depends on the frequency. As the audio frequency goes up the cone excursion goes down. If you are certain that the music you are listening to does not contain any low frequencies that will cause the maximum cone excursion than you can use a higher power amplifier. If you use a higher power amplifier and drive the speaker to beyond its max cone excursion rating the spls will not increase it will sound louder beacuse the higher frequencies will be louder but the distortion due to cone compression will increase dramatically. If you are asking about a midrange driver then you can move the crossover freq up an octave and this will again lower your cone movement. If you are talking about a tweeter, don't shoot me for this but many tweeters cannot sustain continuous sine wave signals at or near their rated power. I have blown many so called 30-40watt rms tweeters with as little as 5 watts rms sine testing. Most high frequency drivers fail because of too low rated power amplifiers being driven into clipping. Most people cannot tell when an amplifier just begins to clip. Clipping results in high frequency harmonics at high power levels and this is what destroys most tweeters. Most tweeters can handle high power for a relatively short period of time. The amount of energy in most music is very low at high frequencies compared to low frequencies. My basement system uses a tri amp configuration. I have never even come close to clipping with the midrange and treble 30 watt amplifiers but the 100 watt bass amp led display shows clipping very often especially when playing some Telarc disks. For your brain to perceive that music is twice as loud you need 10 times the power. Ears are logarithmic. At low sound levels you are probably using a few hundreths of watts.
It should handle more power input toward the top crossover point as excursion will be lower here. That said, there is generally less power in music as you go higher.
I also have the RS52 dome in my (currently being built) system. Where did you get the 10W at 600Hz excursion limit from? What crossover slope are you using?
I also have the RS52 dome in my (currently being built) system. Where did you get the 10W at 600Hz excursion limit from? What crossover slope are you using?
Absolutely spot-on IMO.
Take a tweeter apart some time; you very soon realise that tweeter power ratings are 'music ratings' ie about as useful as 'PMPO' (reemember that?). In truth, no tweeter voice coil [apart - maybe- from some ribbon/magnetoplanar types] has enough thermal mass or radiating area or heatsink ability to withstand more than 3-5W RMS for any length of time.
Just speaking from a headroom standpoint only and not destroying speeds from clipping or heat or over excursion. If my speakers max excursion is reached at 10 watts, and I will be judicious in the use of these 10 watts for said reasons. Will the amp produce those 10 watts faster, more agressively, more dynamically, if it has 40 watts to spare?
For example, let's say the speed limit is 60 miles per hour and lets assum you can not exceed that limit. And you have two cars, one has 100 hp and the other 500 hp. Even though the speed limit is 60 mph, those ride can be very different.
For example, let's say the speed limit is 60 miles per hour and lets assum you can not exceed that limit. And you have two cars, one has 100 hp and the other 500 hp. Even though the speed limit is 60 mph, those ride can be very different.
Hi,
First off, the size of you amp is not as important as how much actual power you send to the speaker. Believe it or not, I have seen more speakers blown by small amps that were pushed then by large amps that were just idling along.
At low frequencies, it is normal for the speaker cone to deflect a lot. But, control of the cone is also determined by the amplifier's damping factor. My 7 watt per channel 2A3 parallel SET tube amps make the cones in my test speakers deflect more then a 40 watt Proton D540. The reason is that the Proton has a damping factor several times as high as the zero feedback triode amp.
So actual power is not the only determining factor. There is also the frequency of the sound sent to the speaker, the damping factor of the amp and the mechanical damping of the speaker in combination with it's cabinet.
Headroom refers to the amount of extra power you have to accommodate peaks in demand from the music you are reproducing with an amplifier. Using the old Proton D540as an example, it is rated at 40 watts RMS into 8 ohms. But, Proton says the amp has a dynamic headroom equating to four times the amp's rated output for peak bursts of power up to 1 second.
A slightly larger amp that is not pushed to clipping is far better then a smaller amp that clips on peaks. This clipping and such is what can kill a speaker. Using a big amp (100 watts or more per channel) and playing it at 2 - 10 watts means you have a lot of dynamic headroom that is undistorted. The use of a large, powerful amp in this way is much kinder to your speakers.
I understand what you are saying but one more question. Let's say you are using a Proton amp which I beleive also has a soft clipping feature. My understanding is that that will protect your speakers. Also it has 6 db of headroom. In that case, would you just purchase a 4 watt Proton. Can't hurt your and you have 6 db of headroom to take you to max excursion.
Actually, the real point here is that it doesn't matter how big the amp is as long as you don't turn it up so much that you destroy the speaker. Where it gets to be a problem is when you use a smaller amp and push the amp into hard clipping. Some solid state amps I have used in sound reinforcement applications would damage speakers on a regular basis when pushed to clipping while others did not. It is a combination of power and the quality of the amplifier that I have found which determine how 'kind' the amp will be to speakers. You are correct in that the Proton does have a switch on the back to enable a soft clipping circuit. This is both to protect the amp and the speakers it is driving. The little Proton D540 is a very powerful sounding amp considering it's 40 watt @ 8 ohm per channel rating.
It is a nice design, with two power supplies. I have never blown one speaker with this amp and I have pushed it to where it's Dynamic Power lamp would flash on the music peaks.
With respect to speakers, there are a couple ways to damage them. One is to overheat the voice coil via too much power delivered to it, which can cause it to either open or short. The second is to drive it such that the speaker cone moves too far and causes mechanical damage to the speaker.
You need to connect a scope across the speaker terminals and gradually increase the volume.
If you reach a point where transients are starting to visibly clip ( which will be a voltage a little below the voltage the amp runs on ) then you need more headroom.
Clipping is what does the damage as it's like putting an equivalent DC voltage across the speaker, which is why more damage is done by smaller amps than large.
If the avaerage power is substantially greater than the rating of the speaker you need to consider uprating those or back the level off a little.
Clean transients won't generally cause damage.
If you reach a point where transients are starting to visibly clip ( which will be a voltage a little below the voltage the amp runs on ) then you need more headroom.
Clipping is what does the damage as it's like putting an equivalent DC voltage across the speaker, which is why more damage is done by smaller amps than large.
If the avaerage power is substantially greater than the rating of the speaker you need to consider uprating those or back the level off a little.
Clean transients won't generally cause damage.
No, put simply... a 10 watt amp run within it's capabilities produces the same output as a 50 watt amp.
You are better thinking in terms of voltage excursion rather than power when talking of transients. Remember a "peak" that causes a 10 watt amp to clip implies a much lower average power when talking of music. Don't underestimate transients.
I measured transients of 40 volts (of either polarity) when testing/developing my amp which into 8 ohms equate to 200 watts peak power or an RMS rating of 100 watts.
I wanted to see just what headroom was needed when you really turn things up.
You are better thinking in terms of voltage excursion rather than power when talking of transients. Remember a "peak" that causes a 10 watt amp to clip implies a much lower average power when talking of music. Don't underestimate transients.
I measured transients of 40 volts (of either polarity) when testing/developing my amp which into 8 ohms equate to 200 watts peak power or an RMS rating of 100 watts.
I wanted to see just what headroom was needed when you really turn things up.
Yes, transient is why I'm also thinking about oversizing.
Please elaborate on the average volume level used and the speaker load. 40V peaks are no joke. Did you measure also the current?
Pardon my ignorance. If I listen to average 85db, i should allow for just 10dB more for the peaks?
I considered 115dB, therefore 30dB of headroom.
Then i did the math with the speaker sensitivity and the amplifier power, listening distance, etc.
OK... Speakers for the test were Celestion SL100 which have a very low sensitivity of 84db/watt and a minimum impedance of around 6 ohms (I think from memory) over the audio band. I was using levels well in excess of "normal". Also to get only a 3db increase in level requires doubling the power and a 3db increase is not a doubling of subjective volume level.
Remember the impedance of a speaker varies with frequency. My B&W 703's have a 3 ohm minimum although they are much more sensitive at around 90db/watt.
In real terms that means they are as "loud" on 1 watt as the Celestion on nearly 4 watts.
Now put the B&W on 4 watts and the Celestion needs 16 for the same level.
Put 16 into the B&W and the Celestion needs 64 watts.
So you can see the speaker efficiency is the biggest factor in determining how loud a system goes.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.