another resonant peak question

[StarryNight]

sorry to beat this horse again but I just got a new DMM and wanted to try measuring resonant peak with my iPod frequency sweep app (I had tried this previously with no luck but that was due to some wiring errors and using a basic DMM). I have followed Joe G's diagram and with the iPod being used for the sweep and I'm getting a reading on the DMM but I'm not seeing the peak as the AC voltage drops as the frequency goes up. My question is if I measure between 4000Hz and 14000Hz I get a steady voltage readings between .775 and .460 VAC - does this sound right as far as having enough voltage for this method? I also plugged the iPod into a small mixing board to get a hotter signal and the meter was at about 1.7VAC but I still did not see any changes on the DMM other than a steady decrease in voltage. This question is obviously coming from a complete novice so I might be missing something painfully obvious!

[cbarrow7625]

Most run of the mill DMM's are only designed to measure up to just above 400Hz, they low pass everything above that. You need to get a DMM that measures all frequencies 20Hz-20kHz. Most spec sheets will tell you the frequency limitations of the meter.

[StarryNight]

sorry I may be off track here but the DMM not measuring frequency, it is measuring VAC (400mV to 750V). The iPod is showing the frequency that I'm sweeping.

[pdf64]

Yes the DMM has a frequency response, most will only measure voltages/currents accurately up to a few hundred Hz. Think about it, if you try to measure a 1V signal at 60Hz and then another signal 1V at 1MHz, will a cheap meter display both as being 1V?

[StarryNight]

ahhhh! thank you both. yes, I see here in the manual that the frequency response is 40-400Hz. I guess $30 for a DMM falls under 'you get what you pay for' category. Perhaps it's time to get a good LCR meter and be done with it.