Why does speaker impedance matter?
Fun fact: it doesn’t.The impedance quoted on a speaker is its nominal impedance - a sort of average. In reality, impedance depends on frequency, and it’s also quite complex, with the phase response varying as well as the effective resistance. This is to be expected - a speaker is a mechanical device based on electromagnets, which are inductive, and it usually has multiple drive units, and a passive filter (crossover) that provides a separate feed to each one. The mechanics of the speaker cone and the cabinet acoustics itself are all reflected back to the electrical impedance “seen” by the driving amplifier.What’s important is that the amplifier is designed to cope with this fairly horrible load characteristic. It does that by essentially having a zero output impedance*. To the speaker, this is a short circuit, which totally damps out all of these nasty peaks and troughs. The amplifier also has to be stable no matter what happens. Any half-decent amplifier on the market will cope, because amplifier design for the most part is a very well-solved problem.Most component speakers have an impedance between 4 and 8 ohms, so most component amplifiers are designed to drive that. There may be specialised speakers having lower nominal impedances, and they might need a more specialised amplfier, but most people don’t have to worry about it. The main thing is not to expect a cheap and nasty amplifier to work well with expensive upmarket speakers.There are other considerations matching an amp and speaker, such as power levels, sensitivity and so on. But most people fret a lot about impedance when it’s really a non-issue. The fretting was already done by the amplifier and speaker designer.Edit: *this applies to solid-state amplifiers, which are 99.99% of them. Much older amplifiers used output transformers which do require a matched speaker impedance for best results. You might also find these on amps used for music performance, but that’s a specialised field. This answer assumes you are largely talking about home hifi systems.
Earphones: Which impedence is best 32 ohms or 16 ohms?
The impedance usually does not specify much about the quality of audio from headphones or earphones.Larger impedance means that the device(cell phone, ipod, mp3 player, laptops...) which powers the headphone will have to provide more voltage for a comparable output.Larger impedance does not matter if you want to use the headphones with laptops or cellphones with greater battery size.The criteria for better audio quality are usually the sensitivity(dB/mW), power handling capacity and frequency range.The headphones with higher sensitivity and power handling capacity give better audio experience but may be on costlier side.As for the frequency the range of 50-25000 hz works just fine. Though many headphones have a higher range giving mind blowing sound quality.The head phones may be circumaural (covering the whole of the ear) or supra aural( covers just the opening of the ear).The two types differ mostly in quality and comfort, with the former one performing better on the parameters.
What is impedance in simple terms (electronics or in general)?
Impedance is a term that describes the relationship between current and voltage of a circuit consisting of resistors, inductors, and capacitors: Voltage = impedance * current. It’s not used outside of electrical engineering, except in “impedance match.”If you want to deliver maximum power (= voltage * current) from a generator to a load, the two must be impedance matched. You might have a powerful generator, but it delivers high voltage and a low current, whereas your load wants low voltage and high current. The result is that little power is transferred. It’s like using a Porsche to tow a trailer.Impedance match enables maximum power to be transferred. It happens when the impedance of the load is the complex conjugate of the impedance of the source. For example, the generator delivers high voltage and low current, and that’s exactly what the load needs.You could say: “I didn’t learn much from this book. It’s a good book, but too basic for me. There was a bad impedance match.”
Is it better to have a lower ohm impedance on a speaker or high ohm impedance?
The choice depends..Usually audio speakers vary in ranges from 4ohms,8ohms,16ohms,32ohmsTypically in audio amplifiers, we use 4ohm and 8ohm. And it is quite obvious that for a fixed output voltage of an amplifier and other identical conditions (like Vcc) , a 4ohm load can drive greater power than a 8ohm one, since P=V*V/R. But do note that while voltage is constant and R is decreased, your current through the amplifier and hence through the speaker load will increase. And so the output push pull stage of the IC or the Bjt you are using will try harder to push and pull current and will get hot. They might cross their limit to deliver current and thermal breakdown will occur. And this is most likely to happen.So in a audio amplifier board, it is always mentioned which load we should use. Either 4ohm or 8ohm. A datasheet is incomplete without this detail. Also for a BJT based amp, you need to find out by calculations how much the device will push and pull current and check the Bjt datasheet which is the maximum current and power it can handle. Put the load likewise.Example a LA4440 amp can handle both 4ohm and 8ohm load, also there are some audio amps which are best suited for 8ohm. And also keep in mind to add the heatsink to the amp or Bjt push pull stageAnd for a headphone device we always use 32ohm loads. Since our ear cannot take in too much sound. 32ohm is the standard one for headphone speakers.
Can I use 4 ohms car speakers to replace 8 ohms car speakers?
Yes! …In my view base on experience you may….Car speakers like any other type of mass produced products do not require nor have to pass a strict QA processes! A QC/QA practice where production outputs are focused mostly on just the mechanical aspects….the looks and aesthetic appearance of the finish product! Electrically, it is very possible only the voice coil’s continuity are validated in every speakers! Impedances are hardly if ever are validated for such applications!The same testing approaches are done during in the car assembly line.. After validating continuity, Technicians will only test the car stereo system for functionality. The system either pass or fail /work or not test approach??? …It is known as the Go-No-Go approach of QA processes!!Impedances testing and validations requires a more technically knowledgeable technician, complex testing equipment and time consuming to implement… Dictated or necessary for an environmentally sensitive and critical application where an intensive /rigid QA/QC processes is the norm!A QA process done on every components used for high end products and applications! Normally use in a different application environment, like home entertainment, theaters, auditoriums and other professional systems!Expensive or high-end cars may have a better or more rigid QA processes!Having said that, impedances of car speakers in general is the least to be concern about specially in automotive audio applications…By the way, theories are limited when applied…..
What happens if I send the left channel and the right channel into one speaker? Will I get twice the power? Will the left and right be mixed together?
Well you should not connect speaker outputs in parallel. It might not damage a good modern amplifier but just should not be done as both should be low impedance sources and will just be seen as shorts to each other which is a fault condition.That said there are two ways you can effect part of this if that is what you want.The first is to make a high impedance input summing amplifier to add the two signals before the final power amplifier together algebraically. Many amplifiers in the past have had a "MONO" switch to do just this and then put the combined L+R signal to both the speaker amplifiers and speakers simultanously. This removes the stereophonic effect and makes the signal seem flat and less dimensional.The other way to do this was a method proposed in the 1970s by Dynaco Inc., a speaker and amplifier manufacturer. They said if you had a spare main speaker and a common ground stereo amplifier you could get an improved depth effect with the 3rd speaker placed in the middle and driven off the plus side (e.g. non common side) with left Plus signal to the speaker + terminal and the right plus signal driven to the speaker - terminal. If you don't understand what I'm talking about don't even try to attempt this. The claim was that this difference signal gave a more spacious signal to an already stereo sound stage with the difference signal going to the middle speaker. It was quite safe to do this with conditions I mentioned beforehand. And its not the same as summing the signal. Out of phase information is amplified and similar L & R material is removed from the center image.