[landofshane]

Hi everyone.

Can anyone help me understand what the power usage of a class D amp would be when there is no input signal?

I know it's not directly a headphone question, but I'm hoping some smart DIYers here may happen to know this stuff

Background:
* I'm running a squeezebox system and want to add more zones.
* I've ordered a class D 15w mini circuit board to experiment with whether it'll do what I need.
* Being a bare component board, there's no power on/off.
* I can use the sqezebox to adjust volume/power instead, but that would mean leaving the amp on all the time.

Having looked through the basic Class D schematics I'm confused as to how efficient they are when there is no input signal. It looks as though everything up to the low pass filter would keep operating even if there is no input.

Am I right in thinking that the power usage of these parts would be absolutely minimal and not worth worrying about and the power usage would only really start when a signal is present to amplify?

I know that as a 15w amp the power usage will be minimal anyway, but if this setup works then I'll probably get a few and also of larger sizes for outdoor speakers.

Thanks for the guidance.

 

[FallenAngel]

From what I've read, Class D has a higher power usage than Class AB amps when idling.
 
They're super efficient and can output a lot of watts with little heat and not a lot of input power but it's not like they're some magical device that breaks the fundamental laws of physics. You need electricity to power the circuit and amplify a signal.
 
I would suggest you find a way to control the on/off switch instead of worrying about how much power an amplifier that runs 24/7 consumes. This just sounds like poor planning.

 

[landofshane]

I wouldn't say poor planning - more cost/benefit.
 
If it's milliamps in standby and runs 16 hours a day, then the power consumption over a year at 8 hrs standby a day is going to be suitably low enough to make automating a power routine not worth it (at that low usage level I'll just use a simple timer plug rather than anything 'smart'')

 

[FallenAngel]

Please don't take my comment as rude, that was not my intention in the slightest.
 
Coming from a science background and being an avid DIYer, my reasoning is that all components that are not used should be turned off. I think it's more of a philosophy than issue of electricity bill. Perhaps the fact that basically all electrical components have a usage lifetime may be considered, but it's not something I generally think about either.
 
Having a classical "hacker" mentality, I think the simplest solution that works is the way to go. If it's stupid but it works, it's not stupid. Have you looked into a way to switch on your amp when you plan to use it? My first thought was to see if you can do that using the squeezebox remote, though I came up with a super cheap alternative that might be even better after giving it some thought. What about wiring up your wall socket that you plug this amp into to your light switch for the room or separate switch, depending on your preference? You mentioned looking at an outdoor system as well. A simple light switch on the wall that powers the wall socket would be very simple. When there's light in the room, the socket is on and your amp is running. When you leave the room, just flip the light switch to turn it off.
 
I have some experience doing this myself as I installed a new light in my living room for reading. Switches are a couple of dollars and installation is about as basic as it gets. Just don't make any assumptions of what else is connected to that wire. Make sure you're only adding a switch for that single outlet and not half of your house.
 
Good luck and let us know what you decide as well as what you find out about the idle current of your amp. It sounds like information everyone would appreciate.

 

[landofshane]

No offense was taken - I wouldn't have asked the question if I hadn't been thinking about options so all perspectives are good!
 
 
The initial testing of the amp (arrived yesterday) confirmed I'm probably going to need 2-3 amps so I'll need to sort a power solution...
 
For the interim solution I've set it up on an remote RF power plug with a raspberrypi as the audio source. The Pi is running PiCorePlayer which runs in memory so can be hard power cycled with no issues, it's also set to resume playing on powering up.
 
It's working quite nicely - turn it on with the remote and the amp powers up and the pi starts playing. The only downside being the 30sec boot time, but that's not a biggie.
 
Longer term (when the other amps arrive) I'll probably add my Arcam amp into the setup and then use it's 12v trigger to switch a relay.

 

[FallenAngel]

Yeah, that was my first idea, remote through the control unit. I thought you were looking for something very simple. Had I known you were capable to link power-up using the Raspberry, I would have suggested that first.
 
Anyway, sounds good and good luck. I was a little proud of myself for thinking up the light switch idea and I'll be implementing that on my brother's deck that I helped him build and wire electrically. We already have lighting using a switch both inside and out, so an audio system that links up to that would be cool.

 

[Dirt McGirt]

Not scientific, but I have Hypex NC400 home audio amps, Class D. It is recommended to always leave them idling. I have and have not noticed any change in home electricity usage. Compare this to the Class A amp they replaced that would flicker the lights when turned on and sufficiently heat the room in the winter..,