USB multimeter or datalogger

[TonyRPH]

Can anyone recommend a cheap USB multimeter or datalogger.

I need AC accuracy for audio measurements (20hz - 40khz) and I'm finding the average meter doesn't fare too well above about 1khz (even my trusty old Fluke) - and besides - I'd like the USB connectivity for data logging..

Any recommendations?

Thanks.

[TonyRPH]

I already have a Picoscope (2204A) and an Owon SDS (model forgotten) digital oscilloscope.

However neither of these give me the option to log the data I want.

I'm looking to get RMS voltage values over a range of frequencies, and then use this data in a spreadsheet and / or gnuplots.

I have tried various opensource scripts / programs to talk to the Owon, but the data I'm getting back is just the actual waveform data, rather than simple RMS values.

Sure, I realise I could calculate the RMS values from the waveform data, but that just complicates things!

So I'm stumped.

[TonyRPH]

Well after much searching I found an Amprobe AM-270 which apparently is good to 20kHz on the AC ranges.

However, it has no PC connectivity, so I had to rule it out.

In any event, as Zad has suggested, I'm going to build a precision rectifier, and feed that into an old Sinometer MAS-343 that I've had for years - this meter has a serial! port and I have located some custom software that will talk to it.

Then I'll be able to log the data as required, although I have almost completed the task using pen and paper and a 'TestLab' AC millvoltmeter that I have. (I did think of trying to tap into this to get the rectified output, but I don't really want to mess about with it)

Rather tedious though!

One final thought was a PC sound card from 'M Audio' as these are supposed to be pretty good as well. I do have an old Sound Blaster Live! 24 bit external USB device, however the ADC has incredibly poor linearity (no surprise there!).

Thanks for the suggestions.