Hey Gang, I found this great article from Andy's Corner at ProGuitarShop.com.   I have included the link at the end so you can go and check out other articles from that site as well.  I liked it enough to share it with all of you.  Enjoy!

Is Your Amp Loud Enough?!

May 30, 2013

By PGS Fitz

There are some common misconceptions out there in guitarland about amps—specifically about wattage, volume, headroom, decibels, etc. Sometimes you think you need two full stacks to get the stage volume you think you want but you just need a 40w combo. Sometimes you think you want a small watt amp that will break up and provide the perfect tone, but you’re not going to hear it over your drummer and his Neil-Peart-tribute-kit with three bass drums AND a gong. This week in Andy’s corner, we’re looking again at your amp to learn a little about the overall ‘volume’ of your amp and all the factors that contribute to it so you can make sure your rig is right for you.

How Loud is Loud?

We’re all musicians. Hopefully we’re all aware of decibels—specifically in protecting our ears from high levels of them! Decibels, or dB, are the measurement used to identify the volume or intensity of a sound. Like the Richter Scale, each increase in dBs is not a linear increase but rather an exponential increase.  10dB is considered ten times more powerful than 0dB, and to the human ear, a 10dB difference is heard as “twice as loud.” This means if you’ve got one amp pumping out 100dB and another pumping out 110dB (which is close to being 1,000,000, 000,000 times as powerful as the smallest audible sound!), the first amp is going to sound like it has half the volume of the second. (Public Service Announcement: we at PGS would like to remind you that exposure to levels above 85dB can cause hearing loss, so take it seriously, yo!)

Watt Do You Mean?!

Part of the equation that helps create an amp’s volume capability is its wattage. We all throw around the terminology: “That dude has a 100watt half stack!” “I bought a little 5watt combo for the house—my wife was complaining about my Rockerverb!” So what IS wattage? While decibels are a measurement of volume, watts are a measurement of energy or in this case, electrical power. Like decibels, watts are not linearly comparable from a volume perspective—a 100w Rockerverb has twice the power of a 50w Rockerverb, but not twice the volume. There’s only about a 3dB difference between the 50w and 100w amps (assuming the speakers are identical; more on that in a bit), which means you may notice a difference in their volume capability, but a ‘twice as powerful’ amp will not be heard/perceived as ‘twice as loud,’ and as we all know—perception is reality.

Speakers of the House

Your amp’s speaker (or speakers) is another crucial piece in how loud your amp will be heard/perceived. Speakers have a dB sensitivity specification, which is a measure of the combination of power input and sound output. Most manufacturers provide this spec in “dB at 1w/1m” – which is decibels produced per 1 watt measured at 1 meter from the speaker on its axis. For speakers, the required power level doubles for each 3dB difference, meaning to get a 97dB speaker as loud as a100dB speaker, the 97dB speaker will need double the power. Essentially, the higher the sensitivity rating, the more efficient the speaker is at converting power input to sound output. A higher efficiency speaker when used in a lower wattage amp can be a very, very powerful thing—and a higher wattage amp with a low-efficiency speaker can be, well, underwhelming.

Getting It Just Right

The most important question to ask in terms of finding the right amp is: what are you going to be using it for?! The amp market has been flooded lately with a ton of low wattage amps that are perfect for home use or small, intimate club gigs; in the right situations (and with the right mics), these amps could probably work for a slightly larger gig, but once there’s a drummer involved, you likely want to move into the 20-40w range, especially if you’re hoping to retain any clean headroom. For full-on club gigs or outdoor gigs, you’ll likely want to clear the 40w bar and have an amp or two that is in the 40-50w range, just to make sure you don’t lose any punch (everything sounds different outdoors, where there are fewer if any reflective surfaces like walls to retain/reflect the soundwaves). When you’re playing Coachella, go ahead and get that wall of 100w Rockerverbs. Remember to consider the amp’s wattage along with the speaker’s efficiency rating in terms of figuring out what is going to provide the proper volume to you in whatever application you’ll be running it in. We all want to be able to hear you, but not be overwhelmed with you (I’m talking to you over there on stage right—they guy who always sneaks over and bumps up your master volume after the sound engineer has everyone’s levels set…#youknowwhoyouare).

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