Db and phase

[Danielb]

Ive seacrched the forum for these answers with no luck.

1. Db? Is this the volume of the sound.

2. Phase? Im lost.

3. Also is the total wattage of a speaker the drivers wattages combined?



That will do for now, thankyou for your help. Ill pick it up quicky. I can read the graphs ok, but i dont know whats good and whats not.

[Grahamt]

1. dB is short form for decibel. Do a search and you will learn plenty. It is a measure of sound pressure.

2. Phase is relative timing. Tweeter relative to the woofer, output relative to the input signal etc and measured in degrees. There is lots of info on phase in any speaker book.

3. Power handling, max watts, is a combination of drivers and crossover.

[Mr Evil]

1) dB (small b, capital B) does represent the volume. It's an abbreviation of decibel, being one tenth of a Bel, although you'll never hear anyone using Bels.

It's a relative, logarithmic scale. When measuring sound pressure level (the volume, if you will) it is usual to use something called the A-weighted scale (denoted dBA), which specifies 0dB to be some specific pressure that I can't remember which is approximately the quietest audible sound.

2) Phase is related to delay. Imagine one complete cycle of a sine wave. The length of this cycle is 360 degrees. Now imagine a second sine wave on top, but starting just as the first sine wave is at its peak. That means it's starting 90 degrees later, so the difference in phase is 90 degrees. I hope that's clear; it's sort of hard to explain without a diagram.

3) You mean the power handling of e.g. a woofer + tweeter combined? That depends on the crossover frequency, as the amount of power in music is not constant, most of it being bass. It will be somewhat less than the sum of the power handling of both drivers added together.

[Danielb]

Decibels is quiet clear. Shame about the other two.

My woofer is going to be 125 watts, midrange around 50watts and tweeter around 20 watts. No idea what crossover to use ill have to get all the stats together first.
So if everything was "Average" what type of wattage would be stamped on the back.

So phase? what are the consequences of it being ?bad? or is it a case of it cant be bad? lol im confused

[Grahamt]

Yes phase is hard to explain. I suggest you get some books on loudspeaker design to help you. There is so much info that cant be explained quickly. Look for books by Vance Dickason, David Weems and John Murphy etc.

[Danielb]

cheers ill take a look, i get the general idea