On 6/9/2018 6:29 PM, Phil Allison wrote:
** To me it seems strange that instruments intended for engineers and service techs to use for all kinds of electronic work have such poor AC response.
I'm sure that there are still laboratory-grade digital multimeters that
cover the audio band, but for service applications, mostly of your AC
measurement requirements aren't for loudspeaker power, but for line
power, and maybe to check out a (line frequency) transformer. I have an
H-P 400D and 4300 analog voltmeters for audio measurements. Their scales
are logarithmic, in dB, cover from millivolts to shocking volts. I paid
less than $25 for each of those and have had them for years. I also have
an NTI Minilyzer that's digital but I think its maximum input level is
+18 dBu, so if I want to check out a devices with a specified maximum
output level of more than that, I have to go the analog route. And the
Digilizer cost a few hundred bucks.
Most analogue multimeters cover at least the audio band and beyond, so if you can hear a sound coming from a loudspeaker, the meter will measure the signal
True, but a decent one is more expensive than a digital multimeter, and
a cheap one may not make as accurate measurements. Depends on what you
need and why you're making the measurement. I wrote an article in
Recording magazine about multimeters and making audio level
measurements, and the bottom line was that you could use a budget priced
meter to calibrate the audio interface for your computer (that you
probably already have) at a frequency that you can rely on the meter to
measure accurately, then use your interface as a "meter" to measure over
the full audio range.
In the 1950s and 60s, the standard bench instrument for professional techs and engineers was a VTVM like this one:
https://www.radiomuseum.org/r/rca_se...st_wv_98c.html
I have one of those on my workbench, and it still works.
For my article, I was reluctant to suggest buying a 50 year old analog
meter that could handle the full audio range, for fear that I'd soon
have to write an article about repairing antique test equipment.
--
"Today's production equipment is IT based and cannot be operated without
a passing knowledge of computing, although it seems that it can be
operated without a passing knowledge of audio" - John Watkinson
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