• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

2,3,4,5-way speakers: how many ways is optimum?

Cosmik

Major Contributor
Joined
Apr 24, 2016
Messages
3,075
Likes
2,027
Location
UK
#1
Passive speaker designers traditionally find a three-way speaker troublesome - apparently - and many stick to two-way. For example:
In my opinion, passive crossovers are useful for small 2-way systems, or where you aren't looking for the ultimate in performance. ...

...When an attempt is made to create a 3-way or even 4-way system, the complexities rapidly become such that the cost of the crossover network can become so high that an active system will actually be cheaper.

...Should you attempt a 3-way passive design, you will almost certainly need to include a Zobel network for the bass driver, as well as resonance correction for the midrange. When you add this complexity it becomes quite obvious that the passive approach will be large, complex and expensive. The losses introduced will be such that sensitivity will be significantly lower than you might like, the damping factor for the woofer will be severely limited by the series inductor, and the system will still be a compromise.
In other words, the passive approach cannot make a good 3, 4, 5 or 6-way speaker regardless of cost.

And the problems with a two-way (active or passive) would appear to be many, including:
  • drivers being stretched over wide frequency range leading to various types of distortion
  • drivers driven too high begin to beam, in contrast to the next driver up, leading to a lumpy dispersion characteristic against frequency
Active systems, particularly those based on DSP would appear to give a more transparent crossover, potentially without phase rotation through the crossover. They can also provide time alignment with the appropriate delays.

If a three-way active is better than a two-way, is a four-way therefore better than a three-way? Why not five-way or more? (putting aside the practical or cost aspects, but even then we might assume that multi-way DACs and amplifiers could be made reasonably cheaply, and that the drivers would have a much easier job to do so maybe their specs could be relaxed).
 

watchnerd

Major Contributor
Joined
Dec 8, 2016
Messages
8,380
Likes
4,890
Location
Seattle Area, USA
#2
If a three-way active is better than a two-way, is a four-way therefore better than a three-way? Why not five-way or more? (putting aside the practical or cost aspects, but even then we might assume that multi-way DACs and amplifiers could be made reasonably cheaply, and that the drivers would have a much easier job to do so maybe their specs could be relaxed).
Once you get past a 3 way (or 3 way plus subwoofer, to deal with room issues), I question if the juice is worth the squeeze, considering:

1. Listening axis / drive distance issues, unless one starts using unconventional shapes (landscape box arrangements, bent/curved towers).

2. It's not that hard to find good quality drivers that can cover a decade (e.g. 250 Hz to 2500 hz, 2500 Hz to 25khz) in the main part of the musical spectrum with good dispersion and low distortion at reasonably high SPL.

3. The only real exception to #2 is in the true sub-bass region, <40 Hz, which is probably best handled via multiple subs for room reasons, as opposed to built into the main LR speakers, anyway.

With a good DSP crossover, I don't see much to be gained in going beyond a 3-way + Sub, at least with conventional dynamic drivers.
 

tomelex

Addicted to Fun and Learning
Forum Donor
Joined
Feb 29, 2016
Messages
810
Likes
330
Location
So called Midwest, USA
#3
Single driver per speaker IMO gives a much better image all the way around. However, active speakers, three way and subs, would be (with DSP) state of the art. Over on Why Believe Facts forum, folks took offense when I said their $100K passive speaker systems were not state of the art, its proven that active crossovers and separate amplifiers are technically superior to any passive speaker system. State of the Art does not always mean ones prefers it though as we all know.
 

watchnerd

Major Contributor
Joined
Dec 8, 2016
Messages
8,380
Likes
4,890
Location
Seattle Area, USA
#4
folks took offense when I said their $100K passive speaker systems were not state of the art, its proven that active crossovers and separate amplifiers are technically superior to any passive speaker system. State of the Art does not always mean ones prefers it though as we all know.
Other than taking offense and having personal preferences, what rationale did they give for claiming passives were better?
 
OP
Cosmik

Cosmik

Major Contributor
Joined
Apr 24, 2016
Messages
3,075
Likes
2,027
Location
UK
Thread Starter #5
Single driver per speaker IMO gives a much better image all the way around.
To me, a single driver implies that it must be a large driver in order to play the bass. Then, it seems to me, it can be regarded as a whole load of smaller drivers all playing the same thing and spaced out over a large area, with the obvious issue of destructive interference leading to beaming at high frequencies. Maybe that doesn't affect imaging per se, but it will affect the tonal balance in the room..?

One of the advantages of a multi-way speaker is that it maintains wider dispersion at higher frequencies - probably *the* difference between what those of us of a certain age heard before 'hi-fi' and then what came after; it was the addition of that tweeter that transformed the hitherto excessively warm sound of single-driver speakers into that clear, clean, neutral 'hi-fi' sound. And if a two-way was good, would a six-way be better..?!
 

tomelex

Addicted to Fun and Learning
Forum Donor
Joined
Feb 29, 2016
Messages
810
Likes
330
Location
So called Midwest, USA
#6
Other than taking offense and having personal preferences, what rationale did they give for claiming passives were better?
Price.
 

tomelex

Addicted to Fun and Learning
Forum Donor
Joined
Feb 29, 2016
Messages
810
Likes
330
Location
So called Midwest, USA
#7
To me, a single driver implies that it must be a large driver in order to play the bass. Then, it seems to me, it can be regarded as a whole load of smaller drivers all playing the same thing and spaced out over a large area, with the obvious issue of destructive interference leading to beaming at high frequencies. Maybe that doesn't affect imaging per se, but it will affect the tonal balance in the room..?

One of the advantages of a multi-way speaker is that it maintains wider dispersion at higher frequencies - probably *the* difference between what those of us of a certain age heard before 'hi-fi' and then what came after; it was the addition of that tweeter that transformed the hitherto excessively warm sound of single-driver speakers into that clear, clean, neutral 'hi-fi' sound. And if a two-way was good, would a six-way be better..?!
Well yes, everything has its weaknesses. However, if you could have a single speaker that passed 20 to 20 with equal dispersion, I think you would have a hell of a sound. Headphones produce low bass, as an example of a single speaker system. Physics wise, if you want regular in room speakers to produce bass, you cant defeat physics, you need large cones to do it best.
 

Blumlein 88

Major Contributor
Forum Donor
Joined
Feb 23, 2016
Messages
9,573
Likes
12,740
#9
Well yes, everything has its weaknesses. However, if you could have a single speaker that passed 20 to 20 with equal dispersion, I think you would have a hell of a sound. Headphones produce low bass, as an example of a single speaker system. Physics wise, if you want regular in room speakers to produce bass, you cant defeat physics, you need large cones to do it best.
Maybe something like the Quad ESL63 in more modern, complex, DSP controlled version. A single panel, but approximated a point source. I can at least in theory see how that could be done. Heck you might do it for the stratospheric prices some current passives cost. I think a vertical line source using the same idea would be good as well. Response, directivity etc could be very well controlled at all frequencies. Even the primitive segmented Quad could pass excellent square waves.
 

RayDunzl

Major Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
9,910
Likes
8,303
Location
Riverview FL
#10

Fitzcaraldo215

Major Contributor
Joined
Mar 4, 2016
Messages
1,435
Likes
565
#11
Sure, a full range, single-point source with no beaming and infinite impulse response is the ideal. But there isn't any such thing.
I am not so sure about point source. In simplistic folklore, that seems an ideal because many instruments radiate sound in point source like fashion. But, what if the performers are spread across a stage and main soloists are near the center? Does an LR pair using phantom imaging between the speakers on playback still benefit from the point source radiation pattern of the speakers? It is hard for me to see why. Actually, and still oversimplified, line source might seem a better paradigm in reproducing the complex direct/reflected sound field the mikes pick up, including phantom images in between.
 

watchnerd

Major Contributor
Joined
Dec 8, 2016
Messages
8,380
Likes
4,890
Location
Seattle Area, USA
#12
I am not so sure about point source. In simplistic folklore, that seems an ideal because many instruments radiate sound in point source like fashion. But, what if the performers are spread across a stage and main soloists are near the center? Does an LR pair using phantom imaging between the speakers on playback still benefit from the point source radiation pattern of the speakers? It is hard for me to see why. Actually, and still oversimplified, line source might seem a better paradigm in reproducing the complex direct/reflected sound field the mikes pick up, including phantom images in between.
That's all solvable in software. ;)
 

Blumlein 88

Major Contributor
Forum Donor
Joined
Feb 23, 2016
Messages
9,573
Likes
12,740
#13
Under what conditions?

Squarish maybe. These are from Stereophile at 1 meter in center of the speaker. I measured some myself displayed upon an o-scope and it was more square at 2 to 2.5 meters (outdoors). The following is a 55 microsecond square pulse done by Stereophile.



Couldn't find the picture of it, but the final QC on ESL 63's was to place the reference ESL63 panel opposite each production unit. Play squarewaves out of phase with a mic carefully positioned in the middle. If they didn't null enough with the reference panel they were rejected. Peter Walker of course said squarewaves meant nothing about music performance it was just an easy QC check.
 

Blumlein 88

Major Contributor
Forum Donor
Joined
Feb 23, 2016
Messages
9,573
Likes
12,740
#14
I am not so sure about point source. In simplistic folklore, that seems an ideal because many instruments radiate sound in point source like fashion. But, what if the performers are spread across a stage and main soloists are near the center? Does an LR pair using phantom imaging between the speakers on playback still benefit from the point source radiation pattern of the speakers? It is hard for me to see why. Actually, and still oversimplified, line source might seem a better paradigm in reproducing the complex direct/reflected sound field the mikes pick up, including phantom images in between.
I don't see why a point source would have any problems doing the central imaging. Would seem to reduce other possible interactions in stereo. Besides microphones are closer to a point source in size. Or maybe we need big old microphones that are sized like speakers. :p
 

Fitzcaraldo215

Major Contributor
Joined
Mar 4, 2016
Messages
1,435
Likes
565
#15
I don't see why a point source would have any problems doing the central imaging. Would seem to reduce other possible interactions in stereo. Besides microphones are closer to a point source in size. Or maybe we need big old microphones that are sized like speakers. :p
Point source seems to work just fine. I just question whether it is an ideal that somehow works better than line source.
 

Blumlein 88

Major Contributor
Forum Donor
Joined
Feb 23, 2016
Messages
9,573
Likes
12,740
#16
Point source seems to work just fine. I just question whether it is an ideal that somehow works better than line source.
Line source would work as well for stereo, interact less with the room and be simpler to construct.
 
OP
Cosmik

Cosmik

Major Contributor
Joined
Apr 24, 2016
Messages
3,075
Likes
2,027
Location
UK
Thread Starter #17
Point source seems to work just fine. I just question whether it is an ideal that somehow works better than line source.
When people talk about a "point source" are they automatically implying that it is omnidirectional?

I regard the ELS63, line arrays and the Kii Three as just variations on the "phased array" concept. And in a way, a single driver at beaming frequencies is doing the same thing.

I see a crucial difference between a phased array that simulates a point source - or a directional point source - and a real point source: the point source simulation is only valid at one point in space, and the room reflections of its individual elements are not the same as they would be for a genuine point source. Does this sound odd to the listener even if only at a subconscious level?

This is where I instinctively like the idea of the multi-way speaker with each driver taking care of its own frequency range. At the higher frequencies (where it matters..?) a genuinely small driver behaves like a real point source, including the direct sound *and* the reflections.
 

Blumlein 88

Major Contributor
Forum Donor
Joined
Feb 23, 2016
Messages
9,573
Likes
12,740
#18
When people talk about a "point source" are they automatically implying that it is omnidirectional?

I regard the ELS63, line arrays and the Kii Three as just variations on the "phased array" concept. And in a way, a single driver at beaming frequencies is doing the same thing.

I see a crucial difference between a phased array that simulates a point source - or a directional point source - and a real point source: the point source simulation is only valid at one point in space, and the room reflections of its individual elements are not the same as they would be for a genuine point source. Does this sound odd to the listener even if only at a subconscious level?

This is where I instinctively like the idea of the multi-way speaker with each driver taking care of its own frequency range. At the higher frequencies (where it matters..?) a genuinely small driver behaves like a real point source, including the direct sound *and* the reflections.
The ESL63 would be considered a phase array. It essentially had 8 segments (I think) from center working outward. The center worked full range, the next segment was not full range, the next even less range until the outer segment was only for lower frequencies. It was a different variation on a multi-way concentric driver. Each segment also had 24 microsecond delay from one segment to the next which caused it to approximate a physical position of a point source radiating from a position 11 inches behind the panel via an opening the size of the panel. Which made it something of a directionally constrained point source.

As for multi-way speakers, each might be a point source for its range of frequencies, but the point sources are at different physical locations and you get interference effects. One could perhaps have a line array of multiple drivers and delays and approximate a point source without those interference effects. Which is sort of what the Quad was aiming to do. It is also what some concert line arrays do these days.
 

watchnerd

Major Contributor
Joined
Dec 8, 2016
Messages
8,380
Likes
4,890
Location
Seattle Area, USA
#19
Kii Three as just variations on the "phased array" concept.
You are clearly a Philistine, the Kii Three is a totally revolutionary speaker with a dipolar cardioid figure-8 that could only have been conceived by a genius, has never been thought of or built before, and is the biggest innovation in the field of auditory playback since the invention of the original Edison cylinder.
 

Blumlein 88

Major Contributor
Forum Donor
Joined
Feb 23, 2016
Messages
9,573
Likes
12,740
#20
You are clearly a Philistine, the Kii Three is a totally revolutionary speaker with a dipolar cardioid figure-8 that could only have been conceived by a genius, has never been thought of or built before, and is the biggest innovation in the field of auditory playback since the invention of the original Edison cylinder.
Shouldn't this read monopolar cardioid pattern?
 
Top Bottom