Comments to date on DRAFT REVISED AES-6id-xxxx, AES information document for digital audio - Personal computer audio quality measurements,
was published 2006-11-10 for comment.
Comment received from Allan Belcher, 2006-11-12
Dear Sir
I would like to comment on the fact that this document does not specify a method for testing non-linear cross talk. I have had recent experience of a faulty professional quality PC based audio system that had severe non-linear stereo cross talk. It took some time to identify this as the source of the problem as it was not revealed by standard tests.
The problem was traced to the stereo digital to analogue converter. Cross talk tests with each channel active with FL in one channel and FL+F in the other channel resulted in a component at frequency F appearing in each output channel of the DAC. Conventional linear cross talks tests as iin 3.11 did not reveal this problem.
Regards
Allan Belcher
Response from Steven Harris, SC-02-01 chair, 2006-11-18
Dear Mr. Belcher
Thank you very much for your comment.
The problem of non-linear cross-talk sounds like an interesting effect. I would like to understand more about the problem in the digital to analogue converter that caused the distortion, as well as studying the best technique for measuring the effect,
I propose that the committee considers adding this measurement to the next revision of AES-6id. AES standards are revised at least every five years, however revisions can be made at any time.
To expedite this process, perhaps you would be available to attend the next SC-02-01 meeting held during the next AES convention in Vienna, May 5-8 2007, where you can raise this topic in person. Alternatively you could send an email to the SC-02-01 reflector to kick off the process. Please include your suggested text describing the new measurement.
Thank you and Best Regards
Dr Steven Harris
Chairman SC-02-01
Reply from Allan Belcher 2006-11-19
Dear Dr Harris
Thank you for the information. I hope to be able to attend the AES convention in Vienna and the SC-02-01 meeting and will decribe the method there as you suggest: I am in the process of preparing a paper on the test and the results.
Regards
Allan Belcher
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