Underpowering speakers

[Mullet Man]

is it a problem if you under power your speakers. Like if I wanted to run these http://www.thezeb.com/p-CDT-Audio-CL...tem-101083.htm off the HU temporarily untill I got a sep amp?

[Raditz]

Its perfectly fine

[geolemon]

There's no such thing as "underpowering" speakers.

heck, the volume knob on your head unit does nothing but regulate how much power your speakers get - turn it down, you are turning your volume down.

(and to drive home how silly the "underpowering" concept is, the relationship between power and speaker output is real interesting to note - in order to double your speaker output, power must increase by a factor of four. So, turning your volume down to the point where the speakers are playing half as loud as they are capable of (which is still darn way loud), you cut your power down to 1/4 of what they are capable of taking. to play them 1/4 as loud as what they are capable of, you would be feeding them only 1/16th of the power they are capable of taking - with absolutely no negative effects from playing speakers at low volume levels )

There are [b]only two ways[/] to blow/harm your speakers (short of putting your foot through them or something like that ):
1) sending them too much power, causing them to fatally overheat
2) overexcursion damage, causing physical damage to the speaker

Since sending less power to the speakers means they will run cooler, that is actually healthier for the speakers.

Since operating them on less power means they will be operating at lower volume levels, they will be reaching lower cone excursion levels, which puts overexcursion damage further out of reach, which is definitely healthier for the speakers.

Hopefully that helps!

to answer your question more directly... there's no harm.
If it is a short term solution, until you save up for that amp, don't sweat it with any component set.
If it is going to be a long term solution (ie. never buying an amp), then you might want to intentionally select a more efficient set of speakers, that require less power to get very loud. You can usually do this pretty easily at most shops that have a demo wall - run a set of speakers off nothing but the head unit, and leave the volume set at one position as you switch from speaker set to speaker set. Listen not only for quality and detail, but which set is louder - the louder speakers are more efficient, requiring less power to get loud.

And personally, for something so critical (playing over 80% of the musical spectrum), i wouldn't pick a set of speakers with anything other than my ears.

[objext]

Geo: I can't believe you missed the main point which leads to people claiming "underpowering" is bad - clipping.

[treefitty]

Originally Posted by objext Geo: I can't believe you missed the main point which leads to people claiming "underpowering" is bad - clipping.

or that it blows out speakers

[geolemon]

Clipping IS sending too much power to your speakers...

If you have an amplifier that is SO small that even dramatic clipping doesn't result in your exceeding the speaker's thermal rating, then even dramatic clipping doesn't harm it, because you haven't reached the point where you ARE overpowering it.

And regardless, not really an issue here, because we're talking about a head unit - it doesn't have a gain knob to be set up like an amp.

But a good point - we could discuss that here if you want, but it definitely has been covered before... a quick search for "clipping" and "underpowering" should pull up enough reading material for a comfortable evening.

[eapavant]

Originally Posted by geolemon Clipping IS sending too much power to your speakers...

Wrong, clipping is distortion. this can happen with to little power or to much power.

[geolemon]

Originally Posted by eapavant Wrong, clipping is distortion. this can happen with to little power or to much power.

Pardon my oversimplification. I'm not wrong, you don't understand what happens when you clip an amplifier...
Hey, if you can describe to me how distortion can damage speakers, without the distortion creating an overpower situation, I'll give you $1M.
Read on.

To understand what happens with clipping, you must understand what happens with a clean signal - the simplest of which is a single-frequency sine wave.
Picture a single sine wave, and follow it:
The curve starts at the "0" center line, and curves upwards, then uncurves as it reaches it's peak momentarily, curving downwards. The curve then passes the "0" center line again and heads down an equal distance that it rose, uncurving again to reach it's lowest point again momentarily, before curving back up to the "0" centerline again. Repeat and repeat.
- Cone excursion follows this waveform, that's why the speaker plays the sound being sent to it. For our sine wave, as the curve rises, the cone is receiving a signal telling it to move out, until it reaches it's excursion peak, when the signal heads in the other direction, telling the cone to move back in... passing the centered "at rest" position, then moving in towards the basket, passing that rearward excursion peak, moving back to the "at rest" position... cycling over and over. (and technically, there are some phase-related issues here... that is, the speaker isn't instant, and its own mass causes the speaker to not necessarily exactly replicate any waveform that isn't a true sine wave... but that isn't really an issue here )

But the real issue is why the speaker motion follows the waveform...

Even though technically this is a phase concept expressed in terms of 0-360 degrees of phase rotation, our subwoofer is a simple in/out motor that can only move in those two directions - effectively changing this whole equation to a [thankfully easier to understand] concept of in and out.
When the waveform is above the "0" center line, the 'power is on' in the "out" direction - the higher the waveform above the line, the greater that heat-creating power - essentially, how much current is flowing in that direction.
And when the waveform is below the "0" center line, the 'power is on' in the "in" direction - the lower the waveform below the line, the greater that heat-creating power in that direction.

With a simple sine wave, we're only sending peak power levels to the speaker instantaniously, for the briefest moment, in each direction, each cycle.

With a clipped signal though, all bets are off.
We're lopping some portion of the top and bottom off the wave (yes - distorting it). And as a result, because of this, the signal is rising to the peak power level faster - and (this is the key) staying there longer. This means the "power is on" - fully - for longer durations each cycle, effectively sending more power through the voice coil - more a function of duration than amplitude.
Duty cycle, if you will - if the power peaks for just 100,000ms each cycle with a clean signal, and you are clipping the signal so that the power peaks and holds for 10,000ms each cycle instead, you would essentially be warming the voice coil with 10x the power (well, not quite, but my trig skills aren't that advanced to work out an exact calc ).

Bottom line is, only power can cause a wire to generate heat (shedding it is another issue - there's a whole cooling system involved in a speaker ... the more power, the greater the heat.
Sending a speaker too much power isn't a problem in itself actually - the problem is a thermal one... the heat generated in the wire from sending too much power through it is the issue - the glue will let loose on the voice coil, turning it into spaghetti.

It is possible to clip an amp that is technically 'too small' (ie: less than the power rating of the sub), and clip the waveform so much that the amplifier is sending much more power than the sub can handle, damaging it thermally - even though the amplifier's output voltage never reached an amplitude any higher than could be reached with a clean, non-clipped setting.

...and even still, as I said originally:

Originally Posted by geolemon If you have an amplifier that is SO small that even dramatic clipping doesn't result in your exceeding the speaker's thermal rating, then even dramatic clipping doesn't harm it, because you haven't reached the point where you ARE overpowering it.

Hopefully that quote will make a little more sense to you now.

[treefitty]

Originally Posted by eapavant Wrong, clipping is distortion. this can happen with to little power or to much power.

do not underestimate the knowledge of geoman

[geolemon]

This is still an oversimplification... the power is still technically being sent in terms of 0-360 degrees of rotation.

And I didn't mention the additional heat related issues involved with clipping - momentum will carry the cone a bit farther when the signal reaches it's amplitude peak, but essentially since the signal stops, factoring out momentum, the cone does as well, so there should be a bit more heating here, since the cone is stopping (well... slowing) at the peaks of excursion.

Heat is ultimately the killer, like I said.

[Fryguy]

Originally Posted by eapavant Wrong, clipping is distortion. this can happen with to little power or to much power.

You sir, are a noob

[trev0006]

Thanks for posting this guys, it saved me a bunch of time reading this.

Originally Posted by Mullet Man is it a problem if you under power your speakers. Like if I wanted to run these http://www.thezeb.com/p-CDT-Audio-CL...tem-101083.htmtirescars off the HU temporarily untill I got a sep amp?

Originally Posted by geolemon There's no such thing as "underpowering" speakers. heck, the volume knob on your head unit does nothing but regulate how much power your speakers get - turn it down, you are turning your volume down. (and to drive home how silly the "underpowering" concept is, the relationship between power and speaker output is real interesting to note - in order to double your speaker output, power must increase by a factor of four. So, turning your volume down to the point where the speakers are playing half as loud as they are capable of (which is still darn way loud), you cut your power down to 1/4 of what they are capable of taking. to play them 1/4 as loud as what they are capable of, you would be feeding them only 1/16th of the power they are capable of taking - with absolutely no negative effects from playing speakers at low volume levels ) There are [b]only two ways[/] to blow/harm your speakers (short of putting your foot through them or something like that ): 1) sending them too much power, causing them to fatally overheat 2) overexcursion damage, causing physical damage to the speaker Since sending less power to the speakers means they will run cooler, that is actually healthier for the speakers. Since operating them on less power means they will be operating at lower volume levels, they will be reaching lower cone excursion levels, which puts overexcursion damage further out of reach, which is definitely healthier for the speakers. Hopefully that helps! to answer your question more directly... there's no harm. If it is a short term solution, until you save up for that amp, don't sweat it with any component set. If it is going to be a long term solution (ie. never buying an amp), then you might want to intentionally select a more efficient set of speakers, that require less power to get very loud. You can usually do this pretty easily at most shops that have a demo wall - run a set of speakers off nothing but the head unit, and leave the volume set at one position as you switch from speaker set to speaker set. Listen not only for quality and detail, but which set is louder - the louder speakers are more efficient, requiring less power to get loud. And personally, for something so critical (playing over 80% of the musical spectrum), i wouldn't pick a set of speakers with anything other than my ears.