a trade show which had a circular face with an LED digital display in the middle and an LED bar display around the circumference. I think that for most recording engineers however, analog VU meters are still preferred. They tell you what you need to know at the slightest glance even if they aren't exactly dead right every time.

Woochifer
08-11-2004, 12:33 PM
The analog version is $10 cheaper, and unless you have a distinct preference for a digital display, the digital version has no clear cut advantages over the analog version. If anything, the analog version allows you to more easily eyeball the prevailing SPL reading when you have fluctuations (like if you're taking readings in a room with a lot of ambient noise or with certain low frequency tones) than with the digital one.

Woochifer
08-11-2004, 12:40 PM
Personally I like the digital types that have both a digital readout and LED bar display. One thing that is very useful is peak holding and sample and hold. This allows you to see either the peak readout over a given period or the average. Analog meters can be difficult to read precisely because of their inaccuracies near their extremes and their lack of sufficent indication markings. Also because of paralax error unless you view them dead on. I've often had jobs where I had to take lots of field readings of electrical equipment so I am particularly aware of this. One of the most attractive I've ever seen was at a trade show which had a circular face with an LED digital display in the middle and an LED bar display around the circumference. I think that for most recording engineers however, analog VU meters are still preferred. They tell you what you need to know at the slightest glance even if they aren't exactly dead right every time.

I think the issue with a lot of the LED displays depends on the range between discrete segments. I know that when I switched over from a tape deck with analog displays to one with digital, I could not match the levels as easily as before. If I'm trying to match levels between sources within 2 db, it was simply easier to do that using the analog display than with any of the digital displayed tape decks I've owned because I did not have to guess how close to "lighting up" a particular LED segment was. With some of the professional equipment I've seen, they have much smaller intervals between segments (and many more of them), and it seems to be a lot easier to take accurate readings when the digital displays are large enough to accommodate narrower intervals.

This is similar to the issue with only being able to interpret SPL readings at whole db intervals using the digital Rat Shack SPL meter. You have no way of guessing how close or how far you are from the next db step up or down. With the analog meter, you can clearly see when to use a 0.5 db step in jotting down the SPL reading, and that happens to match the interval used for most home theater receivers.