I am wondering, what are the pros and cons of single 12inch vs 2x8inch used as woofer in a 3way?
Cons area variances between them is around 10%, 8 inch take less space and is more WAF friendly.
12 inch makes big box.
Both can go deep simiraly, a lot of pro 12 inchers even can't go below 40Hz...
But there are some who can 😉
Just thinking about my future build, and if we would put aside form/space and higher efficiency in pro drivers, than...
What's the reason to buy single 12inch vs 2 8inch to act as woofers in 3 way?
Cons area variances between them is around 10%, 8 inch take less space and is more WAF friendly.
12 inch makes big box.
Both can go deep simiraly, a lot of pro 12 inchers even can't go below 40Hz...
But there are some who can 😉
Just thinking about my future build, and if we would put aside form/space and higher efficiency in pro drivers, than...
What's the reason to buy single 12inch vs 2 8inch to act as woofers in 3 way?
Just a thought,
If you go active maybe a single woofer is enough? I’m looking at adding a single 7.5” Satori woofer to an existing 2way active. Maybe the waf would improve with ease of access via streaming
Curious what you figure out
If you go active maybe a single woofer is enough? I’m looking at adding a single 7.5” Satori woofer to an existing 2way active. Maybe the waf would improve with ease of access via streaming
Curious what you figure out
Do they?
SD of say the Faital 8" 8PR200 is 209cm2.
SD of say Eminence Kappa 12A is 519.5cm2.
I have looked at SD of 8, 10, and 12 drivers and I think the original post was pretty close...two 8's about 30% more than a 10 inch but 10-15% less than a 12 inch. Of course this will differ depending on actual drivers.
Here are the average piston areas of the drivers:
4.5" = 8.3 in^2
5.0 = 11.0
6.5 = 21.6
8.0 = 35.7
10 = 56.7
12 = 82.5
15 = 132.7
I believe I averaged four of each. This was a couple years ago.
4.5" = 8.3 in^2
5.0 = 11.0
6.5 = 21.6
8.0 = 35.7
10 = 56.7
12 = 82.5
15 = 132.7
I believe I averaged four of each. This was a couple years ago.
Depends on the design- dual drivers lets you use a 2.5 way for the bass, very easy way to get baffle correction and some more output and extension. OTOH a single 12" may be a better directivity match in some instances, and larger drivers naturally trend to lower Fs, and more xmax. I'd generally pick the 12 but that's me, and I'd usually be pairing it to a horn.
This depends a lot on how you build it, but if you're willing you can build the dual 8's in an opposed/force cancelling manner, which isn't possible with one 12" driver.
A general rule when I was growing up was: The fewer the drivers, the better. I can't say that philosophy needs any update.
You have to consider the whole design.
I often aim for drivers that are happy 1 octave beyond my crossing point, which means that all the drivers need to be even "wider" than normally thought to be needed.
Spacing the drivers mean that some woofer can be placed closer to the floor to avoid suck-outs and others can be mounted closer to the midrange, to ease up on filter design.
You also have to consider baffle width. A wider speaker isn't just about looks, but also about volume, baffle step and crossover points, and maximum SPL. Very narrow speakers, tend to let the sound "curve" around the speaker create more reflections this way. Where wider speakers with narrow and controlled dispersion via big wave-guides or horns, can control the dispersion better and avoid a few reflections, that small speaker won't.
This means that small design changes actually can make a rather big difference in the perceived difference in sound.
I often prefer a narrow speaker with max 2x8" woofers, to create a speaker that - to me - "disappear" more into the sound field, but still can move air in a "physical" way. This can be done because I do not wish to play very loud and sit in a room that has space around my listening position, but I'm still not far away from the speaker. I also use multiple subwoofers to fill in the lowest notes, that my mains can't faithfully do, and because the response in total becomes more linear. I do prefer too big speakers, since they make me feel that I sit in the near field and let me hear the speakers position more easily - and I want it to disappear - so to speak - so that the illusion of a sound field is more pronounced, rather than being able to hear the sound directly from the speaker.
You can also consider price. If you buy one superb and expensive 12" - maybe the price is equivalent to buying two more normally priced 8" woofers. Maybe you don't mind the looks like of an old JBL, where the cabinet become thinner as it goes from woofer to tweeter. Maybe you put the woofer on the side and do an MTM on the front - many possibilities - but always some compromise. Which one can you live with?
For me, it was the freedom to move around a bit, that led med to chose a speaker with a coax driver. Then I had to build a speaker around that. You start by choosing the part - or compromise - that you least are able to live with, and then you figure out what is left for you to do, to create a complete speaker.
I took the Coax and found the baffle width that was needed to support its design. Then I found the woofer that could reach the coax and fit in the baffle width. I then adjusted the depth of the speaker to support those woofers demand for volume, and finally I could ignore how deep the woofer could actually play alone, since I was adding multiple subwoofer anyway.
So you see.... it all depends on your final goals and the compromises you can live with, and the compromises you are definitely not interested in living with.
There are some differences between a 12 and a pair of 8's. Assuming we are comparing similar drivers from the same manufacturer, such as an SB34NRX75-6 compared to a pair of SB23NRXS45-8, or a Dayton RSS315HF-4 compared to a pair of Dayton RSS225-8:
1) Even though the net Sd of the two 8s may be similar to the 12, the net Vd of the 12 inch driver is usually more, because the 12 typically has more Xmax than the 8.
2) The Fs of the 12 is usually lower than the Fs of the 8's. The Vas of the 12 is usually higher than the pair of 8's.
3) The 8" drivers can operate at a higher frequency before entering breakup. Most 12's have a response that gets a bit ragged above 500 Hz. Most 8's start to get ragged above 1000 Hz.
4) In theory, a pair of 8 ohm 8's in parallel should have the same voltage sensitivity as a single 4 ohm 12. In practice, I think the two 8's usually have a bit more voltage sensitivity.
5) The 8" size is one of the most common drivers on the planet. There is a huge variety of drivers to choose from. It is probably possible to find a pair of 8's that are ideal for a given situation (cost, box size, performance), and there is no comparable 12 which meets the requirements.
6) The obvious difference in driver diameter. A single big woofer drives the cabinet width. If you want a tall thin speaker, a 12" woofer is not going to work.
1) Even though the net Sd of the two 8s may be similar to the 12, the net Vd of the 12 inch driver is usually more, because the 12 typically has more Xmax than the 8.
2) The Fs of the 12 is usually lower than the Fs of the 8's. The Vas of the 12 is usually higher than the pair of 8's.
3) The 8" drivers can operate at a higher frequency before entering breakup. Most 12's have a response that gets a bit ragged above 500 Hz. Most 8's start to get ragged above 1000 Hz.
4) In theory, a pair of 8 ohm 8's in parallel should have the same voltage sensitivity as a single 4 ohm 12. In practice, I think the two 8's usually have a bit more voltage sensitivity.
5) The 8" size is one of the most common drivers on the planet. There is a huge variety of drivers to choose from. It is probably possible to find a pair of 8's that are ideal for a given situation (cost, box size, performance), and there is no comparable 12 which meets the requirements.
6) The obvious difference in driver diameter. A single big woofer drives the cabinet width. If you want a tall thin speaker, a 12" woofer is not going to work.
One more:
7) if you are looking at a high sensitivity 12" PA driver, it may not be possible to find a compatible pair of 8's. Most PA 8's are midrange drivers with an Fs too high to be considered a woofer.
7) if you are looking at a high sensitivity 12" PA driver, it may not be possible to find a compatible pair of 8's. Most PA 8's are midrange drivers with an Fs too high to be considered a woofer.
Thank a lot. Yes, Pro design 12, vs consumer 8, indeed there is no point in ProAudio 8 inchers, as a lot of them are midranges.
I am just thinking about my next project which way to go, with the BMS 12N630 vs Wavecor SW223 or similar, F3 low-mid 30s, high cutoff no more than 400Hz as midrange is not choosen yet.
I do not care about high efficiency speakers.
The update:
But fewer drives is only better if someone achieves their goal with it. 🙂
This^^^^^
Cal nailed it…i would only consider 2 smaller drivers to replace 1 larger when it’s not a matter of size or form factor constraints. Larger drivers are just more ’tactile’ in bass area with a single wavefront coupling better to the room.
I believe in modular systems when there are larger woofers involved……easier to move around, shorter panel lengths than a tower so less resonance it braced properly.……and a mid/tweeter images better on a narrow baffle.
Absolutely YSDR. Thing is you are stating the obvious not philosophizing. The only reason to consider extra drivers is a certain requirement, and, that you are willing to accept the shortcomings along with the benefits by doing so.
The philosophy needs no update. Extra drivers include compromises that should be considered and accepted only when necessary.
I have heard some magical full range systems. Doesn't mean they are the end all, far from it.
What they are is a heck of way to pick a midrange for your 3 way.