You Know What I Never Understood About Those Amps with VU Meters?

AnzacSonata

Super Member
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It seems whenever I've seen one in action, like at a trade show or such, the meters never really seem to "match" the output of what we're hearing....

For example, the meters can bounce along with the input it's receiving while claiming the amp is putting out, say, 100 watts per channel...but the audio won't SOUND all that powerful during real world listening at that level...it's like, the meters are "telling" me one thing but the system is saying something else...

Unless I'm looking at this the wrong way; are these things calibrated in a certain method to account for the mismatch I've always experienced with these power amps?
 
Like this Onkyo:


It seems whenever I've seen one in action, like at a trade show or such, the meters never really seem to "match" the output of what we're hearing....

For example, the meters can bounce along with the input it's receiving while claiming the amp is putting out, say, 100 watts per channel...but the audio won't SOUND all that powerful during real world listening at that level...it's like, the meters are "telling" me one thing but the system is saying something else...

Unless I'm looking at this the wrong way; are these things calibrated in a certain method to account for the mismatch I've always experienced with these power amps?

Peaks of 100watts are not the same thing as 100watts continuous.
 
It seems whenever I've seen one in action, like at a trade show or such, the meters never really seem to "match" the output of what we're hearing....

For example, the meters can bounce along with the input it's receiving while claiming the amp is putting out, say, 100 watts per channel...but the audio won't SOUND all that powerful during real world listening at that level
So what does a 100 watts sound like? or I should say how loud do you think a 100 watts sounds like?
 
That all depends on the speaker and the room the speaker is in.

Our ears generally aren't sensitive to less then 3 db increase/decrease, and generally speaking, a 10 db increase is perceived by our ears as doubling the volume.
doubling in volume requires 10 X the power, so if ten watts is 70 db (I'm totally making these numbers up, but the math is correct) then 100 watts would be 80 db, a percieved doubling in sound.
To double perceptually the volume again, were the loudspeaker capable of it, would require 1000 watts. Herin is likely why the power consumption doesn't match what your ears are experiencing, they are not linear.

Also, those dials are notorious for being inaccurate, and possibly delayed vs what you're hearing at the moment.

HTH.
 
... and watts isn't necessarily all about volume ... it's about control. Starting drivers moving is easy - stopping them at that exact moment when a note achieves perfection can take a lot more power. Ohmmmmmmmm ...

Oh ... and they're not VU meters ... they're power meters.

EDIT >>

My bad ... the Onkyo DOES have VU scale and a button to select it. I'll go to my room now. <G>
 
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On the power level meters on my Kenwood 700M and I suspect many others too have a range, such as -20db, -10db etc. My amplifier has a RMS rating of 170 watts per channel. When the meter range is set to 0db and the meters are at 0db it is putting out 170wpc. At -10db meter range with the meters saying 0db it is putting out 17 watts per, and at -20 range it is 1.7wpc.
 
Using my Pioneer SX-1280 as an example. Turn off the speakers and turn up some good loud music and the meters are bouncing away. They are not showing you anything about how much power is going to your speaker. A lot of meters on stereo equipment are just there for show and have nothing to do with power arriving at your speakers. It is all a scam,LOL. :mad:
 
Meters are mechanical devices. They cannot possibly move fast enough to show instantaneous power, like LED indicators can. So, the designer will pick one of a couple of different ways to show what power is being delivered to the speakers:
  1. Average or RMS power: This is where what you hear is likely represented best by the meters, but peaks will not be seen.
  2. Peak hold: This is where peaks are seen, and the meters are driven to the peak and held there for a long enough time for eyes to see it. Here, average power will be significantly less than what the meters show (for dynamic passages), but you will know when the amp is putting out all it can without distortion. The Pioneer SPEC amps use this method.
LED meters generally let you choose the display method, or a composite, where average/RMS is displayed by the continuous bars, and one LED is held on for a period to show peaks. I believe the Yamaha M series power amps give this kind of choice.

Note that if the signal is a steady tone, peak and RMS/average indications will be the same. Their indications diverge more and more as output becomes more dynamic and complex.

Enjoy,
Rich P
 
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...and then there's the meters on my Sunfire series 2, which show Joules and never move at all unless something is broken.
 
All I know is the old bait caster in the turntable tweak thread assured us all over and over again that we should just trust the engineers and that everything is fine and can't be improved. So don't be a doubter. :biggrin:
 
There was a transition in the late 70's when Meters and LED's were used together, best of both worlds
for those seeking bling and accurate indications.

One well executed example being the Luxman M-6000 and M-4000.

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Using my Pioneer SX-1280 as an example. Turn off the speakers and turn up some good loud music and the meters are bouncing away. They are not showing you anything about how much power is going to your speaker. A lot of meters on stereo equipment are just there for show and have nothing to do with power arriving at your speakers. It is all a scam,LOL. :mad:
Maybe not a total scam.. just because it obviously isn't reading actual watts to the speaker. Pioneer could easily calculate and design a meter to closely approximate watts used because it was an integrated design (no separate preamp) that when the volume knob is set at 10 o'clock or 2 it would be putting out a certain power based (i'm speculating now) on the varying signal strength from whichever input source is being used at the time. So really probably not much difference in true functionality from mine which has meters that read actual watts used, and so when the speakers are switched off the meters stop.
 
I always thought meters were there to mostly look cool.
And cool they do look.
It does mostly do that, but it does give an indication too. I have new LF drivers that dig much deeper than the old ones, and with that there is quite a bit more meter motion on the really deep 25-30hz stuff. That takes considerably more power to deliver and my meters show it is the case. Other than that I never look at them when listening to music.
 
The issue is that with a high or low efficiency, or a high or low impedance speaker, the meter should be reflecting the various load differences, but they are not. They do indeed just look cool.
 
The issue is that with a high or low efficiency, or a high or low impedance speaker, the meter should be reflecting the various load differences, but they are not. They do indeed just look cool.
I agree with impedance, but I wouldn't think that speaker efficiency would have an effect on power output. Take 2 sets of speakers, both 8 ohms and put the efficient pair on speaker A and the inefficient ones on B. Switching between A and B isn't going to effect the watts being produced, just the spl..
 
Here's a brief description of the MC1201's accurate meters. They do lots more than look cool. They serve a purpose that can be seen from across the room even with these old eyes

If the impedance is lower, the output current and power are higher. "Since McIntosh cannot control other manufacturers' speakers, we decided to provide extra output current to drive these mismatched low impedances and to indicate the real output power required to drive them. Therefore the meter circuit in the MC1201 electronically measures both voltage and current, multiplies them, and displays the real output power in watts."
The meter uses a circuit that accelerates the pointer movement. When the pointer reaches its peak excursion, "it pauses only long enough for the human eye to perceive its position, then drops." Fish proudly asserted that the pointer's operation is almost 10 times as fast as a professional VU meter. Another feature of this stupendously large meter is its ability to respond "95% full scale to a single-cycle tone burst at 2kHz." What you see is what you get!
 
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