What to look for in a multimeter?


One quick question to follow my earlier question-- is there any kind of special multimeter that I should use? Radio Shack has multimeters from $19 to >$200. As long as it has two leads and a digital readout, should I be okay with one that is on the more affordable side? What other features besides voltage measurements should I need. Thanks again! d
djjp
Depends on your application. If you plan to use it for simple voltage, current and resistance measurements almost any meter will do providing it has enough resolution for your intended measurements. If you plan to make any AC current measurements make sure that a current clamp accessory is available and that your meter can read True RMS. Multimeters are not the best choice for measuring Audio levels because of their limited frequency response. For level measurements an old HP400EL can be purchased for $150 on the used market. If you plan to do some serious audio work nothing will suit you better than an oscilloscope. A used analog scope can be purchased for $200 to $500 depending on bandwidth but if you have the money, a Tektronix TDS210 digital scope can be purchased. It's a 2 channel, 100MHz digital scope with a sample rate of 1 GS/s for ~ $1000. Even better is the fact that you can add an FFT plugin for a few hundred more that enables you to make measurements in the frequency domain like a spectrum analyzer.
My first suggestion is to forget about Radio Shack's multimeters. You can get way more features for for less money. Take a look at MCM Electronics and see what they have to offer. I do agree that you want to buy "more" than what you think you will need right of the bat, as this will save you money in the long run. Instead of having to buy a seperate capacitance meter, ammeter, frequency counter, etc.. if you get more involved in things, all of these can be had in a VERY reasonably priced multimeter nowadays. Besides that, it's far more handy to have all of these things in one package than to have to drag out several different pieces of test gear to do the job. While an "all in one" multimeter may not have the utmost in resolution compared to top notch seperates, for all practical purposes it will almost always suffice. You can probably find something like that for about $60 - $100 or so. As to something having "auto-range", that is a personal choice. I typically prefer manual settings myself. I have no doubt that "auto-hold" is a nice feature though. Sean
The more you pay, the more accuracy you get. Like many instruments, accuracy is the number one determinant of price. The accuracy can generally be determined by the number of digits of the meter. You can also put stock in the brand name on the meter. Obviously HP or Fluke is better than Brand X. I developed a silver palladium, low ohm resistor series(0.1/1.0/10.0 Ohm)that had a TCR of +/- 25 ppm. We needed to go out and buy a newly developed(by ANY meter manufacturer), 8 1/2 digit ohmeter to accurately plot the TCR. It was the best ohmeter you could buy. And it was $5300. Different applications require different levels of quality. For home audio, you should not spend that much on a multimeter. You don't require a really accurate meter. First, make sure it has the features you require. Then, go for brand. Then go for the best that brand offers for your price. A $50 to $80 unit is fine.
Buy the best you can afford and look for the usual volts and ohms ranges along with autoranging and autohold (this is so you can take readings where you cannot hold the probes and read the display at the same time). The more you pay the more functions you can add, such as frequency and dB readings. Take the time to research the various models available in your price range and choose the model you feel "comfortable" with in actual use (get it out of the box and try it in store) and make sure the display is readable under most conditions. Happy measuring! Regards, Richard at www.vantageaudio.com