Russ Andrews Network Purifier streaming filter
We have looked at a variety of devices for reducing noise in audio systems over recent years and have generally found them to be highly beneficial. However, when Russ Andrews sent me a small, light box I wasn’t very excited at the prospect of reviewing another relatively affordable network filter. What can I say, we all make mistakes!
Looking back to the heyday of vinyl in the sixties and seventies it’s worth noting that there were considerably fewer of the electromagnetic and radio frequency nasties assailing recording studios and the electronics in people’s systems that there are today. In terms of invisible interference, it was a golden age, the hardware might not have been what it is today but some of it was exceptional and none of it had to cope with the quantities of noise in the air and on the mains power that is omnipresent today.
We now have easy access to huge swathes of recordings at remarkably high quality but we also have RFI (radio frequency interference) all around us and EMI (electromagnetic interference) on both the mains and the network connections that provide access to that music. Russ Andrews has been making devices to combat this for many years, these were designed by Ben Duncan and are called Zapperators, they are available in a variety of forms but mostly as Minizaps in plugs to fit the common sockets found on audio components, eg XLR, USB, RCA etc. They are designed to convert RFI and EMI into heat thus lowering the noise floor on components that they are attached to, various other companies make similar devices but these are among the most affordable.
It’s not easy to think of an analogy for this type of filter but it occurred to me that a water filter jug is similar, in that instance sand absorbs contaminants commonly found in tap water such as sediment, chlorine and lead. Zapperators absorb high frequency noise that gets onto the power and data lines and reducing this tends to make the sound more relaxed and natural, which with streaming in particular is very welcome.
The Network Purifier is essentially a battery of eight Minizaps in a thermoplastic enclosure with in- and outputs on RJ45 sockets for use with ethernet cables in a wired network. You can use a Network Purifier in a variety of places around a streaming system: between router and streamer, router and switch and switch and streamer, you can even use several of them around a system. They are apparently compatible with Meridian’s Speakerlink connections used to hook up their DSP loudspeakers, so I suspect that they would also work in other DSP speaker systems but this would require checking with Russ Andrews first.
The Network Purifier contains eight Minizap high frequency filters to clean up the eight conductors in an ethernet cable and these are on a PCB with heavy gauge copper tracks and a gold immersion finish in order to avoid oxidisation. The CAT6 connectors are fully shielded and the Network Purifier can operate at speeds up to 1 gigabit/second, which is way beyond the requirements of audio streaming but others have noted that the extra headroom is not detrimental to end results. The box also has a ground point for draining ground plane noise, something that Russ Andrews has long targeted as a problem in audio systems. We reviewed some of the RA power products recently which made a good case for this approach.
Sound quality
I tested the Network Purifier with the 30cm ethernet cable that comes in the box by connecting to the end of a CAT6 ethernet cable connected to an English Electric 8Switch network switch, and joining the 30cm cable to my Lumin U2 Mini streamer. This was about the simplest arrangement I could make, the 8switch being required to connect the wireless receiver that accepts commands from the streaming app. In this situation the Network Purifier brought some clear benefits, chiefly greater depth of image and stronger timing cues which made the music flow and breathe more easily, the overall effect being greater involvement in the music, significantly greater.
Further listening revealed that the sense of space, scale and speed were also enhanced, a drum track revealing notably more dynamic contrast. The Network Purifier seems to be good at opening up the high frequencies, revealing what’s going on in the treble, which is usually a result of noise being reduced. Sometimes you get a smoothing of the highs with devices like this but here they are better defined with less in the way of glare or grain. It’s a very appealing result for what is quite a modestly priced filter in the scheme of things. It makes the music seem more realistic and three dimensional than some of the competition, and it brings out the huge scale of I’m Free by Symbolico as well as various other tracks.
Connecting a Russ Andrews RF router to the ground point on the Network Purifier using their Technical Ground Weave cable (a total cost of £318) has a pretty dramatic effect on the overall performance. Now the music sounds super open, uncannily natural and very much in the room, the effect is greater than adding the Network Purifier alone to be honest, but you need both to achieve it. It’s a powerful combination, putting space between the musicians as a result of greater image depth and generally increasing perceived resolution to a high degree.
The last test was to see if the Network Purifier would be beneficial when placed between router and switch, just before the 8Switch using the free ethernet cable supplied. The change this brought about was quite an eye (ear) opener, the sound became so deep that it felt like going from two dimensions to three, the stereo was extraordinary. With the first, relatively straightforward track, the sound opened up and the image became far more focussed, while the timing improved quite obviously because more high frequencies were getting through. On the heavily worked Queen Mary by Francine Thirteen the extra drama that this opening of the depth dimension brought out was quite extreme, it was like the filter was revealing detail that the raw feed was suppressing. Which is almost the opposite of a typical filter.
Adding the RF Router in this position smoothed the treble which probably makes it easier to enjoy less impressive recordings, however in order to do this I had to remove it from the Origin power supply on the streamer and, ultimately, I preferred the greater openness of having it there. A second Technical Weave cable is clearly necessary.
Conclusion
I underestimated the Network Purifier, it doesn’t look very special and I had ignored it because bigger, shinier pieces of kit had come along and distracted me. Now I’ve heard what it can do it will remain in the system until Russ Andrews demands its return, at which point I might have to reach into my pocket. Never a pleasant experience!
I have to hand it to Russ Andrews, they have come up with a corker of a streaming enhancement device in the Network Purifier. Don’t let its plain looks fool you, this is a fabulous device if you are into streamed audio, in fact it’s a bargain.