18 inch woofers cost more to make and have very little demand, thats what i think.
An 18 inch woofer or 32 inch woofer is not slow as in sound quality, it will just have a very narrow range of sound and put lots of stress on the coil and cone joint.
Plus the coil will have to be massive and large coil are not sensitive.
besides all the mass will make the cone flap as the large the cone gets the less rigid it becomes.
An 18 inch woofer or 32 inch woofer is not slow as in sound quality, it will just have a very narrow range of sound and put lots of stress on the coil and cone joint.
Plus the coil will have to be massive and large coil are not sensitive.
besides all the mass will make the cone flap as the large the cone gets the less rigid it becomes.
Iron-Wizard said:
Umm... Like I said earlier...
In other words...
A little raft boat can support a couple of people with no problem, but it cannot support an F/A-18 fighter jet, that's why they invented aircraft carriers.
I don't care if a speaker cone is 30 feet in diameter, 4" thick cement and weighs 4000lbs, if the basket, suspension and motor structure is built specifically for THAT cone, then it will work and perform just fine.
How else would they be able to catapult a 60,000lb fighter jet to 150+ mph in 300 feet in less than 2 seconds?!
Because it's BUILT for THAT purpose.
IRC that 60" sub was built by Richard Clark with some funding by MTX and he competed in exehibition (sp?) at an IASCA or dBdrag comp years ago. He had it in the back of a bread truck using modified MRI machines to produce the 20kW used to make the tones. He couldn't compete outright because the truck couldn't stand alone on it's charging system and needed external generators. Because of the truck flexing (A TON) he 'only' pulled mid 150's off the dash at 15 and 10hz. If the truck was ridgid it would have been stupid loud.
Iron-wizard, I am going to have to disagree with you on that...
with a larger diameter cone you need less excursion to sweep volume, so referencing the 18" that i have it has single 2.5" v.c. and has an efficiency of 92dB and a resonant freq. of 19hz(18.6hz measured). With less excursion (8.3mm)you can concentrate the magnets energy onto a smaller area, hence the efficiency.
This is kind of a generalization, I checked the Mmd of a titanic MkIII 15" and it was 208.33g and the Mmd of the rfp-2418 is 200g, the 2418 is a very slightly modified 1418 with only slight changes to get an additional 1.7mm of Xmax, same cone and frame. And this is crazy, my 12" DVC (rfd-2212) has an mms of 215.4g!!
with a larger diameter cone you need less excursion to sweep volume, so referencing the 18" that i have it has single 2.5" v.c. and has an efficiency of 92dB and a resonant freq. of 19hz(18.6hz measured). With less excursion (8.3mm)you can concentrate the magnets energy onto a smaller area, hence the efficiency.
I know you need less excursion to from a large woofer to equal a smaller woofers output but then what is the point of a larger cone, if you get a cone sweep of an inch which is getting common these days a large cone without any ribs like those used on the Tannoys Berkeley it will flex on the outter most edge.
That cone mass your talking about is low for a 15 inch woofer, i would expect it to be above 250 grams if it was a real low blow woofer and not a PA type one?
If you want linner cone travel and we do, the coil will or should be a large one, the smaller coil will give much better sensitivity but this will stress the throat join even more and it would be poking the cone were a larger coil would have a much larger glue join and last longer.
The other reason for a large coil is the heavy gauge winding for high power handling, you can fit more wire on a larger former than a smaller one, its really not common to find a small coil on a large woofer but thats not to say it can not be done, the other thing is the larger the surface area of the coil the better the heat removal is.
I know you need less excursion to from a large woofer to equal a smaller woofers output but then what is the point of a larger cone, if you get a cone sweep of an inch which is getting common these days a large cone without any ribs like those used on the Tannoys Berkeley it will flex on the outter most edge.
That cone mass your talking about is low for a 15 inch woofer, i would expect it to be above 250 grams if it was a real low blow woofer and not a PA type one?
If you want linner cone travel and we do, the coil will or should be a large one, the smaller coil will give much better sensitivity but this will stress the throat join even more and it would be poking the cone were a larger coil would have a much larger glue join and last longer.
The other reason for a large coil is the heavy gauge winding for high power handling, you can fit more wire on a larger former than a smaller one, its really not common to find a small coil on a large woofer but thats not to say it can not be done, the other thing is the larger the surface area of the coil the better the heat removal is.
the point, to get more output with less motion, if you want loud low frequencies, you need either a big woofer that travels "enough" or a smaller long excursion woofer, remember that rule one octave lower needs four times the excursion. Small woofers dont move alot of air so they have to travel more to make up for it.
Titanic MkIII 15", not a PA driver Fs 18-19hz
are you referring to coil length or diameter?
coil length, overhung or underhung, this is part of the design, it doesn't need to be bigger for linear travel.
larger diameter, has nothing to do with linearity, liearity comes from uniform flux in the gap.
Yes you gain cooling ability, but you also need bigger magnets to maintain flux density across the larger gap between pole piece and top plate, bigger former-more windings, heavy gauge higher power handling all your talking about is power handling vs. more power handling.
There are tons of 12's and 15's with small v.c.'s why cant an 18" have one?
2.5" v.c. 250w/500w handling and 92dB efficiency, vented pole piece,...etc. I've driven this thing hard for long periods, it does great. Why do I want heavier coils, more windings and a bigger diameter less efficient coil (your words)? So I can lower the efficiency and run a massive amplifier? Why, this v.c. produces the efficiency and power handling and frequency response that is needed.
You cant' judge a speaker based solely on v.c. diameter, it's a total package. (I'm sureyou know that I'm just saying it)
The important thing is that the Bl is big enough for the mms and the air load the speaker encounters.
This is another generalization, if it's designed to handle it then it will handle it.
Sorry if I sound a little ***** here, I got the impression you were being a bit of a smart *** in your reply, if I misinterpreted than let me apologize right now.
nunayafb, I too was going to point that out about the linear travel...
The diameter of the VC has absolutely NOTHING to do with the linear travel. What DOES have to do with linear travel is the length of the VC, the surround, the spider(s) and the backplate of the magnet structure.
VC diameter doesn't even really determind the sensitivity or power handling of a driver either, well maybe more so with power handling. However, the larger the VC (motor), the more muscle the driver has in controlling the cone and suspension system.
Again, back to the car thing...
You can have an 2.2L inline 4 (Honda S2000) with 240hp and 162ft lbs of torque, all around 8000rpm; OR you can have a older Mustang 5.0L V8 with 225hp and 300ft lbs of torque at around 4000rpm.
If you put both of those engines in two identical cars with everything the same except of the motor (obviously), the V8 powered car is going to win because it has almost double the torque at half the rpms.
Torque (muscle) is what gets the V8 down the road quicker, not the horsepower, and it's because the motor is twice the size. It also has to work much less to achieve the same performance (more efficient - power wise that is).
A larger VC gets the cone moving and stopping much quicker because of the extra muscle. It also has to work much less because of the larger cone picking up where the little cone falls off, making it more efficient.
And yes, the larger VC CAN handle more power than a small VC. Sure you can beef up a small 2.2L 4 cylinder engine to about 800hp with a turbo and NOS, but you can get a 5.0L V8 well past 3000hp with the same kind of mods.
Anyway...
The diameter of the VC has absolutely NOTHING to do with the linear travel. What DOES have to do with linear travel is the length of the VC, the surround, the spider(s) and the backplate of the magnet structure.
VC diameter doesn't even really determind the sensitivity or power handling of a driver either, well maybe more so with power handling. However, the larger the VC (motor), the more muscle the driver has in controlling the cone and suspension system.
Again, back to the car thing...
You can have an 2.2L inline 4 (Honda S2000) with 240hp and 162ft lbs of torque, all around 8000rpm; OR you can have a older Mustang 5.0L V8 with 225hp and 300ft lbs of torque at around 4000rpm.
If you put both of those engines in two identical cars with everything the same except of the motor (obviously), the V8 powered car is going to win because it has almost double the torque at half the rpms.
Torque (muscle) is what gets the V8 down the road quicker, not the horsepower, and it's because the motor is twice the size. It also has to work much less to achieve the same performance (more efficient - power wise that is).
A larger VC gets the cone moving and stopping much quicker because of the extra muscle. It also has to work much less because of the larger cone picking up where the little cone falls off, making it more efficient.
And yes, the larger VC CAN handle more power than a small VC. Sure you can beef up a small 2.2L 4 cylinder engine to about 800hp with a turbo and NOS, but you can get a 5.0L V8 well past 3000hp with the same kind of mods.
Anyway...
Hi nunayafb, yes i am generalization, not being a smarty, just telling you what i think, the thing about the diameter of a coil does not make a more linear woofer in magnetic terms, but the smaller the diameter of the spider damper the more linear the travel tends to be, something to do with it being gyroscopic and woven, i have played with lots of dampers and when there new without the coil hole, and you poke your finger in the centre you will see it flex and change shape alot, its not close to being round, it gets square because of the weave, when you glue a small coil into that damper its improve but when you push it out the damper will change shape again, less squaring but still its there, the bigger the coil is on the damper the less squaring you find happens in the damper, this affect how linear the cone travel is at high excursion, just my two cents.
You can have a large coil with a thinner winding which would increase the sensitivity but that is more a PA woofer and those have higher Fs and does not sound like the same thing as your Titanic.
If the flux is uniform in the coil gap, then the BL will be low? correct me if am wrong.
I think you will find more 15 inch woofers with 3 inch coils rather than 2.5 inch coils, i know alot of companies just use the same magnet system used on there 12 for the 15, not saying it cant be done, Its just a 15 with its own custom made or tooled magnet system will have better performance over the smaller magnet system and coil.
You can have a large coil with a thinner winding which would increase the sensitivity but that is more a PA woofer and those have higher Fs and does not sound like the same thing as your Titanic.
If the flux is uniform in the coil gap, then the BL will be low? correct me if am wrong.
I think you will find more 15 inch woofers with 3 inch coils rather than 2.5 inch coils, i know alot of companies just use the same magnet system used on there 12 for the 15, not saying it cant be done, Its just a 15 with its own custom made or tooled magnet system will have better performance over the smaller magnet system and coil.
Mr Chops you have confused me well and truely and I am a mechanic in El segundo
The Honda has only 4 pistons, the V8 has double, all petrol engines only give around 15%, the reason is the V8 is not tuned for power but smoothness and balance and a long life, torque alone does not give fast acceleration, its a combination of both HP and torque, the only difference is the amount of mass, the Honda will lose much of its speed and acceleration if you add another hoche and the V8 wont, the larger coil is similar to your V8, the larger mass Mms wont affect its acceleration if you like, is that what your saying, is that what am saying? what is being said?
You really like cars i think Mr Chops
The Honda has only 4 pistons, the V8 has double, all petrol engines only give around 15%, the reason is the V8 is not tuned for power but smoothness and balance and a long life, torque alone does not give fast acceleration, its a combination of both HP and torque, the only difference is the amount of mass, the Honda will lose much of its speed and acceleration if you add another hoche and the V8 wont, the larger coil is similar to your V8, the larger mass Mms wont affect its acceleration if you like, is that what your saying, is that what am saying? what is being said?
You really like cars i think Mr Chops
Hi guys !
lots or people are saying : a 18" is slower and so on.
But I think we are speaking of subwoofer here from 16hz to 80hz not higher.
Then if you want a 12" or a 15" that can do 16-80hz, let me guess, you are speaking of Peerless, JBL GTI, Adire...
These speakers are realy heavy, the bl/mms ratio is between 75 and about 100.
I do think the Bl/mms ratio should be multiplied by the Sd of the driver : a larger speaker will have to move less and will be more efficient.
So I really don't think 18" and 21" speakers are B.S. to do 16-80hz but what we all know is that they are expensive and takes a lot of room.
This is why I will have to stick to low efficiency 15" speakers even if all my equipement is made of high efficiency speakers. Maybe this is not a big problem above 80hz.
lots or people are saying : a 18" is slower and so on.
But I think we are speaking of subwoofer here from 16hz to 80hz not higher.
Then if you want a 12" or a 15" that can do 16-80hz, let me guess, you are speaking of Peerless, JBL GTI, Adire...
These speakers are realy heavy, the bl/mms ratio is between 75 and about 100.
I do think the Bl/mms ratio should be multiplied by the Sd of the driver : a larger speaker will have to move less and will be more efficient.
So I really don't think 18" and 21" speakers are B.S. to do 16-80hz but what we all know is that they are expensive and takes a lot of room.
This is why I will have to stick to low efficiency 15" speakers even if all my equipement is made of high efficiency speakers. Maybe this is not a big problem above 80hz.
Hehe, another car myth.
I will prove you wrong my friend.
What's faster?
A Dodge Ram SRT10 with a Viper engine with 525 lb-pi?
A Dodge Ram with the brand new diesel engine with 600 lb-pi?
Basically same vehicule.
Another explanation...
Looking at top speed, horsepower wins again, in the sense that making more torque at high rpm means you can use a stiffer gear for any given car speed, and thus have more effective torque *at the drive wheels*.
Another explanation : Check Horsepower and Torque "At the Wheels" part of the article.
http://www.car-videos.net/articles/horsepower_torque.asp
Let calculate using those formulas.
Honda S2000 specs :
http://www.hondanews.com/CatID2071?mid=2005090951875&mime=asc
Horsepower 237 @ 7800 rpm
Torque 162 @ 6800 rpm
Ford Mustang GT 1994 specs :
http://members.tripod.com/Mr5oh/94gt.html
Horsepower 215 @ 4200 rpm
Torque 285 @ 3400 rpm
Let put both engine in the S2000 body shell and assume 100% efficiency so the hp rating is at the wheels.
Transmissions Gear Ratios:
1st gear 3.133
2nd gear 2.045
3rd gear 1.481
4th gear 1.161
5th gear 0.942
6th gear 0.763
Final Drive Ratio 4.1
Total Ratio
1st = 12.85
2nd = 8.38
3rd = 6.07
4th = 4.76
5th = 3.86
6th = 3.13
Tires = 245/40R17 so 77.6 inches circumference.
7800 rpm redline speed in each gear for the S2000 : 43.1 66.0 91.1 116.3 143.3 176.9
4200 rpm redline speed in each gear for the Mustang GT : 23.2 35.5 49.1 62.6 77.2 95.3
So the Mustang GT is at 95.3 mph maximum with this transmission final drive ratio, so let's calculate the torque of both cars at 91.1 mph so each car is near enough shift point in their respective gear.
5280 feet in a mile
91.1 mph = 481008 ft per hour = 5772096 inches per hour
5772096 / 77.6 = 74383 tires revolutions per hour
74383 / 60 = 1240 RPM
Let calculate the RPM for the Mustang since we are not exactly at 4200 RPM.
4200 RPM = 95.3 mph
? RPM = 91.1 mph = 4015 RPM
Horsepower = ( Torque x RPM ) / 5252
215 = ( ? x 4200 ) / 5252
? = 267 lb-ft
We also know that it develops 285 lb-ft at 3200 RPM.
So let say that the torque rating at 4015 RPM is 275 lb-ft.
? = ( 275 x 4015 ) / 5252 = 210 HP
Now about the "outside the torque range statement at the top end"
Honda S2000 torque at 7800 rpm is :
240 = ( ? x 7800 ) / 5252
? = 161.6 lb-ft
That's close enough to torque peak of 162 lb-ft at 6800 rpm.
Now the interesting part :
Wheel RPM = 1240 rpm @ 91.1 mph
HP Mustang GT = 210 HP with 275 lb-ft @ 4015 rpm
HP Honda S2000 = 240 HP with 161.6 lb-ft @ 7800 rpm
Mustang GT (torque at the wheels rating) :
210 = ( ? x 1240 ) / 5252
? = 889.4 lb-ft
Honda S2000 (torque at the wheels rating) :
240 = ( ? x 1240 ) / 5252
? = 1016.5 lb-ft
I will prove you wrong my friend.
What's faster?
A Dodge Ram SRT10 with a Viper engine with 525 lb-pi?
A Dodge Ram with the brand new diesel engine with 600 lb-pi?
Basically same vehicule.
Another explanation...
Looking at top speed, horsepower wins again, in the sense that making more torque at high rpm means you can use a stiffer gear for any given car speed, and thus have more effective torque *at the drive wheels*.
Another explanation : Check Horsepower and Torque "At the Wheels" part of the article.
http://www.car-videos.net/articles/horsepower_torque.asp
Let calculate using those formulas.
Honda S2000 specs :
http://www.hondanews.com/CatID2071?mid=2005090951875&mime=asc
Horsepower 237 @ 7800 rpm
Torque 162 @ 6800 rpm
Ford Mustang GT 1994 specs :
http://members.tripod.com/Mr5oh/94gt.html
Horsepower 215 @ 4200 rpm
Torque 285 @ 3400 rpm
Let put both engine in the S2000 body shell and assume 100% efficiency so the hp rating is at the wheels.
Transmissions Gear Ratios:
1st gear 3.133
2nd gear 2.045
3rd gear 1.481
4th gear 1.161
5th gear 0.942
6th gear 0.763
Final Drive Ratio 4.1
Total Ratio
1st = 12.85
2nd = 8.38
3rd = 6.07
4th = 4.76
5th = 3.86
6th = 3.13
Tires = 245/40R17 so 77.6 inches circumference.
7800 rpm redline speed in each gear for the S2000 : 43.1 66.0 91.1 116.3 143.3 176.9
4200 rpm redline speed in each gear for the Mustang GT : 23.2 35.5 49.1 62.6 77.2 95.3
So the Mustang GT is at 95.3 mph maximum with this transmission final drive ratio, so let's calculate the torque of both cars at 91.1 mph so each car is near enough shift point in their respective gear.
5280 feet in a mile
91.1 mph = 481008 ft per hour = 5772096 inches per hour
5772096 / 77.6 = 74383 tires revolutions per hour
74383 / 60 = 1240 RPM
Let calculate the RPM for the Mustang since we are not exactly at 4200 RPM.
4200 RPM = 95.3 mph
? RPM = 91.1 mph = 4015 RPM
Horsepower = ( Torque x RPM ) / 5252
215 = ( ? x 4200 ) / 5252
? = 267 lb-ft
We also know that it develops 285 lb-ft at 3200 RPM.
So let say that the torque rating at 4015 RPM is 275 lb-ft.
? = ( 275 x 4015 ) / 5252 = 210 HP
Now about the "outside the torque range statement at the top end"
Honda S2000 torque at 7800 rpm is :
240 = ( ? x 7800 ) / 5252
? = 161.6 lb-ft
That's close enough to torque peak of 162 lb-ft at 6800 rpm.
Now the interesting part :
Wheel RPM = 1240 rpm @ 91.1 mph
HP Mustang GT = 210 HP with 275 lb-ft @ 4015 rpm
HP Honda S2000 = 240 HP with 161.6 lb-ft @ 7800 rpm
Mustang GT (torque at the wheels rating) :
210 = ( ? x 1240 ) / 5252
? = 889.4 lb-ft
Honda S2000 (torque at the wheels rating) :
240 = ( ? x 1240 ) / 5252
? = 1016.5 lb-ft
simon5 said:
Actually, I was referring to the earlier >1993 models with the 5.0L motor, not the <1994 modular 4.6L. The redline of the 5.0L is actually 5200rpm, not 4200rpm. And it's rated at 225hp and 300 lb-ft. (at the crank)
Also, I forgot to mention that obviously the transmission and differential would have to be switched out for the appropriate motor.
However, how would things turn out if using the Mustang's trans and diff with the S2000 motor?
You know, all of this talk about engine swapping makes me want to do the same thing. I have a Mazda Miata and there ARE kits out there to do a direct drop-in of a Ford 302ci motor.
And I would just like to point out that by the looks of that last post of yours, you have entirely way too much time on your hands. LOL
At any rate, you know what I was trying to get at with this whole analogy thing anyway. Not to mention that we have once again wondered off course with the thread topic. OOPS!
Yeah I know what you wanted to say and yeah we are seriously off-topic but I need to destroy that car guy myth.
If you have more horsepower, you can go faster, period. I'm not talking about acceleration here, only terminal velocity, top speed.
BUT, assuming you have the perfect right transmission for the job and sticky tires, AGAIN, the one with the more horsepower *should* win. I say *should* because if the torque curve is flat and the other one is peaky, that could change results.
I was talking about those 5.0 liters motors. The 4.6 liters arrived only in 1996. I used the 1994 because the 1995 had 240 HP.
I can use everything from the Mustang GT, will check later. It will have the same results. You can say it using the HP = ( Torque x RPM ) / 5252 formula. HP will not change, RPM of the tires will change, but it will be the same for both engines. So the "torque at the wheels" will be higher for the S2000 again.
So, in the end, you are right, Torque is everything, but it's torque at the wheels that's important and you are going to achieve the most torque at the wheels with the engine that got the most power.
If you play a bit with the formula, you see that :
Torque at the wheels = ( HP x 5252 ) / RPM of the wheels
Assuming same tires, you can only play with HP to increase torque at the wheels! Now, you could say that what increasing low end torque would do? Well, it would increase low end HP, because it's a formula. Increase torque, you're in fact increasing HP at the same time at some place in the power band. Increase HP, you're in fact increasing torque at the same time at some place in the power band.
So, why all people love torque? Because not all of us like to drive at 8000 rpm all day to be in the power band when a Mustang will be in the power band at 3000 rpm. It also important for towing.
If you have more horsepower, you can go faster, period. I'm not talking about acceleration here, only terminal velocity, top speed.
BUT, assuming you have the perfect right transmission for the job and sticky tires, AGAIN, the one with the more horsepower *should* win. I say *should* because if the torque curve is flat and the other one is peaky, that could change results.
I was talking about those 5.0 liters motors. The 4.6 liters arrived only in 1996. I used the 1994 because the 1995 had 240 HP.
I can use everything from the Mustang GT, will check later. It will have the same results. You can say it using the HP = ( Torque x RPM ) / 5252 formula. HP will not change, RPM of the tires will change, but it will be the same for both engines. So the "torque at the wheels" will be higher for the S2000 again.
So, in the end, you are right, Torque is everything, but it's torque at the wheels that's important and you are going to achieve the most torque at the wheels with the engine that got the most power.
If you play a bit with the formula, you see that :
Torque at the wheels = ( HP x 5252 ) / RPM of the wheels
Assuming same tires, you can only play with HP to increase torque at the wheels! Now, you could say that what increasing low end torque would do? Well, it would increase low end HP, because it's a formula. Increase torque, you're in fact increasing HP at the same time at some place in the power band. Increase HP, you're in fact increasing torque at the same time at some place in the power band.
So, why all people love torque? Because not all of us like to drive at 8000 rpm all day to be in the power band when a Mustang will be in the power band at 3000 rpm. It also important for towing.
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