ifi iPower wall wart
Posted by: bunter on 29 November 2015
Hi all. I thought there might be some interest in the results from replacing the stock wall wart power supply on my Arcam irDac with the ifi iPower. Please bear in mind that this is in the context of a humble, simple and pretty old system in which the Arcam irDac is a very recent purchase. I was using a Rotel RCD955BX 'discrete' CD player, which is now the transport via coax to the dac, going into Nait 3 amp and Epos ES11 speakers. Analogue source is an LP12 which I love but really needs fettling. Cables are NACA5, Flashback Phono-DIN and Mark Grant digital coax.
I have been very happy with the irdac as a source - it really shows how much digital technology has moved on since the Rotel was built. I have, however been looking into linear power supplies for some time as I had a feeling the switching supply supplied with the dac was holding it back. Some experiments with a variety of power supplies for LaCie hard drives confirmed that the sound would change (sometimes for the better) if using stiffer regulated PSUs. I don't have the cash for a good regulated linear supply at the moment.
The iPower has a subtle positive effect on just about every aspect of the dac's performance that makes it well worth £40. I'm not going to try and describe it in depth and I have no idea if I could spot it in a blind test but I'd say there is more clarity and swing to the music as well as less harshness - and that means I tend to turn the volume up more (interestingly the rest of the family are asking me to turn it down less, but that could be because I haven't had the Sunn 0))) and Gyorgy Ligeti out for a while) I've definitely been listening to more music since I bought it.
The iPower looks like a bog standard switching PSU and comes with no instructions. The connector on the end of the lead looks like it should fit the dac but doesn't - you have to fit one of the adaptor tips that come with the supply. This fits ok although I'd prefer a snugger, more secure fit. I can't compare it to the more expensive linear PSUs on the market but, for the money, I'm happy with it.
Posted on: 29 November 2015 by hafler3o
Definitely worth investigating! And has the potential to be far more influential on the sound of systems involving routers/switches/NAS etc than any fancy ethernet cable. As long as you don't blow up your kit plugging in the dc 'inverted' 
Posted on: 29 November 2015 by bunter
Yes, you have to make sure you order the right voltage model for whatever you want to power and have a close look at the polarity of the connector before you plug anything in! It does come with an adaptor that gives centre negative if you need it.
Posted on: 12 January 2016 by Mike-B
I've bought an ifi Audio iPower for my Netgear GS105v4 switch.
I confess I'm OCD over RFI, switching & other random electrical noises & as a result I've tried to reduce it as much as possible with screened cables, ferrite & correct LAN grounding. I don't have anything that I can hear that I believe is caused by noise, but I have an inch that needs scratching wrt SMPS noise on the LAN - hence the new power supply.
Its claimed this iPower SMPS has an exceptionally low noise floor @ ~1uV, compared to a typical low noise linear power supply with ~20uV & a consumer grade SMPS that's typically 1000uV.
It's arrived this pm & I'm all set to do some comparative testing with meters & Mk-II audio receptors.
I will post some more as & when .......... but it needs to be over on Streaming Audio as in my case its all about LAN & the Netgear switch
Posted on: 12 January 2016 by nigelb
Very interested to hear your findings with the switch power supply.
Posted on: 12 January 2016 by nigelb
It is quite a claim for a SMPS to have a lower noise floor than a good quality linear power supply. I am no expert, but is this technically possible to achieve with a SMPS?
Posted on: 12 January 2016 by Simon-in-Suffolk
i really don't think this is such a huge challenge if designed properly and there are some good SMPS with exceedingly low noise as used in sensitive radio circuity - but they are typically expensive and often as expensive as their linear counterparts but are a lot smaller.
One consideration is the noise - or switching noise caused back in the mains - and with a bandscope/spectrum analyzer you can sometime see this and its harmonics appearing in the EM field around the mains. Some advanced SMPS have an adjuster to slightly move the switching frequency if this happens to be causing interference or intermodulation carriers with fixed clocks in the connected device (perhaps mostly appropriate for radio devices). I have yet to see this detail applied to audio device SMPS, no doubt as most hifi consumers would not know how to adjust this or have suitable measuring equipment to set.
Simon
Posted on: 12 January 2016 by nigelb
Thanks Simon. But the ifi Audio iPower is only £40. Surely it can't be less noisy than a good linear power supply. Maybe we should wait for Mike's findings before passing judgement.
Posted on: 12 January 2016 by Simon-in-Suffolk
I agree, we should wait.. and of course it may be sufficiently quiet for the application Mike is putting to.. and running a network switch isn't usually considered a very sensitive device.
Simon
Posted on: 12 January 2016 by Mike-B
NigelB, if you look at iFi iPower www blurb they do go some way to explain, albeit a very very simple light touch. They say the power supply has active noise cancellation; this is a well established technology where the noise pattern is overlaid by a negative copy of itself & it neutralises it - think of noise cancellation headphones. Plus there is a lot more filtration on the DC output than the average wall wart. Also don't assume a LPS is quiet, it will contain some rectifier ripple & voltage regulation noise.
Posted on: 12 January 2016 by nigelb
Mike - Interesting stuff. If the iFi powering the switch does produce an audible improvement, even subtle, then it is a very cheap (no brainer) upgrade.
Look forward to your findings.
Best
N
Posted on: 12 January 2016 by ChrisSU
Mike, I'll be interested to hear how you get on with this. I've been tempted to take a punt on one myself, but never got round to it yet.
Did you find one that matched the supply of the GS105? I don't have the info to hand just now, but I remember checking a while ago and there didn't seem to be one that exactly matched it.
Posted on: 12 January 2016 by nigelb
I believe the GS105 needs the 12V version of the iFi which is available from the cable equivalent of Toys R Us.
I too would appreciate Mike's opinion here however.
Posted on: 12 January 2016 by ChrisSU
According to their respective websites, the iFi is 12V/1.8A, whereas the Netgear is 12V/1.2A, which seems like quite a difference. I just wondered if that would be a problem.
Posted on: 12 January 2016 by nigelb
I have looked at sites selling the GS105 and the rear power socket has printed above it 12V=====0.5A. So even more disparity with the 12V/1.8A rating of the iFi. Better wait for Mike to pronounce (or blow up his switch)!
As they say a little knowledge is a dangerous thing.
Posted on: 12 January 2016 by Mike-B
Thats not a disparity, its amps in reserve.
The important part is 12V, thats fixed & should not be deviated from
As you point out the Netgear SMPS output is 1A or 1.2A, however its OK (good in fact) to have the new SMPS able to produce more, so 1.8A means its got amps in reserve.
However its got even more reserve than you guys have suggested as you have only looked at half the data, if you look at the switch data it shows power consumption to be ~4 watts = 0.333 amps, so its got a very good reserve even with its own SMPS.
More later ......
Posted on: 12 January 2016 by Simon-in-Suffolk
Yes as said, the PSU has the max current draw whilst still maintaining the regulated voltage output. It is totally acceptable and typically normal on a regulated powersupply to have a lesser load connected to the PSU. So a PSU offering upto 2 amps @ 12 volts will be absolutely fine with a load of say 100mA. This is why the PSU uses regulation.
Simon
Posted on: 13 January 2016 by nigelb
Mike & Simon, Thanks for the clarification.
Mike - I would be interested to hear about both the noise measures you are able to make and the (any) aural differences (hopefully improvements) with the iFi.
Cheers
Posted on: 13 January 2016 by Mike-B
OK ...... I'm just about to post the story so far in Streaming Audio
