Very specific one here - has anyone compared the consumption of a SN2+HiCap running in pre-amp only mode with a NAC282+NAPSC+HiCap?
I ask as the SN2 setup obviously has a much larger transformer than the NAPSC, and I’m guessing it’s powered on for the digital section. Am hoping that the amps themselves aren’t drawing power in preamp-only mode.
I don’t have a meter of my own (yet).
No but the size of the transformer isn’t relavent to consumption here. Just what is downstream of it drawing current.
A wattmeter is tremendously useful around the house and only cost about $20.
Yeah I can see that it would be a helpful tool, based on the revelations mentioned on this thread.
I am not as well versed in electrical engineering as I would like to be… so appreciate the comment re: what determines the actual power used in an amplifier. So in this case the consumption shouldn’t be massively different between these two pre-amplification setups if they otherwise would use the same power amp and speaker?
Well amplifier design plays a large role. Some are in fact passive. Others use more or less bias current. There are 101 possible design decisions that will affect any two preamps.
Not understanding how the SN disables the power amp stage, it is very hard to answer that question. Is it really disabled or is it just not used? In which case, the class A portion of the first few watts would always be active.
Again it comes back to measuring and wattmeters are really simple devices designed for everybody. At a guess, I’d say that the consumption of a SN2 in preamp only mode would be the minimum power consumption rated on the back. Unlike power amps, preamps do not vary that much depending on whether a signal is selected or not and the gain is often subtractive rather than additive so volume plays a smaller role than you might think.
If you order a wattmeter today, you’ll have your answer by the weekend (not second hand from a forum user) and have a handy tool for understanding consumption around the house.
If you have a smart meter with an In House Display, you may be able to use this, assuming you can find a point when your house is at an even usage. E.g. kids in bed, partner requested not to turn lights on, etc. Of course you may get the odd kick in from your fridge/freezer, but it should give you a close idea. You will see earlier in the thread my results for NAC82/HC/Napsc, so you just need the difference for the SN2
I have measured the idle power consumption of my SN2:
Could I refer to a post I made some months back Mains voltage and XPS fuses - Hi-Fi Corner - Naim Audio - Community
Thank you. That is very helpful. My mains supply is about 50 years old so I will get it checked out in the near future.
I have one of these new-fangled smart meter things which tells me our house idles at 4-6 pence per hour with a few lights on, the fridge/freezer doing its thing and a couple of set-top boxes on standby; this is with the system on. Turning the system off reduced consumption by 1 pence per hour so I inferred from this that it costs me 24 pence a day to leave the system powered; that equates to £87.60 a year. I guess it costs a bit more when it is in use.
Cheers,
Ian
Managed to get my hands on a meter - very interesting, and as mentioned… something I’m sure I’ll find useful. Tried a few different configurations and measurements. SN2 as pre higher consumption vs. the dedicated pre. Also SN2 as full integrated only marginally higher than SN2 as pre.
Naim power amps seem to idle with comparatively low current consumption, I have not tested mine but it runs a lot cooler than my SuperUniti. I guess that down to all the processing going on in the SU.
If I remember i’ll put the power meter in circuit and give it a work out.
I measured a 250.2 at 15W idle with the SN2 only 19W idle which, to me, was an indicator that just keeping that transformer powered up is costly. In my system, they didn’t go up much with relatively loud volume… only 2-3W more… and almost none at low volume.
Yes that sounds right, transformers are typically very efficient so just a few watts is required to keep them energised with no load, the rest is drawn by controls and bias current through the various stages of the amp which add up to the 15W you measured, the extra 2-3 Watts when ‘playing’ with lots of speakers is all that is required to create loud! :0)
Amazing, and yet I still want a 250W/ch amplifier !
Transformers themselves under no load pull nothing. You might get residual current drawn by the regulation circuits etc. But even that’s often near zero. I have many non Naim linear power supplies and if you unplug the output but leave the supply itself on, their green LED isn’t even enough to shift a wattmeter above 0.0w.
For example, if you wanted to know what a HiCap really draws for itself, put the wattmeter on a HiCap that is connected to no other gear at all and turn it on. Any reading you get won’t be the transformer. It’ll be everything in the HiCap after the transformer.
I just drove my wife’s car round town in eco pro, I reckon I’ve offset this months power consumption…
You haven’t, but you could probably offset the power consumption of that journey by turning off your HiFi for a few years 
I guess mine uses about 100W. To put things in perspective a wash and tumble dry cost that. Cooking a meal using the oven about the same. Likewise the fridge and freezer which are large. Mostly LED lights now.
I can think of many wasteful things humans do that would make a bigger difference if they didn’t. I will probably add solar panel. I expect one day they will wack up the standing charges for those who don’t draw much electric from the grid!
As it is if I listen to music I’m probably not doing more wasteful things.
Phil
With an air source heat pump, an electric range oven, and an electric car, the hifi’s power consumption is the least of my worries 
ditto… 
in the freezing depths of Winter, we can ‘burn’ up to 65Kwh electricity per day…in the Summer this ‘reduces’ to around 15/20Kwh per day (car charging dependant)…keeping warm, cooking, & driving is getting expensive, with more to come I fear…(perhaps time to move ‘southward’ or emigrate…)
…meanwhile, enjoy the music, the Hi-Fi is left on 24/7…
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