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Are dual woofered / multiple driver speakers better than single?

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miggyboys's picture
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I've some questions about speakers with multiple / single woofers...

A number of top speakers only have a single woofer and tweeter whereas other designs have multiple woofers / separate bass & midrange.

Do multiple woofers make a difference to the separation of sound and delivery? i.e. do many speakers with multiple woofers output the lower ranges through one woofer and the mid range through the other woofer or do they more often work in tandem?

Can a single woofer and single tweeter really do it all? And do speakers with multiple woofers have more difficulty in producing coherent and unified sound?

PMC Twenty.23s are £2000, have a single woofer and single tweeter, yet create a beautiful soundstage and wonderful musical sound.

Dynaudio Excite X32 are £1800 and have two woofers and a tweeter and once again, are a fantastic sounding speaker.

What have your experiences been and does anyone have any preferences?

I know some of you are going to say 'It's whatever sounds best that counts' which I agree with but I'm wondering if there is any technical superiority or difficulty with one design over another!

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plastic penguin's picture
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Multidriver speakers

Technically a single bass/midrange should be better than the average multi-driver. The main issue IMO is timing: The more drivers you have timing really can become an issue. That said, get a good quality multidrive floorstander and they time as well as any single coned speaker.

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Are dual woofered / multiple driver speakers better than single?

plastic penguin

I'm inclined to think it isn't easy getting multiple woofers working together in unity. But surely it must be better having a speaker with a separate mid range and bass woofer so each frequency range has better seperation. Design wise, it's 'separating the separate' so frequencies have their own dedicated channels....?

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AV: Sharp LC-46LE831E, Denon AVR-2310, Sony BDP-S363, SkyHD, Mordaunt Short Genie 5.1, various QED & IXOS interconnects, QED Silver anniversary speaker cable.

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RE: Speakers

These are all very relevant questions....and (stating the obvious) comes down to design, cost and implementation.

- TL speakers can often get deeper bass from less / smaller drivers, due to the design

- I think a well sorted crossover is a requisite.....and some are more complicated than others

- Kef and Tannoy have the tweeter in the centre of the mid-range, which helps.

- Eclipse make large pods with a single driver, which will give no intigration problems, lightening transients, with amazing timing and imaging....but at the expense of the frequency extremes.

- Panel type speakers (eg. Electrostatics, Maggies etc), can sound incredible, but don't go as low as some.

Everyrthing is a compromise, it's just where you wish to make it.

Personally I like the scale of a floorstander, but if I had a small room, would probably have a standmount which often gives better performance at their price point.

To get a well sorted Floorstander with multiple drivers, you are probably looking at £1700+

All IMO.

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It is all down to design and execution. Both can work well, and both can be a disaster.

I'll have to write later as we're about to close... Smile

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plastic penguin's picture
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Are dual woofered / multiple driver speakers better than single?

miggyboys wrote:

plastic penguin

I'm inclined to think it isn't easy getting multiple woofers working together in unity. But surely it must be better having a speaker with a separate mid range and bass woofer so each frequency range has better seperation. Design wise, it's 'separating the separate' so frequencies have their own dedicated channels....?

IMO if all the drivers don't pull in the same direction at the same time then timing, and subsequent imaging can be effected. This where MAs really excel: For their price they time as well as any speaker I've heard at the price and some.

Obviously Cno and David can go into more of the technical side - that's the way I read it.

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RE: Speakers

plastic penguin wrote:

Obviously Cno and David can go into more of the technical side - that's the way I read it.

It's over to David then!   excellent!

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RE: Speakers

banging head against wall banging head against wall banging head against wall

(Duplicate)

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Maybe

I'm by no definition the most technically adept person on this forum. I do think that there are ups and downs to both but fewer drivers have fewer problems and is the technically superior option. One reason is that crossovers get increasingly complex to implement properly, the point at which the woofer crosses over to the tweeter can stand out like a sore thumb if the crossover isn't designed properly. The midbass can also sound detached from the subbass. The enclosure gets more difficult to design too. 

I have seen heard great implementations of both at the same price and I can't honestly tell you that speaker a at price x sounds better than speaker b at price x because it is either single or multidriver. However, I have heard low powered tube amps with single driver speakers and megawatt amps with multi driver speakers and the former sounds much closer to a live acoustic performance or vocal solo while the latter sounds more like a concert venue.

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Yes, and no.

I don't think you can say that any one design is superior to the other - as I mentioned earlier, it is down to how well the design is implemented and executed. In theory, a single full range driver should be the best in this respect, for obvious reasons. But, you'll usually find that these types of drivers aren't as good at the frequency extremes as it is in the upper bass to lower treble. This is where a two way comes in, so you have a driver that can deal with mid and bass, and let a separate driver do the higher stuff. This allows the drivers to do less work, and reach farther out into the frequency extremes. The drawback with the two way is the crossover, which can have a detrimental effect depending on how well it is designed. Most speakers will be two way, because its cheaper and easier to produce. A three way speaker allows the three sections of the frequency range (bass/midrange/treble) to be concentrated on by a driver that is specifically designed for the job. In a two way the bass driver has to reach as low as possible as well as reproducing midrange, which tends to affect the quality of the latter. A three way system means the bass tends to be cleaner because the driver doesnt need to produce frequencies above those that it is comfortable with, and it wont negatively affect them either. The midrange gets its own driver, so doesn't have to compromise itself by using a large roll surround, or directly affect frequencies well above what it really needs to do (or you could say, what it shouldn't be doing). It can sound cleaner because it isn't negatively affected by large cone movements. The treble unit can play cleaner and more precisely because it doesn't have to go deeper than it is comfortable with, because that load has been eased by the midrange driver. All in all, everything sounds cleaner and tighter because of the dedicated drivers.

Other speakers may steer clear of the three way design and utilise two mid/bass drivers, which increases efficiency. Using two drivers shares the work of one, so the bass cones don't have to travel as far to reproduce low notes. As well as higher power handling, this can mean a cleaner midrange, and a tighter bass because of the lower cone excursion. The drawback with timing probably isn't too much of an issue as they're both on the same (front) face of the cabinet, and will be the same distance from you, so won't cause timing issues. Those two bass drivers, perhaps working up to 3kHz as an example, will be producing a lot of directional frequencies (above 150/200Hz as a rough guide), and with two drivers producing the same frequency range, you're creating a perceived 'centre' for those frequencies, which is in between the two mid/bass drivers. This is shifting the focus of those frequencies further away from the centre of the treble unit - unless you place one mid/bass driver above the treble unit and one below - you now have a perceived centre which is the point of the treble unit. This creates, very basically, the illusion that a coincident driver produces - all frequencies coming from a single point. There are still issues with this compared to coincident, but that's for the designer to worry about, and I'm digging myself deeper here Smile

So ideally, all the drivers should be placed as close to each other as possible in order to try and produce a coherent sound that isn't 'smeared' due to multiple drivers here there and everywhere. An example of how to do something like this well is the KEF Blade - treble and mid down to 350Hz on the front face of the speaker (UniQ array), and the rest produces by four bass drivers, two on each side of the cabinet. These bass drivers are quite a distance from the UniQ array, but placed in such a way that from the listening position it sounds like all frequencies are coming from the same point. From a timing point of view, you'd expect the whole sound to be quite askew, but all this has been taken into consideration during the design - after all, there'd be no point producing a speaker that is 'reference' in some areas and downright awful in others.

Jack from KEF will be able to explain it all better than me as he is a speaker designer (and I'm not), so I'll see if he can jump on and give his take, or correct anywhere I've gone wrong.

Just one thing to add that I've just thought of regarding dual mid/bass drivers - I've always felt from experience that a larger, long throw single mid/bass driver (like those we used to see in bigger speakers in the 70's) produced a nice, weighty, full sound. In comparison, two smaller short throw drivers seem to lack that fullness, but can be noticeably faster - some may say leaner too, but I'd actually say more accurate, and able to pick out subtleties that can be lost in a larger driver. So overall, I'd prefer a few smaller bass drivers to one larger driver. I'd say its the same with subs - I'd rather have two smaller drivers than a larger single driver (with equivalent area). The larger driver can sound initially impressive, but won't sound as fast or be able to produce tiny subtleties like the two smaller ones.

Anyway, I'm off to watch a film before its too late!!

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RE: Yes, and no.

David can you elaborate ?.

 

 

Lol   twisted

miggyboys's picture
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RE: Three way drivers potentially lean towards the best then?

Plasticpenguin - thanks for your input as always.

shafesk - interesting to hear your fb regarding tube amps.

CnoEvil thanks for your input on the engineering.

David, wow, what an explanation! Excellent! Certainly answers a lot of my questions. You say one design isn't better than the other as it's down to the execution etc which I'd agree with wholeheartedly. But you appear to lean slightly towards three way as each driver can then handle bass / mid range / treble / the extremes better, though it would have to have a first class crossover inside as it's more of a complex design?

Just for clarification for myself and anyone else reading this, a speaker with two identical woofers and a single tweeter - would this be classed as a two way speaker? If so, would it be more common in this design that both woofers handle mid range and bass equally or would it be the case that the bass and mid range is split between them? (which I would then think is a three way speaker).

Thanks

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AV: Sharp LC-46LE831E, Denon AVR-2310, Sony BDP-S363, SkyHD, Mordaunt Short Genie 5.1, various QED & IXOS interconnects, QED Silver anniversary speaker cable.

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RE: Three way drivers potentially lean towards the best then?

miggyboys wrote:
David, wow, what an explanation! Excellent! Certainly answers a lot of my questions. You say one design isn't better than the other as it's down to the execution etc which I'd agree with wholeheartedly. But you appear to lean slightly towards three way as each driver can then handle bass / mid range / treble / the extremes better, though it would have to have a first class crossover inside as it's more of a complex design?

In general, I would say that I prefer a well designed three-way speaker for full range. But to get a good three-way speaker, yes, the crossover needs to be very well designed. I think this is why you don't really see many budget three-way speakers - the cost of the crossover and the extra drivers means they're usually around £1k and upwards.

 

Quote:
Just for clarification for myself and anyone else reading this, a speaker with two identical woofers and a single tweeter - would this be classed as a two way speaker? If so, would it be more common in this design that both woofers handle mid range and bass equally or would it be the case that the bass and mid range is split between them? (which I would then think is a three way speaker).

Usually, two identical woofers will be producing the same signal. This will be a two-way system. A 2.5 way system won't have a dedicated driver for midrange - it still works the same as a two-way, but will have an extra bass driver for lower notes (the Spendor A5's are an example of this). So what seems to be the midrange driver will be full bass/midrange, and the lower bass driver will produce lower bass only - for example, 700Hz and below, depending on how the crossover is designed.

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RE: Three way drivers potentially lean towards the best then?

David, thanks, you are the man. Top explanation.

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AV: Sharp LC-46LE831E, Denon AVR-2310, Sony BDP-S363, SkyHD, Mordaunt Short Genie 5.1, various QED & IXOS interconnects, QED Silver anniversary speaker cable.

Thanks

Miggyboys