I have a 2A 12v walwart power supply using to power a 2x50W RMS amplifier TPA31162D (voltage range from 5v to 26v)
running some bookshelf style speakers. I used a multimeter to measure the current and voltage to calculate the watts RMS to the speakers and both speakers are each using about 20W at maximum volume with some distortion
but the power supply's maximum is only 24W where are the extra watts coming from? is it from the capacitors in the amplifier using stored energy between each cycle of the sinewave? is it the power supply being underrated?
I did have a 1A 12v power supply previously but it would cut out and restart if the volume was too high. just right as it reaches the point where it just barely starts to distort.
but with the 12v 2A power supply I have it I can turn the volume all the way up and it distorts and doesnt cut off at all.
its a class D type amplifier that uses about 50 to 150mA of idle current (uses more idle watts when inputting higher voltage to it. since the voltage is higher but the idle curent is about the same. it makes the heatsink warm up but it doesnt get overly hot at 24v. just fairly warm. it doesnt instantly burn my finger if I touch it. it just gets uncomfortable after a few seconds of grabbing the heatsink)
the inductors are the thing that gets the hottest at 24v.
but at 12v the heatsink and inductors are stone cold even at maximum volume so I just prefer it to run at 12v. it outputs plenty enough volume and loudness at 12v 2A anyways. plenty loud enough volume
running some bookshelf style speakers. I used a multimeter to measure the current and voltage to calculate the watts RMS to the speakers and both speakers are each using about 20W at maximum volume with some distortion
but the power supply's maximum is only 24W where are the extra watts coming from? is it from the capacitors in the amplifier using stored energy between each cycle of the sinewave? is it the power supply being underrated?
I did have a 1A 12v power supply previously but it would cut out and restart if the volume was too high. just right as it reaches the point where it just barely starts to distort.
but with the 12v 2A power supply I have it I can turn the volume all the way up and it distorts and doesnt cut off at all.
its a class D type amplifier that uses about 50 to 150mA of idle current (uses more idle watts when inputting higher voltage to it. since the voltage is higher but the idle curent is about the same. it makes the heatsink warm up but it doesnt get overly hot at 24v. just fairly warm. it doesnt instantly burn my finger if I touch it. it just gets uncomfortable after a few seconds of grabbing the heatsink)
the inductors are the thing that gets the hottest at 24v.
but at 12v the heatsink and inductors are stone cold even at maximum volume so I just prefer it to run at 12v. it outputs plenty enough volume and loudness at 12v 2A anyways. plenty loud enough volume
Multimeters can only reliably measure sine waves at low frequencies, so your measurements might be off. Note that the TPA3116D2 only does 2x 11 W at 4 ohms with a 12 V supply. Other than that, music has a lower crest factor than sine waves.
The high heat sink temperature is because most of such amplifier boards have undersized heat sinks, which is okay if you do not crank it.
The high heat sink temperature is because most of such amplifier boards have undersized heat sinks, which is okay if you do not crank it.
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I played a variety of frequencies between 10hz and 100hz and the voltage reading stays about the same.
my multimeter is true RMS for AC range
the 11W reading must be with no distortion because it for sure puts out more than 11 watts per channel at full volume with distortion/clipping.
it'd make my old 30 RMS 120W peak 4" speakers dustcaps get quite warm at max volume with no distortion.
my new speakers have much better cooling. vented pole piece and bigger motor structure and coil and they are rated 40W RMS 80W peak and they dont even get warm after 20 minutes of sinewave frequency sweeps and tones at full volume no distortion.
my multimeter is true RMS for AC range
the 11W reading must be with no distortion because it for sure puts out more than 11 watts per channel at full volume with distortion/clipping.
it'd make my old 30 RMS 120W peak 4" speakers dustcaps get quite warm at max volume with no distortion.
my new speakers have much better cooling. vented pole piece and bigger motor structure and coil and they are rated 40W RMS 80W peak and they dont even get warm after 20 minutes of sinewave frequency sweeps and tones at full volume no distortion.
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Let's assume the principal rule of thermodynamic still apply: no more energy leaves a system than what enters the system. And, normally less due to losses in the system.
You have a rather simple setup with a DC power source and two AC outputs. If you really want to know, you need more multimeters to measure the input voltage and input current simultaneously together with at least the AC voltage on the loads.
The power supply may give more than 2A at least for a while. If rated correctly, the 2A are continuously.
You measure the voltage and current for each speaker but if the voltage and current are not in phase you get a wrong power calculation. Try with resistive dummy loads instead.
Though a suffering world need miracles like this, my classical education tells me to be skeptical.
You have a rather simple setup with a DC power source and two AC outputs. If you really want to know, you need more multimeters to measure the input voltage and input current simultaneously together with at least the AC voltage on the loads.
The power supply may give more than 2A at least for a while. If rated correctly, the 2A are continuously.
You measure the voltage and current for each speaker but if the voltage and current are not in phase you get a wrong power calculation. Try with resistive dummy loads instead.
Though a suffering world need miracles like this, my classical education tells me to be skeptical.
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I measured 3.1 amps on the power supply and 11.9v DC at the power supply input while running maximum sinewave at full volume. and i sweeped through the sinewave find where it uses the most current.
maybe the amplifiers big dual 8800uF capacitors could be helping keep the power up?
maybe the amplifiers big dual 8800uF capacitors could be helping keep the power up?
The 2x8800uF can keep the power up for transients but not for longer periods (>1Sec.).
11.9V times 3.1A is almost 37W. We are approaching an understanding.
Could the discrepancy be due to phase differences between the load voltage and current? If they are not in phase you overestimate the power loss.
11.9V times 3.1A is almost 37W. We are approaching an understanding.
Could the discrepancy be due to phase differences between the load voltage and current? If they are not in phase you overestimate the power loss.
no idea. i just think its weird that im getting the readings that I am from my speakers. compared to what the power supply is capable of.
I evidently trust your DC measurements on the power supply. 37W from a 24W supply, not bad.
It is more difficult to measure the power consumption with an AC signal because it on top of voltage and current includes the phase angle. You cannot do that measurement with just normal multimeters. With a purely resistive load it is simple because the phase difference is zero.
I believe this to be the reason for your surprising results. We can assume the laws of thermodynamics to work a little longer.
It is more difficult to measure the power consumption with an AC signal because it on top of voltage and current includes the phase angle. You cannot do that measurement with just normal multimeters. With a purely resistive load it is simple because the phase difference is zero.
I believe this to be the reason for your surprising results. We can assume the laws of thermodynamics to work a little longer.
Dear FauxFrench, I suggest you don´t waste time here.
User realflow100 is widely known for posting trick questions to induce other members get into endless threads, in good faith of course, trying to explain his impossible data.
Why does it happen over and over and over?
Don´t know, there´s a label which explains this kind of provocative postings but out of courtesy I won´t use it.
Just for your information, here´s a brief sampling of earlier posts ... and I am just skimming the surface:
* Can a car amplifier run off of a 9 volt battery?
Could a 9 volt battery even turn on a small car amplifier? (one that's less than 300 watts) Full brand new alkaline 9v's not the rechargeable kind
I got a 9.6v type 9v LSD NIMH battery now.
its 230mAh but quite durable giving out over 6 amps if shorted and easily sustaining an amp or two without heating up.
* Can you have a strand of wire so thin it wont burn out?
* Tweeter making a faint hiss with no wires plugged into it?
somehow the tweeter is getting electricity to make white noise faintly.
and there is absolutely no amplifier plugged into the speaker or the tweeter. completely unplugged from any possible power source.
* thermal conductivity of duck tape/duct tape?
* 12v 5AH powersonic F1 + 6x500F super capacitors jump vehicle?
and not any vehicle but: "our dodge ram V8 2500 gas truck"
and so on and on and on.
Oh well.
I dont know what you mean by trick questions but thats a load of hogwash.
I just asked a question. and want a simple answer. thats all.
thread closed
I just asked a question. and want a simple answer. thats all.
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