Master Asylum wrote:
| Now this is a moderately ok setup, but most good head units can put out like 20wRMS x 4. And you are definitely missing out on the advantage of those speakers, being able to take a lot and go big. If that's all the power you are wanting, I'd get lower power rating. I am personally running 5.25" with 60wRMS rating and 6"x9" with 75wRMS. All of them fully powered or slightly overpowered. |
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Gotta chime in here because some common misunderstandings about power have been driving me bonkers lately:
You don't need a lot of power to make good speakers sound good.You don't need to match RMS ratings of speakers to make them sound 'right.'A doubling of power only yields a 3db gain in SPL.3db is small. It takes an increase of 10db for material to sound twice as loud to our ears.You only use the EXTRA power when you're cranking it past what the weaker amplifier can reasonably produce. Underpowering DOES NOTHING BAD TO SPEAKERS. Lets use Master's system, lets say 70x4 and the 35 watt system as an example. Let's assume the speakers are all 90db efficient. Let's assume at full rated power, both channels driven, the amplifiers have similar distortion characteristics.
Our question: how much of a difference does the big bad extra 35 watts make?
Well, 1 watt will produce 90db. 90db is loud. Prolonged exposure to 90db can cause gradual but premanent hearing loss!
2 watts will produce 93db. 93db is slightly louder than 90db.
4 watts will produce 96db.
8 watts will produce 99db. Here we almost have a doubling of perceived volume!
16 watts will produce 102db. Now we're over 100db. This is quite loud. Many sources suggest not to listen above 100db for more than 15 minutes or you risk speeding up hearing loss quite rapidly.
32 watts will produce 105db. All authorities on hearing loss say that music should not be listened to above this level for longer than 10 minutes.
-----we've now reached the point where distortion will start entering the system via the pushed 35w amplifier ---- however, and this is important too, it isn't like the amplifier just dies at 35 watts or just stops there. It keeps putting out more power, it just adds some distortion. Better quality amplifiers will add distortion above rated power at a slower rate. And we've still got max power, remember. If the amplifier needs to reach deep for a nice 107db blast, it usually can! -----------
Alright, lets test that big bad 70watts. Oh, it only adds another 3db. It can produce 108db within its rated distortion level. Woopie. You gained 3db at a point where you shouldn't be listening to music for longer than handful or two of minutes anyway. Good job.
From this you might be saying, "then why do I always hear that underpowering harms speakers?" The author of
www.bcae1.com said it best on this topic. It was something like, "underpowering doesn't harm speakers, idiots with the volume control who clip the amplifier harm speakers." Check out that page. Set your gains correctly and know the point at which you can't turn the volume dial and you won't have to worry about this problem.
Also, you may be asking yourself, "then why can't I just use my 20w rms headunit?" The answer is because not all amplifiers are created equal and manufacturers are dishonest with their ratings. You simply cannot pack powerful amplification into such a small package. Period. With a full-range signal w/ all channels driven, distortion will be much higher than most (almost all) manufactureres list at their rated rms number. Even then, a good amp will be much cleaner.
(caveat - as class d / chip amps become more popular and better researched, we may see some class d head units that can compete with some separate amplifiers... something tells me that head unit manufacturers aren't really too interested in this though).
New Project: 2003 Pathfinder
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