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How Loud is 5 Watts

Shout really loud -- that's how loud 5 watts is. "Heaphone level" level corresponds to about 20 mW, about the power available from a small signal tube amp. Thus a 5 watt amp is 5 / .002 = 2,500 times louder than the desired 20 mW "headphone level". Human perception, like most natural response, abides a logarithmic function.

"Last week, I played a 35W amp on full blast (but not clipping) through a Marshall 4x12" cabinet loaded with Celestion Vintage 30's, which have a sensitivity of 100dB. I took out a sound pressure level meter and put it 10 feet away from the speakers. The 35W amp produced a clean power level of 117dB, which is only 3dB quieter than an airplane landing." »

Human "loudness" perception, relative to 50 watts:

500 W - tenfold increase in power "sounds about" twice as loud.
100 W - twofold increase in power "sounds about" 25% louder.
50 W - unity.
15 W - threefold decrease in power "sounds about" 2/3rds as loud.
5 W - tenfold decrease in power (1 order of magnitude) "sounds about" 1/2 as loud.
0.5 W - hundredfold decrease in power (2 orders of magnitude) "sounds about" 1/4th as loud.
0.005 W (50 mW) - thousandfold decrease in power (3 orders of magnitude) "sounds about" 1/8th as loud.

A 5 watt amp is *a thousand times too powerful* and "sounds about" eight times too loud, compared to the target "headphone level" of 20 mW.

X% louder = 2^log10(P2/P1) * 100%

40 watts is 94% as loud as 50 watts.
30 watts is 86% as loud as 50 watts.

25 watts is 81% as loud as 50 watts.
22 watts is 78% as loud as 50 watts.

20 watts is 76% as loud as 50 watts.
18 watts is 74% as loud as 50 watts.

15 watts is 70% as loud as 50 watts.
12 watts is 65% as loud as 50 watts.

10 watts is 62% as loud as 50 watts.
9 watts is 60% as loud as 50 watts.

8 watts is 56% as loud as 50 watts.
7 watts is 55% as loud as 50 watts.

6 watts is 53% as loud as 50 watts.
5 watts is 50% as loud as 50 watts.

4 watts is 47% as loud as 50 watts.
3 watts is 43% as loud as 50 watts.

2 watts is 38% as loud as 50 watts.
1 watt is 31% as loud as 50 watts.

3/4 watt is 28% as loud as 50 watts.
1/2 watt is 25% as loud as 50 watts.

1/4 watt is 20% as loud as 50 watts.
1/10 watt is 15% as loud as 50 watts.

50mW is 13% as loud as 50 watts
20mW is 10% as loud as 50 watts.

10mW is 8% as loud as 50 watts.
5mW is 6% as loud as 50 watts.

1mW is 4% as loud as 50 watts.
0.5mW is 3% as loud as 50 watts.

0.1mW is 2% as loud as 50 watts.
50uW is 1.6% as loud as 50 watts.

10uW is 1% as loud as 50 watts.

SOURCE: http://www.amptone.com/g112.htm

Material herein added and updated constantly; presented for inspirational and educational purposes per Fair Use.

Last modified 17 Dec 2020

Milbert Amplifiers, The Most Musical Amplifiers. Made in USA since 1986.
Milbert Amplifiers
The Most Musical Amplifiers
Made in USA since 1986

8051 Citation Drive #C
Gaithersburg, MD 20877 USA
phone 202-558-5502