# Determining a Spec

Discussion in 'Amps and Cabs [BG]' started by cassanova, Sep 4, 2010.

1. ### cassanova

Sep 4, 2000
Florida
I've seen amps that have 102 db 1 [email protected] meter. Then I've seen them at 98. At what point when reading the spec sheets would this number indicate efficiency or inefficiency?

2. ### Plstrns

Feb 4, 2010
Texas
Speaker or Enclosure, not amp.

If everything else is equal, (it never is) each db of sensitivity equates to a ~10% increase in volume.

3. ### will33

May 22, 2006
austin,tx

I assume you're talking about speakers/cabinets.

Higher number = more sound coming out per watt going in but don't take that as a hard and fast rule. It varies with frequency, a speaker could be 94db in the lows with a spike up top at 105 or something. These numbers are fudged a lot to make products look better on paper. If you're looking at an actual spec sheet with response charts, etc. you can actually tell what you're looking at. If the print in an ad for a cab just says "X db" there isn't much knowledge to be gained from that. It's more likely to steer you in the wrong direction than it is the right one.

4. ### will33

May 22, 2006
austin,tx
Search something like "speaker specs" on here. There's a bunch of threads explaining the details with several posts/links to real engineers.

5. ### cassanova

Sep 4, 2000
Florida
Yeah, I meant speaker/enclosure, not amps. My bad.

6. ### will33

May 22, 2006
austin,tx
Rule of thumb is a difference of 3db is a small but noticable change in volume. A difference of 10db appears to be twice as loud (or half as loud if you're going the other way). To gain 3db you have to double power assuming the speaker can handle it. To gain 10db you have to have 10 times the power, again assuming the speakers(s) can handle it. Having higher SPL speakers is cheaper and easier way to get louder than having huge power trashing your speakers. Adding more speakers will get you louder than adding more power. Generalities here, there are exceptions to everything.