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SPDIF iPurifer®: Jitter Performance Test Results - Part 2/2
DAC 1 - AK4113 & AK4490 - high-resolution jitter spectrum of analog output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz & 64,130pS of 250Hz Squarewave Jitter added; 24-bit data sourced from AP2. Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz. Red trace without SPDIF iPurifier®, Blue trace with SPDIF iPurifier®
Without the SPDIF iPurifier® we can see that practically all of the jitter (64,130pS) simply ‘rides through’ causing gross distortion, which actually has the worst peaks past the -70dB upper limit of our graph. It should be noted that here aforementioned -70dB figure is equivalent to less than 12-Bit actual resolution.
Adding the SPDIF iPurifier® completely eliminates all distortion products relating to the 250Hz jitter frequency and the low-level 229Hz tone in the digital signal, though some low-level sidebands at what appears to be multiples of the mains frequency (50Hz) remain – these are likely caused by noise pickup from the internal mains transformer of the DAC itself (those are outside the remit that SPDIF iPurifier® can cure as they are picked up AFTER the SPDIF iPurifier®).
Summary: SPDIF iPurifier® eliminated all 64,130pS of the source jitter.
Jitter Performance Score:
DAC 2 – CS8416 & CS4398 - high-resolution jitter spectrum of analog output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz & 64,130pS of 250Hz Squarewave Jitter added; 24-bit data sourced from AP2. Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz. Red trace without iFi iPurifier® SPDIF, Blue trace with iFi iPurifier® SPDIF
The picture without the SPDIF iPurifier® parallels DAC 1 but the results are even worse. Practically all of the jitter (64,130pS) simply ‘rides through’ causing gross distortion which actually has the worst peaks past the -70dB upper limit of our graph. Further, there is a lot of added low level ‘noise alike’ or a-harmonic jitter below -115dB. Not that it matters much, given the gross amounts of jitter passing through. Again, the aforementioned -70dB figure is equivalent to less than 12-Bit actual resolution.
Adding the SPDIF iPurifier® completely eliminates all distortion products relating to the 250Hz jitter frequency and most of the low level 229Hz tone in the digital signal. Some low level sidebands at what appears to be multiples of the mains frequency (50Hz) remain. These are likely caused by noise pickup from the internal main transformer of the DAC itself and it can be seen a few distortion spikes related to the 229Hz signal poking up just above the noise.
Summary: SPDIF iPurifier® eliminated all 64,130pS of the source jitter.
Jitter Performance Score:
DAC 4 – TC-DICE & PCM1792 - high-resolution jitter spectrum of analog output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz & 45,250ps (w/o iP SPD) & 64,130pS (with iP SPD) of 250Hz Squarewave Jitter added; 24-bit data sourced from AP2. Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz. Red trace without iFi iPurifier® SPDIF, Blue trace with iFi iPurifier® SPDIF
The DAC completely failed to lock onto our 64,130pS jitter signal and would onlylock do so with the SPDIF iPurifier® in the chain.
Lowering the jitter added value to 45,250pS allowed the DAC to lock by itself. Once properly locked, this DAC shows what can be achieved if 10 times or more the money of any of the above DACs is spent primarily on precision engineering and not on fancy casework. In effect, this DAC ‘eats’ all the jitter regardless if the SPDIF iPurifier® is used or not.
Summary: SPDIF iPurifer® improved the system by increasing the ‘locking range’ of the DAC 4 by ~40% (from 45,250ps to 64,130ps of jitter).
Jitter Performance Score:
Wherever generic, PLL-based SPDIF receivers are used (regardless of a DAC’s price), the potential benefit of the SPDIF iPurifier® is quite tremendous; the worse a source is and the better the DAC quality, the greater outcome from having the SPDIF iPurifier® in the chain.
The SPDIF iPurifier® will upgrade the SPDIF input of all DACs regardless of these machines’ price; from entry to an ultra high-end level of performance. The SPDIF section is no longer the ‘weak link in the chain.’
DAC 1 - AK4113/AK4490
DAC 1 - AK4113 & AK4490 - high-resolution jitter spectrum of analog output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz & 64,130pS of 250Hz Squarewave Jitter added; 24-bit data sourced from AP2. Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz. Red trace without SPDIF iPurifier®, Blue trace with SPDIF iPurifier®
Without the SPDIF iPurifier® we can see that practically all of the jitter (64,130pS) simply ‘rides through’ causing gross distortion, which actually has the worst peaks past the -70dB upper limit of our graph. It should be noted that here aforementioned -70dB figure is equivalent to less than 12-Bit actual resolution.
Adding the SPDIF iPurifier® completely eliminates all distortion products relating to the 250Hz jitter frequency and the low-level 229Hz tone in the digital signal, though some low-level sidebands at what appears to be multiples of the mains frequency (50Hz) remain – these are likely caused by noise pickup from the internal mains transformer of the DAC itself (those are outside the remit that SPDIF iPurifier® can cure as they are picked up AFTER the SPDIF iPurifier®).
Summary: SPDIF iPurifier® eliminated all 64,130pS of the source jitter.
Jitter Performance Score:
- BEFORE: 0 out of 10;
- AFTER: 9 out of 10 (some 50Hz jitter from the power transformer remained).
DAC 2 – CS8416/CS4398
DAC 2 – CS8416 & CS4398 - high-resolution jitter spectrum of analog output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz & 64,130pS of 250Hz Squarewave Jitter added; 24-bit data sourced from AP2. Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz. Red trace without iFi iPurifier® SPDIF, Blue trace with iFi iPurifier® SPDIF
The picture without the SPDIF iPurifier® parallels DAC 1 but the results are even worse. Practically all of the jitter (64,130pS) simply ‘rides through’ causing gross distortion which actually has the worst peaks past the -70dB upper limit of our graph. Further, there is a lot of added low level ‘noise alike’ or a-harmonic jitter below -115dB. Not that it matters much, given the gross amounts of jitter passing through. Again, the aforementioned -70dB figure is equivalent to less than 12-Bit actual resolution.
Adding the SPDIF iPurifier® completely eliminates all distortion products relating to the 250Hz jitter frequency and most of the low level 229Hz tone in the digital signal. Some low level sidebands at what appears to be multiples of the mains frequency (50Hz) remain. These are likely caused by noise pickup from the internal main transformer of the DAC itself and it can be seen a few distortion spikes related to the 229Hz signal poking up just above the noise.
Summary: SPDIF iPurifier® eliminated all 64,130pS of the source jitter.
Jitter Performance Score:
- BEFORE: 0 out of 10;
- AFTER: 9 out of 10 (some 50Hz jitter from the power transformer remained).
DAC 3 TC-DICE/PCM1792
DAC 4 – TC-DICE & PCM1792 - high-resolution jitter spectrum of analog output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz & 45,250ps (w/o iP SPD) & 64,130pS (with iP SPD) of 250Hz Squarewave Jitter added; 24-bit data sourced from AP2. Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz. Red trace without iFi iPurifier® SPDIF, Blue trace with iFi iPurifier® SPDIF
The DAC completely failed to lock onto our 64,130pS jitter signal and would only
Lowering the jitter added value to 45,250pS allowed the DAC to lock by itself. Once properly locked, this DAC shows what can be achieved if 10 times or more the money of any of the above DACs is spent primarily on precision engineering and not on fancy casework. In effect, this DAC ‘eats’ all the jitter regardless if the SPDIF iPurifier® is used or not.
Summary: SPDIF iPurifer® improved the system by increasing the ‘locking range’ of the DAC 4 by ~40% (from 45,250ps to 64,130ps of jitter).
Jitter Performance Score:
- BEFORE: 8 out of 10 (couldn’t lock onto the source signal);
- AFTER: (a ‘strictly’) 10 out of 10.
Conclusion
- The SPDIF iPurifier® can dramatically reduce jitter in
thesystems (around a thousand times in the cases observed) equipped with DACs based on a ‘text-book’ SPDIF digital receiver design. Yet differences between SPDIF receiver architectures remain observable and sowillare sonic differences.
- SPDIF iPurifier® will also improve the sound by providing galvanic isolation to the system.
- SPDIF iPurifier® will also improve the ‘locking range’ of the DACs with anti-jitter.
- SPDIF iPurifier® cannot cure jitter noise if the noise is created AFTER the SPDIF iPurifier®, e.g.: 50Hz power transformer noise pick up by the DAC.
Wherever generic, PLL-based SPDIF receivers are used (regardless of a DAC’s price), the potential benefit of the SPDIF iPurifier® is quite tremendous; the worse a source is and the better the DAC quality, the greater outcome from having the SPDIF iPurifier® in the chain.
The SPDIF iPurifier® will upgrade the SPDIF input of all DACs regardless of these machines’ price; from entry to an ultra high-end level of performance. The SPDIF section is no longer the ‘weak link in the chain.’
