6 Dec
Jitter Evaluations
Back in 1998, while working for a large microphone company I co-chaired an AES working group on Digitally-interfaced microphones (the standard has been published as AES-42). One of the members of our diverse, international group was Julian Dunn, a brilliant engineer from UK who wrote a lot about jitter measurement and specification. I got to work with Julian during several AES meetings until his untimely passing several years ago. His papers are still online, but they are not very easy to comprehend, so here is a summary of the issue:
Jitter is the most important and the least understood parameter in the quality of digital to analog converters. Everything else is already state of the art. Jitter refers to clock instability. The less stable the clock, the more jitter, the more mushy the audio quality. To the human ear, jitter makes audio detail less sharp, like a photo that’s out of focus.
Ok, so everyone doesn’t have an expensive jitter analyser at home. But fortunately, we have a good analyser built-in right into our heads and that’s our ear. There is an easy way to compare audio DACs by just listening for particular instruments in the mix. The instruments typically used for this purpose are the cabasa and the triangle. Both feature wide spectral content and therefore are most affected by jitter.
So now, if you are comparing two DAC products, pick a familiar music track that has those instruments on it and listen for how they reproduce. It will be very easy to tell the difference between the products. I say this because we know that CEntrance DACport will give you excellent results, comparable to products costing 10 times as much. Now it’s up to you to make the test.
Posted by Vlad on 06.12.09 at 5:05 pm
Interesting. Can you name a few good song titles for this test?
Posted by admin on 06.12.09 at 5:05 pm
In general, I’d recommend to stick to the material you like and know well when comparing different pieces of playback equipment. This way you will remove the variable of unfamiliar music.
Warning – What goes below may appear biased, and after all isn’t that’s what the music industry is all about?
Many people use Donald Fagen records for rich arrangements that still leave alot of space in the music due to moderate amounts of compression (Morph The Cat, Kamakiriad, Nighfly) and I’d include anything recorded by Bruce Swedien in general (he worked on many Michael Jackson albums). In that family, also go for Quincy Jones – he has immaculate taste for production quality.
A surprising amount of smooth jazz features the cabasa, guiro, maracas and other latin percussion instruments. Consider Chuck Loeb’s Balance. Last but not least, I’d include Pat Metheny with, say We live Here, but that’s just a start… Let your ears be the judge!