Time for a new stereo

[LaborOfLove]

I already have two pioneer 8"s wired and connected, but I want a new stereo and another pair of speakers. If each of the speakers has a 200 watt max and a 40 watt nominal, what output from the head unit would I need? I'd rather not have a separate amp if I can avoid it. Would I need a 4x40 or a 4x200?

 

[bruceb58]

You can use anything as a head unit as long as each channel doesn't have more than 200W which a head unit won't.

 

[gm280]

Just to let you know that wattage does not mean volume. Wattage is more of a quality issue then a volume issue. True higher wattage usually means more volume capability, but not always... It really depends on the speakers abilities. Example, you can have screaming high volume on 10 watts, but the quality isn't going to be there... But this is a huge subject to cover here on a short post! Just make sure you buy a balanced system and I think you'll be okay... JMHO!

 

[LaborOfLove]

So how do I pick out speakers that'll rattle my eardrums? Recommendations?

 

[gm280]

First thing you have to understand is the DB (decibel) system. Here is a very good thing to always remember. For every 3 DB increase in wattage the volume is doubled! That IS a very powerful statement and can lead you to your system setup. For example. If you're looking for speakers that state they output X number of DB's at a certain wattage, then you have values to work with. I'm sure you've seen such statements about 89 DB at 1 watt 1 meter. That means standing in front of that speaker at 1 meter away, when 1 watt is input to that speaker, the sound pressure level will be 89 DB. And since you know that for twice the volume you have to add 3 more DB then you know two watts will equal 91 DB, and twice more wattage (4 watts) will equal 94 DB and so on. So if a speaker is listed as being able to handle X watts, that IS the absolute max you can input without that speaker failing...or there about! And knowing the wattage to DB formula, you can see how any speaker will make sound pressure (volume) with that given information. So balance any system knowing that both the amp AND the speakers need to be matched and how much volume (spl, sound pressure level) any setup can produce... It is pure mathematics... When I was building my speakers in my shop. I actually took all the speakers available and balance the woofers, midranges and tweeters to make sure all three were of equal SPL and able to accept the wattage the same. Then I created speakers that would sound balanced through out the frequency range without any segment being louder or quitter. There are more things to consider but that will get you what your wanting I'm sure. Cross-overs and impedance and ohmage and other things come into play designing speakers but factory made speakers with the receiver/amp will work if you match them up correctly. Hope that helps a little.

 

[KD4UPL]

gm280, excellent post!

OP, you don't want and amp but you want speakers that will "rattle your eardrums". Obviously that's a really subjective statement but it sounds to me like you need an amplifier. Most head units have amps that are maybe 20 to 35 watts RMS x 4. Amps can be had up to well over 100 watts RMS per channel with as many channels as you need. Power differences aside, a quality external amplifier will generally have less distortion, better frequency response, better damping, better dynamic range, etc. than an equivalent power section in a head unit. Head unit amps are designed to give a little power in a system where someone values simplicity and low cost. To really get any volume, especially in a noisy boat environment, you will want an external amp.
Generally you don't want the amp's RMS power rating to exceed that of your speakers but that's not an absolute rule. When an amp is run beyond it's capabilities it "clips" the waveform going thru it. This is what will "blow" a speaker. You're probably more likely to damage a speaker by running a too small amp too hard and making it clip than getting clean power from an amp that is technically over your speaker's power rating. '
Example: A speaker rated for 50 watts RMS fed with a distorted clipped signal form an overdriven 30 watt RMS amp will likely be damaged over time. That same speaker fed a nice clean waveform from a quality amp rated at 60 watts RMS will likely live a long happy life.

 

[bruceb58]

3 dB in power does not corespond to double sound pressure.

http://www.gcaudio.com/resources/howtos/voltageloudness.html

 

[gm280]

bruceb58, you are correct. To get a 3 DB change (increase) in sound pressure you have to doubling the output wattage to the speaker. If I previously stated that incorrectly I apologize... That is how anybody can determine the total DB any speaker is capable of producing. Between the manufactures specified DB rating at one watt per one meter and the DB rating at that setting and distance and also knowing the total wattage that speaker can handle, you will know the total volume that speaker can produce without damage... I guess I know what I am saying, but maybe not so clear trying to explain to others...