Decibel to Wattage Relations

[HolyDirt]

Hey guys.
Anyone know exactly the wattage to decibel relations on typical high gain amps? In other words, how much louder is a 100 watt head compared to a 50, and a 150 compared to 100. I know there is no set standard, because some 50 watters are louder than others, but I'm talking in general.

 

[Artie]

Re: Decibel to Wattage Relations

Its generally accepted that you double the power to achieve a 3db increase.
And, it takes ten times the power to double the percieved loudness.

 

[tone4days]

Re: Decibel to Wattage Relations

additionally, one must consider speaker efficiency in converting electrical energy to sound pressure (assuming proper load balancing) ...

this really needs to be an 'ear' thing in practical terms because there are so many variables (including mfrs intentionally under rating their amps for marketing purposes) ...

not too many guys carry a sound pressure level meter with them .. although one wonders if premature deafness could be reduced if we did

cheers
t4d

ps - hey artie, very cool moniker - "mojo's minions" ... how long have you had that? .. i just made UTS today (i guess by crossing 1500 posts) ...

 

[Artie]

Re: Decibel to Wattage Relations

ps - hey artie, very cool moniker - "mojo's minions" ... how long have you had that? .. i just made UTS today (i guess by crossing 1500 posts) ...

I'm not actually sure. I hardly ever pay attention to that, and I just noticed it myself a few weeks ago. I think its one of those "custom" things that Scott does when he feels like it. :laugh2:

(I sent him a PM thanking him.)

 

[HolyDirt]

Re: Decibel to Wattage Relations

Its generally accepted that you double the power to achieve a 3db increase.
And, it takes ten times the power to double the percieved loudness.

If a 100% increase is 3 db more, how much is a 200% increase? (aka, comparing a 50w to a 150w).

 

[skyydogg01]

Re: Decibel to Wattage Relations

the problem here is that decibels are a logarithmic function and watts are linear. yes, doubling the power will only increase 3db ... but those 3 db is twice as loud as the original signal. go to this site for info on decibels

 

[tone4days]

Re: Decibel to Wattage Relations

the problem here is that decibels are a logarithmic function and watts are linear. yes, doubling the power will only increase 3db ... but those 3 db is twice as loud as the original signal. go to this site for info on decibels

SKYY, gotta be careful ... you are correct about the log/linear part ... but electrical power doesnt translate directly to acoustic volume .. it is dependent on a) Frequency response of speaker b) efficiency of speaker c) distance from acoustic source, d) ambient reflection and absorption, ...

and even more important is the caveat about not over interpreting advertised wattage ratings as a determiner of just about anything ...

cheers
t4d

 

[skyydogg01]

Re: Decibel to Wattage Relations

SKYY, gotta be careful ... you are correct about the log/linear part ... but electrical power doesnt translate directly to acoustic volume .. it is dependent on a) Frequency response of speaker b) efficiency of speaker c) distance from acoustic source, d) ambient reflection and absorption, ...

and even more important is the caveat about not over interpreting advertised wattage ratings as a determiner of just about anything ...

cheers
t4d

this is true. but considering all factors the same then my statement would be true. am i correct on this one?

 

[tone4days]

Re: Decibel to Wattage Relations

well, i'm not sure how to interpret your assertion .. i know that you are not completely wrong, per se ... but there are limitations to how correct you are ...

for example, at low power levels, bass frequencies do not get 'as loud, as fast' when you increase power .. it takes MORE than 10x the power in bass frequencies in order to achieve the same perception of loudness (google 'fletcher munsen curve') ... and at very high SPLs, there is no practical way to measure 'twice as loud' ... it is not completely linear a relationship at all volume levels at all frequencies

i'm not ragging on ya, bro .. i am more trying to disabuse the young bro who started this thread of the mistaken notion of "whose D1CK is bigger just cus he has an amp rated at such and so watts" ... too many guys get caught up in numbers to describe music-related topics ... this science/engineering stuff is interesting to a point, but i hate to see guys buy into advertising or macho-ism about gear instead of using their ears and their heads .. how friggen loud do we need to get? once you have more than enough to make yourself deaf, isnt it plenty? kinda like nukes during the cold war ... once we each had enough nukes to eliminate the worlds population, wasnt it enough? .

</rant>

sorry

cheers
t4d

 

[skyydogg01]

Re: Decibel to Wattage Relations

i see your point and you are very correct. i forgot about the frequency curve thingy. i stand corrected.

 

[some_dude]

Re: Decibel to Wattage Relations

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.

I don't know of any charts that have decibles on them, as two amps of the same wattage can sound quite different in volume. Plus, there's the whole speaker efficiancy thing...

 

[tone4days]

Re: Decibel to Wattage Relations

i give up :smack:

 

[MrHeavyMetal]

Re: Decibel to Wattage Relations

Let me help out a little with a real world application. Go to Radio Shack and purchase a decibel meter. Plug into your amp and hit an A chord and start cranking the master output volume knob. Measure approximate db levels at each #. With a 50+ watt amp thru a 1X12 or 2X12 much less a 4X12, believe me, you'll get to 110-120 db pretty fast and you'll have plenty of #'s left on the volume knob. Anything over 105-110 will make your ears hurt. Over 120 dB and your asking for tinnitus. Now what were you saying...

 

[some_dude]

Re: Decibel to Wattage Relations

Over 120 dB and your asking for tinnitus.

I must've missed that one....could you say it again please?


:laugh2:

 

[Simon_F]

Re: Decibel to Wattage Relations

So where are Wattage's relations? :boggled: