I'd like to upgrade the amp for my Vandersteen 3A Sigs, but am a bit confused on whether or not I need to stay within the band of wattage (100 - 200 into 8 ohms) that is *strongly* recommended in the manual. I've read several articles/blogs/forum posts stating that exceeding the recommend power range for a loudspeaker system should be of a little concern, as long as you don't "push them too hard". What exactly does that mean? How much risk of damaging my speakers would there be if I used a 300 W/ch (into 8 ohms) amp with my speakers? I have a fairly large room, if that makes a difference. I appreciate any advice, as you all seem to be very knowledgeable about audio and have a lot of experience. Thanks, Rob
I have not had any problems exceeding the suggested wattage range. Pushing them hard means playing them loudly with a distorted signal from the power amp or section of an inregrated/receiver. It is the distortion or clipping that blows your speaker. In many cases having an under powered amp is the reason that a speaker blows. The reason for that is that the small output amp strains when trying to get to the desired volume, that straining pushes the amp into clipping and sending a distorted or irregular wave form to the speakers. So the bottom line is not to drive your speakers with distortion, powerful will likely distort at higher volume than a small amp will. All that said it is of course possible to exceed the speaker's ability to fill the room at the volume you desire. You can blow the drivers simply by sending a more powerful signal than they can deal with. I don't know if your speakers have a very limited maximum output in terms of Db, and thus the stern warning from the manufacturer. A Db meter can be bought at Radio Shack, they are inexpensive. Never the less the most dangerous and most likely problem remains distortion IMO.
Exactly. And when that distortion is being caused by an over driven amp, it's going to be excessive heat that literally "fries" your drivers. Mechans is dead on. Unlimited power eliminates this factor from the scenario. I would definitely not use a classical cd to see how far I could go with my speakers, but buzzing due to over driven speakers versus buzzing due to an over driven amp is way less dangerous. Just turn down the volume and be reasonable.
I second the previous comments. Probably the most common speaker damage scenario is blown tweeters resulting from the distorted signal that would be produced if an underpowered amp is asked to put out more power than it is capable of.
Based on some rough calculations, your speakers should be able to produce an SPL (sound pressure level) of about 100 to 102 db at a listening distance of 4 meters (about 13 feet), when driven by an amplifier rated at 200 watts into 8 ohms. Most listeners would be unlikely to raise the volume level high enough to send more power than that into the speakers. And even if you did, it would probably just be on occasional brief peaks, which would probably not do any harm as long as the amplifier's maximum power capability is not exceeded.
@Stevecham: 1) very large room. ~16'x24', it opens to the kitchen and the ceiling is vaulted and transitions from about 8' in the kitchen to 18' in the front of the room. primary listening position is ~13 ft from speakers. 2) I'm not sure about the dB level. Normally, listening levels are moderate, but occasionally I like to crank it. I am very protective of my hearing though, so if I begin to experience any discomfort, I always back it off a bit.
@Mechans, @Csontos, @Almarg, thanks for your input. This is the impression that I've gotten from my research so far, but it is always nice to be reassured some more.
It is my understanding that it's distortion that blows a speaker. As long as the amp is putting out clean power you would be fine. I used a Classe ca 300 which puts out 600 watts into 4 ohms & 300 watts into 8 ohms my 104/2 speakers sound great with no issues what so ever.
I can't remember the last time I had amps that actually fell within the recommended range --- below the upper limit, anyway -- for the speakers I was using, and I've never had a problem.
I'm sure Elizabeth can handle a little levity. But all kidding aside, It is very easy to slowly fry your drivers too. It may still sound clean even though the amp is seriously clipping. In this case you won't end it with a bang, but turn it on the next time and the voice coils could be warped and rubbing or output is way down because a short has welded the coil in places. 30 years later, I still have a grudge against NAD for burning up my beautiful B&W DM7's in exactly this way.
Having repaired speaker systems for a couple decades; I can assure you that high powered amps can damage low power rated systems. Crossover capacitors are rated for only so many volts, and lots of manufacturers skimp there. I've lost count of how many aluminum electrolytics(cheap/cheap) I've seen popped like firecrackers. The drivers themselves(cone or dome type) can EASILY exceed their maximum linear excursion range and either bottom(and crush) the voicecoil, or destroy it on the top edge of the magnet structure. Then there is the ubiquitous fried/overpowered voice coil, caused by more wattage than the driver was designed for. Overdriving an amp causes clipping(very high freq distortion- resembles a square wave on an O-scope), which a crossover network will pass first to the tweeter, and toast it. Owning a shoppe in Winter Park(FL), surrounded by over eighteen college campuses, and a plethora of live(and canned) music venues; I saw LOTS of damage caused by overpowering. However; I would estimate the clipping damage(tweeter replacements) to have been twice as high(post traumatic college party syndrome). I always recommended a higher powered amp as safer, and cleaner sounding, for any given system.
@Rodman99999 - I'm a little confused by your response. Maybe I am misunderstanding, but you seem to be saying that you've seen a lot of damage to speakers being driven by amps rated higher than the speaker mfg's recommended wattage, but in the end you "always recommended a higher powered amp as safer, and cleaner sounding, for any given system". I guess you are saying a high power rating for an amp is good (even if above the mfg's recommended range), as long as you don't go overboard on the dB's? Is that correct?
I can answer for Rodman, You got the point. Clean undistorted power at moderate levels will be fine. The only concern is that you may want tp play quite loudly. I don't know your lifestyle, but as Elizabeth said as long as you are fairly sober and aren't a closet headbanger. If you want to blast music for a party or yourself then you might want to buy a spare set of Cerwin Vegas. I am not kidding they aren't crazy expensive and are capable of high SPLs.
YES- You've both gotten the point, precisely. For those customers that came in with toasted tweeters; I gave a little clipping demo and sermon. I also had a little tweeter protection circuit(that I built), comprised of two zener diodes, hot-melt glued into a small round heatsink. When the voltage of the incoming signal(after the high-pass x-over section) exceeded the diode rating, that would go to ground, protecting the tweet. Audibly invisible at normal(below clipping) listening levels.
The wattage rating is the maximum wattage a speaker can handle before they burn out, and has nothing to do with the Fidelity limit per wattage limit!
30 watts rms is all that most speakers can handle without causing distortion to the audio signal.
Why would you want to drive a speaker at 300 watts any way?
A distortion lesson...
A customer in Holland was having P.A. speakers blown out even when they were operated under the maximum wattage rate. This speaker was damaged by having the spider separate from the cone after 2-3 days of use. We did a frequency sweep on a new speaker to see where the cone would put out less acoustic energy. By plotting the speakers output with a Microphone-amplifier then to a Vdc converter we could see at what frequency the speaker cone was frozen-mechanically due to cone surface aberrations.
That is, one part of the speaker was traveling in a different direction causing, in this case, enough force to rip the voice coil off from the cone. Speaker in use was a 12 inch woofer with 7 inch long slope to the spider.
The mechanics is then: Frequency of ~975 Hz, Feet = 1.17 and inches = 14.01: 7 inches one one side 7 inches up the other side of the cone center - half of the woofer was going out the other half moving in.
This twisting motion tore the speaker apart at 23 watts input.
Distortion is our point here, anything over 30 watts into a speaker develops distortion, which is far above the Fidelity limits of most Speakers.
100 watt, 300 watts; if you want noise you will get it - just as long as your speaker does not burn out !
That just sounds like a poorly engineered driver. That thing would tear itself apart eventually even at moderate levels. The main concern in over driving a speaker is exceeding it's X-Max rating.
Sounds more as though they were trying to produce low bass freqs, in a pro environment, with a 12" driver. Too much EQ, too small a driver, and(as Mr C intimated)exceeded it's X-Max. 12" make good mid-bass drivers, in pro applications. 30 Watts is virtually nothing, in a pro setting.
08-23-12: Cjl >The wattage rating is the maximum wattage a speaker can handle before they burn out, and has nothing to do with the Fidelity limit per wattage limit!
To be pedantic it's a thermal limit if you feed the speaker pink noise (equal power in each octave) with a 6dB crest factor (difference between peak and average) with a 50Hz second-order high-pass and 5KHz second-order low-pass.
With about 7 octaves in that range the tweeter is seeing about 1/7 of that power and more than 30W of high frequency energy into a 200W rated speaker could fry it.
You can also reach the mechanical limits at much lower power levels at low frequencies.
Output at the maximum linear excursion into full space for various representative drivers at 3 feet is as follows at 120, 80, 40, and 20Hz. Mechanical limits are often 6dB higher although you can still run out with just a few Watts.
Size Driver Sd (cm^2) x xmax (mm) 120Hz 80Hz 40Hz 20Hz 4 1/2" Seas W12CY001 50 x 3 89dB 82dB 70dB 58dB 5 1/4" Peerless 830873 88 x 3.5 95dB 88dB 76dB 64dB 6 1/4" Seas L16RN-SL 104 x 6 101dB 94dB 82dB 70dB 7" Seas W18EX001 126 x 5 102dB 95dB 83dB 71dB 8.5" Seas W22EX001 220 x 5 106dB 99dB 87dB 75dB 10" Peerless 830452 352 x 12.5 118dB 111dB 99dB 87dB
>Why would you want to drive a speaker at 300 watts any way?
Nice jazz recordings yielding a pleasant 85dBC at the listening position can have listening position peaks of 103dB from each channel that could be 110dB at the speaker with 7dB of loss due to distance.
Although less than 3W RMS with a 85dB/1W/1 meter speaker that's 300W peak.
Of course, consumer power amplifiers are rated with a 3dB crest factor so an amplifier rated at 150 FTC Watts would do a fine job in that situation.
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