iFi iPurifier 2 - Reviews, Impressions and Discussion Thread
Jan 5, 2017 at 5:32 PM Post #466 of 587
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SPDIF iPurifer®: Jitter Performance Test Results - Part 2/2
 
 

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:
 
  1. BEFORE: 0 out of 10;
 
        
 
 
  1. 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:
 
  1. BEFORE: 0 out of 10;        
 
       
 
  1. 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 lock 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:
 
 
  1. BEFORE: 8 out of 10 (couldn’t lock onto the source signal);
          
       
 
 
  1. AFTER: (a ‘strictly’) 10 out of 10.             
 
       
 
 

Conclusion

 

 
 
  1. The SPDIF iPurifier® can dramatically reduce jitter in the systems (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 so will are sonic differences.
 
  1. SPDIF iPurifier® will also improve the sound by providing galvanic isolation to the system.
 
  1. SPDIF iPurifier® will also improve the ‘locking range’ of the DACs with anti-jitter.
 
  1. 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.’
 
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Jan 8, 2017 at 11:56 PM Post #468 of 587

Condocondor

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Technobear,

I've noticed that I lose a little bit of bass response with my iPurifier2 going into my iDSD BL.  Does your bass response return after the iPurifier2 warms up?  I find that I can turn my 3D+ off when I use the Purifier but not the X-Bass+.  I'm using the generic blue USB cable for now and the Beyer T5p.2.  Have a Kimber Ag and a Silver Black Dragon on the way to audition. 
 
Jan 9, 2017 at 8:25 AM Post #469 of 587

technobear

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Technobear,


I've noticed that I lose a little bit of bass response with my iPurifier2 going into my iDSD BL.  Does your bass response return after the iPurifier2 warms up? 


Yes. This is exactly how I discovered that the Gemini cable does things - including adding bass - but when iPurifier2 is warmed up then adding and removing Gemini no longer makes a difference. I wrote about that somewhere here.
 
Jan 9, 2017 at 6:53 PM Post #470 of 587
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Boys and girls, just a quick reminder. We'll attend to UK's world famous  Sound & Vision - Bristol Show. As per usual, we'll show a new thing or two there, so if you're around, please come and visit us! 
 
 
The date: 24th - 26th of February
The place: Marriott City Centre Hotel, Lower Castle Street, Bristol, BS1 3AD
The brand: iFi Audio / suite 11

 
 
 

 
 
 
For further info, please take a look here:
 
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See you on the spot!
 
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Jan 12, 2017 at 4:43 PM Post #471 of 587

furllan

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I am using an ipurifier 2 for about a week, and I'm really enjoying it. It really bring out the best of my system.
 
In fact, I'm enjoying it so much that I'm considering adding other devices of this kind into my chain, like the jitterbug, the uptone regen or even both. Any thoughts on that?
 
Jan 12, 2017 at 4:48 PM Post #472 of 587
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  I am using an ipurifier 2 for about a week, and I'm really enjoying it. It really bring out the best of my system.
 
In fact, I'm enjoying it so much that I'm considering adding other devices of this kind into my chain, like the jitterbug, the uptone regen or even both. Any thoughts on that?

 
No harm in trying stuff! And gizmos you've mentioned are affordable, which should make your decission even easier.
 
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Jan 12, 2017 at 5:14 PM Post #473 of 587

furllan

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I've read some complaints about the ipurifier not going along very well with the regen, have anyone heard about that?
 
btw, anyone in this thread uses the regen + ipurifier combo? I'd like to know your impressions.
 
Jan 12, 2017 at 6:07 PM Post #474 of 587

gr8soundz

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  I am using an ipurifier 2 for about a week, and I'm really enjoying it. It really bring out the best of my system.
 
In fact, I'm enjoying it so much that I'm considering adding other devices of this kind into my chain, like the jitterbug, the uptone regen or even both. Any thoughts on that?

 
I have a Jitterbug on one end and the iPurifier 2 on the other end of my usb cable. Combo works great and both pieces add to the overall improvements.
 
Haven't tried the Regen but from specs seems like it would be redundant to pair a Regen with the iP2.
 
 
Jan 12, 2017 at 7:08 PM Post #475 of 587

furllan

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I have a Jitterbug on one end and the iPurifier 2 on the other end of my usb cable. Combo works great and both pieces add to the overall improvements.
 
Haven't tried the Regen but from specs seems like it would be redundant to pair a Regen with the iP2.
 


Good to know that. I'll probably get a jitterbug myself to see how it goes in my system.
 
Did you notice any downsize in sound quality from using both the ipurifier and the jitterbug together?
 
Jan 12, 2017 at 7:22 PM Post #476 of 587

gr8soundz

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Did you notice any downsize in sound quality from using both the ipurifier and the jitterbug together?

 
Just the opposite.
 
I got them at different times so was able to hear slight improvements from each piece alone. Can't remember which improved what best (though IIRC the iP2 had a larger effect) but I haven't used a bare usb cable with any of my dacs since.
 
 
Jan 12, 2017 at 7:28 PM Post #477 of 587

Krutsch

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  I've read some complaints about the ipurifier not going along very well with the regen, have anyone heard about that?
 
btw, anyone in this thread uses the regen + ipurifier combo? I'd like to know your impressions.

 
Yes, I am doing just that: USB --> REGEN w/ Linear Power Supply --> iPurifier 2 --> Bel Canto REFLink (USB-to-SPDIF converter).
 
I am surprised how well that combo works with a Cubox-i4 Pro running Roon Bridge.
 
The advantage is that the REGEN provides very clean power to the iP2, just before the iP2 does its magic. Really clean sound and compares favorably with my Bryston BDP-1 with AES output into the same DAC, which is really saying something.
 
Jan 12, 2017 at 8:13 PM Post #478 of 587

furllan

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Well, I've just ordered a jitterbug, lol.
 
Curious to see what it will do to my system quality, and how it will come along with the iPurifier. I'll post impressions here once I have my hands on it.
 
Jan 12, 2017 at 10:45 PM Post #479 of 587

stuck limo

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Just the opposite.
 
I got them at different times so was able to hear slight improvements from each piece alone. Can't remember which improved what best (though IIRC the iP2 had a larger effect) but I haven't used a bare usb cable with any of my dacs since.
 

 
Can you describe the sound without the Jitterbug vs with the jitterbug?
 
Jan 13, 2017 at 6:38 AM Post #480 of 587

Lohb

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Jitterbug made the treble brittle/artificial in my chain so I just moved on to iP2.
 
Could not be happier. iP2 brought my entry-level HRT DAC closer to MOJO technicalities/presentation.
 

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