Multi smaller bass drivers vs single larger bass driver

I have two systems in which one has (2) 6.5 inch drivers that handle the bass signal and another that has (1) 10 inch driver that handles the bass. In addition the multi bass driver speakers have a narrower front baffle, slightly wider than the driver, while the larger woofer sits in a much wider box making the front baffle close to twice that of the other speakers. Both are three way and both are close to each other in efficiency. The overall sound is so different from each. The multi driver speaker have much more air and in the room presence while the speakers with the wider front baffle and larger driver has much more umph behind the sound including a much more powerful bass sound which gives these speakers a live at a concert feel as opposed to the live in the studio feel of the other.

I am sure part is due to different electronics driving each along with the size difference of the rooms but is this difference I hear primarily due to the large single woofer and wider front baffle verses a series of smaller stacked drivers and a narrower front baffle design?

 

It is impossible to say if the primary reason for different sounding speakers is related to multiple woofers vs. a single woofer. The other factors - crossover, cabinet design, driver design, room acoustics, etc. - are all far too important. The question is impossible to answer definitively.

 

I thought they could be the case but was wondering if any hobbiest who builds speakers might have an opinion based on their experience.

 

As a general rule, smaller woofers are faster but they simply cannot go as low. You'll get more pop out of those 6.5" drivers and probably a little 3D mid bass imaging. A larger woofer will be slower but produce lower frequencies. Hits you more in the chest. My main setup also has two 6.5" drivers and I run dual subs to fill in the low end. I like it because I still get the pop from the mid bass and the rumble from the subs. There are, of course, exceptions to that rule, but there's a reason REL fancies smaller drivers. They're fast and sound musical.

 

Possibly Dr. Bose will chime in on the subject.

 

Interesting. I also have supplemented the multi bass driver speakers with (2) subs that have 10 inch woofers. I also get a deeper rumble and certainly feel those really low notes but still the 10 inch woofers really gives you an at the concert feel where the smaller drivers give a more intimate feel. Maybe this is due to a more refined pin point sound stage they give and probably as mentioned up post differences in components and room size. I was guessing though a lot also has to do with again up post, quickness and throw distance of the difference in woofer designs along with magnet size. I also feel the width of the baffle has to play some role but I'm not sure technically why.

 

This is one of the things that keeps the hobby interesting. The variety of speaker designs. I’ve tried many speakers over the past months and it was quite the learning experience.

Last month I compared the newer KEF R11 to my R700. The R700 has a design similar to your Ref 3, with two 6.5” LF drivers. The R11 has four of them. Interestingly, due to other design flaws/considerations/price-point/etc., the R700 had a lot more apparent bass response than the R11. It was not subtle. I think it was a sloppier bass, and the R11 was controlling it better, but the ultimate effect did not have the same emotional impact.

Anyhow, I’m moving up to the Ref 3 this week myself.

 

I believe you will love them. I am extremely happy with mine. A very refined sound.

 

I've been building speakers for over 40 years.

Agitater's opinion is spot-on, there are just too many variables.

Speakers needn't and typically don't have any characteristic sound based on appearances, other than smaller speakers typically having less bass compared to larger ones.

 

I agree, "...based on appearances,...", but wider front baffle and large single woofer is more than just a difference in appearance, it is a design choice, therefore why one over the other and does that choice have anything to do with the resultant sound and sound stage one might favor / enhance over the other?

 

Yes design choices. But just too much to condense here briefly.

 

Phil Jones Bass (ie bass guitar) make a range of pro audio electronics and speaker cabinets. His designs use multiple 5" drivers Products – Cabinets | Phil Jones Bass

 

IME, the woofer mass and suspension type has the greatest impact on the differences you've described.

If you were to swap out those 6.5" drivers for ones made of paper cones and fabric surrounds, I all but guarantee they'd produce greater dynamics and rhythmic punch. Thick rubber surrounds essentially fight/damp the driver's motor. Although your speakers may have similar specs according to the manufacturers, I bet the slim towers are less efficient in reality.

 

The rubber surrounds generally aren't very thick, and are highly compliant, so I don't think contribute much to the linear motion damping, most of that is handled by the spider and the magnetic flux, but they do act as an impedance termination for vibrations traveling through the cone, so can provide important damping there. One problem is that the surrounds do move partially in antiphase to the driver, so you do lose some efficiency there, in addiition to the termination losses.

And two 6.5 " drivers would typically be closer in radiating area to a 8" driver, it would take closer to three of them to equal a 10" driver. But that 8" or 10" driver would still typically have a lower resonance point than the 6.5" drivers, and different box tuning.

 

Hi Davey,

Do you know what two 5 inch woofers would add up to for one driver?

 

My floorstanders have dual 6.5¨woofers. I run them full range, and like on half of my records I don't have to turn on my sub, which I reserve for recordings with weaker mixed-in bottom end. They go down to 39 hz +/- 3db, but there's a lot of life down to 30 as well. Sometimes the sound is indistinguishable from my 12¨sub. They sound as if they had a good 12¨single woofer each. Take a look at modern bass guitar amps; they feature 4 smaller drivers instead of a 15¨ or 18¨ single one, and are the choice of many modern bassists due to their versatility; they do bring the house down :

free image hosting site

 

It's hard to say unless you know the actual driver, then you can look up the effective cone area. But typically, a 5" driver will have about a 4" cone, so cone area = pie are squared = 12.6 square inches.

So two times that is about 25.2, so that would equal a driver with a cone diameter of about 5.7", or roughly a 6.5" to 7" woofer, depends how the size is measured, driver companies measure their drivers all kinds of different ways, sometimes a 7" driver is measured to the outside edge of the frame, sometimes it's to the outside of the surround, or the bolt hole circle, or ...

 

Here's one for you, I recently owned Revel Performa M22 monitors with one 6.5 inch bass driver. These were rated to 45hz I believe. At the same time I had a pair of the newer Performa F206 floorstanders which had two 6.5 inch woofers and were rated to 39hz.
The M22s filled the room with much more bass than the F206s. It shocked me and a good friend who visits regularly. And this was with test tones as well as music. I played a 32 hz tone on both speakers and while it was lacking on both, the M22s gave more down there.
I traded the F206s to a guy who's only complaint was the lack of bass. I also sold the M22s to a member here, he was happily surprised at the bass output of the monitors.
This just illustrates there's a lot more than driver size, or even the number of drivers at work when it comes to bass output.

 

OP - I started a thread on this a while back that got some interesting discussion Floorstanders with one large woofer or multiple smaller ones? not sure if you saw / searched, but it's always good to share past thoughts.

 

So - which one do you like more?

 

In my experience, where my journey years ago saw 10", 12" woofers in my mains, etc then many years of "smaller" and multiples, my recent return to 13" woofer a year and a half ago has eliminated my need for external sub, etc. I am not a big fan of external subs, prefer big woofer (s) in the main after years of iteration.

 

I recently moved to a new apartment. On the previous one I had my set up in a 10 square meters room, I now have around double that size.
My AVR is a Pioneer SC LX-76 from 2012 (Elite range in the US) with 9.1 channels of amplification but I have it set up to bi-amp the three front channels (using two of its power stages for each speaker) and single amp for the two surrounds. Speakers are 4 B&W DM601 (original series from 1996), a CC6 center channel and a recently bought B&W ASW 608 subwoofer that features an 8 inch driver (a mix of paper and Kevlar) on a sealed enclosure. The B&W DM 601's have 6" Kevlar woofers.
In the room the set up is in, there are carpets, a big L-shaped sofa, a big solid wood piece of furniture where equipment sits, so there is little room for resonances, I have big Marroquian tapestries on the walls and thick courtains on the balcony door.
At first I thought I'd have a problem with bass, regarding to stereo only, a pair of 24 year-old speakers (that still sound great, made in the UK) with 6" woofers and a small subwoofer with an 8" driver on a sealed enclosure, I don't like bass reflex subwoofers, I prefer the lower amount of bass of sealed enclosure but its more controlled bass.
To my surprise I get plenty of bass, even some deep bass from such a small and inexpensive subwoofer. I use the Pure Direct mode when listening to music so there's no bass management and subwoofer gets muted unless I'm playing a 5.1 SACD or BD-Audio. I'm surprised by the amount of bass the tiny 6" Kevlar woofers of the B&W DM601, I can clearly hear Michael Anthony's or Geddy Lee bass guitar just with the DM 601's, no subwoofer used. Impressive.

 

both designs have pros and cons. unfortunately larger baffle / larger driver speakers have one major "pro" (the ability to produce bass more effortlessly) because as the driver gets larger in area (piston) it requires less travel (excursion) to excite the same volume of air.
however the advantages stop there. larger drivers are less capable of producing higher frequencies which is why a good sounding larger driver speaker usually is a three-way design- which brings up another set of challenges and compromises. typically two-way large woofer designs are severely compromised in the midrange and have a smooth, recessed presentation which is made worse because of prominent, free flowing bass response.
larger / wider baffles also create challenges- meaning that they require filters to reduce the reflected midrange and treble frequencies caused by such a large surface area of the baffle. in addition they offer less precise sound imaging and are much more finicky about where they are positioned and aimed.
narrow baffle speakers attempt compensate for their smaller woofers by adding multiple drivers and highly tuned bass reflex or transmission line ports. their advantage is that they can easily reproduce higher frequencies and often a two or 2.5 way design can sound excellent- more neutral and balanced. however the bass will not have the quality or impact that a larger driver can manage so effortlessly. narrow baffle speakers also require less filtering because they have less area to reflect sound which also gives them more horizontal high frequency dispersion- meaning a much larger broadcast spread of the upper midrange and treble ranges- which leads to easier positioning and superior imaging.

 

So, what's the "sweet spot" - narrow(er) baffle speakers with a sub?

 

2 things,
1- with 2 6.5” drivers you have 13” of cone are as opposed to the 10”.
2- Enclosure and x-over design make a huge difference

An example that I can give is Polk made the RM 1000 bass module. It consists of 2 6.5 inch drivers mounted firing opposite each other but offset on a center mounted baffle board within the box in a push pull band pass configuration, with a 10” passive radiator firing down on the bottom of the box. One look at these and you’d laugh your tail off, but the hit hard and sound great.

Dissection of an old Polk sub reveals a design i've never seen before (pics)