Assume we're going to create a massive 3-way bookshelf with a tweeter, a dome midrange, and a large single 12" woofer, in the vintage manner of the Yamaha NS-1000, ADS L980, AR-91, etc.
In woofer selection, I found there's a very similar frequency response between the 12” woofer and the 12” subwoofer. Assume we’re going to cross the low-pass filter of the bass unit in the 300–500 Hz region, which is quite low when used together with the DOME midrange.
If the price of a 12" woofer and a 12" subwoofer is the same, as said earlier, their frequency response is identical, and with modern designs, they can both go flat up to beyond 1 kHz. Should we buy a 12" subwoofer instead? What are the advantages and disadvantages of using a 12-inch subwoofer as a woofer?
In woofer selection, I found there's a very similar frequency response between the 12” woofer and the 12” subwoofer. Assume we’re going to cross the low-pass filter of the bass unit in the 300–500 Hz region, which is quite low when used together with the DOME midrange.
If the price of a 12" woofer and a 12" subwoofer is the same, as said earlier, their frequency response is identical, and with modern designs, they can both go flat up to beyond 1 kHz. Should we buy a 12" subwoofer instead? What are the advantages and disadvantages of using a 12-inch subwoofer as a woofer?
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@GM is essentially right. But his explanation is a bit brief.
Subwoofer and woofer differ by nomenclature only. I mean, what is a '5" subwoofer' that sits in a typical subwoofer in a big box store plastic cabinet and a 10" woofer that play much louder and clearer in an auditorium?
A typically subwoofer has a much longer excursion than a midwoofer. And so the traditional BL(x) and Sd(x) vary so much, I think manufacturers seemed to not bother with optimizing for Le(x) or frequency response. Some (sub)woofers can play only to about 100 or 200 Hz before the frequency response drops like a rock.
Essentially what you're looking for is something that meets your needs for sensitivity, frequency response and volume displacement. Of and cabinet volume.
You write the rules.
If you want to crossover around 300-500Hz region, you want a driver that plays nice and smoothly to 300-500Hz AT LEAST. Preferably an octave more to 600-1000Hz.
A few good options that are currently available the SB Acoustics SB34RNXL driver and the Dayton Reference Series RSS315HFA-8.
Subwoofer and woofer differ by nomenclature only. I mean, what is a '5" subwoofer' that sits in a typical subwoofer in a big box store plastic cabinet and a 10" woofer that play much louder and clearer in an auditorium?
A typically subwoofer has a much longer excursion than a midwoofer. And so the traditional BL(x) and Sd(x) vary so much, I think manufacturers seemed to not bother with optimizing for Le(x) or frequency response. Some (sub)woofers can play only to about 100 or 200 Hz before the frequency response drops like a rock.
Essentially what you're looking for is something that meets your needs for sensitivity, frequency response and volume displacement. Of and cabinet volume.
You write the rules.
If you want to crossover around 300-500Hz region, you want a driver that plays nice and smoothly to 300-500Hz AT LEAST. Preferably an octave more to 600-1000Hz.
A few good options that are currently available the SB Acoustics SB34RNXL driver and the Dayton Reference Series RSS315HFA-8.
As above. If they are essentially the same then woofer vs subwoofer would just be terminology.
In practice things tend to be more optimised - most woofers don't have the costly excursion capability and such low fs expected from a 'true' subwoofer. Conversely, in many (but not all) cases a woofer would offer lower distortion in the higher frequency range. But there is overlap and 300-500hz is a fairly low crossover too, so depending on your design goals either could be considered; depends entirely on the characteristics of the specific driver, not what it is called.
Though 300-500hz being fairly low places more demands on the midrange. So I would spent time making sure that had the necessary distortion and response characteristics to cross over low enough whilst still reaching the highs that you need from it before beaming or well before breakup.
In practice things tend to be more optimised - most woofers don't have the costly excursion capability and such low fs expected from a 'true' subwoofer. Conversely, in many (but not all) cases a woofer would offer lower distortion in the higher frequency range. But there is overlap and 300-500hz is a fairly low crossover too, so depending on your design goals either could be considered; depends entirely on the characteristics of the specific driver, not what it is called.
Though 300-500hz being fairly low places more demands on the midrange. So I would spent time making sure that had the necessary distortion and response characteristics to cross over low enough whilst still reaching the highs that you need from it before beaming or well before breakup.
There are two areas of interest where a subwoofer might (and usually does) differ from a woofer:
1. Subwoofers are not designed to do midrange well. You might find a few that actually do, but it tends to not be the norm. The concern here is not frequency response only, but primarily distortion.
2. Subwoofers tend to have lower sensitivity than mid/bases (woofers). Not a problem if you're going active or partly active.
1. Subwoofers are not designed to do midrange well. You might find a few that actually do, but it tends to not be the norm. The concern here is not frequency response only, but primarily distortion.
2. Subwoofers tend to have lower sensitivity than mid/bases (woofers). Not a problem if you're going active or partly active.
I’m in the planning stages for a build sharing values which are similar to yours.
The power response near the crossover region where the tweeter and midrange meets is not terribly difficult with these modern drivers. Choosing woofers, however, appears more challenging since there are so many. There are multiple facets and goals that a builder wants in order to make the build worthwhile.
Between woofers and subwoofers, the differences I look for are frequency response, irregularities in the impedance curve, sensitivity that meets the target, and T&S modelled low frequency extension.
You will find that subwoofers are usually higher excursion drivers with lower sensitivity and a lower frequency fundamental mechanical resonance. Sometimes they are unusable above a couple hundred Hz, due to cone modal behaviours, but others are as good as woofers up to a few kHz, demonstrating the name is often more of a marketing tactic. Again, you can use frequency response and impedance to gauge the driver’s midrange band to some extent.
You'd have to inspect the photos and the datasheet, looking out for things like:
-Xmax that does not exceed your needs too much. Only you can answer what your needs are — some people seem willing to suffer through bad sound 99% of the time, holding out for occasional parties where they can impress friends by cranking the volume to 11, which makes it all worth it. There's nothing wrong with that of course, but sometimes people forget to reflect on conflicting needs.
Then it's a series of educated guesses like:
--skinny rubber surrounds or cloth, not inch thick tyres (this should help weed out most of the bass-monsters quickly),
--low mms (maybe 40~50g), small diameter voice coil (1.5" - 2"), small dust cap — at some point it begins to encroach upon guitar speaker territory where the entire emphasis is on high midrange sensitivity, so a balance needs to be struck. FaitalPro and other "pro audio" brands could be worth a browse.
--low mid-range impedance. If a driver with 6 ohm DC resistance can manage to stay under 20 ohms up to 4 or 5 kHz, then that is a good result for a 12" nominal size.
-Xmax that does not exceed your needs too much. Only you can answer what your needs are — some people seem willing to suffer through bad sound 99% of the time, holding out for occasional parties where they can impress friends by cranking the volume to 11, which makes it all worth it. There's nothing wrong with that of course, but sometimes people forget to reflect on conflicting needs.
Then it's a series of educated guesses like:
--skinny rubber surrounds or cloth, not inch thick tyres (this should help weed out most of the bass-monsters quickly),
--low mms (maybe 40~50g), small diameter voice coil (1.5" - 2"), small dust cap — at some point it begins to encroach upon guitar speaker territory where the entire emphasis is on high midrange sensitivity, so a balance needs to be struck. FaitalPro and other "pro audio" brands could be worth a browse.
--low mid-range impedance. If a driver with 6 ohm DC resistance can manage to stay under 20 ohms up to 4 or 5 kHz, then that is a good result for a 12" nominal size.
My son wanted a bigger speaker for his electronic drum kit, so as a joke, I used some parts sitting on the shelf to design a 2 way.
It has a 2" aluminum cone subwoofer stitched to a 1.4" titanium compression driver.
The difference in sensitivity of the two driver is some 12dB... so it needs to be matched actively.
Passively, you're dumping (and wasting) a heap of power into the resistors just to attenuate the HF driver, so I wouldn't recommend that approach.
It has a 2" aluminum cone subwoofer stitched to a 1.4" titanium compression driver.
The difference in sensitivity of the two driver is some 12dB... so it needs to be matched actively.
Passively, you're dumping (and wasting) a heap of power into the resistors just to attenuate the HF driver, so I wouldn't recommend that approach.
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Both drivers being the same diameter, you essentially trade sensitivity for excursion capability when looking at a midbass vs subwoofer. Thats the main difference.
The byproducts of a typical subwoofer design is increased Le, Mms and optimized Qts for specific enclosure design permitting better low end extension and output. Excursion is traded for midrange bandwidth, but there are other peripheral requirements to properly drive either type of speaker.
A dedicated subwoofer will have a cone profile which is as stiff as possible ie. conical with stiffening rings and thicker sidewall. A heavy and wide surround is needed to keep the VC precisely centered during long cone excusrions.
A midbass typically needs a lighter curve linear cone profile with better internal dampening while having lower mass for decent sensitivity and midrange linearity. The surround and suspension are much lighter and thinner for better high frequency performance with good linearity. The suspension will typically have lower compliance than the enclosure air space, allowing the driver to perform well in small enclosures.
Large magnets and thicker upper pole plates on a midbass with shorter VCs = high sensitivity and low excursion.
Subwoofers have much longer VCs with less windings in the magnet gap at any given time = lower sensitivity and increased excursion capability.
Le will typically be much lower on midbass drivers to get more extended midrange response with a shorter VC.
On subwoofers you'll find long multilayered VC windings which are needed for higher BL with a heavier cone and more excursion for better low frequency output. These longer VCs will typically have much higher Le and aren't good for enabling response into the upper mids. Alot of back EMF is generated on these drivers which put greater demand on amplifier dampening capability. High output impedance amplifiers don't do well with this sort of speaker.
The byproducts of a typical subwoofer design is increased Le, Mms and optimized Qts for specific enclosure design permitting better low end extension and output. Excursion is traded for midrange bandwidth, but there are other peripheral requirements to properly drive either type of speaker.
A dedicated subwoofer will have a cone profile which is as stiff as possible ie. conical with stiffening rings and thicker sidewall. A heavy and wide surround is needed to keep the VC precisely centered during long cone excusrions.
A midbass typically needs a lighter curve linear cone profile with better internal dampening while having lower mass for decent sensitivity and midrange linearity. The surround and suspension are much lighter and thinner for better high frequency performance with good linearity. The suspension will typically have lower compliance than the enclosure air space, allowing the driver to perform well in small enclosures.
Large magnets and thicker upper pole plates on a midbass with shorter VCs = high sensitivity and low excursion.
Subwoofers have much longer VCs with less windings in the magnet gap at any given time = lower sensitivity and increased excursion capability.
Le will typically be much lower on midbass drivers to get more extended midrange response with a shorter VC.
On subwoofers you'll find long multilayered VC windings which are needed for higher BL with a heavier cone and more excursion for better low frequency output. These longer VCs will typically have much higher Le and aren't good for enabling response into the upper mids. Alot of back EMF is generated on these drivers which put greater demand on amplifier dampening capability. High output impedance amplifiers don't do well with this sort of speaker.
So it’s 2” diameter VC and the gap and coil dimensions are for an overhung motor with a geometry based excursion of 5/8” peak to peak.
Which is about 8mm one way.
So it could be a Low excursion subwoofer or high excursion woofer.
What’s more useful is a frequency response and impedance curve. T/S parameters handy too
Which is about 8mm one way.
So it could be a Low excursion subwoofer or high excursion woofer.
What’s more useful is a frequency response and impedance curve. T/S parameters handy too
Here’s an example of a driver marketed as a 12” subwoofer (ie: <120Hz)
Here are the minimum information to check it it’s suitable for woofer use (ie. ~50Hz to ~300Hz)
When you have a close look at the specification for subwoofers for auditoriums, concerts, festivals and general outdoor use, you will find that they play no lower than 30Hz.
But what they do above 30Hz they do with great authority (130dB@1m)
This is where the meat of bass is IMHO.
So a lot depends on what your seeking.
It’s true what @profiguy says- many subwoofers are not suitable for woofer use (eg. car audio subwoofers).
On the other hand drivers designed for PA use usually don’t in sizes less than 15”
Meanwhile your Sonos or Amazon subwoofer is a 5”-8”. Sure it can play 40Hz. But it is limited to about 85dB@1m.
The PA subwoofer does 130dB…
Do you how low you want to reach (F3/F6/F10) and how loud you want to go? (dB@1m)
Here are the minimum information to check it it’s suitable for woofer use (ie. ~50Hz to ~300Hz)
| Impedance | 8 Ω |
|---|---|
| Resonance Frequency | 29 Hz |
| Sensitivity @ 1W/1m | 85.9 dB |
| Rated Noise Power | 175 W |
| Minimum Impedancee | Zmin | 6.8 | Ω |
|---|---|---|---|
| Voice Coil Inductancee | Le | 0.768 | mH |
| Mechanical Q Factor | Qms | 12.5 | |
| Electrical Q Factor | Qes | 0.69 | |
| Total Q Factor | Qts | 0.65 |
| Effective Piston Area | Sd | 491 | cm2 |
|---|
| Maximum Linear Excursion | Xmax | 15.2 | mm |
|---|
When you have a close look at the specification for subwoofers for auditoriums, concerts, festivals and general outdoor use, you will find that they play no lower than 30Hz.
But what they do above 30Hz they do with great authority (130dB@1m)
This is where the meat of bass is IMHO.
So a lot depends on what your seeking.
It’s true what @profiguy says- many subwoofers are not suitable for woofer use (eg. car audio subwoofers).
On the other hand drivers designed for PA use usually don’t in sizes less than 15”
Meanwhile your Sonos or Amazon subwoofer is a 5”-8”. Sure it can play 40Hz. But it is limited to about 85dB@1m.
The PA subwoofer does 130dB…
Do you how low you want to reach (F3/F6/F10) and how loud you want to go? (dB@1m)
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