So how much power do you really need for domestic listening ?

[fotios]

I agree, that 2 X 150Wrms/8Ω - at least - it is the proper power. Personally, i prefer 2 X 170Wrms/8Ω and above . I have in process a true symmetrical power amplifier (2 power modules per channel in bridge mode, so 4 power modules total). That means, the main inputs will be balanced and the optional secondary single inputs will be converted as well in balanced. With two main xformers of 300VA each one (because i have these in my stock), i expect a power of 150Wrms/8Ω per channel.

 

[Xoc1]

Sine or square wave?

Unfortunately with most CD's today a 0db sine wave is not enough to set a maximum level. As nearly all cd recordings are digitally clipped square there are certain signals that will cause overshoot in the DA converters. This can apparently produce peak levels that may be as much as 6db over!
http://www.ebu.ch/fr/technical/trev/trev_310-lund.pdf
Admittedly this is gross distortion, but do you want to add to that by clipping the amplifier?
At the moment I have 86dB speakers and I am running 150W per channel, This has proved adequate to avoid clipping, as I can hear the speakers running out of dynamics before the amp clips. At normal levels this give an effortless perfomance, with confidence that the amp is not running out of headroom.

 

[multisync]

my parents stereo cabinet was 2.5 watts per channel and they always said "turn down that DA-N STEREO"

 

[krachkiste]

I have the large Maggies. Every time I built a more powerful amp, they sounded even better. The last mono amps I built for them were 800W each. What I found most interesting was that with more power I didn't listen as loud as with less power, but it sounded better. In my opinion, you have enough power when you can't hear any difference with a more powerful amp.

But this seems to be more a question of amplifier quality, than just a power issue.

With increased rail voltage (maximum Power), the "quality" of the amp will (usually) be better at the same outputpower if design is left the same. (of course this is not universally true, but its an effect to take into concideration, i think)

Moreover, DACs can also overshoot, not to mention the amps and preamps in the chain.

But I agree, your method gives a good indication.

I am running my Tannoy Reveal 6 with a 30W (manages 17Vp +X) amp I built, and I never got anywhere near clipping during everyday listening.

I once had my scope hooked up and at about 10Vp at the speaker terminals I stopped because it was becoming unpleasantly loud. (thats about 8W, so reasonably close to your 12.5W)

I would conclude, its always good to have some headroom (whatever "some" might be), even if it's just because the amps are getting better the less of their maximum power you use.
(that is of course unnessisary if you used a good amp in the first place )

so a 100W should be enough for home use, given some less efficient speakers. And if they are even less efficient, then I would guess you know about that, and that you also know you might need a little more power.

 

[a.wayne]

I have the large Maggies. Every time I built a more powerful amp, they sounded even better. The last mono amps I built for them were 800W each. What I found most interesting was that with more power I didn't listen as loud as with less power, but it sounded better. In my opinion, you have enough power when you can't hear any difference with a more powerful amp.

Agree, I have never heard a speaker that never benefited from more power , a lot is needed for good dynamics and energy. When you have achieved the right amt of amplification you will find there is no need to play loud, as your system will get soft and grow as live music does. Playing loud is a necessity for those with poor macro /micro dynamics ...

 

[fotios]

Empirically speaking:
A power amplifier has enough power to drive a speaker, if it can do the woofer to make "plof - plof" (that means the voice coil is moved outside from the magnet assembly) without audible distortion in low-mid frequencies. Only by this way you can be sure that your amplifier has enough power .

 

[Bob Cordell]

So just how much power do you need at home... the next time you are wondering whether to build that 500 watt monster amp.

I recently got my hands on a sound level meter (C weighted) and was (pleasantly) surprised at just how low the levels were that I normally listen too. At the listening position around 70db (average level) is plenty for normal listening. The meter shows around 75db peaks (125ms response)

So that got me thinking... if you have CD with test tones at 0db, a little experiment that's easy to do.

You turn the amp up to what is the loudest you would ever normally listen on a music CD. Stop the CD and disconnect the speakers. Now play the test tone and measure the RMS voltage at the amplifier terminals. Make sure your meter reads AC accurately at the frequency chosen... probably around 100hz is best if your test disc has that. Disconnecting the speaker saves your ears and maybe even the amp as many may not like delivering a lot of power continuosly if the heatsinking etc is marginal.

What does that tell us ?

Well the fact the tone is recorded at 0db (make sure it is), means that that is the maximum signal you can ever get from the CD player. No transient in a music program from CD can ever exceed that level. It's cast in stone.
So lets say the meter showed 10volts RMS. We will also assume an imaginary load of 8 ohm (because you actually measured with no load) for these calculations. We assume the amp would maintain it's output when loaded.
So 10 volts RMS across 8 ohm is (10*10)/8 which is 12.5 watts RMS. That implies that an amp rated at that output would in fact deliver all you ask of it, cleanly and with no clipping.

Following this reasoning my "ideal" target amplifier would be around 20 to 30 watts RMS. Once you reach that level then it takes a relatively large increase in power to get a "noticeable" increase in volume. A doubling of power gives a 3db increase which is not as noticeable as you think and certainly not twice as loud. With my speakers which are rated at 90db efficiency for 1 watt, that implies a max peak level of around 102 to 105 db. The average of course would be far lower, and not only that, these measurements are based on 0db or maximum output from the CD player being reached on music program which is unlikely.

So what's your ideal power rating for an amplifier ? How loud do you really listen ?

Hi Mooly,

How much power you need in your amplifiers depends on the dynamic range of the music, the sensitivity of your loudspeakers, the size of the room, and how far you are seated from the speakers. There are a lot of factors, but the numbers can get ugly fast in the worst case, so we have to be cautious about generalizations.

Peter Smith and I conducted listening and measurement workshops at RMAF2006 and HE2007. Workshop #5 dealt with exactly your question. Some of the results were stunning, both to us and the participants. You might want to go to my website at Cordell Audio: Home Page and click on the RMAF tab, then click on Workshop 5. There is a summary there of what we did.

I built a peak+average meter with dual digital readout that held the maximum of the rms and peak values for 3 seconds so one could read it. It read out directly in watts referenced to an 8 ohm load. If you drive the meter with a sinewave, both meters read identically.

The peak meter could see a 10 us peak. The better the music is recorded, the bigger the numbers. We played a very well-recorded CD by Rickie Lee Jones with over 14 dB crest factor. The sound level was realistic in a standard hotel room (not uncomfortably loud). The speakers were 83 dB 1 watt 1 meter. They were powered by a 250 wpc amp.

The peaks hit 250W. The biggest peaks resulted from a mean thwack on a snare drum. This test was certainly cause for pause. BUT, remember that 10 dB in speaker sensitivity is a factor of ten in power. If you speakers are 93 dB efficient, then you need only 25W for this (if you are just in ahotel room).

Most music available today unfortuantely has very little crest factor, and that is why a small amplifier will sometimes drive you out of the room.

Cheers,
Bob

 

[philmagnotta]

Well the fact the tone is recorded at 0db (make sure it is), means that that is the maximum signal you can ever get from the CD player. No transient in a music program from CD can ever exceed that level. It's cast in stone.
Hi Mooly:
That is not 100% correct. Inter-sample peaks often occur in the tracking and mastering stages. They don't normally show on convention digital metering.
TC Electronic released some white papers a while ago showing common 6dB crests above the so-called legal limit.
Standard players are ususally set to 2 volts rms when fed 0 dbFS and many players will over load when playing these "overs" or actually produce the extra signal gain in what ever condition.
I'll see if I can locate the article and reply back.

 

[stocktrader200]

I am amazed by the number of that post trying to build or repair 500 watt plus amplifiers. I built a 3 channel class D and stuffed it into my old pioneer receiver.
The RMS power sits at about 100 w / 8ohm or 200 / 4 ohm. (Subwoofer)
using existing power supply with 22000 uf more capacitance.
This is way more then adequate as the digital power meters seldom exceed 5 watts/ ch. peak when played loud.
Running this thing to it's maximum would shake the walls loose.

higher power levels require higher voltage / slower switching transistors as well as fewer (and poorer) choices of speakers that wont burn up when driven hard

 

[destroyer X]

1 watt to each channel

And some reserve for peaks....nothing more than 25 watts rms.

Observe the power you listen usually.

regards,

Carlos

 

[philmagnotta]

Sorry, I see that another has already provided the link I was looking for. regarding over 0dB signals.

 

[tinitus]

At the level I listen at 99% of the time I estimate that 20watt total would be more than sufficient
I do have heavy 40watt AB, and when really loud I can cranck them up close to their full output
I guess 100watt would do fore the louder days

But I cant stand it very loud fore more than 10 minutes
And afterwards everything sound like crap

To me, just about everything sounds better the more you can turn down the level

I think the major problem is that most speaker fall apart at low levels
And those that excel at low levels are really not fit fore playing loud

Its the general rule "whenever you make a choise, you always dismiss something"

Ofcourse its possible to design a "do it all", but it will still be a compromise

If you want exstreme quality, maybe look into stability factors caused by temperature
Some could make equal claims fore speakers

 

[Steve Dunlap]

higher power levels require higher voltage / slower switching transistors as well as fewer (and poorer) choices of speakers that wont burn up when driven hard

I would disagree about the transistors and speakers.

 

[fotios]

The voice coil of a speaker is fried, usually, from the distortion (clipping etc) caused from amplifier, and not from excess of power which can break the terminals of voice coil and/or the rip of spider due to excessive movement of cone. Unfortunately, constructors of domestic speakers they refer only the sensitivity e.g. 89dBSPL/1W/1m. They refer as well the maximum power that can sustain the speaker. No one of them refers the maximum efficiency of speaker and in which power. Instead, most PA speakers refer both, e.g. sensitivity = 98dBSPL/1Wrms/1m and maximum SPL = 122dB/350Wrms/1m. Only this is helpful for the choice of power amplifier.

 

[wahab]

According to the power requirements displayed by there, it
seems that people have as much as 10db differences when
it comes to ears absolute sensitivity..
I ve no other explanations about the ones that are asking
for 100 to 200W/ channel , unless they are half deaf...

 

[picowallspeaker]

I would disagree about the transistors and speakers.

Disagree ? Uh ? Oh yes ! Obvious !
Nowadays , I use my 40 Wpc amp on 16 Ohm tv speakers ,elliptical , OB ehm ,quite OB...imagine...and a multisectional conical horn (original paper spools ....!!)
EDIT :and a huge (in comparison) sub ,with a huge coil derived from one channel (might go active someday...)

 

[destroyer X]

This is a matter of personal taste...or how bad the drivers are

To listen....we need a very low power....observe television set power, for instance;;;;very low...1 to 3 undistorted watts each channel....specified as 10W each channel (10% distortion).

Some guys want to make rain...observe the speaker almost do not move:

YouTube - Make it rain with 1000w RMS (~125db)

regards,

Carlos

 

[rdf]

The simple elegance of Mooly's suggestion might be getting lost. The idea is to measure what you really require in your domestic circumstance. 250 watts wouldn't be enough for me because I would quickly be evicted and without walls.

 

[Cal Weldon]

"So how much power do you really need for domestic listening?"

Is this a before or after beer question?

 

[satoru]

Dear Mooly,

As Bob mentioned, the music, listening style, room, speaker, etc all affect the power requirement. But not like designers for commercial units, we DIYers can design amps just for ourselves to fit our own needs, right? I thought that was your intention on asking us the power level we need.

I may be on the lowest side for the loudness. My power amp output level (following your method) was roughly 0.25W with 90dB/m/w speaker in a lively room. The power needed for my canal-type earphone was less than 10 microW (on a 103 dB SPL unit). This low level of power requirement leverages me from using conventional output transistor pairs but venture into using TO-220 pairs instead, with way lower power supply voltages. The world is quite different there

Of course, this cannot be generalized...

Best regards,
Satoru