Multiple Drivers -- Headphones vs. Speakers

[escapedturkey]

Why do high-end speakers require multiple drivers (tweeter, mid-range, woofer), while high-end headphones only need one driver?

Thank you.

 

[Jahvetti]

Multiple drivers in loudspeakers are needed to controll the radiation pattern of the sound. There are also good single driver loudspeakers, but they must be carefully positioned in the room, to get the desired sound out of them. Also the efficiency can be much higher with multi driver designs.

The room is not relevant in headphone listening, so there is no real need to have multiple drivers. Also the needed efficiency is quite low.

 

[Carl]

Larger dynamic drivers have a hard time doing a wide frequency range and remaining linear, so using two or three drivers allows then to pick speakers that operate linearly over a particular frequency range and end up with a wide, flat frequency range. Well, at least in theory.

Planar speaker technologies like electrostatics are better at opperating across a broad frequency range, so it's much more common to find them using only one or two transducers.

 

[slwiser]

For speakers check out Omega at AudioCircle for speakers with single drivers.

 

[Doug411]

From the basic physics: every moving object has a mass, so it has a resonance frequency at which it can do a periodic motion with highest efficiency.

Please visit this website for further info

http://www.schoolscience.co.uk/conte...dioch3pg1.html

As you see from the website, you need multiple driver units to flat out the overall frequency response in the audible sound range.

Then a question: I know there are some single unit speakers!

Please see this link

http://melhuish.org/audio/response.html

A well designed driver can produce very wide range of frequency with very flat response. But, even the world's best full-range driver (arguably this: http://www.manger-msw.com/en/produkte/msw_inhalt.html ) rolls off below approximately 100Hz and above 10kHz. So we need compensations - which are complex cabinet or super-woofer (to enhance bass) and super-tweeter (to enhance treble)


Then another question: Isn't it better when there're as many as drivers as possible to flatten the frequency response?
Yes, if we only consider the frequency response, but absolutely no if we consider the coherence and timbre of the sound. And, as the frequency flattening networks are basically lossy component, the more drivers you have the less the efficiency of the loudspeaker system: you need more powerful amplifer to drive them - powerful amplifier is hard to make to have linear response => it costs $$$.


Last question: How headphones work well with a single driver?

Answer: Drivers in headphones don't need to move much: they do not have to produce very loud sound (high amplitude). What they only need is to fill our ears with the sound, not the entire room.

Hope this helps.

Doug

 

[Carl]

Quote:

Originally Posted by Doug411 the more drivers you have the less the efficiency of the loudspeaker system: you need more powerful amplifer to drive them - powerful amplifier is hard to make to have linear response => it costs $$$.

And the more powerful the amplifier is, the harder it is to make it sound good, and the more expensive the parts required to do so.

 

[hugz]

Right at this moment I'm listening to some music on my single driver speakers. Look into "full range drivers" or "wide range drivers". I'm not really sure why single driver speakers are so much less popular than multiple driver speakers. Compared to my dalis the single driver speakers sound a bit bright and lacking in bass, but that's largely becuz they're not in any cabinet at the moment. I somewhat suspect that multiple driver speakers are easier to market to people. Someone with a wad of cash sees two pairs of speakers and one has 3 drivers and the other only has one driver.. which one do you buy? The 3-way of course. I remember the look on my parents faces when they saw that my speakers only had 1 driver

Multiple driver speakers need crossovers, which is a component in the signal path. Components in the signal paths tend to degrade the sound, and crossovers are no exception. Also, by having multiple drivers you have multiple sources of sound waves which can interact with each other (however adding a bass reflex or rear horn to a single driver would be harmful in this regard as well, i would imagine

In the end both methods have advantages and disadvantages. Single drivers have no crossovers and less intefeerence but multiple drivers are able to use many drivers which are optimised for a particular frequency range to cover the whole band. Single drivers tend to be more efficient (so you can use SETs!!). Also single drivers seem to me to have a strangish benefit to me..... if you buy $300 worth of drivers for a 3-way speaker than each driver costs $100 each. If you buy $300 worth of drivers for a single driver speaker, each driver is worth $300. So rather than using 3 mediocre drivers you're using 1 high end driver.

edit: i like single drivers. insert bias and grain of salt

Double edit: in my short experience, multiple-driver speakers tend to be able to cover the frequency band better, but single drivers do the mid range better. So single drivers will provide you with the sweetest instrumentals and vocals, but fall behind in the lower bass and upper treble. The question is that of preference for the listener. My fullrangers (without a cabinet) seem to be able to produce bass down to 40hz (connected to my cheap soundcard and my crapy receiver... see sigature) and treble up to at least 16khz (where my frequency sweep stops), but with loss of volume

 

[slwiser]

hugz

Excellent post. They also seem to be very efficient and in general terms requiring much less amplification.

Quote:

Originally Posted by hugz edit: i like single drivers. insert bias and grain of salt

 

[nelda]

Quote:

Originally Posted by escapedturkey Why do high-end speakers require multiple drivers (tweeter, mid-range, woofer), while high-end headphones only need one driver? Thank you.

AKG K340 have 2 drivers. Dynamic+Electret. One for low to medium freq and the other one for high freq.

 

[Duggeh]

Lets not forget that many companies tried 2-way headphone designs. Usually with less success than the K340 though.

 

[sgrossklass]

^ Nice, umm, eccentrophones.

N-way (mostly 3-way) systems are a good idea in speakers due to the following reasons:

1. Directionality. The larger a driver is compared to the wavelength, the more directional it will be. Normally you want speakers to be either as omnidirectional as possible (gives good results in damped rooms) or highly directional. Fullrange drivers, as you may have guessed, have strongly frequency-dependent directionality.

2. Efficiency. You need a certain diaphragm area to get as much energy as possible into sonic waves. An 8 cm driver will have some difficulty pushing a 100 Hz tone.

3. Power Output: Related to point 2. You may have noticed that a large room also demands a fat subwoofer (with e.g. 30 cm driver), while lesser ones with smaller drivers may fail to cope and be driven into the stops in extreme cases. You can interpret this as the sonic impedance of the large room being smaller, requiring a bigger "coupling capacitor" (speaker driver).

4. Linearity: Fullrange drivers are quite prone to IM distortion at higher volume since at some excursion the magnetic field tends to be weaker than around the zero excursion point. This also is an issue with 2-way speakers (IMD between bass and mids).

Now in headphones, we only have a pretty small "room" to fill with sound, extremely high power output is not required, and like it's been said directionality also isn't that much of an issue. A good opportunity to eliminate the effects of crossovers, which are not without their drawbacks either.

 

[sgrossklass]

Quote:

Originally Posted by poulou Hello does this mean that a single driver IEM is better than multiple drivers in case we could equalize the signal with a perfectly transparent filter ("linear phase")? (I' must choose between ER4s/ES3/UE10...) thank you Alex

IEMs are somewhat different beasts altogether. The problem with these is that balanced armature drivers apparently aren't as wideband as would be desirable, so 2-way designs well implemented should be capable of performing better. I'd go with what people say about the performance of the various models considered.

 

[Uncle Erik]

Great discussion of fullrange drivers in this thread!

I'm in the fullrange camp, too. I remember the day when I realized that the music coming from a 1939 tube radio I restored sounded more coherent and "real" than some multibuck audiophile setups I've listened to. The bandwidth of AM is pretty limited, I jacked my CD player into the mono phono input on the radio. That was a revelation, and I started down this path. To get such beautiful sound from prewar gear was stunning.

Sure, multiple drivers can be done well. I really enjoy the ProAc clones. But for the price and sheer simplicity, nothing can touch single drivers with simple tube amps. A lot of that goes for headphones, too, which is a big reason I love cans. If you do your homework, you can build a very musical and highly enjoyable SET/singledriver stereo for under $500. It'll give you years of enjoyment for what some people pay for a power cable.

If you (or anyone else) is interested, some good brands are Fostex, Lowther, Jordan, and Moth Audio. The Jordan JX92S is special... I've got enough speakers, but might order a pair for a future project. They're about $380 US a pair. And I'm quite pleased with the Moth Audio Cicada. You can get those for $240 US a pair from Eddie current. Of course, there are many other drivers out there, too. Field coil fullrange speakers (e.g. Supravox) are pretty interesting, too.

 

[F107plus5]

One rule-of-thumb that has worked well for me is to pick speakers with drivers having a crossover point higher than the range of the human voice.

That, or be sure that the speaker has a VERY well designed crossover network!

If voices ain't right, it's OBVIOUS!!!


.......we had an old 10" theater speaker that was the full-range of the day(down to 70 "cycles")and it WAS GREAT!!! A ten incher that did highs!

Amazing!

 

[sgrossklass]

Quote:

Originally Posted by F107plus5 .......we had an old 10" theater speaker that was the full-range of the day(down to 70 "cycles")and it WAS GREAT!!! A ten incher that did highs! Amazing!

That is pretty impressive indeed - 3" widebanders can hit about 20 kHz, thus I'd expect a 10" driver to be good for no more than about 7 kHz. That covers a good bit of the highs but still is far from great highs extension. Normally there tends to be a bump in frequency response before it drops off, this may have helped subjective perception.

Yes, this wideband stuff has some appeal. People don't like the 'fat sound' of old tube radios (caused by a bump in upper bass and lower highs) for no reason... sadly, today's portable radios frequently have a hard time keeping up with '70s sets when it comes to speaker sound, which is all the more obvious if you live here where you can pick up an old Grundig or such without too much effort. At least there are some retro-style sets from various manufacturers with pretty good sound now (apart from the well-known Tivoli Model One, e.g. Sangean WR-1/2 or TEAC SL-D90).