Re: Testing The Frequency Response Of A Room

"Soundhaspriority" wrote ...
"Mike Rivers" wrote ...
"Soundhaspriority" wrote:
The Radio Shack instrument does not have a regulated
>> power supply. Besides an inaccurate mike and lack of
>> calibration, measurements are not very
>> repeatable.

Bob, you start out so good, and then you throw in a piece of crap like this. A battery is about as good a regulated power
supply as you can get, until it dies (which will be obvious since the meter has a Battery Test function)..

The RS digital SPL metter has only a "low battery"
indicator on the LCD display. So we are at the (undocumented) mercy of whatever the designers decided is "low".

In one sense a battery is a rather low-impedance source.
But OTOH, its output voltage droops over its useful
period. I wouldn't use the word "regulated" to describe
that behavior.

[snip]

Mike, I'm staring at it. Cat no. 33-2055 "Realistic Sound Level Meter" (digital.)

The measurement is not repeatable. Repeated use over a short interval results in a series of readings that drift down, just like a flashlight that dims if turned on for a few minutes. Turning it off for a period revese the effect, as the battery
depolarizes.

With a fresh battery (as recommended in the manual)? Or with whatever happens to be installed at the moment?

Are you actually seeing the effect of battery voltage droop,
or the effect of the SPL averaging function?

It has no battery test function.

Lack of a battery test function (not to mention lack of
calibration or measured FR) reveals the Radio Shack meter to be a mass-market consumer gadget trying to look like a piece of serious test equipment. I'm not saying that it has no practical use, but not in any objective way.
.

Relevant Pages

  • Re: EF 28-80mm f/2.8L IS USM... when?
    ... right to me based on how little effect I seem to have with my battery ... + IS) if all three measurements were steady, ... take pictures the greater the effect of the AF's power consumption. ... Taking shots rapidly may very well be typical of the way you take ...
    (rec.photo.digital)
  • Re: EF 28-80mm f/2.8L IS USM... when?
    ... Canon hasn't produced any 70-300 f/1.4 L IS lenses. ... battery life for the 1D M II batteries. ... AF measurements are "peak". ... Discounting shooting continuous sequences of shots, ...
    (rec.photo.digital)
  • Re: Tonghui TH2821A LCR Meter
    ... > If you want to find bad electrolytics, I don't think you can find ... battery and DC adapter or replacing the battery. ... They are supposed to be interchangeable, but the NiCd ... still by far the best bargain for LCR measurements I have found ...
    (sci.electronics.design)
  • Re: Front light bulbs - LED vs. halogen vs. krypton vs. xenon...
    ... hopefully Stephen will be able to take some measurements. ... when battery voltage is higher than 4.25 Volt. ... with alkaline or NiMH cells. ... As far as I can tell the regulating circuit is inside the light head. ...
    (uk.rec.cycling)
  • Re: Repair Triplett 930PL Meter?
    ... I've not needed it for resistance ... I tried a few other measurements using a bettery charger and the ... but the AC voltage readings are wrong if no 1.5 volt battery is in place. ...
    (sci.electronics.repair)