Wednesday, February 1, 2017

How many watts do I need?











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The HB Project and the HB Channel supports Hi-Fi Klubben Poor sound ruining good music. How many watts do I need for my speakers? They are brand X, type 3 and 60 watts. It's a question I hear a lot. So time for an answer. Let me start with the 60 watts. What these speakers are, they are not 60 watts. They can be 60 kilos, 60 pounds or 60 euros, but not 60 watts. Incandescent lamps can be 60 watts, which means they are 60 watts of power consume per hour..

This can be specified as light bulbs operate at a fixed voltage: 230 Volt here in Europe, 110 volts in the United States, and so forth. The resistance of the filament is so selected that, when the data voltage a data stream will run. The wattage can you easily calculate. But speakers only been a constant voltage speaker when I meet with a test tone. When playing music varies the voltage with the music. And changed the voltage also changes the flow and thus the wattage. There is another difference with a light bulb because it only on a solid 50 or 60 Hz frequency works while speakers work until at least 20 kHz while resistance AC, such as music signals, the frequency changes. taxability.

Why does it say in the instructions that your speakers 60 watts? The usual specification is "loads up". It is similar to tires which code for 200 km / h is. That does not mean they own 200 km / h, but bad they are suitable for cars with a maximum speed of 200 km / h. If you were to mount these tires on a car that is much harder than they might overheat and clapping..

They can easily be used in cars, for example, only 150 km / h. Most speakers use a type of linear motor which is actually a voice coil - a coil which is wound around a cardboard koter, which is suspended in a permanent magnetic field. Now, by sending an alternating current through the coil, which will be attracted and repelled and thus the do move attached thereto cone. The problem is that not all power is transformed into movement, there is a considerable part of the power that is converted into heat, as with the light bulb. When there is too much heat build up may melt the voice coil or off causing the can no longer move freely in the magnetic gap. In both cases, the electrical circuit is interrupted and stops the speaker. The usual term is here, "the speaker is blown up" when in fact the voice coil is broken. Unfortunately, this means that the speaker must be repaired by a specialist. It is the heat.

But your players can reach 60 watts, then your amplifier should be no more than 60 watts, right? Error!.

As I have already explained the problem is caused by heat and heat through the amount of energy that is in the music signal. Your amplifier must be able to immediately produce peaks. But such peaks are very short, contain little energy and therefore produce little heat buildup. Only when very high compression is applied or when the amplifier must provide more than he can, the amount of energy in the waveform is very high. This is audible as distortion. It is caused when the amplifier is not able to reproduce those peaks while the average level goes up. When an amplifier such as a sound wave plays at maximum power, the waveform remains fine. If we further increase the gain, as now then the part is not displayed above the maximum level and the signal is tipped as here. If we compare the original signal thus, we see that it is wider and therefore contains more energy. The energy in the normal waveform is such as the blue portion, while the uncapped signal extra energy add as shown in red..

The output voltage is thus not higher but still remains high longer and gives the voice coil less time to cool between the maximum stresses in. In addition, the distortion caused by this extra energy causes at harmonics of that frequency. It is therefore not recommended to use an amplifier that has less power than necessary. While too much power, within reasonable limits, does not cause problems and sound can improve. Another cars.

The advantage of too much power is similar to a car that has more power, even when there is a speed limit of 130 km / h as in the Netherlands. Because the car is then able to catch up quickly because it accelerates faster. If you've ever ridden the periferique with a full load a car with too little power, then you know exactly what I mean. But although power do you need? That depends largely on the speakers but also from the amplifier and the dimensions of the room. It is similar to asking how much power should have your car. If it is a square 4 x 4, you could probably do even need significantly more power to 130 km / h driving than when it is a very low two-seater sports car because it has much less air resistance. Car manufacturers do not publish resistance measurements of a car but the resistance coefficient. But we want to know how fast a car goes where engine produces a specific output. And that is exactly what loudspeaker manufacturers: the specify how much sound - Which we experience as loudness - is produced by one meter as 2.83 volts is offered on speaker connections. Sometimes used 1 watt at 1 meter but that's what produces 2.83 volts in an 8 ? speaker. It is usually written as db / 2,83v / 1m. The loudness in dB sound pressure level or dB SPL. An average value is 89 dB, providing very inefficient speakers 82 dB and very efficient speakers, such as hearing speakers can even produce 105 dB / 2,83v / 1m. In previous videos I suggested to listen to about 80 dBSPL (A) so if you stick to it, then a 1 watt amplifier should suffice as you have an 8 ? speaker to 82 dB / 2,83v / 1m. You would have indeed 82 dB sound pressure level but there would be no reserve for spikes, called headroom (headroom). For pop and rock is 14 dB headroom sufficient for acoustic music and classical music is 20 dB a safe number. However, it is likely that your speakers are near the 89dB / 2,83v / 1m. Moreover, you are not at 1 meter and you have two speakers in stereo setup. Calculate your needs.

You can now calculate the approximate power requirement and if you can not do in dBs count, you could first watch my video 'The dB explained'. But I also put a link to an Excel spreadsheet by this video. Download this sheet, enter the sensitivity of your speakers and the desired headroom. Now you can look up the desired volume in the green column and in the yellow column Reading the power per channel. That's easy..

So that's it?.

Sorry, no, there is still the question of whether the amplifier can deliver enough power. Again there is a parallel in the car world, couple named. Wikipedia defines it as follows: "Torque or moment is a measure of the rotational effect of a force on an axis..

In other words, it is the instantaneous force that is required in order to get a car in motion. Diesel engines and turbocharged gasoline engines have a much higher torque and can be a heavy car allow faster acceleration to the speed where the air resistance is the main factor. The torque of the amplifier In a stereo amplifier outputs a voltage to the speaker after which current to flow. If the voltage remains high, for example because it is a bass note with great energy, the amplifier must be able to continue to supply power, otherwise the amplifier the control over the loudspeaker lose. We can be glad that one is a specification for speaker output, but helaast There is no specification for a steady stream of supply of the amplifier. Add to that the frequency varying impedance and you understand that it is impossible on the basis of specifications to find the right amplifier for your speakers. Yes, that helps .....

Thanks Hans, which was useful information, I hear you say. I know, life sucks and then you die. Unless you have ears, because then you can just listen. The total loudness is the result of the ability of the amplifier and the speaker of the efficiency. Such as the top speed of the car is mainly determined by the ability of the engine and the resistance of the body. The control over the bass is mainly due to the possibility of the amplifier power to supply plus some properties of the speaker. Just like cups of a car is the most important factor for pulling power, such as towing, hill and driving from a standstill. Reviewers often tell or amplifier is capable of delivering high current when a speaker needs it. A reputable dealer is also a good source for this knowledge, but if you Dealer used as a source of knowledge, of course you do not take his knowledge to buy on the web. Yet? There is nothing wrong with buying on the web, but not when you first knowledge of a dealer steals In conclusion.

One final note..





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