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Old 15th March 2012, 04:47 PM   #1
diyAudio Member
Join Date: Mar 2012
Default Measurement advice

Hey guys,

I'm an EE student working on a senior design project. I need to be able to measure dynamic range of a system > 100 dBA, THD+N < 0.5%, and response 100-10kHz +/- 3dB. Unfortunately we don't have the easy solution of a dedicated HP/Agilent audio analyzer on hand, so I'm wondering what your second go-to's would be as far as measurement equipment.

I have an original RME Multiface I, which meets the specs (dynamic range just barely). If I wanted to use this, is there a free measurement software suite I could download? The only free suite I know about is roomEQ wiz and I don't think that it takes dynamic range measurements? Do any of you have experience using LabView with audio interfaces?

A qualm I have with the multiface though is that the ins/outs are balanced, and we need to measure an unbalanced network so I believe that this would further lower the dynamic range of the multiface by 3dB + 3dB = 6dB for the loss at the input and output. Correct me if I'm wrong here.

Unfortunately, it seems that all of the network analyzers available have lower frequency ranges which are too high, or are older models which don't meet the dynamic range spec. Our oscilloscopes only have a dynamic range of 50dB as well.

Thanks for any advice!
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Old 15th March 2012, 05:39 PM   #2
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Join Date: Dec 2004
Location: Israel
RMAA for test-bench measurements,
WaveSpectra for FFT and 'scope-style':

With wavespectra - make sure you don't select 2 different soundcards for input and output - they will be out-of-sync, and you'll have dropouts of samples with LF glitches.

With ballanced inputs, you can take the (-) lead and connect it to RCA GND at the DUT side - you'll efficiently cancel-out the cabling issues.

Wanna dig to the mantras of dynamic range? PCM4222EVM is 150$ ADC evaluation board with 125db and up to 192khz/24bit.
For 192kHz you'll need soundcard capable of 192kHz SPDIF input (not every card is able to do this).

Last edited by s3tup; 15th March 2012 at 05:44 PM.
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Old 16th March 2012, 02:01 AM   #3
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Cool, thanks for the reply. It looks like RMAA will be able to do the job.

Out of curiosity, do you have any knowledge about using LabView or Matlab for audio device characterization?
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Old 16th March 2012, 03:08 PM   #4
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Join Date: Dec 2004
Location: Israel
I don't really know labview/mathlabs, but Matlab easily loads the wav files. You can record something, trim it in some editing software like audacity (audition), and then play with it in Matlab, if you know what you do and what you need
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