Speakers

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OH man Radio Wave USA 86 Posts	Posted - 02/08/2003 : 23:16:00 Say you have two speakers with the same power output One has a higher resistance (and thus a smaller current) and the other has a lower resistance (and a greater current) Which of the two is "better"? Does one have an advantage over the other? ============= This space intentionally left blank. Dave "dav2008" Groysman Alert Mentor now
FZ Gamma Wave United Kingdom 2222 Posts	Posted - 02/09/2003 : 00:02:21 I reckon the lower resistance one is better... V = IR therefore I = V/R Power = I*V Hence, assuming your pd across the speaker is constant: P=(V²)/R So theoretically, the lower the resistance, the greater the power of the speaker.... ------------- "....this will be one battle we will regret. Mark my words..." FZ 11/14/2002 Alert Mentor now
BoulderHead Gamma Wave Canada 2364 Posts	Posted - 02/09/2003 : 00:46:26 quote: Say you have two speakers with the same power output If you are saying that both are playing equally loud despite twice the current having to flow in one than the other, then for my money I'd take the one which plays at the same amplitude but with less power consumption. If you look at the specifications of speakers you will often see a value given for the sensitivity of the speaker. If all else was equal between two speakers I would be more inclined to purchase the one with the higher sensitivity because it will play louder than the other for a given input level... In other words; why waste amps if you don't have to? quote: One has a higher resistance (and thus a smaller current) and the other has a lower resistance (and a greater current) By resistance I think you mean impedance. quote: Which of the two is "better"? Does one have an advantage over the other? Understanding what the specifications mean can be an advantage when making a decision on which pair is 'better'. It doesn't tell everything however and ultimately I want to hear how they sound. One may have a more narrow frequency range that it can react to, or it may have some non-linearity associated with its frequency responce that you might prefer to avoid. Conservative, n. A statesman who is enamored of existing evils, as distinguished from the liberal, who wishes to replace them with others. -- Ambrose Bierce Alert Mentor now
voyeur Visible Light Wave USA 577 Posts	Posted - 02/09/2003 : 00:48:30 Power rating IS how much power they will use so they will use the same power regardless of resistance if they are about the same in efficiency. How much resistance a speaker has is usually meant to inform you what to hook it up to. A good amp in a professional sound installation can have 4, 8 and 16 ohm outputs. You connect to the matching resistance or you can match the resistance with a series or parallel speaker connection. Whether a speaker is 4, 8 or 16 ohms has little to do with quality of sound or power. Most speakers are about the same efficiencey so the real indicator of power usage is going to be it's rated power regardless of it's resistance. Assuming the 2 speakers are rated for the same power, you will see a major difference between the 2 speakers only if one is significantly more efficient than the other. And the one that is more efficent could just as likely be the lower resistance as the higher. This is because you won't have to crank the amp up as high to get the same sound level out of the more efficient speaker. Alert Mentor now
emu Radio Wave Canada 87 Posts	Posted - 02/09/2003 : 02:53:43 It depends on the amplifier you're stuck with. When you consider 1000 watts @ 8 ohms versus 1000 watts @ 2 ohms, it comes out to the same thing. Even though the voltage is lower and the current higher for the 2 ohm speaker, they have the same potential to be loud. Consider a dual voice voil speaker with 2 four ohm coils. Put them in series(8 ohm) and pass a current of 1 ampere, you get X as the Bl(or motor force). Put them in parallel(2 ohm) and now pass a current of 2 amperes - we must maintain the 8 watts used in the prevous scenario(8V1A). Now we have 4V2A. If we measure Bl, we still get the same Bl. The motor force is determined by the current and turns of wire in the gap. Even though we double the current for the same power, we have half the turn because the coils were previously in series (2y turns) and now in parallel(y turns). So logically we'd think more current and more turns means louder. Not so, more current means heavier wire, more turns also adds weight. It's a compromise between the mass of the speaker's cone and the magnet strength we need for a certain type of box. The main factor that determines a good speaker is a good motor. A good magnet, gap geometry, coil, suspension and mass. These all come together and determine a specification commenly referred to as Qts, or quality factor. Qes is the damping of the magnet on the voicecoil, lower means better transients(or more faithful sound). A Qes of roughly 0.2 - 0.6 is ideal. Then Qts should also be in the 0.2 - 0.6 range. Lower for vented boxes and higher for sealed. A good speaker is one that has a box properly built for it. Usually, when you buy a speaker of worthy quality, you get a sheet of specs with it. These specs and a tons of free programs you can download off the net will help you find the ideal box for your application and then experiment. The box is over half of the total sound. BTW, speaker don't output power, they dissipate it(Do they ever). Most speaker are roughly 1% effecient before being loaded in a box. The highest effeciency you can hope to achieve is roughly 15% with an amazing speaker and a massive horn. Where's the beef? Alert Mentor now
nowonmai Radio Wave Ireland 26 Posts	Posted - 03/06/2003 : 12:08:09 the lower the impedance, the more sensitive the speaker. in other words, an 8 ohm speaker won't give you the fidelity that a 2 ohm will Alert Mentor now

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