We have something special for you today. Lots of things have been said about jitter, and here's our take on the case.
SPDIF iPurifer®: Jitter Performance Test Results - Part 1/2
Background
To show what the SPDIF iPurifier® can do and how it can improve DACs from the inexpensive through to the very expensive, we used the ‘Jitter Generation’ function of the Audio Precision 2 test system to create a ‘J-Test Signal’ (the industry standard for testing and widely used by magazines, including Stereophile, USA).
The Audio Precision 2 artificially creates a specific, known amount of jitter and then measures how much it is reduced by the SPDIF iPurifier®. Hence it is quite quantifiable AND informative as a measurement tool.
The Methodology
Audio Precision 2 (AP2) generates a signal with 64,130pS of jitter (measured via loopback into AP2) using a
square
wave waveform at 250Hz. The specific settings are simply chosen to create a gross amount of easily visible jitter. The test results are scaled to be comparable with those by Stereophile (USA).
DACs Tested
The majority of DACs (>80%) in the market use either AKM or Cirrus Logic SPDIF
receiver
chips, hence one DAC using each of these was selected.
The DACs tested are listed below:
- DAC 1: AKM based, AK4113 Receiver & AK4490 DAC Chip, RRP US$400
- DAC 2: CS based, CS8416 Receiver & CS4398 DAC Chip, RRP US$500
- DAC 3: BB/TC based, TC Audio DICE Chip as Receiver & PCM1792 DAC Chip, RRP US$5,000
The last DAC was included because of two reasons; very high asking price, which indicates its high-end shelf affiliation, and its SPDIF inputs’ specific ‘anti-jitter’ circuitry. It was interesting to see how well it’d work next to DACs with ‘vanilla’ input circuitry.
Stay tuned, there's more!
