Denon AVR measured power not making sense

[siggen]

This is a cross post from another thread (probably posted in wrong thread. I am not sure how to edit/remove it )

I measured power usage with a kill a watt meter on my Denon x4300H. 90 watt without music, up to about 125 watt at 75dBSPL at MLP (using a calibrated Umik-1 + REW SPL Meter). So about 35 watts into 2.0 out into 90dB efficient speakers at 14 feet. Playing with peaks to 80+ dBSPL. This is unexpected, because the hometheater SPL meter page indicates much less power needed for this SPL. What am I doing wrong? This post here seems to measure similar numbers at similar settings - https://audiosciencereview.com/foru...23-stereo-amplifier-review.45462/post-1621869


Of course, this also did not explain why the Denon's volume goes up from setting of 65 at this measuring level to 98. It cannot possibly produce even 10 dB more power. How do I make sense of this?

 

[DVDdoug]

I think you are assuming that all of the additional power consumption is going to the speakers. That's not necessarily the case. Usually an amplifier heats-up with more output to the speakers, indicating that more power is being wasted as heat when the volume is turned-up.

Of course, this also did not explain why the Denon's volume goes up from setting of 65 at this measuring level to 98. It cannot possibly produce even 10 dB more power.

The power coming-out depends on the input signal, volume control setting, and the gain of the amplifier. It's possible that you have a "weak" signal coming-in (or a low digital level).

 

[siggen]

Input is from an Nvidia Shield HDMI into the Denon AVR. I assume its "full" range from there. Volume set to 65 (out of 98).

 

[AwesomeSauce2015]

I think you are assuming that all of the additional power consumption is going to the speakers. That's not necessarily the case. Usually an amplifier heats-up with more output to the speakers, indicating that more power is being wasted as heat when the volume is turned-up.

I'm not even going to start on the signal level issues, as that could be any number of things...

However, I will mention a few things:
1. Measuring SPL levels is always tricky, peak vs average, weighting, etc, all play into the number you see. For example, I wouldn't use a long-averaging, A-weighted meter to measure the volume of a kick drum. -- So basically, it is possible that there is actually much more sound energy than your measurement indicates.

2. Speaker sensitivity: Speakers aren't just "90db efficient". Chances are, the speakers you have can't put out 90db with 1 watt of input power in the bass region. Additionally, room gain will mess with this.

3. Amplifier inefficiency: You have an old receiver, which also has a bunch of amp sections in it, as well as a bunch of other hardware for video and audio processing. All of these will add up to higher idle power draw, as well as inefficiency when you turn it up. -- This could partially explain why you see a 35 watt increase when you play music. -- Denon quotes the idle power draw as 110w.

4. Amplifier volume settings: Unless the volume control is given in DB increments, like on many modern receivers, there is no guarantee that it is a linear control, or that it corresponds to any specific SPL values. If your receiver has an auto-calibration system, I would encourage you to run it as it should calibrate the speaker levels.

5. You can't really measure amplifier power from the wall, music has peaks which will be absorbed by the amp's power supply, and various inefficiencies in the unit will lead to weird readings. For example, I had an onkyo amp which would pull 30w just by turning it on, and since I barely used it (desk setup), the reading never changed. In that setup, my computer & two monitors were by far the biggest power draw...

So my point is that if your speakers are actually good speakers, and the receiver isn't broken, you probably have a good amount of amp power. In my parents' house, they have a pair of Q950s in their living room (with a couple SB-2000 subs), powered by a yamaha RX-V6A (Because it works with musiccast, and has good power), We can hit 110DB-C on a peak meter, and the system is comfortable at around 100db-C, though my ears (and the neighbors) aren't! This is a big living room + kitchen open floor plan.

 

[VintageFlanker]

I think you are assuming that all of the additional power consumption is going to the speakers. That's not necessarily the case

Correction : that's absolutely not the case.

 

[delta76]

This is a cross post from another thread (probably posted in wrong thread. I am not sure how to edit/remove it )

I measured power usage with a kill a watt meter on my Denon x4300H. 90 watt without music, up to about 125 watt at 75dBSPL at MLP (using a calibrated Umik-1 + REW SPL Meter). So about 35 watts into 2.0 out into 90dB efficient speakers at 14 feet. Playing with peaks to 80+ dBSPL. This is unexpected, because the hometheater SPL meter page indicates much less power needed for this SPL. What am I doing wrong? This post here seems to measure similar numbers at similar settings - https://audiosciencereview.com/foru...23-stereo-amplifier-review.45462/post-1621869


Of course, this also did not explain why the Denon's volume goes up from setting of 65 at this measuring level to 98. It cannot possibly produce even 10 dB more power. How do I make sense of this?

very strange. I have had to Denon X AVR (3400 and now 4700), and measuring is quite similar
- Idle for 3400 is 73w, 4700 is 83w
- Playing at reasonably loud volume, increased to 74w and 84w. note that the power plug has accuracy of 1w so actually might be less.

mine is tower speaker with relatively high sensitivity (92.5dB/W/m), but they draw only 1w or less (stereo) to produce >= 80dB

 

[siggen]

Thanks, sounds reasonable. I would like to try out a good, clean 200+ watt amp to compare if there any obvious improvements, if the Denon is lacking power.

 

[siggen]

very strange. I have had to Denon X AVR (3400 and now 4700), and measuring is quite similar
- Idle for 3400 is 73w, 4700 is 83w
- Playing at reasonably loud volume, increased to 74w and 84w. note that the power plug has accuracy of 1w so actually might be less.

mine is tower speaker with relatively high sensitivity (92.5dB/W/m), but they draw only 1w or less (stereo) to produce >= 80dB

I have the b&w 803d4. This is in 2 channel mode, sub off. 14 feet distance. I tried this with both my Denon and my emotiva xpa-3 gen 1, and both shows about 30 odd wats of power increase over idle. This is to get 75 to 80 dBSPL. My room also opens to a kitchen and then to adjoining large room.