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In Reply to: RE: Multimeter with max voltage hold posted by triode3 on July 16, 2017 at 05:01:41
I should have mentioned: They are indeed a very flat four ohms in the bass, which is what will matter for power, so extrapolating power from voltage from bass-heavy music should work well enough.
I just want a rough idea of power drawn.
I did something like you propose several years ago with my actively biamped MGIIIa's, placing the DMM across the woofer. Typically my peak listening volume is around 85db, perhaps going to 90db at times. IIRC I measured a peak voltage around 12V which would calculate to 36 watts. The amplifier I was using produced 500 wpc at 4 ohms. I concluded that the measurement was pretty much useless but that my amplifier was more than capable for my listening levels.
I don't remember the brand of my DMM but I purchased it around 10 years ago for ~$50 on Ebay. It has a peak hold function but is not true RMS.
If I were to buy another DMM, I would get one with LCR function. For my use, the meter is accurate enough and I really don't need true RMS. You can peruse Ebay and find something suitable for under $70. FWIW I did buy a used scope a few years ago for around $250 (Tektronics 2336).
BTW I did measure the inductance of the woofer it was a fraction of a mH (I don't recall the exact value) so it is essentially purely resisitive.
I married the perfect woman. The downside is everything that goes wrong is my fault.
You might want to use a single sinewave for your measurement as capturing AC across a broad complex audio spectrum will require more than just a multi-meter. Many are good to about 1-KHz (1-ms) and some higher end models (that triode mentioned) are good only to about 4-KHz (250-uS).
BTW the decades old Fluke 187 & 189 were replaced years ago with with the Fluke 287 and 289 but these are in the $450 - $600 range.
The Fluke 87 V (5th gen) is around $350 - $400.
Some lower cost models that measure True RMS AC may do what you want. In Fluke terminology look for features like Min/Max, AutoHOLD, Fast Min/Max.
I don't think a multimeter will do the job. It takes time to sample the signal so you may never get a good reading of transient peaks. You will probably need an oscilloscope or maybe a storage oscilloscope.
Another approach would be to use a CD with tone-bursts. These are sinusoidal signals that produce a short burst and then turn off for 19-times the length of the tone-burst. You can feed the speaker a large voltage without damage because the average power would be only 1/20th the power of the tone-burst. I fed my Thiel CS3.7 speakers a 50-volt tone-burst at 1000-Hz to check the amplifier for clipping and also check the speaker for distorting. The amplifier just began to clip at 50-volts but the speaker had no audible distortion. This wasn't the case with a 400-Hz tone-burst. The speaker began audibly distorting above 36-volts although the amplifier exhibited no distortion at all.
Be sure to wear ear plugs for tone-burst testing.
400-Hz Tone-Burst ................................................... 1000-Hz Tone-Burst
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