ClassD amps

[Scott_Arm]

So, I just got a new smart hydro meter. That means I'm going to be billed at different rates, depending on the time of day. Peak hours will be more expensive and off hours will be less expensive.

I'm looking to improve my energy efficiency and one of the ways I'm thinking of doing this is switching my amplifier to a ClassD, if I can find something affordable , comparable and considerably more energy efficient. That means a sub $1K CAD amplifier.

Right now I'm using a Cambridge Audio 540A v1 (http://www.cambridgeaudio.com/suppo...ur 540A high performance integrated amplifier)

So I'm looking for something like 50 watts into 8 Ohms, >92dB signal to noise, reasonable THD and pretty flat frequency response. Please don't chime in about tubes, classA, ClassAB being better ... This is really something I want to do in terms of efficiency and space, as long as it's affordable. I'm also into minimalism. The less extra features I don't want, the better. I don't even care much about tonal controls for bass and treble. I pretty much always keep my amp on the direct mode to bypass the tonal controls.

Anyone have a suggestion? Most of what I see is geared to much higher end users or much lower end users. I saw Rotel sells power amps, but that gets too expensive. Esoteric has a really expensive ClassD integrated.

I have a CD player and a record player, but I have a phono pre-amp. I might even ditch the CD player and play my CDs from my computer. I could also sell the phono pre-amp for good coin if the amp had a good phono stage. My subwoofer is likely going to be sold.

The next thing to go after that will be my PC.

 

[MfA]

You could try to get a second hand Sunfire amp, it should be in the same range of energy efficiency (it's essentially a class D amp as a power supply feeding an AB amp).

If you are going hippy buying second hand should be a given anyway

 

[Scott_Arm]

You could try to get a second hand Sunfire amp, it should be in the same range of energy efficiency (it's essentially a class D amp as a power supply feeding an AB amp).

If you are going hippy buying second hand should be a given anyway

I took one look at the Sunfire website and all I could see was $$$$$$$$$ and was scared away.

 

[V3]

I thought the one you got there is already pretty energy efficient. Maybe what you want is more efficient loudspeakers. Try a front loaded horn, you can drive those with 5W Amp.

 

[Scott_Arm]

I thought the one you got there is already pretty energy efficient. Maybe what you want is more efficient loudspeakers. Try a front loaded horn, you can drive those with 5W Amp.

Mine is classAB. It takes 515watts to put 100watts out. Some of the ClassD amps could do 100watts out with maybe 120 watts in.

 

[V3]

In a scheme of thing I thought that's pretty good efficiency. Much better than class A amp. Well if you must go with Class D, how about PS Audio Trio C100 Integrated Amp ? I think its around your budget.

 

[Scott_Arm]

In a scheme of thing I thought that's pretty good efficiency. Much better than class A amp. Well if you must go with Class D, how about PS Audio Trio C100 Integrated Amp ? I think its around your budget.

It might be good for a classAB. Not sure. Much better than a pure ClassA, anyway.

That integrated amp looks nice, but it's a little out of my range. I think it'll be closer to the $2K CAD mark. I've found a few things, but most of them are higher power than I need and are $500-$1000 more expensive than I can afford.

I'm going to buy one of those little power meters that monitors kWh, so I can figure out what my stereo is actually costing me.

I'm not sure who else has smart metering, but the idea is they charge different rates on electricity during the day, based on how high the demand is. There is a schedule you can look at during winter or summer months that will tell you when the peak hours and off hours fall. Of course, most of my heavy use with entertainment equipment will fall into peak hours, so I will probably get billed higher than I did before. Previously they would take your total kWh and use some formula to guess what was at peak and what was off peak.

It's probably a good thing to be buying something more energy efficient anyway, as long as that something is within' my means.

 

[MfA]

I took one look at the Sunfire website and all I could see was $$$$$$$$$ and was scared away.

E-bay says some of the older models go for just shy of 1K$ on average second hand.

 

[WhiningKhan]

I'm going to buy one of those little power meters that monitors kWh, so I can figure out what my stereo is actually costing me.

Honestly, audio amp is not what I would be worried about first (or even at all) regarding energy consumption. Or do you actually listen to music with maxed volume for a significant time every day? I'm betting you will find a lot more energy spent by your PC than the audio equipment.

Those energy meters are quite useful, and cheap nowadays.

 

[Scott_Arm]

Honestly, audio amp is not what I would be worried about first (or even at all) regarding energy consumption. Or do you actually listen to music with maxed volume for a significant time every day? I'm betting you will find a lot more energy spent by your PC than the audio equipment.

Those energy meters are quite useful, and cheap nowadays.

You are exactly right. I got one of those meters today and checked out my amp.

Listening to music at my normal listening volume, which is fairly loud, my amp and CD player were drawing 50watts ... I was expecting much much higher. My amp is rated at 515 watts max, so I was sure I'd be over 100 watts at least. How the hell could you ever push this amp to 515? My subwoofer seems to use very little the way I have it balanced. I don't have it booming really hard. I have it balanced in for music, so I'm not really concerned about it. My PC seems to be less than 100 watts at idle and my monitor is around 60 watts.

 

[V3]

Average room size don't need to use that much power. But power need increases very very quickly as room gets larger or your listening distance from speakers increases. So I suppose you'll stick with your current rig ?

 

[WhiningKhan]

Listening to music at my normal listening volume, which is fairly loud, my amp and CD player were drawing 50watts ... I was expecting much much higher. My amp is rated at 515 watts max, so I was sure I'd be over 100 watts at least. How the hell could you ever push this amp to 515?

The dynamic range in music is large. If your _average_ output power from amp is 100 watts, it would be so damn loud that you couldn't be in the same room. Remember, typical sensitivity of loudspeakers is around 90dB at 1W input power, measured one meter away.

Then again, if the average output of amp is 1W, the short dynamic maxima in the music may still take tens of watts to reproduce without distortion. Audio amps need to be able to handle transient power, not that much sustained power.

 

[Jawed]

Listening to music at my normal listening volume, which is fairly loud, my amp and CD player were drawing 50watts

How much power when the system is playing as quietly as possible, literally so that you can barely hear music?

Jawed

 

[WhiningKhan]

How much power when the system is playing as quietly as possible, literally so that you can barely hear music?

Just to be a smartass before Scott_Arm answers: I would expect almost the same power usage, referring to what I wrote above.

 

[Scott_Arm]

Just to be a smartass before Scott_Arm answers: I would expect almost the same power usage, referring to what I wrote above.

I think you're right. I think it was 40-45 amps and my typical listening volume pushed it to around 50 amps. Right now I'm measuring my computer and LCD for the week. Once that is done, I can go back and measure some stuff on my stereo.

I switch my stereo right off with a power bar instead of just leaving everything on standby, so that's probably the biggest power saving I can get out of it.

The amount of power that those ClassD amps use must be insanely small for a user like myself.

 

[Gubbi]

The amount of power that those ClassD amps use must be insanely small for a user like myself.

If you're only using 40-50watts for the entire stereo (amp+CD player), you're only seing 15-20 watts in each channel. Your amp is rated for 525 watts (~250 in each channel), probably with a 4 ohm load. This gives a rail to rail supply voltage of ~33 volts.

If you're using 8 ohm speakers, this means that only 3.5-5 watts per channel goes into the speaker, the remaing 11.5-15 watts/channel is wasted as heat in the amplifier.

If you have speakers with a decent 90dB/W sensitivity this gives a sound pressure of 96dB at one meter, - quite loud (remember the human ear perceives sound volume logarithmicly).

Assuming a class AB amplifier.

For a class D ("digital") amp, you'd spend 4-5 watts per channel.

Cheers

 

[Gubbi]

How much power when the system is playing as quietly as possible, literally so that you can barely hear music?

At -50dB (quiet, but still audible) or 0.002 watts , the current draw would be 15.8 miliamps, so you spend ~0.5watt in the amplifier for the 0.002 watts in the speakers. - Per channel

Cheers

 

[Scott_Arm]

If you're only using 40-50watts for the entire stereo (amp+CD player), you're only seing 15-20 watts in each channel. Your amp is rated for 525 watts (~250 in each channel), probably with a 4 ohm load. This gives a rail to rail supply voltage of ~33 volts.

The speaker is rated at 50 watts (rms) per channel into 8 Ohm. The 515 watts is the maximum power consumption rated for the amp.

Oh, and it is class AB, which is a lot more efficient than I thought it was (up to 78% from http://en.wikipedia.org/wiki/Electronic_amplifier#Class_B_and_AB)