Wave File Analysis Software....

[mrfeedback]

I have the need to measure sonics differences caused by different audio cables.
I reason that one method would be to record a (any) particular musical passage to hard drive via a high quality A/D convertor - I have access to a couple of high quality studio convertors.

I intend to record the same musical passage from the same source several times as wave files using only different audio interconnect leads.

I would like to then compare these files digitally, and then analyse any differences for changes in FR, phase, amplitude, spectrum etc.

Anybody have experience or knowlege of any of this, or know of suitable software to perform these tasks.

Thanks, Eric.

[wintermute]

Hi Eric,

You may be able to use rmaa for some of this???

http://audio.rightmark.org/

Tony.

[mrfeedback]

Hi Tony,
Thanks for the link.
I have downloaded it but will have to wait till new year to try it out.

Regards, Eric.

[Paul Ranson]

Keith Howard wrote a couple of articles on exactly this in HFN recently. He exploited a sound card that could be sync'd to an S/PDIF signal so that the samples would always be in the same place. IIRC he had some problems getting good correlations between recordings when there was no difference in the system.

See http://www.audiosignal.co.uk/freeware.html for some supporting software.

Paul

[johnferrier]

Originally posted by Paul Ranson
Keith Howard...exploited a sound card that could be sync'd to an S/PDIF signal so that the samples would always be in the same place.

See http://www.audiosignal.co.uk/freeware.html for some supporting software.

Interesting stuff at audiosignal.uk.


JF

[mbroker]

Cool Edit and Sound Forge should be able to manipulate the WAV files appropriately. I believe that both have trial versions.

Mark

[millwood]

the problem I see with this approach is that it requires precise timing on both recordings, and you can get timing differences from a lot of things, like mic placement, internal clocks, room sonic properties for example.

if you reconstruct the original waveform from the 44.1khz samplings, you create artifacts based on the algorithm you used, and the "articificial" differences in the original recordings (due to timing for example) would persist.

the alternative is to measure "characteristics" of the two waveforms. there, the law of large numbers kicks in, but you lose some resolution because of that.

You can do for example some time series analysis (SAS can do that), or FFT on the waveforms. Time series analysis is however sensitive to each data point so you need to make sure that both series line up exactly - hard to do.

there are lots of software packages that can do FFT and it is far more robust.

[Thunau]

Originally posted by mrfeedback
I have the need to measure sonics differences caused by different audio cables.
I reason that one method would be to record a (any) particular musical passage to hard drive via a high quality A/D convertor - I have access to a couple of high quality studio convertors.

I intend to record the same musical passage from the same source several times as wave files using only different audio interconnect leads.

I would like to then compare these files digitally, and then analyse any differences for changes in FR, phase, amplitude, spectrum etc.

Anybody have experience or knowlege of any of this, or know of suitable software to perform these tasks.

Thanks, Eric.

I did exactly what you are describing using Wavelab from Steinberg. I did a test of a power cord. You can see it
Here

The trick is to trim all recordings to start and end at exactly the same sample. You have to zoom in in time and amplitude and be really careful about it. An offset of a single sample will give you bad results.

[Pjotr]

Again:

http://www.goldwave.com/

The demo version of Goldwave is fully functional and has lots of analysing features.

Also have a look at Sample Champion:

http://www.purebits.com/

Its RTA has lots of correlation analysing features. But it is not free.

Cheers

[Paul Ranson]

The setup used by Keith Howard uses the digital output of the CDP to clock the ADC, so the samples for each test pretty much line up. This allows you to test with a standard hifi setup.

He appends a level and synchronisation header onto the test material so that compensation for gain drift etc can be automated.

It's worth digging out his articles, it was far from trivial to get two measurements of the same setups showing no change. And, IIRC, when his CDP was powered off/on it would generate different output for the same CD, which is an unexpected artifact of its internal processing.

Paul