Wattage?

[feeble!]

I'm sure I remember someone (Tav?) saying something about watts not having anything to do with how loud your amp can go, is that true?

Can anyone explain to me how it's all measured?

[soundian]

Heh, yea, someone explain it in less than three pages.

I hope you know logs.

[craig deadenstereo]

After a certain point, yes.

What determines the loudness of an amp is the speakers really. i.e. number of them, their sensitivity etc.

What the wattage of an amp means is that if an amp is 100W it will stay clean up to a high volume. This is called headroom. Whereas a 20W amp will distort quicker.

You could wire up the 20W amp to a 4x12 and if you crank it up full it would be just about as loud as 100W amp. I suppose if you get something that's 150W like a triple rectifier it would be louder than a 20W, but not much. You could get a significantly louder clean sound though.

a 5W amp won't go as loud as a 150W amp, so there is a certain factor of wattage equalling volume.

This is all based on valve amps. Dunno exactly the way this works with SS amps, but volume does have a higher correlation with wattage there.

[Tav]

There's articles on it and they have been posted here before. Basically you need ten times the wattage to go twice as loud. So 10 to 100 or 50 to 500. Have a look through the forum and you might come across.

[Monk Rocker]

Originally posted by soundian:

Heh, yea, someone explain it in less than three pages.

I hope you know logs.

If you have a 100W valve amp and crank it to 10 onstage, soundian will smack you in the face with a large log.

Succinct enough?

[soundian]

Originally posted by Tav:

There's articles on it and they have been posted here before. Basically you need ten times the wattage to go twice as loud. So 10 to 100 or 50 to 500. Have a look through the forum and you might come across.

I've always been told that 6dB was twice as loud. Which works out at roughly 4 times the wattage.

Looking though some websites though, it's not definitive, some give it as 6, some as 10 and some hedge their bets between the two.

[soundian]

After much research, Tav's right. To double in volume you need 10 times the power. This is a very subjective measurement though. To some people 7 or 8 dB will sound twice as loud, 7 being 5 times the power.

But doubling the sound pressure is 6dBspl. Normally written dB, just to confuse everyone. This is not subjective and can be accurately measured.

[Tav]

Yeah it's a confussing subject. Basically you don't need a whole lot of watts though. For venues with just the vocals going through the PA i.e Drakes you might need the volume/headroom of a 50/100 watt but your never going to crank it to 10. Then I presume when you get to places like Kef where everything goes via PA you can get away with 1 speaker and as little watts as you like or even no speaker and a digital amp modeller...though soundian wouldn't be impressed with your inferior digital technology.

[soundian]

Originally posted by Tav:

Yeah it's a confussing subject. Basically you don't need a whole lot of watts though. For venues with just the vocals going through the PA i.e Drakes you might need the volume/headroom of a 50/100 watt but your never going to crank it to 10. Then I presume when you get to places like Kef where everything goes via PA you can get away with 1 speaker and as little watts as you like or even no speaker and a digital amp modeller...though soundian wouldn't be impressed with your inferior digital technology.

Yeah, I'm likely to hit it with a large log apparently.

[Guest Ibid]

Amplifiers do not distort, they clip. It's the driver in the speaker that distorts. How loud a speaker is is usually shown as its sound pressure level or SPL. SPL is the distubance in the air caused at a distance of 1 metre from the speaker when the speaker gets fed a signal of 2.83 Volts, which is around 1 Watt from an amplifier into a speaker impedance of 8 Ohms.

The decibel scale is a logarithmic scale that compares, not measures, a given sound intensity to the intesity of human hearing. So a 10dB increase represents a doubling in volume. So 131 dB is twice as loud as 121 dB.

Where dB's get confusing is the large numbers of units used in the pro sound engineer world, such as dBu, dBVU and dBFS and so on. So you must compare like with like. Local councils like to fuck venues around by quoting varying types of dB's in order to get the result they want. I recently stiffed Moray council when I carried out an independent review of a survey they done where they ordered a venue to restrict the SPL of bands to a dB measure that was actually much less that the normal background conversation of a pub containing 30 people!!!!

Wankers!