Re: Advice for new system
Like everything, the answer is...it depends. You're asking some pretty unspecific questions which makes answering difficult.
1) If you keep it close, it's usually not an issue...example 80W RMS speakers being given 100W. Typically, that's fine. But some dudes throw caution to the wind and hammer on drivers with more power than they ever needed, and the life of the driver reflects that...sometimes. LOL! Some drivers are tanks and can take a pounding and just keep on ticking.
2) 92 db is a generalization. Speaker sensitivity is a T/S parameter that only tells one piece of the puzzle. The only things that make drivers "louder" are more volume, more power, or more cone area. (In general terms)
3) Absolutely yes, size matters. You obviously are not going to get good sounds from a car equipped with only 2" computer speakers. A properly designed system with appropriately sized drivers and amplifiers powering them (and a DSP in a perfect world) is the best way to get "good sound" in a given space.
Welcome to the site BTW. There's a ton of good dudes with vast knowledge on this spot...
Re: Advice for new system
Don't get hung up on power numbers. The way speakers are rated for power is misleading. A 100w rated tweeter will be fried if you send it much over a few watts of power. Speakers are rated based on music and music has around a 3db/oct slope so 100w at 20hz is only like 1/2w for your tweeter frequencies. So a 100w rated tweeter is really only a 1/2w actual tweeter. The only speakers that will actually use all the power is your subwoofer, and then only when you max out your volume.
Re: Advice for new system
:welcome: while we don't mind answering questions, looks like you may need a foundation from which to ask them. This link is great for diving into this stuff :)
Good luck in your quest
http://www.bcae1.com/
Re: Advice for new system
1- its fine to overpower it, just not 10-20x the power it actually needs. Tweeters don't really need a whole lot of power 100 watts may be 10x the power it needs. Set proper Gains.
2- Speaker/Driver Sensitivity means 1 Watt would provide that loudness over 1 meter. double the power = +3db more, Adding a speaker to be specific, every similar quality speaker you add doubles the sound intensity. This doubling of sound intensity increases loudness by 3 decibels. More speakers mean more air displaced, which results in more volume there are glass ceilings and diminishing returns to this.
3- Size of the speaker does matter depending on if you are doing 2-way or 3-way a smaller tweeter or midrange can be more beneficial than a larger one depending on what application you are doing [in terms of sound quality]. Usually if you just want to BLAST and forget sound quality Size does matter for SPL.