Confused about dB's, Sensitivity....

[jack70]

You are also confusing "sensitivity" and "efficiency."...

...So, Jack, you are right even if a little confused over terms; A LOT has been glossed over here, but the basics still hold.

Hi Chuck...
Yeah, you're right about sensitivity vs efficiency... but I was trying to avoid getting too deep into that for fear of losing some people. When I said: "The Electrical energy of the amp is totally dependent on the "efficiency" of the speakers, I was using the term "efficiency" generically & rather loosely, to explain a more general point to a whole thread of listeners who seemed to have overlooked the point (on DB's). "Technically" they're quite different, but in non-technical jargon, they're addressing the same issue.

You're absolutely right to clarify it though. For time limitations (& so as not to confuse some), I just tried to shed some light on the apparent "inconsistencies" between Amplifier specs (db's), and speaker/load specs (db's) that many were "mixing up." The primary (of many) reasons is the fact that different speaker systems have different unique transfer functions (call it efficiency...as a general-type-term here)....LOL.

You're also right about the room and other aspects which effect real-life acoustical input to our ears. I totally avoided getting into that, and other issues of impedance and frequency anomalies (what you called "crest factor"), etc... would have been a little too long for me.

Your explanation of peak power demands for speaker playback is better explained than what I did... it's something many people should appreciate when thinking about what an amp is theoretically called upon when reproducing real life (demanding/difficult) sounds, and why high power amps are needed for that (generally). This aspect of sound, transient response and dynamic range, are the most important things that makes amplified sound appear "real". It's a primary reason why we can hear the difference between a live sound in the next room, and a recorded one. I'm not saying other aspects aren't important, but dynamic range is the hardest to master, simply as a technical "problem".

In fact your whole post should be edited a bit and bookmarked so that newbies could get some insight into some of these issues. It's explained rather well.

BTW, I often use my (very efficient) JBL-15" drivers (low end) together with very inefficent mids + tws. Tri-amped, etc... lots of "problems" and issues trying to get things balanced.

Too Much Sound Pressure=Semi-Deaf
will kill your hearing. No doubt about it. I know my hearing would be a little better if I had not been a recording engineer...even though I was careful with the dbs. Most sound mixers need increasingly higher volumes to mix tracks. Many times the client needs to be wowed. So you pump it up. Met alot of senior engineers who mixed by the #'s and experience because their hearing was shot. Continually high sound pressure will make you progressively...deaf.

My uncle spent years around jets... this was back before they spent a lot of care about those things. You think your SPL's were high in the studio? LOL. His hearing was shot.

Even worse than continual high levels of sound are impact sounds (machinery or guns). I try to put in earplugs when even hammering nails... the sound profiles are very narrow... but the levels are VERY loud. You can hear your ears twitch if you pay close attention. Nerve damage is permanent. I remember one private party were we played in a small basement (I played bass in a cheesy R&R band)... my ears were ringing for hours... but I was young... and stupid.