Hello all,
I am aware by a thread on this forum that the Netgear 105E and maybe 108E do benefit by Ifi Power X power supplies but a bit expensive for me for buying without an option to return it.
So could anyone here please recommend a good place to buy 12 V medical power supply which is SMPS.
After all the Chord 8Switch does use one?
I’ve changed SMPS’s and used them on two different Netgear switches & my current Cisco.
I did this at various times so none were consecutive and A/B comparisons where not really possible. All I could say is each time the replacements bettered the originals.
I did try an iFi and when it was working it was excellent, unfortunately it failed after about 6 months and was returned under warranty.
I’m not sure why you want a ‘Medical’ grade, but I’ve had mine for over 6 years
Its a Friwo MMP15 (Friwo is a Germany cmpy)
In the box was a selection of power plug configs and a good selection of DC plug variations including polarity reversing.
The DC cable is much thicker that Netgear or iFi
I checked its RF emission using a MW /SW radio, that was reasonably quiet.
I measured DC voltage off & on load (6W load) and that proved to be very stable and a very small 0.02vDC drop under load.
Friwo specs show DC ripple is <=120uV(pp), so overall it looks like a pretty good & stable SMPS.
SQ when compared to the Cisco SMPS … the changes are subtle but positive.
Indeed, I am not sure ‘medical grade’ has a meaningful understanding or exact meaning… There is how ever compliance to IEC 60601 group of standards that specifies safety and performance requirements for safety to patients and operators in a medical environment… not sure that relevant for hifi use… I guess it might be more likely to fail closed / safe than other devices, so less likely to zap your switch on a PSU fail.
But if you want to use such a device, they key thing to check is product conformity to IEC 60601… that will be in the certifications for the product, other than that it’s just marketing blah.
Hi Simon, the Friwo SMPS I have complies with EN60601-1 and comes with cert.
I bought it simply because I had previously tested one and it gave very steady 12vDC with a very small volt drop under load. (see previous post)
Excellent, your GP can use it in their consulting room 
well that is what Chord English Electric advertise that they supply a medical grade PSU with their 8 Switch…
Without stated conformance to medical electrical equipment standards, it means nothing and is just marketing sales blah… I would disregard it and question anything that is stated. It sounds like it could be similar to the sort of thing RA got into trouble with with the Advertising Standards Authority a few years back.
I’ve seen a medical grade " Friwo 18W Plug Adapter 12V dc Output, 1.5A Output" PN EDV1960976RS medical grade for under £30. I suppose that’s still better than the really cheap adaptors we normally find comes with a switch/modem etc
Interestingly I was looking up the CE European logo, and came across this
For products that require the mark, companies only need to ensure their product meets the applicable standards through testing, provide a declaration, and then place the mark on their product. Certain categories such as medical devices, require testing by an accredited third party called a Notified Body.
In order for a medical device to receive a CE mark, the process is more intensive. Designers must submit samples and technical documents for external inspection by any of a number of Notified Bodies. These bodies review the product documentation, and depending on the requirements will review test reports or conduct their own testing to ensure a product complies with the regulations.
I’ve worked for two Notified Bodies over the years for PPE and Electrical Cable.
The NBs will audit the company, review their test results. But more importantly will commission independent testing to the appropriate standard with a UKAS (or other Accredited) Test Laboratory.
That way you are not just reliant on the companies own testing. It’s a complex process, but does work well.
DG…
I strongly doubt you will find a better ps and less expensive than the ifi power x. When I tried the Ifi power ( non x ), the Israeli one , for 400 euros, was better, but not night and day. The real difference was with the Uptone JS1, for 1k. On the Neatgear GS105.
Better save and buy later the EE8 from Chord. Only opinion, of course.
The Cisco 2960 8tcl , white model, was better than Netgear gs105 with a good lps. I would not bother with ground or not ground.
Buy a good condition Cisco 8tcl , white model, and don’t bother.
The EE8 will be better, however you streamer is separated from your dac, so the difference will be less significant.
A high quality powerblock would be perhaps more mandatory to really upgrade your network.
But however it will cost 6 times at least the price of the Ifi power x.
There is research relating to use of medical PSUs for audio. The PSUs are characterised by:
Low electromagnetic interference (EMI): To minimise interference with other medical devices, these power supplies must meet stringent EMI requirements
Insulation: They have a high insulation between input and output
Low risk of leakage currents: To ensure the safety of patients, they must reduce leakage current flow to a minimum
typically they also have good ripple/noise rejection. However the key attribute for streaming audio appears to be the low leakage current (it was mentioned as <75uA for medical approval, with some measured ~10uA) as this is what leads to common mode noise generation, a significant source of disturbance to our sensitive devices.
In measurements the Ifi Power X returned high levels of unfiltered switching noise on the output, for the money a decent linear PSU is almost within reach and likely a much better option.
Yes, but if no compliance to the appropriate electrical standards to medical appliances, it’s just marketing rubbish.
Anybody can say anything, and possibly trip up with the ASA in the UK if anybody was minded to take it to court… which likely would happen if anybody took such claims seriously.
Medical devices have low noise, fail safe, and have higher fail insulation values. Medical Ethernet compliance for example supports higher DC galvanic isolation for example.
The same can be said for avionics grade , low EM emission grade , medical grade… all only marketing sales blurb and take with a pinch of salt unless conformance tested to the appropriate regulation or standard. Commercial/industrial products formally list their compliances such as EM compliance, which are typically ‘type’ tested.
Early on in my career this was an area I was involved with, being an international Recommendations Rapporteur for the ITU… so can speak from professional experience with regard to conformance testing.
With regard to IEC 60601 which covers the use for the medical industry… its a set of standards electrical and mechanical compliance. I believe the standard requires the standard compliance must be stamped on the products name plate so non ambiguous … possibly to counter unscrupulous marketing elsewhere.
EM emission standards, (ie EMI) for multimedia professional/industrial product emission and immunity standards include CISPR 32 and 35 respectively.
It worth noting that these standards not only include emissions, but also immunities from external disturbances or emissions.
The CISPR standards specifically cover EMI/RFI across a range of sectors covering automotive, multimedia, radio, scientific and medical etc. this tends to be what hifi products are sensitive to.
Simon, sorry for not getting it, but I’m confused at the point you are making.
Are you saying these words alone dont mean much, unless they also say IEC 60601 compliant? I’m unclear on whether you think medical grade is good or bad, or more likely I am missing something in your response.
Yes, unless the compliance to is stated to particular level using one of the mentioned standards it doesn’t mean much.
60601 is primarily about patient and operator safety as well key electrical performance such as EM compatibility in the medical environment …
I would suggest for hifi use, the key standards to look for if such things are important are RFI/ EMC standards and those include CISPR 32 and 35… which specifically cover audio equipment for use in the domestic environment (hifi)
There is class B compliance, and the more relaxed class A compliance
Look for CISPR 32 or EN 55032 compliance in your product specs.(in Europe… may be different elsewhere in the world)
The 2960 is compliant to CISPR 22 (which is now placed by CISPR 32) Class A for example. CISPR 32 is harmonised with EN55032.
Once you have checked the product compliances choose the product that gives the sound you like
Thanks. The Friwo PS I previously mentioned doesnt mention CISPR but does say it conform to EN 55032:2015, so all good - cheers
Out of interest, I have just checked my netgear mesh PS, and was surprised to see that it was actually LPS
Though there are two classes as I said. Class A is more relaxed and noisier, class B is tighter and lower noise. You don’t say which, so perhaps align with the relaxed noiser standard?
Linear power supplies can still be made cheaper than SMPS. The reasons for not supplying linear are often related to non component costs like logistics and storage. Having a uniform stock that is broadly compatible globally that you can move around where needed often makes the slightly higher cost of an SMPS more economical overall.
I’d not assume that just because a power supply is linear it is good, just as I wouldn’t assume just because it is SMPS it is bad.
One of the best quality linear power supplies I ever saw supplied with a product was the one that came with the US model Super Nintendo. I recently recapped one and it was way overengineered. Simple compoents. Expensive caps. A 200w EI core. Disguised as a cheap wall wart.
I think the biggest issue with the Netgear switch is whatever power supply you swap in, it’s still a 2 pole non earthed device. As such, if it was me, I’d make no change at all unless it was to swap out the switch.
LPS is the abbreviation for Limited Power Source . In the IEC 60950 safety standard, the flame retardant case/enclosure is required for an IT product.
I suspect it still is an SMPS
They can, but cheap linear power supplies are notoriously in efficient, and wasteful of energy. Sure inefficient Linear PS produce less EMI compared to larger more efficient Linear PS due to the smaller Linear PS absorbing the interference energy due to its increased in efficiency, though the EMI tends to be of lower frequencies in Linear PS compared to the higher frequencies of SMPS.
I agree with your point of the perils noise wise of non earthed and double insulated products… horrible generators or conveyers of common mode noise.
Hadn’t seen this before, so did some reading of it.
An LPS rated power supply is designed for safety reasons to conform to a maximum permitted output voltage, output current and output power rating. Regulatory agencies have created many designators for power supplies which conform to different sets of specifications. The LPS (Limited Power Source) requirements are specified in the IEC 60950-1 standard and are used to define power supplies with the maximum performance capabilities mentioned above. The benefit to customers of LPS power supplies is system installers can follow relaxed requirements regarding the wiring and physical installations of loads powered by modules certified as LPS. Understanding the basic specifications for LPS power supplies will help to explain why certain power supplies qualify as LPS while others do not.
Power supplies which qualify as LPS are recognized as unlikely to cause electrocution or a fire due to the limitations on the output current and voltage they can deliver to a load. The following is a summary of the specifications for power supplies certified as LPS with inherent power delivery limits:
VA = Volts * Amps
Voc = Open circuit output voltage (no load)
DG…
