Feeding speakers too much power

[Quattro Pete]

Theoretical question... say you have a pair of 2-way bookshelf speakers designed to handle 100W continuous / 140W short term. If you were to feed it (clean) power somewhat in excess of this, is it the woofer or the tweeter that is at a higher risk of getting damaged first? Assume standard dance/pop/hiphop material with plenty of bass, if that matters.

Can the woofer get physically damaged from over-extension, or is that not even possible?

 

[mechanicx]

I'm no audio expert but I think tweeters are more suseptible to damage from over power. Woofers can be physically damaged from over extending. I've seen that before. Usually you can see or hear it and redduce the volume. Of course it is somewhat dependent on the signal and if it bass heavy, treble etc.

 

[aquariuscsm]

Power clipping (distortion) is what kills speakers more vs wattage. What kind`ve speakers do you have,and what kind`ve amp are you using?

 

[gathermewool]

When I was younger, I over-powered some speakers and it was the woofer surround that was damaged from over-extrusion after a bit of time.

If you're basing the power levels on the RMS output listed in the spec sheet for the receiver then worry not. A good output, in my limited experience will have just as much (or little) chance of damaging speakers as under-powering; some will argue there's less chance with a higher, cleaner power source, since you won't be adding in tons of noise while cranking up the volume trying to hear what a cleaner source will produce at a lower volume.

 

[dave123]

Have you ever seen the movie Back To The Future

 

[Errtt]

All depends on speakers and other components within the system.
If the bias is off, running near max will do more harm then a system with correct bias. DC output can kill speakers.
There are different tweeter, x-over etc too.
^ yes... distortion/clipping is not generally a good thing.
Check & set bias for cleaner sound. Low power needs/wants higher efficient speakers, but having a little headroom is a good thing to.
Match speaker ohms to output. Those that dip down during play makes it harder on amps.

If you have to push a lot to get decent sound, then something may not be right. Might want to do a DC output check. Typically if it gets to far off, the protection relay should prevent output, but some don't have that protection relay. They couple to output/capacitance.

 

[JavierG]

You are more likely to damage speakers from using an underpowered amplifier that puts out higher distirtion levels than by using a highpowered amplifier that puts out a clean signal.

 

[swirlparanoid]

The whole blowing a speaker because its under powered myth is because when its under powered the person keeps turning it up way past the amps limits and clips the signal like crazy which will cause a speaker to fry in a hurry. No speaker in history has ever been blown by being under powered. (when given a clean unclipped signal)

If you have a quality amp i dont see why it would be a problem, depending on how much your talking about overpowering it. If its a HT receiver i would be very skeptical though. Most HT receivers dont do anywhere near rated power.

speaker brand?
amp brand?

 

[Quattro Pete]

Originally Posted By: JavierG
You are more likely to damage speakers from using an underpowered amplifier that puts out higher distirtion levels than by using a highpowered amplifier that puts out a clean signal.

Yes, I perfectly understand that. My question was strictly about clean power.

 

[Quattro Pete]

Originally Posted By: aquariuscsm
Power clipping (distortion) is what kills speakers more vs wattage. What kind`ve speakers do you have,and what kind`ve amp are you using?

Speakers are Jamo C603 (6 Ohm). Amp/receiver is HK 3490 with the following specs, although my question was purely theoretical, and not related to this specific setup. I just wanted to know what will give in first if too much clean power was thrown at the speakers.
Code:


Stereo Mode:

Continuous Average Power (FTC):

120 Watts per channel, 20Hz – 20kHz @
150 Watts per channel, 20Hz – 20kHz @


Input Sensitivity/Impedance: Linear (High-Level): 200mV/47k ohms

Signal-to-Noise Ratio (IHF-A): 95dB

Frequency Response @ 1W (+0dB, –3dB): 10Hz –110kHz



High Instantaneous Current Capability (HCC): ±45 Amps

Transient Intermodulation

Distortion (TIM): Unmeasurable

Rise Time: 16 µsec

Slew Rate: 40V/µsec



Power Requirement: AC 120V/60Hz

Power Consumption:

 

[aquariuscsm]

Sounds like a nice system!

 

[97tbird]

Originally Posted By: JavierG
You are more likely to damage speakers from using an underpowered amplifier that puts out higher distirtion levels than by using a highpowered amplifier that puts out a clean signal.


This - nail on the head.

 

[pcoxe]

Speaker voice coils need to have low power time or special construction in order to dissipate heat. Continuous hi-volume sound levels may overheat the windings and short or burn out the voice coil. Consider how hot a 100 watt light bulb gets during operation.

 

[digitalSniperX1]

Of course too much power can burn them up. Especially at LOW frequencies.

Harmonic distortion sourced from an amplifier, i.e. clipping...can and does damage tweeters...as others have indicated. It's a dynamic situation their crossovers can't handle effectively allowing short bursts of DC through their voice coils.

But make no mistake. Bottoming out woofers effectively shorts an amplifier through the speaker winding since during the bottoming out interval, the speaker is not generating any back EMF. it's akin to holding a DC motor stationary which causes them to burn up.

 

[digitalSniperX1]

the entire 100 watts of an amplifier are not delivered as heat. Some of those watts actually do produce audible sound waves

And amplifiers aren't outputting anywhere near 100 watts continuously. The dynamic range in music can be 90db or more. If the "quiet sounds" were at 1 watt, which is actually fairly loud in any modern speaker, the amplifier would have to output 1 billion watts to produce the loudest of sounds. (90 db over 1 watt is 1 billion watts).

But as you said, heat definitely destroys things, including speakers.

 

[Hermann]

A speaker only reproduces the signal that it is being fed. When a amp hits hard on a big bass note the distortion can go from virtually nil to 20-30% in a instant.

Here's a BITOG analogy. A driveshaft is bent 20 degrees and you run it, the u-joints ect don't last long. Send a speaker 20% distortion over a period of time,the voice coils start to rub and eventually the speaker quits working when the wiring on the voice coil get worn through.

 

[digitalSniperX1]

I wouldn't worry about using an amplifier rated higher than the speaker's rating. You're not going to drive them with all that power.

And if your woofers "pop" by hitting their endstop...turn it down. Woofers usually take a bit of abuse before they die.

Tweeters on the other hand, as others have hinted at, aren't nearly so durable. They can blow in an instant without audible warning.

 

[swirlparanoid]

The speakers you listed go down to 45hz. Great for a bookshelf speaker but still probably wont satisfy you by themselves since you like bass heavy music. Ever thought of getting a sub? Then you could set the crossover higher on the bookshelves and wouldn't have to worry about blowing the woofers as much...

 

[Quattro Pete]

Originally Posted By: swirlparanoid
The speakers you listed go down to 45hz. Great for a bookshelf speaker but still probably wont satisfy you by themselves since you like bass heavy music. Ever thought of getting a sub? Then you could set the crossover higher on the bookshelves and wouldn't have to worry about blowing the woofers as much...

I actually do have two powered subs in this setup to cover the low end. The problem is that it's just a stereo receiver with no bass management so I don't have the ability to limit the amount of bass going to the speakers themselves - they always get full range of frequencies, regardless.

 

[Quest]

OK, here's the facts RE: loudspeakers, amplifiers and speaker driving:

(1)speakers sensitivity ratings are not directly related to power handling capabilities.

In other words: your (Jamo) speakers may be rated to 100Watts max. @ a 1second duration, and beyond that duration, your woofer voice coil may overheat and burn out.

Speakers that are capable of handling 100Watts power continuously are mostly those that are those typically comes with aluminium voice coil former and/or aluminium voice coil wires (copper clad) to assist heat dissipation.
Some high power, continuously duty P.A. or stadium professional sound re-enforcement speakers, etc. (Beyma or JBL comes into my mind)

(2)in high-end audio we have a saying: the first watt (from the amplifier) is the most important watt. If an amplifier cannot reproduce the 1st watt "faithful" enough, the rest of the output (in terms of wattage) isn't gonna matter any more.

(3) sound pressure level (in Decibel form), is logarithmic, meaning that it does not obey the linear rule.

So, for a 90dB/1W/1m (referenced @ 2.83V), when you are sitting 1m away from your speaker (on-axis) and feed 1watt into your speaker, you get 90dB out of it. In order to produce 93dB, you need 2Watts; to get 96dB, you need 4Watts; 99dB, you need 8watts, and so on and so forth.

(rough formula: in order for a given sensitivity speaker to up 3dB, you need to double the amplifier's output power that feeds it)

(4) home speakers are (IMHO) fairly low efficiency, with sensitivity typically around mid 80s dB/1W/1m (ref @ 2.83V) to early 90s dB/1W/1m (ref. 2.83V). Some elaborate designs that occupy horn or some kind of sound re-enforcements may get as much as mid 90s dB/1W/1m (ref @ 2.83V).

(5) tweeters, esp. those that came with ferrofluid cooling(very common nowadays)) can handle power, provided that they are being fed with AC (and no DC in it). Most of the ferrofluid cooled tweeter burnouts happen to solidstate (transistor-based) low-quality, low-power output amplifiers that clip early (or violently, depending on how you'd like to translate it) and clipping sends DC down the speaker drivers, thus killing the tweeters.

Tube amps, on the other hand, requires an output transformer (except OTL, which is another subject) and even when set to clip, doesn't burn out tweeters all that easily.

(6) how well an amplifier can drive speakers with relative ease (nowadays it is so easy/inexpensive to produce high power output with relatively less distortion than, say, 50+ yrs ago) has to do with how relatively easy the speaker impose it's loading to the amp.

If the speakers exhibit very difficult impedance loading behaviour across the entire reproducible audible audio spectrum, then even though it seems relatively high sensitivity on paper (e.g. 91dB/1w/1m ref: @ 2.83V), your may need still need a solid state amp capable of producing some serious 300Watts of clean, low distortion power in order to make them sound properly.

If the speaker impedance loading behaviour is on the "easy" side, then you don't need much (maybe a few watts to 50Watts? of clean, low distortion power) to make them sound nicely.

Sorry if this sounds overly complicated to you.

Q.