Woofer Size: small ones can beat out larger size?

I remember in the 70's and 80's that the larger the woofer, the more bass you would expect to come out of a speaker cabinet, so one would expect a speaker with a 12 or 15 inch woofer to produce more bass than a speaker with a 6 or 8 inch woofer. The result however, would be a gigantic cabinet that was almost the size of a small refrigerator and sometimes have one or more large drivers. Is it possible that a speaker with an 6 inch woofer can outperform a 10 inch woofer given the right cabinet, quality of driver and power input? I would also think that a smaller woofer compared to a 15 inch would produce a tighter, cleaner bass, no?

With subwoofers there's always a tradeoff. To get good bass, general thinking is you need a large driver in a large cabinet to reproduce the waveform necessary for full 20HZ-80HZ reproduction. You can tradeoff a larger driver for a smaller one, but it requires more excursion, which means more power. But you have to be careful not to drive the smaller woofer to distortion.

If the driver can reproduce the output without distortion and works well within its limits there's no problem, but what usually happens is the smaller driver falls short of the task and starts to distort under higher power requirements. Tighter, cleaner, lower, bass is impossible for a smaller driver, the physics just isn't there. I own a Klipsch SW8 subwoofer, but I use it only to reporduce upper bass, which it does very well. I use my Legacy Focus mains with 3 12" subwofers and setup in a biamp configuration to reproduce deep bass for my system. Good luck with your search.

given the right cabinet, a 10" driver could give the same amount of bass as a 12" in the same cabinet. but it would produce different bass. and no, bigger drivers will have the tighter, cleaner bass...

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Originally Posted by cocopeep

I remember in the 70's and 80's that the larger the woofer, the more bass you would expect to come out of a speaker cabinet, so one would expect a speaker with a 12 or 15 inch woofer to produce more bass than a speaker with a 6 or 8 inch woofer. The result however, would be a gigantic cabinet that was almost the size of a small refrigerator and sometimes have one or more large drivers. Is it possible that a speaker with an 6 inch woofer can outperform a 10 inch woofer given the right cabinet, quality of driver and power input?

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It's possible - but as mentioned there's tradeoff. First, and most obvious, is cost. If you expect a 6" woofer to produce bass on par with a 10" woofer, it's not going to come cheap. There's a few things that are needed. As mentioned, longer excursion larger woofers typically have bigger, stronger motors that offer longer excursion, so it'll move in and out further. That 6" driver has 1/2 the area basically of a 10" woofer, and per mm of excursion the volume of air it sweeps is going to be dramatically lower as a result. So you've really got to beef up the excursion.

There's a downside to long-throw woofers though. As you increase the excursion you increase the requirement for a sufficiently strong motor. The further the woofer moves out, the greater the chance of distortion. Not to mention, the transient response of the longer excursion is usually poorer than the smaller one. Personally, I've observed transient response to be a much more important factor in how good a woofer sounds for low bass than distortion. Our ears become less sensitive to frequencies and distortion below 50 Hz, but if you start stretching out and missing notes, your going to hear it.

I have a sub I built with a 15" woofer with decent excursion for the size, but nothing as extravagant as some 15" woofers have. I built mom and dad a 12" sub whose woofer had 80% longer excursion. It'll play about as loud, but requires 3 times the power to play just as loud, and doesn't sound as good at higher volumes. But the box is less than half the size, so again, we're back to a question of tradeoffs.

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Originally Posted by cocopeep

I would also think that a smaller woofer compared to a 15 inch would produce a tighter, cleaner bass, no?

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A few decades ago that was probably true, but that was because of different driver technology. Today's it's just the opposite.
In my example above, my 15" woofer has far better sound quality because it doesn't have to work nearly as hard to play low and loud as the smaller woofer, and it moves more air with each sweep. Because it doesn't work as hard, the motor never loses "control" of the woofer, there's less distortion, better transient response.
My 15" woofer is considerably cheaper than the 12", and requires 1/3 the power. I built it a better sub for about 1/2 the price. The tradeoff is I have a 20" cube in my room compared to mom's much smaller subwoofer.

I have to laugh a bit at some of the subwoofers I see on the market today. It almost seems like subwoofer's are sold by watts and inches alone when I walk into some stores. You see lots of 10" and 12" woofers with very low resonance frequencies that reduce the efficiency of the driver, so they mate it with a high watt amplifier. I saw one kid turn down a rather modest 12" sub because the 10" sub had 1200 peak watts or something foolish. compared to the 600 watts the 12" unit had. He didn't even listen to them. The 12" sub was a much better unit.

You have a choice of three design goals.
1) Small Size
2) Efficiency
3) Deep Bass.
You can have only two:.

a) A large enclosure with an efficient speaker that produces a lot of deep bass
b) A small enclosure that needs a lot of power driving the speaker and produces a lot of deep bass.

You cannot have a small enclosure that's efficient and produces a kot of deep bass.

It's all in moving of air. A small speaker needs a greater excursion than a larger speaker to move the same amount of air. And, the smaller the speaker gets, the more power it's lkely to need to move that air.

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Originally Posted by markw

You can have only two:.

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I like your evaluation. :)

Back in the 70s, I worked for a hi-fi shop that sold ADS speakers along with Magneplanar, Acoustat, and Dayton-Wright. The ADS approach was to double up using smaller (7" or 8") woofers to perform as a larger driver.

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Originally Posted by markw

It's all in moving of air.

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Which is why our planars must have huge surface area.

rw

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Originally Posted by E-Stat

The ADS approach was to double up using smaller (7" or 8") woofers to perform as a larger driver.

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I loved the 710 and 810. they had the best sound of any speaker in that size/price range I could find then.

Would that I could afford them at the time.

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Originally Posted by markw

I loved the 710 and 810. they had the best sound of any speaker in that size/price range I could find then.

Would that I could afford them at the time.

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I liked them but I could only afford the ADS L570 speakers. Single 8 inch woofer and dome tweeter. Beautiful cabinets with the perforated metal grill. They are still being enjoyed by the gentleman who bought them.

Around that time I was transtioning from a pair of Wharfedale 40 C's to a pair of JBL Lancer 55's, or "the thunderlizards" as they came to be known.

The ported Wharfedales couldn't handle the power.

.

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Originally Posted by basite

given the right cabinet, a 10" driver could give the same amount of bass as a 12" in the same cabinet. but it would produce different bass. and no, bigger drivers will have the tighter, cleaner bass...

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This is not necessarily true and really depends on the application. A smaller driver has the advantage of speed and clarity within its optimal operating range. The advantage of the larger bass driver is DB output capability, potentially higher Q factor, and extension. the larger woofer will extend lower than, say, 25hz without strain and distortion than the smaller woofer. that is why larger woofers are used for subwoofer applications (but that doesn;t mean a smaller woofer won't shake the house). Most smaller woofers will be severely challenged to hit 18hz without noticable distortion. On the other hand, a smaller well-designed woofer such as the ceramic coated 6" woofers in well executed ported design such as my Monitor Audio GR60s are incredibly fast and coherent, while putting out more bass than most people will need in the average sized room.. It really depends on what range one expects the woofer to cover. Many large state-of-the-art speakers have large enough cabinets to accomodate two large 15" woofers per cabinet, but will instead opt to use a smaller woofer for midbass for its speed and coherence in its optimal range of operation. Very few large woofers have sufficent speed to keep up with very fast speakers such as the Martin Logans for example. One must keep in mind that midbass and deep bass performance are also a function of the preamp and amp..:2:

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Originally Posted by kexodusc

It's possible - but as mentioned there's tradeoff. First, and most obvious, is cost. If you expect a 6" woofer to produce bass on par with a 10" woofer, it's not going to come cheap. There's a few things that are needed. As mentioned, longer excursion larger woofers typically have bigger, stronger motors that offer longer excursion, so it'll move in and out further. That 6" driver has 1/2 the area basically of a 10" woofer, and per mm of excursion the volume of air it sweeps is going to be dramatically lower as a result. So you've really got to beef up the excursion.

There's a downside to long-throw woofers though. As you increase the excursion you increase the requirement for a sufficiently strong motor. The further the woofer moves out, the greater the chance of distortion. Not to mention, the transient response of the longer excursion is usually poorer than the smaller one. Personally, I've observed transient response to be a much more important factor in how good a woofer sounds for low bass than distortion. Our ears become less sensitive to frequencies and distortion below 50 Hz, but if you start stretching out and missing notes, your going to hear it.

I have a sub I built with a 15" woofer with decent excursion for the size, but nothing as extravagant as some 15" woofers have. I built mom and dad a 12" sub whose woofer had 80% longer excursion. It'll play about as loud, but requires 3 times the power to play just as loud, and doesn't sound as good at higher volumes. But the box is less than half the size, so again, we're back to a question of tradeoffs.


A few decades ago that was probably true, but that was because of different driver technology. Today's it's just the opposite.
In my example above, my 15" woofer has far better sound quality because it doesn't have to work nearly as hard to play low and loud as the smaller woofer, and it moves more air with each sweep. Because it doesn't work as hard, the motor never loses "control" of the woofer, there's less distortion, better transient response.
My 15" woofer is considerably cheaper than the 12", and requires 1/3 the power. I built it a better sub for about 1/2 the price. The tradeoff is I have a 20" cube in my room compared to mom's much smaller subwoofer.

I have to laugh a bit at some of the subwoofers I see on the market today. It almost seems like subwoofer's are sold by watts and inches alone when I walk into some stores. You see lots of 10" and 12" woofers with very low resonance frequencies that reduce the efficiency of the driver, so they mate it with a high watt amplifier. I saw one kid turn down a rather modest 12" sub because the 10" sub had 1200 peak watts or something foolish. compared to the 600 watts the 12" unit had. He didn't even listen to them. The 12" sub was a much better unit.

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Thank you for your reply, very in-depth! I learn something every day. Something else however, what if in a tower speaker, you see alot of 6 1/2, 7 1/2 woofers, mabye 2 in one speaker cabinet. In a good speaker cabinet design, I'm wondering if 2 - 6 1/2 woofers are able to equal the bass output & quality of a 10" or larger driver?

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Originally Posted by cocopeep

Thank you for your reply, very in-depth! I learn something every day. Something else however, what if in a tower speaker, you see alot of 6 1/2, 7 1/2 woofers, mabye 2 in one speaker cabinet. In a good speaker cabinet design, I'm wondering if 2 - 6 1/2 woofers are able to equal the bass output & quality of a 10" or larger driver?

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If I recall my basic math from high school (graduated in '67), the formula for area of a circle* is (radius X pi (3.14)) squared.

So. for a 10 " speaker we would have (5 X 3.14) squared, or (15.7 X 15.7), or 246 sq inches.

A 6.5" driver would be (3.25 X 3.14) squared, or (10.20 X 10.20), or 104.1 sq. inches.
Double that for two drivers, and you have 208 sq inches of driver space.

* Yeah, yeah. Technically it's a cone but I'm not gettin' into that math. Simply measure the actual distance along the cone from the edge to the center and use those numbers. this may not be exact but it's close enough fr government work.

Remember, this does not take into account the excursion, efficiency, enclosure design, and many other factors that I'll let others worry about, although you may want to get a book or two on this if you're really interested.

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Originally Posted by markw

If I recall my basic math from high school (graduated in '67), the formula for area of a circle* is (radius X pi (3.14)) squared.

So. for a 10 " speaker we would have (5 X 3.14) squared, or (15.7 X 15.7), or 246 sq inches.

A 6.5" driver would be (3.25 X 3.14) squared, or (10.20 X 10.20), or 104.1 sq. inches.
Double that for two drivers, and you have 208 sq inches of driver space.

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Hopefully your math teacher gave you an F! ;)

The formula for surface area of a circle is pi*(r*r) "pi-r-squared"

For a 10" speaker, the surface area is (5*5)pi = 78.5 square inches

For a 6.5" speaker, the surface area is (3.25*3.25)pi = 33 square inches.

You can't directly correlate surface area with bass extension though, as the size of the body producing the wave is relevant. 25 2" drivers will never produce an 18Hz wave even though the surface area would be the same as a 10" driver. 2" drivers just aren't capable of that kind of extension... excursion can only compensate so much before it causes unacceptable distortion.

This is very interesting indeed. I auditioned PMC loudspeakers about two years ago and found that for such a small driver they had mid bass that was quite extended. Now due to their drivers being loaded within what PMC called "time line-porting" their cabinets those little drivers looked like tweeters not mid units at all, and the mid bass was big and fantastic. Could some speaker mfg make a loaded designed port for a 6" driver configuration with lets say 4 or 5 of the 6" drivers or even smaller in a time line ported design and bring a sub bass sound to the soundstage......??? Now I know this requires power but my question asks if it is possible in design theory and within smaller cabinets......?

PMC, Renaud-"spell on that one please", PSB, Axiom are just a few with some of this going on. Maybe I'm just talking out my ARSS...LOL......anyway ready, set, GO

Later Dudes
:dita:
P.S. Does anyone know what speaker I have in my little corner, I do so lets see who else can figure that one out in here. And by the way do you know how long it took me to find that picture even with the net at my disposal.....? almost a year.........

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Originally Posted by markw

I loved the 710 and 810. they had the best sound of any speaker in that size/price range I could find then.

Would that I could afford them at the time.

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I owned a pair of late-model 710's under the Braun label -- very nice speakers for sure.

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Originally Posted by cocopeep

Thank you for your reply, very in-depth! I learn something every day. Something else however, what if in a tower speaker, you see alot of 6 1/2, 7 1/2 woofers, mabye 2 in one speaker cabinet. In a good speaker cabinet design, I'm wondering if 2 - 6 1/2 woofers are able to equal the bass output & quality of a 10" or larger driver?

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Put two bass drivers in a cabinet and you require twice the cabinet volume of a single unit.

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Originally Posted by canuckle

Hopefully your math teacher gave you an F! ;)

The formula for surface area of a circle is pi*(r*r) "pi-r-squared"

For a 10" speaker, the surface area is (5*5)pi = 78.5 square inches

For a 6.5" speaker, the surface area is (3.25*3.25)pi = 33 square inches.

You can't directly correlate surface area with bass extension though, as the size of the body producing the wave is relevant. 25 2" drivers will never produce an 18Hz wave even though the surface area would be the same as a 10" driver. 2" drivers just aren't capable of that kind of extension... excursion can only compensate so much before it causes unacceptable distortion.

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But, remember, LBJ was president then.

I think I did mention that there were more factors involved. Excursion was one of 'em.

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Originally Posted by cocopeep

Thank you for your reply, very in-depth! I learn something every day. Something else however, what if in a tower speaker, you see alot of 6 1/2, 7 1/2 woofers, mabye 2 in one speaker cabinet. In a good speaker cabinet design, I'm wondering if 2 - 6 1/2 woofers are able to equal the bass output & quality of a 10" or larger driver?

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As canuckle mentioned, there's more than just excursion to consider.
Those 2 6-1/2" drivers probably won't have as low a frequency of resonance as a 10" woofer in a similar application despite moving almost as much air. We're back to trade-offs again.

But don't worry, there's a lot of good speakers these days that are tuned reasonably low (ported designs) that will produce decent quality bass with just 1 or 2 6-1/2 woofers that covers most of the musical spectrum.

If you really want to get that last bottom octave, you can always add a subwoofer. When properly used, I would argue a good subwoofer is a much better investment than going from a bookshelf to a tower speaker just to add a woofer or two and get a few extra Hz. A lot of companies charge ridiculous amounts extra to go from the small bookshelf monitor to their matching tower speaker. And usually, in my experience, the bookshelf/subwoofer combo will sound better and be more cost-effective for a number of reasons.

Sub used to be frowned upon by alot audiophile traditionalist types. Early on nobody knew how to use them properly, and there weren't many good sounding, affordable models either, so I'm not surprised. In the last 3 or 4 years or so subs have come a long way, and people's understanding of how to use them has grown as well. They're cheaper, more powerful, better sounding, and more sophisticated than just a few years ago. It's been sort of a quiet revolution. But it all comes back to the lower resonance frequencies, lower distortion, and ability to sweep larger volumes of air that gives subwoofer's a big advantage.

There are a number of speakers with 5-7" drivers that can reach down to 40Hz with enough SPL to create a fairly full range listening experience. My bookshelf speakers are an example of this, using a 5.5" driver. Below 40Hz you've got mostly organs or electronic music and I don't listen to either enough to feel I'm missing out on anything. In the future when I'm not so limited by budget and space I am certain I would pursue something that could reach lower but at 40Hz you're really getting the most out of a lot of music.

Small drivers vs large drivers depends a lot on implementation and component choice. I do find that speakers with smaller drivers sometimes have better immediacy or transient response but it's not a guarantee. Same for subwoofers, I've not been a fan of most systems I've heard based around woofers much larger than 12 or 13", most of the subs I enjoyed best were in the 8-13" range and some designs based around 8-10" woofers (such as the Martin Logan Depth which I enjoyed and was delighted to see my parents purchase) had the immediacy I've found to be better with some smaller drivers and the depth and punch of bigger woofers. But with the new drive systems and everything, the larger woofers are a lot better than they used to be.

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Originally Posted by O'Shag

This is not necessarily true and really depends on the application. A smaller driver has the advantage of speed and clarity within its optimal operating range.

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I think this was almost universally true at one point in time. Today, larger woofer's are not "slower" unless they have a relatively weaker motor system (with respect to the mass of the woofer).

Consider 3 woofers, a 6", 10" and 15" unit, all used in cabinets with system Q's of 0.707.
Each woofer is asked to play a 40Hz tone at 90 dB (I use this example because I have tests with woofers of the same product line/motor designs).
The 6" woofer requires 6.7 mm of excursion (which could be problematic since many only have 4-6 mm available.
The 10" woofer requires 2.3 mm of excursion (max of 8 mm)
The 15" woofer requires exactly 1 mm of excursion (max of 10 mm).

It's easy to see the larger woofers operating at much lower stress need to move shorter distances, and remain well within the realm of their motor's optimal operating range. The lower and louder the music you play, the "faster and clearer" you can expect a larger woofer to perform. The 15" woofer barely has to do anything at all compared to the 6' woofer which is operating near 100% of it's abilities.

Cocopeep.

Basically all you have to do here is listen to some of these. Plenty of speakers for example claim 40hz which for most music is fine but what type of 40hz are you getting. Play bass heavy music on my "built for rock" Wharfedale Vanguards at 110db and then play a Totem Model One at very high level on bass heavy techno trance with synthesizers that cover the entire bandwidth and it will be very easy to see that the small drive and small cabinet of the Model One has traded a LOT. But they are wife friendly and apartment living friendly and look sexy and at low levels hooked up to a Denon like mini-system not too bad - pricey but...that is subjective.

Listening to a lot of the big loudspeakers of yesteryear here in Korea (which is odd since space is a premium yet wide baffle high efficiency is the thing to get here) big drivers big cabinets have a visceral appeal that small speakers simply don't possess. In fact all small standmounts make me immediately want to add a subwoofer and I have never heard a sub/sat that sounded good (impressive though but that is different).

Even my speakers while standmounts are physically large and being designed for corners are aided immensely in terms of sensitivity and bass depth by the corner loading. I am pleased by the results - Hi-Fi Choice measured my standmount as 25hz -3db (89.5 db not in corners which means 92-94db in corners) and can play to 108db without dropping under 5ohms...the woofers are very low excursion - they barely move even under heavy bass at high volumes. Meanwhile the Wharfedales with the same music flap like someone standing in front of an armed Dick Cheney.

Granted one could argue the accuracy of the big JBL speakers of yesteryear but boy are some of these a lot of fun. It's a shame their management did some stupid things and the products and name value is in the dumper. I'd like to see what could have been done with better cabinets and internal caps, wiring, crossovers, and drivers.

The other thing you might want to check is the parts quality - sometimes the marketing is there to hide the "we use cheaper ass small drivers and cheaper ass wood and less of it, but we can write baffle gab white papers and charts to illustrate that cheap crap is better." The speaker industry is no different than any other field where marketing convinces that good is bad and bad is good. IMO

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Originally Posted by Feanor

I owned a pair of late-model 710's under the Braun label -- very nice speakers for sure.

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We sold many a very good system using a Sonus cartridge in a Philips 212 table with an H-K receiver (430/730) driving 710s/810s.

rw

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Originally Posted by cocopeep

Is it possible that a speaker with an 6 inch woofer can outperform a 10 inch woofer given the right cabinet, quality of driver and power input? I would also think that a smaller woofer compared to a 15 inch would produce a tighter, cleaner bass, no?

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One factor I haven't heard discussed yet is that of coherency, an important characteristic to me. The "tightness" you mention in bass is largely determined by its upper or mid bass performance, not at the bottom per se. The challenge with using large woofers is getting them transitioned seamlessly to the upper drivers at the upper part of their range. In some designs, one is aware of The Bass, The Midrange, and The Treble.

As of late, I have developed a greater appreciation for the value of treating room bass nodes. All rooms are inherently non linear in their bass response. Equalization is an obvious answer, but can involve some sonic compromises IMHO if run full range. For my HT system, I chose to use a relatively high crossover point from the Polk bookshelves (using a 6" woofer) to the powered 12" subs. While the Polk's respond to 50 hz, I wanted to use the EQ to flatten all the room nodes up to 200 hz via the subs. That has worked out very well.

rw

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Originally Posted by RGA

Basically all you have to do here is listen to some of these. Plenty of speakers for example claim 40hz which for most music is fine but what type of 40hz are you getting.

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Exactly. That's one reason Totem makes pretty specific statements about what room sizes the speakers are intended for so you can get reasonable output at 40Hz. You won't get deafening output compared to larger speakers and if you're a basshead or listen to lots of the synth stuff it'll fall off on you but aside from that, and in a room that isn't too big, you can get good/satisfying/acceptable output down to 40Hz from those bookshelf speakers.

In short, I agree with you. It depends on a few things.

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Originally Posted by markw

But, remember, LBJ was president then.

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LB who? :p

:lol: