A Test. How much Voltage (power) do your speakers need?

[tktran303]

Uh oh. I think I've started the watt war, or people are getting fooled by watts.

200W allows me to hit dynamic peaks cleanly at 10dB more (about twice as loud) than my 20W bedroom amp. It has little to do with perceived loudness level (or as some people have asserted, a need for my apparent deafness :-P)

We typically listen with only about 0.01-2W. (-20dB, to +3dB of the rated x dB/2.83V sensitivity of our speakers)

Not 6 zeroes.

[GM]

Originally Posted by AndrewT

70dB (0.0000001) below 1W would in a pair of 90dB/W @ 1m speakers, result in about 15db of SPL when listened to @ ~2.4m

I hope I read and typed the correct numbers of Zeros?

And if our speakers can reproduce peaks of 20dB above that 1W level (maybe 200Wpk after allowing for 3dB to 4dB of power compression), then our audible range would be from -69dB to +20dB or about 89dB of total home reproduction audible range. Maybe a very quiet room, with no wind blowing, no mice walking across the floor and one stops breathing for a moment to hear the quietest passages.

Don't believe so if I'm understanding you:

90 dB/W Vs 70 dB/'x'W = 2^[[90-70]/3.01] = 0.01 W

200 W would limit it to ~3 dB of dynamic headroom before subtracting in any loss over distance.

Not sure how you're arriving at max audible range of recorded music in room since ~ -69 dB is relative to 0 dB and a quiet room will have a noise floor of around 40 - 50 dB.

GM

[radiosmuck]

I got interested in amplifier power after purchasing a little 2020A amp to drive my computer speakers. I was so impressed withthe sound, I connected the amp to my large, vintage, 15 inch Tannoys, not expecting to much.
Anyway, the little amp has replaced the McIntosh 6100 I was using and I love it.
The 2020A amp is only rated at a couple of watts into 15 ohms but it is not wanting for volume, clarity and attack.
Bernstein's recording of Stravinsky's Rights of Spring just sounds amazing, the soft parts are soft and the loud parts make me jump.
The test show 0.4v which calculates out at .085 watts for my 15 Ohm speakers.
What am I missing here, is it that modern speakers are so inefficient and is my old treasures seem to be better than money in the bank?

[AndrewT]

Originally Posted by GM

Don't believe so if I'm understanding you:

90 dB/W Vs 70 dB/'x'W = 2^[[90-70]/3.01] = 0.01 W

200 W would limit it to ~3 dB of dynamic headroom before subtracting in any loss over distance.

I don't understand what you are trying to say here, But I will comment on your last point

Not sure how you're arriving at max audible range of recorded music in room since ~ -69 dB is relative to 0 dB and a quiet room will have a noise floor of around 40 - 50 dB.

first if we, or he, cannot hear the -70dBW and we/he can hear the -69dBW level then for that room under those listening conditions that -69dBW (sent to the speaker) would be the audible limit.

If we now send a high power pulse of around 100Wpk that should generate an SPL that is +20dBW above the 1W reference level. But we know that speakers suffer power compression. To achieve an actual SPL level equivalent to +20dBW we would need to send more power, I assumed 3dB more power for 3dB of power compression at the 200Wpk level.

Now the upper limit of our domestic system is +20dB and the lower limit of audibility is -69dB. This gives a range of audibility of 89dB.

[Mooly]

Originally Posted by Mooly

Someone do the test and see

Very rough and ready... One (as in not a pair) Celestion SL100 (efficiency 84db/w) and I could hear 2mv pk/pk 1Khz sinewave across the terminals at around 6 feet distance. The impedance at that frequency is 18 ohms. So the power is 0.000000028 of a watt.

[AndrewT]

That is quiet. You have good ears and a quiet room !

Is that level -seventy odd dBW, or are you into the -80s?

[Mooly]

Originally Posted by AndrewT

That is quiet. You have good ears and a quiet room !

Is that level -seventy odd dBW, or are you into the -80s?

You mean me ? We posted together.

My little Farnell SPL meter shows around 25 to 30 dbc as the noise floor in the room the test was done.

[Pano]

Originally Posted by tktran303

It depends on how high your volume knob is turned up (well duh!)
But that depends on what you are listening to.

Well yes, but that has been stated ad infinitum in the thread. Have you read the first few pages? I have taken pains to ask folks to adjust the volume as loud as they ever do. Hopefully that will be on dynamic tracks. But not everyone listens to dynamic recordings.

The idea behind the test is to measure what you actually use. Most of us know the range we use on the volume knob. It isn't all that complicated. Sure, you need to pick some dynamic tracks, but that has already been stated - over and over. Find the highest point you ever use on the volume knob and measure there. Everything else will be equal to, or below that.

[tktran303]

But not everyone listens to dynamic recordings.

Presto!

[Pano]

And if they don't, then how much headroom do they need for what they actually listen to?