Speaker amp question. on a budget.
 

I have a pair of 4x6" rated 40 watts RMS @ 4 Ohms, each, and a pair of 6x9" rated 55 watts RMS each @ 4 Ohms . I got lucky that the resistance is the same which makes amp shopping much easier but still leaves the question "what rating should my amp be? 40, 45, 50, 55 watts RMS x 4 channel?" I'm very aware of the dangers of "underpowering" and "overpowering", thats not the issue. With proper tuning i need to know what would be the "least harmful" option to power all 4 together? Im assuming 40 watts. Thanks again guys!

I would actually go with a healthy 60 or 55 and set up your gains accordingly. The thing is that it's better to overpower them than underpower them since if you underpower them, you'll find yourself pushing the speakers a lot harder than if you overpower them, which at that point, the speaker would sound distorted since it's not made to handle power after a certain threshold.

Besides, it would be easier to tune the amp to not blow up the 40 watt speakers than having to handle the clipping of the 55 watt speakers.

Exactly ^^, as long as the power is clean, overpowering works.

Yup. Clipping speakers with an underpowered amp is a no-no.

Amps are usually rated lower than they actually test so the lowest rms is what you're going to want to go with probably.

Just don't be confused by max power vs. continuous RMS power.

I must say that went smoother than expected especially after reading another forum where someone asked the same question. But that makes complete sense thanks for clarifying!

I see where your getting that, my sub amp which advertises 800watts RMS came with a certificate saying it actually puts out 937watts RMS. I think rockford does he same

Yup a lot of the decent amps are like that.

Now, I am no audio expert, but if you lower down the volume on your head unit, aren't you reducing the amount of watts going to all your speakers? If underpowering speakers were so bad, wouldn't it be bad to bring down the volume on your speakers?

http://www.bcae1.com/2ltlpwr.htm

Thats because those terms are referring to full volume. Underpowering ruins the amp and speaker because at high volume the speaker is drawing more power than the amp can properly put out, which causes the amp and speaker to distort. overpowering ruins the speaker because at full volume the amp is putting out more power than the speaker can handle which also causes distortion. Improper 'gain set' is the same thing pretty much. At least this is what I've been told over the years. If I'm wrong somebody please correct me

you silly mouse
 

:haha: LOL NO YOU DIDNT'T!!!

We're a small community so we can't really be douchey. :coolio:


The thing about watts in general is that the more power the alternator/battery puts out, the more watts the amp will put out. Those RMS ratings are sketchy but it beats the older system where each brand had a different way to reach the power rating.

Your amp will put out more power with the engine running at 14.0 volts than if it were on accessory mode with a battery that puts out 12.6 volts. This is why they tell you that with the engine idling at 2200 @70mph, your amp will get more power than if the car was idling at 500.


You have a point... You can have a 15 watt amp and run 80 watt speakers with them no problem. In fact, this gets done with head units all the time. The head unit usually doesn't put out more than 18-22 watts rms and a max of 40-52 watts peak. There's no problem with that until you crank up your head unit to max volume. That's when speakers start to blow out. Usually, you're not driving the speakers on 35 (max volume for Alpine and JVC/Kenwood). If you ever tried this, you would notice that the sound is very distorted. The vocals aren't clear and the frequencies get muffled out (so the instrumental actually ends up sounding very muddy). If you listen to your music like this for extended periods of time, then you burn up the voice coil. It makes the speaker hard and it smells really nasty.

For the next example, I will be using the specs for an average Alpine head unit.

Here's where the underpowering/overpowering thing comes into play. A low volume is considered to be anywhere between 0 and 12. Here, the amplifier doesn't use up any power to drive the speaker. It can practically use the voltage from simply being on "Standby" to produce power at these volumes.

Anywhere from 13 to 25 is considered peak volume. Around this range, you're meeting the average watt rating. If your radio can go up to 35 and 13-25 is your peak, here is where you can start burning up speakers. If you underpower them, it will sound very weak at peak volume. Your natural instinct is to raise the volume. As the speaker tries to please you and sound louder, the signal being fed to it becomes distorted. Usually with an underpower speaker, the sound frequency will clip.

Check this out.



The danger of overpowering, is burning up the voice coil from too much heat.


You missed the clipping part. The main reason underpowering is bad is because at full volume, you square off the signal, whereas overpowering, the voice coil burns from excessive heat since more power = more heat.

The gain set and the bass booster are basically meant to line up the signal with what the speaker can handle, but there's that misconception that 4volts on the gain is low and that 2 is good since you want it loud, BUT if the radio doesnt have a 2 volt preout, then there's no point of setting your gain at 2 volts. It's the same concept as maxing out your volume at 35 when your speakers are only designed for frequencies in the 20-25 range.