I read some of his threads.
I think i might not understand the physics behind making loud bass.
My understanding is that, we feel bass throw our body. We feel the pressure that is apply from the sub. So the goal then is to make large pressure changes in the room at the fz of the bass (also why bass is not directional). So then we need a sub that can displace lot of air to make this pressure changes.
I do not know if i am correct. So if anyone could explain the physics behind this, i would real appreciate it. I really would like to learn.
I think i might not understand the physics behind making loud bass.
My understanding is that, we feel bass throw our body. We feel the pressure that is apply from the sub. So the goal then is to make large pressure changes in the room at the fz of the bass (also why bass is not directional). So then we need a sub that can displace lot of air to make this pressure changes.
I do not know if i am correct. So if anyone could explain the physics behind this, i would real appreciate it. I really would like to learn.
Here's the 2 IST drivers compared to the daytons:
Each comparison is 4 drivers: (which is sort of silly since the IST builds have much higher driver cost and amplification costs).
The ISTs are given a total of 20ft^3 w/22hz tuning, the Daytons are given 40ft^3 2/27hz tuning.
This is the figured the same was as before, looking at the maximum drive level before it's not linear somewhere in the useful range and applying that as the signal level. (keep in mind that this assumes that the Xmax ratings from IST given as an honest Xmax rating. I would question the rating very much personally).
You can see that the 4 IST drivers will out perform the 4 Daytons on the very low end (by as much as 5-6DB). The power requirements to achieve that gain are pretty hefty though.
Here's what happens when we feed them the same power:
From 30-100hz, the cheap daytons in big boxes average 4X the efficiency with an average ~6DB advantage for the same input power.
The IST subs suffer from the same problem that the RCF drivers compared before do.. Long throw designs are inherently less efficient.
---------------------------
I have no idea how to begin to explain the physics but perhaps the following graphs will help make some sense of things.
Sealed Box IST Pi:
Cone excursion:
The pinkish line is 4 of those IST Pi jobs slapped in 20ft^3 SEALED box with 4800W signal level. Notice how without the tuned vent in place to share the load around the tuning frequency, the cone movement just goes higher and higher as the frequency goes lower. Also notice, The loss of efficiency. So there we have an example of a set of speakers "displacing" a LOT of air that are getting less work done than speakers that are working in accordance with a reflex enclosure to effectively move more air even though the cones move a lot less.
Each comparison is 4 drivers: (which is sort of silly since the IST builds have much higher driver cost and amplification costs).
The ISTs are given a total of 20ft^3 w/22hz tuning, the Daytons are given 40ft^3 2/27hz tuning.
This is the figured the same was as before, looking at the maximum drive level before it's not linear somewhere in the useful range and applying that as the signal level. (keep in mind that this assumes that the Xmax ratings from IST given as an honest Xmax rating. I would question the rating very much personally).
You can see that the 4 IST drivers will out perform the 4 Daytons on the very low end (by as much as 5-6DB). The power requirements to achieve that gain are pretty hefty though.
Here's what happens when we feed them the same power:
From 30-100hz, the cheap daytons in big boxes average 4X the efficiency with an average ~6DB advantage for the same input power.
The IST subs suffer from the same problem that the RCF drivers compared before do.. Long throw designs are inherently less efficient.
---------------------------
I have no idea how to begin to explain the physics but perhaps the following graphs will help make some sense of things.
Sealed Box IST Pi:
Cone excursion:
The pinkish line is 4 of those IST Pi jobs slapped in 20ft^3 SEALED box with 4800W signal level. Notice how without the tuned vent in place to share the load around the tuning frequency, the cone movement just goes higher and higher as the frequency goes lower. Also notice, The loss of efficiency. So there we have an example of a set of speakers "displacing" a LOT of air that are getting less work done than speakers that are working in accordance with a reflex enclosure to effectively move more air even though the cones move a lot less.
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Hi Jhon,
Just make sure you balance all info, including that of mine.
But... Since you asked!....
"Good subs for dubstep, trance" means to me you need the extended low end necessary for the dub(step) and 'hard hitting' low/lowmid for definition and impact for kick driven dance music. In other words; the highest efficiency in the 40 – 120Hz range and able to produce extended low end, below 40ties.
Although I don’t know the Mach IXL-18.2.2. and Pi18 myself, they seem to have a low motor/high mass ratio compared to extended low frequency PA drivers from traditional brands. Together with their low Fs these Mach drivers look more optimised more for (Home) Theatre use to me, to be honest. That doesn’t necessarily mean you can’t build decent PA cabs with them, but realise;
1. How will they mechanically hold under PA conditions (especially when power compression and dynamic compression comes into play).
2. Low sensitivity between 40 and 120Hz so you will need a lot of them.
3. Are they lacking impact in the kick range and cause more ‘rumble’ than defined low end?
Roughly speaking, traditional PA basreflex subs balanced for max SPL versus low end;
12inch = 50/55Hz (-3dB from 75/90litres)
15inch = 40/45Hz (-3dB from 120/150litres)
18inch = 33/40Hz (-3dB from 160/260litres)
21inch = 26/33Hz (-3dB from 240/450litres)
That means four to eight 18inch basreflex subs could do the trick for 500 people. But since Dub(step) is requested, use (at least) a couple of 21” that are crossed around 60Hz, together with four 18" cabs.
To raise efficiency of the system you can also look into tapped horn designs, there are plenty around like Epa already mentionned. These have a higher efficiency so you need less. Although the name suggests they sound like horns, they sure have their own specific character that is different from FLH or BR.
The advantage of Tapped horns (actually they act more like tapped pipes) is that the excursion of the cone is used both ways to load the horn/pipe. In other words the Volume displacement is kind of doubled over the full bandwidth compared to a basreflex. TH’s (Tapped Horns) are therefore two times more efficient as basreflex cabs. Another benefit is you can design them in such way they can force a driver to play lower while keeping the excursion under control.
If you design or choose a TH for PA of high efficiency, make sure their -3dB point stays above the Fs of the driver. The disadvantages compared to basreflex is that they are more complicated to design, more difficult to build and they are bigger. One factor people should realise, in stacks the -3dB point doesn’t drop much.
Traditional horns (Front Loaded Horns = FLH) have the highest efficiency and if designed properly and they can sound very good. The disadvantage is that if you want them to play flat and below 60Hz you’ll need a lot of them or build gigantically large ones. Not a realistic solution for 500people gigs.
In the end there there are advantages and disadvantages for every system. Just balance all the info you can get and imply them in your own goal without going crazy or unrealistic. It's all a matter of enough knowledge, experience, personal preference and not at least economics.
Good luck hunting!
Just make sure you balance all info, including that of mine
. But... Since you asked!....
"Good subs for dubstep, trance" means to me you need the extended low end necessary for the dub(step) and 'hard hitting' low/lowmid for definition and impact for kick driven dance music. In other words; the highest efficiency in the 40 – 120Hz range and able to produce extended low end, below 40ties.
Although I don’t know the Mach IXL-18.2.2. and Pi18 myself, they seem to have a low motor/high mass ratio compared to extended low frequency PA drivers from traditional brands. Together with their low Fs these Mach drivers look more optimised more for (Home) Theatre use to me, to be honest. That doesn’t necessarily mean you can’t build decent PA cabs with them, but realise;
1. How will they mechanically hold under PA conditions (especially when power compression and dynamic compression comes into play).
2. Low sensitivity between 40 and 120Hz so you will need a lot of them.
3. Are they lacking impact in the kick range and cause more ‘rumble’ than defined low end?
Roughly speaking, traditional PA basreflex subs balanced for max SPL versus low end;
12inch = 50/55Hz (-3dB from 75/90litres)
15inch = 40/45Hz (-3dB from 120/150litres)
18inch = 33/40Hz (-3dB from 160/260litres)
21inch = 26/33Hz (-3dB from 240/450litres)
That means four to eight 18inch basreflex subs could do the trick for 500 people. But since Dub(step) is requested, use (at least) a couple of 21” that are crossed around 60Hz, together with four 18" cabs.
To raise efficiency of the system you can also look into tapped horn designs, there are plenty around like Epa already mentionned. These have a higher efficiency so you need less. Although the name suggests they sound like horns, they sure have their own specific character that is different from FLH or BR.
The advantage of Tapped horns (actually they act more like tapped pipes) is that the excursion of the cone is used both ways to load the horn/pipe. In other words the Volume displacement is kind of doubled over the full bandwidth compared to a basreflex. TH’s (Tapped Horns) are therefore two times more efficient as basreflex cabs. Another benefit is you can design them in such way they can force a driver to play lower while keeping the excursion under control.
If you design or choose a TH for PA of high efficiency, make sure their -3dB point stays above the Fs of the driver. The disadvantages compared to basreflex is that they are more complicated to design, more difficult to build and they are bigger. One factor people should realise, in stacks the -3dB point doesn’t drop much.
Traditional horns (Front Loaded Horns = FLH) have the highest efficiency and if designed properly and they can sound very good. The disadvantage is that if you want them to play flat and below 60Hz you’ll need a lot of them or build gigantically large ones. Not a realistic solution for 500people gigs.
In the end there there are advantages and disadvantages for every system. Just balance all the info you can get and imply them in your own goal without going crazy or unrealistic. It's all a matter of enough knowledge, experience, personal preference and not at least economics.
Good luck hunting!
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`
As with any horn, you will need EQ to get flat frequency response; as well as a low crossover point (IE 60hz) to avoid the resonant nodes but that also means the sub won't see a world of energy being thrown at it unless you're running it hot (which addresses the issue above regarding thermal power handling. In the narrow bandwidth of ~15hz to 60hz with electronic filters on either end of the spectrum, and EQ to correct response there's no reason it shouldn't sound great.)
Here are the measurements deal with the measured issues correctly and you'll get great results - this is with the more robust TC SOunds 5400 however - not the Mach V:
http://www.data-bass.com/data?page=system&id=45&mset=42
Without a horn, home theater style drivers won't be up to the task of P.A., and without a home theater style driver, no P.A. sub will be up to the task of 15hz reproduction.
As with any horn, you will need EQ to get flat frequency response; as well as a low crossover point (IE 60hz) to avoid the resonant nodes but that also means the sub won't see a world of energy being thrown at it unless you're running it hot (which addresses the issue above regarding thermal power handling. In the narrow bandwidth of ~15hz to 60hz with electronic filters on either end of the spectrum, and EQ to correct response there's no reason it shouldn't sound great.)
Here are the measurements deal with the measured issues correctly and you'll get great results - this is with the more robust TC SOunds 5400 however - not the Mach V:
http://www.data-bass.com/data?page=system&id=45&mset=42
Without a horn, home theater style drivers won't be up to the task of P.A., and without a home theater style driver, no P.A. sub will be up to the task of 15hz reproduction.
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ok
I would really like to have a sub that sounds colorful, and not like a machine that moves air. I guess the IXL-18 would not be good at this.
I think that one sub is not going to cover everything from 10-100hz well.
May be using more then one tip of sub, tuned for more practical spec for the drivers would be better?
What if i use 4 peavey low riders 18, in the ported box. And high-pass then at 40hz (is it 40 to 90hz that you feel it in the chest?). And have 4 tapped horns low-passed at 40hz. Would this be more practical for what i am looking for.
Clean colorful bass, but still have the very low kick.
I would really like to have a sub that sounds colorful, and not like a machine that moves air. I guess the IXL-18 would not be good at this.
I think that one sub is not going to cover everything from 10-100hz well.
May be using more then one tip of sub, tuned for more practical spec for the drivers would be better?
What if i use 4 peavey low riders 18, in the ported box. And high-pass then at 40hz (is it 40 to 90hz that you feel it in the chest?). And have 4 tapped horns low-passed at 40hz. Would this be more practical for what i am looking for.
Clean colorful bass, but still have the very low kick.
The son of my colleague has a small DJ pa rig and is specialised in D&B. He uses for his lowmids 4 x HD15 style horns (crossed at 90Hz - 180Hz) on top of 4 x Tapped Horns 18" loaded (-3dB at 36Hz with eq outdoors crossed at 90Hz and lowcut set at 29Hz). That's definitely louder and very punchy compared to 4 basreflex boxes and doesn't give the feeling anything is missing in the low end. If you want to play below 36Hz at high levels indoors aspect physical building problems such as; light diffuser panels, tiles from system ceiling ect that can come down...
I think that building a pile of very huge tapped horns to cover a bottom "20-40hz" is going to add uneccessary cost to the system with very little benefit. I understand you want the system to sound "good" but you also have to realize that if you are playing electronic music to begin with, then there is really no "reference" for what "good" is. It's not like you are trying to reproduce a an instrument. Even if the system is not ideally "musical" sounding, electronic bass drops are going to pound face and excite the crowd regardless.
I guess the question at this point really should be... What is the budget and what do you already have available to use?
I'd also be interested in knowing what the mains in the system are capable of. What sort of x-over point do they need to work right etc etc.
I guess the question at this point really should be... What is the budget and what do you already have available to use?
I'd also be interested in knowing what the mains in the system are capable of. What sort of x-over point do they need to work right etc etc.
That said, if you would still like to maintain the ability to be musical while playing loud hard and deep. I think you may really have to consider a move in the direction of more watts and higher quality drivers.
Examples of 18" drivers that are REALLY going to be good at this:
RCF L18P200-N 18" Woofer Speaker 294-880
RCF L18P400 18" Woofer Speaker 294-886
RCF LF18G400 18" Woofer Speaker 294-890
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=294-892
A lot of what makes those drivers good for this, including the 21" RCF that I posted some simulations of before, is beyond what can be properly described in a theoretical graphed response chart. These drivers have a ton of overhead (usable excursion beyond Xmax rating with compression), and by my understanding, are built to some very tight tolerances. Granted they are more expensive, however, you can count on them being top notch as far as sound quality is concerned provided you have plenty of clean amplification. RCF drivers are very common in studio environments where critical "flat" listening is important.
Examples of 18" drivers that are REALLY going to be good at this:
RCF L18P200-N 18" Woofer Speaker 294-880
RCF L18P400 18" Woofer Speaker 294-886
RCF LF18G400 18" Woofer Speaker 294-890
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=294-892
A lot of what makes those drivers good for this, including the 21" RCF that I posted some simulations of before, is beyond what can be properly described in a theoretical graphed response chart. These drivers have a ton of overhead (usable excursion beyond Xmax rating with compression), and by my understanding, are built to some very tight tolerances. Granted they are more expensive, however, you can count on them being top notch as far as sound quality is concerned provided you have plenty of clean amplification. RCF drivers are very common in studio environments where critical "flat" listening is important.
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Attachments
Hi Brian,
Your example seems to prove my point as 95dB is not a typical sensitivity figure for high efficiency PA cabs. Although the words "high efficiency" should have been "high sensitiviy", thanks.
Your example seems to prove my point as 95dB is not a typical sensitivity figure for high efficiency PA cabs. Although the words "high efficiency" should have been "high sensitiviy", thanks.
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Look at the cabinet size. Not many PA cabinets that size are that efficient down low. If the single-driver TH suggestion I gave is not sensitive enough, use two of them - result should be a sensitivity of around 101dB/2.83V/1M and good down to 40 Hz in a cabinet that's a bit less than 160 l net.
Edit: cabinet size for single-driver TH is 79 l net.
I think you missed my point. Besides two of them makes the total sensitivity from 95dB single unit to, 98dB two units in my view....and these figures are given with 2.83V and no further specifics.
Again, if you want to get the highest sensitivity from your PA sub you need to design the -3dB point above the Fs of the driver. That doesn't necessary mean that is the limit. You can design a TH that goes lower but at cost of sensitivity and/or max SPL.
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Please ignore the following:
Why is it that every time someone posts a TH simulation on this forum, it includes more useless information above 100hz than it does useful information below 100hz. Maybe I'm out of my mind here but if we are simulating the characteristics of a driver in the bass performance region, shouldn't more of the chart be dedicated to, idunno, the bass region? Looking at a TH simulation anywhere on this entire forum tells me more about how bad a driver is at producing higher frequencies in a TH than how good it it as producing lower frequencies. I can't comprehend this. Does the program not have a setting to "cut off" the useless information being displayed?
Again, you should ignore this entire post as it is very off topic and should not have been posted.
Thank You,
Eric
Why is it that every time someone posts a TH simulation on this forum, it includes more useless information above 100hz than it does useful information below 100hz. Maybe I'm out of my mind here but if we are simulating the characteristics of a driver in the bass performance region, shouldn't more of the chart be dedicated to, idunno, the bass region? Looking at a TH simulation anywhere on this entire forum tells me more about how bad a driver is at producing higher frequencies in a TH than how good it it as producing lower frequencies. I can't comprehend this. Does the program not have a setting to "cut off" the useless information being displayed?
Again, you should ignore this entire post as it is very off topic and should not have been posted.
Thank You,
Eric
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With both drivers in parallel, impedance halves, adding 3dB to the sensitivity rating. That, plus the 3dB you get from the additional box, giving a total of 6dB. 95+6 = 101 dB/2.83V/1M into the 4 ohm load.
IMO, box size and desired cutoff frequency are the primary determing factors of how efficient a PA sub design can be. Or, expressed in another way, if I want a cutoff point of 40 Hz and a net box size of 160 l or less, I suspect it might be quite difficult to get any design that's significantly more efficient than 98dB/1W/1M.
I got a frequency analyzer to look at the music i play. It is funny, the most common lowest fz is 40-35hz. There is some below 35hz in the dubstep, but those peaks are uncommon. The dubstep is not really that low, mainly above 40hz.
I have the plans for the titan 48 and tuba 60.
I have the tuba 60 but it is big, so i think i should put the lab 15 in the titan 48. And build 4 titans. Also you can v plate then witch would increase their low fz sensitivity.
I have the plans for the titan 48 and tuba 60.
I have the tuba 60 but it is big, so i think i should put the lab 15 in the titan 48. And build 4 titans. Also you can v plate then witch would increase their low fz sensitivity.
Hornresp can be used for designing any range of speakers, the log display is what it is. You can enlarge the LF area if you want to look at it in more detail.
That said, response above crossover is not "useless information", even with a 24 dB per octave crossover upper peaks an octave or two higher are easily heard.
hornresponce is a simulation program for al types of boxes,also mids.
i cant see any irrelevant information on the graps,nore useful information missing.
@ john
as you see now, its more sensible to design something with f3 30~40 hz.
if you reed more here on this forum ,most of the pro guys(not me included
)wil advise this.regards erik
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Actually it's not that difficult if you use Extended LF PA drivers with their -3dB point above their Fs. But if you want me to be more precise make sure the 1/3WL is above the the Fs of the driver. So again your statement makes my point, thanks.
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