Intro
Contents
Our research on the impact of a data network on sound reproduction never stops. Although some studies seem to be similar, the perspective is often slightly different. Now we look at the influence of power supply and power filtering on jitter, noise and playback quality. The outcome…? Just check out this article.
We actually took three measurements in this test:
- Noise from the adapter/power supply. With and without power filter
- Noise from the Ethernet port. With and without a filter at the power supply
- Phase noise / Allan Variance. With and without a filter on the power supply
What we are curious about is the audibility of a good power supply and a moderate one with and without a power filter. We also want to see if this can be linked to the results from the measurements we took.
Measuring equipment
We are using the following equipment to perform the measurements:
- Aeroflex PN9000 with Axtal 100 MHz reference: phase noise / Allan Variance
- Prism dScope III
- Tekbox LISN
- Tekbox Common mode / differential mode splitter
- Picoscope 5000
- CDN-T8 network isolator
- Rigol 815 spectrum analyzer
- Rigol Electronic DC-Load
- Variable / sliding resistor (for a clean 1A ‘load’ on the adapters)
Test candidates
- Netgear GS108(E)
- Dlink 108 V3 and V4
- Dlink 1100
- Zyxel 1200-08
- IFI iPower 12V
- Lineair power supply from AliExpress
- Sbooster BOTW 5V
Let’s start looking at the results.
Sir,
Thank you!
Sean
Sirs,
Trying to follow your D-Link advice but cannot distinguish DGS-108 Version 3 from 4.
D-link does not assist and email to D-Link not returned.
Mine also says on Box: 8 port Gigabit desktop switch. One light on each port.
On bottom says: H/W Ver.:E1.
Very much enjoy your testing!
Best!
Sean
Hi Sean. Version E1 is version 4. Version 3 is indicated as C6.
I’ve used an iFi SupaNova (included filter) power cable in the network box + an IEC C14 to Schucko female before the distributor for switches. This way all the equipment (router, switches, media converters) benefit from the power filtering.
For grounding the switches (better said, EMI/RFI draining) one can also use the ToughCable Connector Ground from Ubiquiti which can be plugged in one free Ethernet port. I prefer padding the interior of metal casing of the switch with copper adhesive foil and insert a drain copper wire or screw and then plug it (with a regular banana connector) to the special jack in the iFi / SilentPower AC iPurifier (that can be plugged in a free Schucko outlet).
a question: what kind of filters did you use?
It is a filter between the power supply and the switch.
the question was more related to brand and model
Can you elaborate bit more on this?
“What we clearly see with all switches is that it is crucial to ground things properly: that significantly reduces the noise floor. “
What else do you need to know? Grounding the switch – for example the casing – lowers noise.
There’s no ground connectors on normal switches so I o wondering how you go about this. Entreq for example have ground RJ45 connectors connected to ground boxes. But as I understand you you mean adding a cable to the chassis somewhere and connect to mains ground or?
The D-Link switch has a grounding screw on the case, for instance. Connect a wire from the case, with the D-Link from the screw, to the earth connection of an earthed plug and put that plug into an earthed socket. We tested it like that a few times, and it is clearly audible.
Only do so when you know what you are doing.