Understanding amplifiers

[02SteelBlue]

Four speakers in the vehicle, all rated to handle 100 watts rms.

If my head unit puts out 25x4 rms, and there's a 75x4 amplifier, I understand the more power aspect.

However, if my head unit is 75x4 rms, is there any benefit to having the amp power the speakers as opposed to the head unit?

 

[Jramos013]

I would say your HU is the 25w rms one. Using the 100rms rated speaker would sound ok but once you crank it up it will start to distort. The idea of the amp is that you can hear it louder and cleaner, not distorted.

 

[02SteelBlue]

I would say your HU is the 25w rms one. Using the 100rms rated speaker would sound ok but once you crank it up it will start to distort. The idea of the amp is that you can hear it louder and cleaner, not distorted.

Ok, so amp power is cleaner than head unit power. And I'm taking away that speakers under less watts distort? So the higher the volume (more watts) the less distortion?

https://www.crutchfield.com/p_130DS4120B/Pioneer-DEH-S4120BT.html?avf=Y
This is my head unit. If you go to details, then the general category, it lists the head unit output and the mosfet internal amp output. Is this additive?

I guess bypassing all of that and getting power straight from an amp is preferred. Will I need to match the amp output to the speaker rms, or am I ok with a 75x4 rms to 100 watt rms speakers?

Apologies for my confusion. I thought I had it somewhat figured out, until I didnt.

 

[g.hayduke]

Power ratings are always relative to a certain level of distortion. And distortion will increase at higher output levels. An example would be 100 watts RMS @ 10% distortion just to illustrate the point.

What you want is minimal distortion (though in a TJ, you don't need to sweat it too much). There is no real need to match amp output to speaker power ratings. However, more clean amp power is generally a good thing. Just keep in mind that if you push an amp near it's limits, the high distortion levels can actually blow speakers, especially tweeters (high frequency drivers). So, there is really no such thing as too much clean amp power but too little can and does blow speakers.

An ideal setup with an amp is to have preamp outputs on your head unit. Hook the preamp outs to the amp inputs (usually rca jacks) and connect the amp outputs to your speakers. Many head units do not have preamp outputs. Many amps have speaker-level inputs. So if you head unit has no preamp outs and your amp has speaker-level inputs, an alternative hookup would be connecting the head unit speaker outs to your amp speaker-level inputs.

 

[02SteelBlue]

Power ratings are always relative to a certain level of distortion. And distortion will increase at higher output levels. An example would be 100 watts RMS @ 10% distortion just to illustrate the point.

What you want is minimal distortion (though in a TJ, you don't need to sweat it too much). There is no real need to match amp output to speaker power ratings. However, more clean amp power is generally a good thing. Just keep in mind that if you push an amp near it's limits, the high distortion levels can actually blow speakers, especially tweeters (high frequency drivers). So, there is really no such thing as too much clean amp power but too little can and does blow speakers.

An ideal setup with an amp is to have preamp outputs on your head unit. Hook the preamp outs to the amp inputs (usually rca jacks) and connect the amp outputs to your speakers. Many head units do not have preamp outputs. Many amps have speaker-level inputs. So if you head unit has no preamp outs and your amp has speaker-level inputs, an alternative hookup would be connecting the head unit speaker outs to your amp speaker-level inputs.

Thank you!

 

[89grand]

Most headunits on the market produce no more than 15 watts per channel of usable power. If they produced much more, the headunit would need a separate power supply.

More amplifier power is always better to have, and today, even tiny Class D amplifiers can produce a decent amount of power. The speakers rated power handling really means next to nothing for the most part. It tells you nothing about how loud it can get, and I can guarantee that my 200wpc B&K home amp or even my 150wpc AudioSource home amp could destroy any coaxial car speaker on the market with little effort if I played a low frequency sine wave through it connect to any coaxial at half, or even a quarter of their maximum output.

Think of how much power your TJ seems to have when driving it. If you added a supercharger (an amp) the power difference would be easily noticed in daily driving. That's basically the same idea as using a separate amplifier. Even a 50w x 4 amp would be very noticable in overall volume level ability over the headunits built in amp.