What is the meaning of amplifier & Speaker Power ?

[allofficialmail@yahoo.com]

Say a speaker and an amplifier specs says that maximum permissible power that it can handle is 100 Watts @ 6 Ohms.

Is that mean :

1- When the volume level is gradually increased from 0 to 100%, Power will also gradually increase (from 0 to 100 watt) that reaches to the speaker.

25 % Volume - 25 Watt @ 6 Ohms
50 % Volume - 50 Watt @ 6 Ohms
75% Volume - 75 Watt @ 6 Ohms
100 % Volume - 100 Watt @ 6 Ohms

2- When Volume level is Low or moderate (say@50%) that time Power which source to the Speaker is in terms of continuous Power or RMS Power ?

3- When volume level is Max (100%) that time power which is source to Speaker PMPO (Peak power) not RMS Continuous power ?

Thanks.

 

[Fantastic]

The volume control, controls the voltage levels. Power is voltage squared divided by speaker impedance. So it isn't a direct indication of power.
Amps don't GIVE power to speakers . The speaker 'DRAWS' power from the amp ! How much it draws depends on the speaker impedance.

Music is NOT a continuous signal. It's varying continuously in level and hence in power. Typical listening levels could be 1 or 2 watts average. But peaks could be 10 times higher like percussion sounds like drums etc.
The volume control position while it controls the volume level cannot be construed as 25 % power at 25 % position. It depends on the level of the signal at the input of the amp.
For example if one DAC gives an output of 1 volt at max output and another DAC gives 2 volts at max output , bot connected to the amp , the volume level at the same physical setting will be different for both DAC's. It does not mean that one DAC is better than the other because of the 'volume' difference at one setting.
It's a fallacy to think that max volume is max output. You could reach max output even at 50% rotation if your input signal from the source is high !

Some people compare amps by referring to their volume control position. That's rubbish. It all depends on the amplifiers internal gain and the input signal level at the amp. This varies greatly from system to system and so the volume control position is not indicative of anything significant about the system. If the volume control has to be turned a lot it just means the input signal level is not very high for that amp.

 

[raghupb]

The volume control, controls the voltage levels. Power is voltage squared divided by speaker impedance. So it isn't a direct indication of power.
Amps don't GIVE power to speakers . The speaker 'DRAWS' power from the amp ! How much it draws depends on the speaker impedance.

Music is NOT a continuous signal. It's varying continuously in level and hence in power. Typical listening levels could be 1 or 2 watts average. But peaks could be 10 times higher like percussion sounds like drums etc.
The volume control position while it controls the volume level cannot be construed as 25 % power at 25 % position. It depends on the level of the signal at the input of the amp.
For example if one DAC gives an output of 1 volt at max output and another DAC gives 2 volts at max output , bot connected to the amp , the volume level at the same physical setting will be different for both DAC's. It does not mean that one DAC is better than the other because of the 'volume' difference at one setting.
It's a fallacy to think that max volume is max output. You could reach max output even at 50% rotation if your input signal from the source is high !

Some people compare amps by referring to their volume control position. That's rubbish. It all depends on the amplifiers internal gain and the input signal level at the amp. This varies greatly from system to system and so the volume control position is not indicative of anything significant about the system. If the volume control has to be turned a lot it just means the input signal level is not very high for that amp.

Fantastic has explained it very well. Volume is not an indication of how much power is being drawn.
Also since sound pressure level and gain are measured in dB, the system is non-linear from a mathematical perspective.

Typically in an all analog system, Volume control is deciding the voltage level at power amp input; by extension the voltage level at preamp output.
Gain of an amplifier is usually fixed by design to say somewhere between 24 - 30dB. This is voltage gain as the amp is working on voltage input.

Assume that the power amp is designed with a gain of 27dB; this means it will amplify the input voltage by a factor of ~22.
Another important number is the power amp's sensitivity; this is the voltage it needs to see at its input to give full output (normally in the 1.5-2V range)
Note this has nothing to do with the preamp inputs' sensitivity (normally in 100-300mV range for regular non-phono inputs)

Here is how the system works:
- preamp takes a line voltage (usually a fixed value) and prepares the signal for power amplification; one can call it the preparation amp
- volume control tracks the input signal and keeps it within the max input of power amp
- in a box with both pre and power amps the design will take care of staying well within limits
- power amp presents an amplified signal to the speaker (voltage V)
- speaker will present an impedance to the voltage (simplified to resistance R)
- current required to sustain the voltage is is sourced by the power supply of the unit (simplified by I = V/R)
- if the power supply cannot source the required current, the power amp's voltage is clipped; this is when bad things start to happen

Cheers,
Raghu

 

[allofficialmail@yahoo.com]

Fantastic has explained it very well. Volume is not an indication of how much power is being drawn.
Also since sound pressure level and gain are measured in dB, the system is non-linear from a mathematical perspective.

Typically in an all analog system, Volume control is deciding the voltage level at power amp input; by extension the voltage level at preamp output.
Gain of an amplifier is usually fixed by design to say somewhere between 24 - 30dB. This is voltage gain as the amp is working on voltage input.

Assume that the power amp is designed with a gain of 27dB; this means it will amplify the input voltage by a factor of ~22.
Another important number is the power amp's sensitivity; this is the voltage it needs to see at its input to give full output (normally in the 1.5-2V range)
Note this has nothing to do with the preamp inputs' sensitivity (normally in 100-300mV range for regular non-phono inputs)

Here is how the system works:
- preamp takes a line voltage (usually a fixed value) and prepares the signal for power amplification; one can call it the preparation amp
- volume control tracks the input signal and keeps it within the max input of power amp
- in a box with both pre and power amps the design will take care of staying well within limits
- power amp presents an amplified signal to the speaker (voltage V)
- speaker will present an impedance to the voltage (simplified to resistance R)
- current required to sustain the voltage is is sourced by the power supply of the unit (simplified by I = V/R)
- if the power supply cannot source the required current, the power amp's voltage is clipped; this is when bad things start to happen

Cheers,
Raghu

-----------------------------
Dear Mr. Raghu,
I am an Electrical Engineer. I know about I (Current), Voltage (V), R (Resistance or Impedance), W Power terminology.

But I don't have practical knowledge about a Power Amplifier. I had studied about it (in subject Analog Electronics) during my Engineering.

Now I am planning to buy a starting range Home-theater (5.1) unit for my home use. Now I started digging about it but it is quite hard to recall those which I studied in Engineering long back.

I know that Current = Voltage/Resistance
Power = Voltage x Load current
I know Speaker Impedance R in Ohms & Amplifier's Power output P in Watts. Now as per the equation (I=V/R) & V & I are unknown.

This is true that, if the power supply cannot source the required current, the power amp's voltage is clipped; this is when bad things start to happen

How to choose the right Matching Speaker for an Amplifier?
How do I know that the maximum current the speaker will draw can be source smoothly by the amplifier?

For an Example: I have shortlisted

Yamaha Bookshelf speaker (NS-PA150, 5 Channels Speaker Package)

NS-PA150 - Speaker Packages - Yamaha - India

Center Speaker:
Two 8cm cone woofers and 1.4cm balanced dome tweeter
Frequency Response 65 Hz38 kHz
Nominal Input Power 30 W
Maximum Input Power 80 W
Sensitivity 86 dB/2.83 V/1 m
Impedance 6 ohms

Rest all speakers (Surround & Front L/R Speakers)
8cm cone woofer and 1.4cm balanced dome tweeter
Frequency Response 60 Hz38 kHz
Nominal Input Power 20 W
Maximum Input Power 60 W
Sensitivity 82 dB/2.83 V/1 m
Impedance 6 ohms

Amplifier model Pioneer VSX-329 5.1 channel
http://www.pioneer-audiovisual.eu/sites/default/files/datasheets/english/VSX-329.pdf

5 Channel
Amplification type: Direct Energy
105 W/Ch (@6 Ohms 1 kHz THD 1% 1 Ch Driven)

Subwoofer:
YST-SW030 - Subwoofers - Yamaha - India

Dynamic Power: 130 W
Frequency Response: 28 -200 Hz
Down firing, front Port.

Mr. Raghu, can please suggest me, this Pioneer Amplifier and Yamaha speaker can be good choice to choose like they are made for each other.
Are they good matching.


It is be so kind of you if you give suggestion.

Thank you.

 

[afj]

-----------------------------
Dear Mr. Raghu,
I am an Electrical Engineer. I know about I (Current), Voltage (V), R (Resistance or Impedance), W Power terminology.

But I don't have practical knowledge about a Power Amplifier. I had studied about it (in subject Analog Electronics) during my Engineering.

Now I am planning to buy a starting range Home-theater (5.1) unit for my home use. Now I started digging about it but it is quite hard to recall those which I studied in Engineering long back.

I know that Current = Voltage/Resistance
Power = Voltage x Load current
I know Speaker Impedance R in Ohms & Amplifier's Power output P in Watts. Now as per the equation (I=V/R) & V & I are unknown.

This is true that, if the power supply cannot source the required current, the power amp's voltage is clipped; this is when bad things start to happen

How to choose the right Matching Speaker for an Amplifier?
How do I know that the maximum current the speaker will draw can be source smoothly by the amplifier?

For an Example: I have shortlisted

Yamaha Bookshelf speaker (NS-PA150, 5 Channels Speaker Package)

NS-PA150 - Speaker Packages - Yamaha - India

Center Speaker:
Two 8cm cone woofers and 1.4cm balanced dome tweeter
Frequency Response 65 Hz38 kHz
Nominal Input Power 30 W
Maximum Input Power 80 W
Sensitivity 86 dB/2.83 V/1 m
Impedance 6 ohms

Rest all speakers (Surround & Front L/R Speakers)
8cm cone woofer and 1.4cm balanced dome tweeter
Frequency Response 60 Hz38 kHz
Nominal Input Power 20 W
Maximum Input Power 60 W
Sensitivity 82 dB/2.83 V/1 m
Impedance 6 ohms

Amplifier model Pioneer VSX-329 5.1 channel
http://www.pioneer-audiovisual.eu/sites/default/files/datasheets/english/VSX-329.pdf

5 Channel
Amplification type: Direct Energy
105 W/Ch (@6 Ohms 1 kHz THD 1% 1 Ch Driven)

Subwoofer:
YST-SW030 - Subwoofers - Yamaha - India

Dynamic Power: 130 W
Frequency Response: 28 -200 Hz
Down firing, front Port.

Mr. Raghu, can please suggest me, this Pioneer Amplifier and Yamaha speaker can be good choice to choose like they are made for each other.
Are they good matching.


It is be so kind of you if you give suggestion.

Thank you.

you should use specifications only as a guideline in matching your setup, and its not the be all and end all. products with exactly the same specs will differ not only in performance, but also and mainly in sound quality. generally when i pair my setup, i always take an amplifier that is of 10-30% higher wattage than the continuous output rms wattage of the speaker. since the amplifier starts distorting the SQ as it reaches closer to maximum output. so from your specs, they do seem a decent match. from a sound quality point of view, i would rather go with a yamaha amplifier rather than a pioneer. also chances are it will be a better match with the yamaha speakers, esp if youre buying without auditioning

 

[allofficialmail@yahoo.com]

you should use specifications only as a guideline in matching your setup, and its not the be all and end all. products with exactly the same specs will differ not only in performance, but also and mainly in sound quality. generally when i pair my setup, i always take an amplifier that is of 10-30% higher wattage than the continuous output rms wattage of the speaker. since the amplifier starts distorting the SQ as it reaches closer to maximum output. so from your specs, they do seem a decent match. from a sound quality point of view, i would rather go with a yamaha amplifier rather than a pioneer. also chances are it will be a better match with the yamaha speakers, esp if youre buying without auditioning

---------------------------
Hello,
You said
"when u pair ur setup, u always take an amplifier that is of 10-30% higher wattage than the continuous output rms wattage of the speaker"

Q- What is continuous output rms wattage of the speaker means ?

Yamaha NS-PA150 specs says Nominal Input=20 Watts & Maximum Input=60 Watts.

Which one will be considered as continuous output rms wattage of this speaker? (20 watts or 60 watts)

Thanks.

 

[greenhorn]

hi fi equipment manufacturers try to dress up the specs saying maximum input etc. Look for an RMS rating. everything else is subjective.
It is sad that yamaha is not providing RMS figures. For a japanese manufacturer, its strange not to see any EIAJ ratings.

This is bad, in the sense that you really do not know how much power these speakers can take, and if they die tomorrow because of too much power sent to them (this has happened to hfv forum members)
they will claim that too much power was sent and not honor the warranty claim.

I know some of you will say nominal should be the RMS figure, but where does yamaha say that ?

 

[afj]

---------------------------
Hello,
You said
"when u pair ur setup, u always take an amplifier that is of 10-30% higher wattage than the continuous output rms wattage of the speaker"

Q- What is continuous output rms wattage of the speaker means ?

Yamaha NS-PA150 specs says Nominal Input=20 Watts & Maximum Input=60 Watts.

Which one will be considered as continuous output rms wattage of this speaker? (20 watts or 60 watts)

Thanks.

firstly, i stand corrected. its not output, its input wattage to the speaker

from the specs, it seems like it would be 60 watts rms as max continuous. i would go with atleast a 80w amplifier.

 

[greenhorn]

taken from the product manual for another yamaha speaker

When using an amplifier with a rated output power higher than the nominal input power of the speakers, care should be taken to never exceed the speakers maximum input

Looks like nominal is the RMS figure, and the Pioneer has way too much power.

"keeping volume levels low" is just not feasible, and you would always have to live with the damocles sword of the amp blowing up the speakers hanging over your head. If someone wanted to operate those speakers, you'd need a 20WPC reciever - I doubt if any are available

 

[allofficialmail@yahoo.com]

firstly, i stand corrected. its not output, its input wattage to the speaker

from the specs, it seems like it would be 60 watts rms as max continuous. i would go with atleast a 80w amplifier.

----------------------------
Hi Again,
Under which circumstance the speaker will draw Max 60 watts and when it will draw 20 Watts ?

 

[greenhorn]

----------------------------
Hi Again,
Under which circumstance the speaker will draw Max 60 watts and when it will draw 20 Watts ?

speakers do not draw power - they are passive elements, and you can assume that they draw current based on the voltage levels the amp sends and the rated impedance.

Since they are rated 6 ohms, a 19V RMS signal from the reciever will cause it to draw 60W, and a 11V signal from the reciever will cause it to draw 20W

 

[allofficialmail@yahoo.com]

speakers do not draw power - they are passive elements, and you can assume that they draw current based on the voltage levels the amp sends and the rated impedance.

Since they are rated 6 ohms, a 19V RMS signal from the reciever will cause it to draw 60W, and a 11V signal from the reciever will cause it to draw 20W

------------------------
Hi Again,

Say for example: @ 6 Ohms
When only 1 channel of the amp is active, say it supplies max 100 watts.
When 2 channels of the amp are active, it can supply max 70 watts.
When all 5 channels of the amp are active, it can supply max 40 watts.

You said that the Amps output power should be 10~20% higher than the speaker.

Now selection of 5 Speakers for the Home theater to match the Amp's output Power.

Do I have to select 34 watts speakers
(i.e. 34 watts + 20 % = 40 Watts @ 5 channels are driving at the same time)

OR

Do I have to select 58 watts speakers
(i.e. 58 watts + 20 % = 70 Watts @ 2 channels are driving)

 

[greenhorn]

------------------------
Hi Again,

Say for example: @ 6 Ohms
When only 1 channel of the amp is active, say it supplies max 100 watts.
When 2 channels of the amp are active, it can supply max 70 watts.
When all 5 channels of the amp are active, it can supply max 40 watts.

This is because this is an entry level receiver and the power supply is not sufficient to supply full power to all channels at once - and it is designed with the assumption that usually in a movie, all channels do not get driven at full volume always - this may not hold good always

You said that the Amps output power should be 10~20% higher than the speaker.

I have not - I belong to the school of thought which says that the amp should have an RMS rating of around 70-80% of the speakers RMS power

Now selection of 5 Speakers for the Home theater to match the Amp's output Power.

Do I have to select 34 watts speakers
(i.e. 34 watts + 20 % = 40 Watts @ 5 channels are driving at the same time)

OR

Do I have to select 58 watts speakers
(i.e. 58 watts + 20 % = 70 Watts @ 2 channels are driving)

If you have decided on the receiver, I would go with 50-60W RMS capable speakers, with slightly higher capacity for the fronts if you plan on using it for music as well

 

[afj]

----------------------------
Hi Again,
Under which circumstance the speaker will draw Max 60 watts and when it will draw 20 Watts ?

what those numbers mean is that you would need to give those speakers a minimum of 20w amplifier power, and a max of 60w (at continuous levels). so you technically you can use an amplifier with min 20w rms. or a max of 60w rms and play it at 100% volume. but at 100% volume there will be distortion. so you can use a 80w rms amp and play it at 75% volume, so as to not have the distortion. pl note, these numbers arent to be taken at exact values, but as a guideline. generally you will be able to hear the speakers peaking out - the min you start finding distortion, stop giving it more volume

 

[allofficialmail@yahoo.com]

what those numbers mean is that you would need to give those speakers a minimum of 20w amplifier power, and a max of 60w (at continuous levels). so you technically you can use an amplifier with min 20w rms. or a max of 60w rms and play it at 100% volume. but at 100% volume there will be distortion. so you can use a 80w rms amp and play it at 75% volume, so as to not have the distortion. pl note, these numbers arent to be taken at exact values, but as a guideline. generally you will be able to hear the speakers peaking out - the min you start finding distortion, stop giving it more volume

------------------------------------
Greenhorn Quoted that:

Taken from the product manual for another yamaha speaker
Quote:
When using an amplifier with a rated output power higher than the nominal input power of the speakers, care should be taken to never exceed the speakers maximum input
Looks like nominal is the RMS figure, and the Pioneer has way too much power.


What do you say on this instruction in the Yamaha User manual.

Do you still say that a 70 watts per 2 channel driven amp can be used without damaging the speakers. (Speaker's Minimum Input 20 Watts & Maximum input 60 Watts)

 

[raghupb]

70W per speaker is enough power to make any speakers scream.
Crown Audio - Professional Power Amplifiers
Use these calculators to figure out stuff related to your home setting.

Cheers,
Raghu

 

[afj]

------------------------------------
Greenhorn Quoted that:

Taken from the product manual for another yamaha speaker
Quote:
When using an amplifier with a rated output power higher than the nominal input power of the speakers, care should be taken to never exceed the speakers maximum input
Looks like nominal is the RMS figure, and the Pioneer has way too much power.


What do you say on this instruction in the Yamaha User manual.

Do you still say that a 70 watts per 2 channel driven amp can be used without damaging the speakers. (Speaker's Minimum Input 20 Watts & Maximum input 60 Watts)

60w would be the continuous power wattage in rms. 20w is the min wattage amplifier required. i dont know of anyone that uses the minimum as a guideline to buy an amp. peak wattage of the speakers would be more than 60w. though not specified, it would be about 100w +/-

pl read my post again. i said that a higher power amplifier should be used, but not at maximum volume

 

[allofficialmail@yahoo.com]

60w would be the continuous power wattage in rms. 20w is the min wattage amplifier required. i dont know of anyone that uses the minimum as a guideline to buy an amp. peak wattage of the speakers would be more than 60w. though not specified, it would be about 100w +/-

pl read my post again. i said that a higher power amplifier should be used, but not at maximum volume

-----------------------
Hi Again,
Your statement: Higher power amplifier should be used, but not at maximum volume.

Instance 1:
During user increases volume level, he cannot know how much voltage that Amp is supplying that time to the 6 Ohms speaker. So he does not know how much Power is being given at that volume level to the speaker.

Question 1: Is there a provision in the amplifier that user can see how much power is being given to speaker ?

Instance 2:
If an user has lower power amp than then speaker.
Say Amp's max power is 50 Watts at 2 channel driven and connected speaker's max input is 100 Watts.

In this case, even when user will keep the volume at 100%, max power can be delivered to speaker is 50 watts and speaker can still handle another more 50 Watts of power.

Question 2:
Why it is not recommended to have more power speaker then Amp ?
Is't it safe for Amp?

Thanks.

 

[raghupb]

-----------------------
Hi Again,
Your statement: Higher power amplifier should be used, but not at maximum volume.

Instance 1:
During user increases volume level, he cannot know how much voltage that Amp is supplying that time to the 6 Ohms speaker. So he does not know how much Power is being given at that volume level to the speaker.

Question 1: Is there a provision in the amplifier that user can see how much power is being given to speaker ?

Instance 2:
If an user has lower power amp than then speaker.
Say Amp's max power is 50 Watts at 2 channel driven and connected speaker's max input is 100 Watts.

In this case, even when user will keep the volume at 100%, max power can be delivered to speaker is 50 watts and speaker can still handle another more 50 Watts of power.

Question 2:
Why it is not recommended to have more power speaker then Amp ?
Is't it safe for Amp?

Thanks.

There you go again dissecting specs and analyzing them in isolation.
Speakers are transducers that convert electrical energy into sound energy.
This is where the dB SPL number comes into play. Speaker manufacturers spec this as efficiency.
It is guideline to estimate how loud the speaker will sound in your listening room.
Since it is impossible to specify absolutely how loud they will be in all rooms, the standard is defined as follows:
X dB at a distance of 1m when fed 2.83V signal from the amp
How does this translate to Watts since it is not possible to know the amplitude of the signal?
Here goes, more math (2.83x2.83)/R
8 ohm speaker load - 1W/1m
6 ohm speaker load - 1.33/1m
4 ohm speaker load - 2W/1m

Sound energy decreases with increase in distance from speaker.
So a speaker that claims 83dB SPL and 8 ohm nominal impedance produces this much sound at 1m:
1W - 83dB, 2W - 86dB, 4W - 89dB, 8W - 92dB, 16W - 95dB, 32W - 98dB and so on ...

Say your ears are 8 feet from speaker and you are using 1 speaker only; you will need to lop off ~10dB from the 16W/1m number to get 85dB SPL.
85dB is very loud. Now think about having 2/3/5/7 speakers and a subwoofer in the listening area.
If you give say 50W per speaker simultaneously to all speakers and the subwoofer is cooking its own brew the only sure result is a headache.

Don't ask me how I know all this; if you do I will pull out my "Harry Potter wand" and zap you with more math.
All of the above is irrelevant once you audition a few systems and like one of them.

Cheers,
Raghu

 

[afj]

-----------------------
Hi Again,
Your statement: Higher power amplifier should be used, but not at maximum volume.

Instance 1:
During user increases volume level, he cannot know how much voltage that Amp is supplying that time to the 6 Ohms speaker. So he does not know how much Power is being given at that volume level to the speaker.

Question 1: Is there a provision in the amplifier that user can see how much power is being given to speaker ?

Instance 2:
If an user has lower power amp than then speaker.
Say Amp's max power is 50 Watts at 2 channel driven and connected speaker's max input is 100 Watts.

In this case, even when user will keep the volume at 100%, max power can be delivered to speaker is 50 watts and speaker can still handle another more 50 Watts of power.

Question 2:
Why it is not recommended to have more power speaker then Amp ?
Is't it safe for Amp?

Thanks.

ans to ques 1
there is no indicator that i know of

ans to ques 2
for any unit (speaker or amplifier) it will not perform at its best when it is running at 100%. you will find distortion. therefore if you use a lower power amplifier, then for example, when the speaker is running at 80% and the amp is running at 100%, you will find distortion in sound. also if the speaker is able to draw more power than what the amp is capable of producing, there may be clipping in the amp.

if you give more amp power than the speaker power, then you can get the best performance out of your system in terms of sound quality. having more amp power is called head room. you will know when your speaker is coming close to maximum - you will start finding distortion. with usage you will come to know your speakers limitations. as soon as you feel the distortion or the speaker is playing louder than it can handle, you scale back on the volume. there is no mathematical calculation here. you have to go by feel and by your ears. so by no means can you play the amp at 100% in this scenario. there will be high chances of the speaker blowing