Hi ! I want to build 3 ways pro loudspeaker
My problem is to find a pro subwoofer to made a close to flat 20-100hz at a cheap price any Idea ?
The easy solution is to building a 2 ways loudspeaker with active subwoofer but It's not my goal
My Low mid have 99db
And my horn have 99db (w/resistor)
Thanks in advance 🙂
nicK
My problem is to find a pro subwoofer to made a close to flat 20-100hz at a cheap price any Idea ?
The easy solution is to building a 2 ways loudspeaker with active subwoofer but It's not my goal
My Low mid have 99db
And my horn have 99db (w/resistor)
Thanks in advance 🙂
nicK
Will this be with active DSP/crossover or passive? I ask because the power needs to get a subwoofer driver to have flat SPL to 20hz along with your other drivers, is going to be a huge power difference and you'll have to pad down the mids and treble heavily, just to get it close to the 20hz side of things and I would assume you would need at minimum a 200+ watt amp to run this at lower SPL listening levels. It'll have low output at any significant distance. Your mid & horn have 99db sensitivity? You won't find a large subwoofer with that sensitivity and you won't hear 20hz at the same SPL as 2000hz. Are you trying to avoid a powered subwoofer?
Very best,
Very best,
Yes, in the SUB area it is almost always the case that you need "Bucks for the Bang" (sorry, couldn't resist that one). Going to 30 Hz at high levels takes a lot more effort than 40 hz and going to 20 Hz instead of 30 Hz is yet another big step. Maybe you can explain further what you'd like to achieve in tems of levels and use case.
Regards
Charles
Regards
Charles
Yep, to maintain sensitivity you have at 100Hz all the way down to 20Hz, assuming direct radiating system, you'd need (100/20)^2 of volume displacement, 25x what you have now. So if you have 15" low mid, it's got about 850cm2 cone area, so you'd need about 21000cm2 worth subs assuming it has to be same excursion. If you can double excursion on subs you could slash cone area in half to maintain volume displacement, ~10000cm2. Perhaps you can slash it further by bass reflex or some other resonator. Nevertheless the system gets quite big, 10000cm2 is about 8x 18", so perhaps you can relax on the sensitivity requirement to keep it manageable size and cost, and use power and long excursion drivers to get some output at 20Hz, perhaps just one good 18" in big box and amp.
Example using relatively cheap B&C 18TBW100 in 300litre reflex box could give about 90db / 1W / 1m sensitivity and max about ~110db at 20Hz before excursion limit. If you need more max output you must use driver with more xmax, or multiple drivers to keep on increasing the volume displacement. To make a ~96db / 1W / 1m system you need four drivers and 1200litre enclosure. To get 99db would need few more and bit more size.
But, if you have enough power available perhaps the sensitivity doesn't matter that much and if the driver can take some power, you could reduce box size. Or, perhaps you don't actually need 20Hz extension but 25Hz, or 30Hz, and the system gets even smaller and cheaper.
So, be sure what your requirements actually have to be and then try to find a way that is suitable compromise to with your expectations, between output capacity, extension, size and cost.
But, if you have enough power available perhaps the sensitivity doesn't matter that much and if the driver can take some power, you could reduce box size. Or, perhaps you don't actually need 20Hz extension but 25Hz, or 30Hz, and the system gets even smaller and cheaper.
So, be sure what your requirements actually have to be and then try to find a way that is suitable compromise to with your expectations, between output capacity, extension, size and cost.
Last edited:
Keep in mind that if crossed over passively the price for necessary coil for a 100 Hz low pass may be similar to that of a subwoofer.
And you probably need to flatten the upper impedance peak too, further adding to the crossover cost.
Well, it's just reality, sometimes one has to look it into eye and notice all things we want aren't necessarily doable. Aand, if there really isn't anything we could do about it then it's a good learning opportunity, perhaps our initial assumptions were bit off and similar performance is actually available within the reality!🙂 I don't know what kind of a system you are set out to build but can say 15" bass in main speakers is already quite nice in home use, so much so that I've never checked what numbers are achieved.
"Pro" woofers tend to have a high Fs. Cheap woofers have a small Xmax. A bandpass type enclosure could be used to maximize the sensitivity in a narrow bandwidth. The money you spend building the cabinet will offset any savings on a cheap woofer.
Maybe you need to clarify your needs. At least WE need to understand what you want to do with those speakers.
Are you sure you want/need flat to 20?
This is realy low. Even IMax may not go down 20 flat ...
For home audio a lot of manufacturer are specifying -3db in room. Not anechoic ...
Look at the klipsh kpt-1802-hls sub.
It's a single 18 horn loaded pro cinéma made for dolby atmos 102db. So this kind of sub may fit your needs.
They claim sub-20.
BUT it's 26hz at -3db 21hz at -10db
Mesure 190x120x80 cm
And they recommand 2200w amp.
Are you sure you want/need flat to 20?
This is realy low. Even IMax may not go down 20 flat ...
For home audio a lot of manufacturer are specifying -3db in room. Not anechoic ...
Look at the klipsh kpt-1802-hls sub.
It's a single 18 horn loaded pro cinéma made for dolby atmos 102db. So this kind of sub may fit your needs.
They claim sub-20.
BUT it's 26hz at -3db 21hz at -10db
Mesure 190x120x80 cm
And they recommand 2200w amp.
Anybody can explain me why I can find a 2 ways loudspeaker with only one 5 or 6 inch woofer with the Spec like 20-20khz +/- 2dB but I need to have 8x 18" to do the same with my future setup !? 😳
Yeah, they don't have about no output at 20Hz, very little. Because of physics of sound you'd need a lot of volume displacement to get output at 20Hz. Also, don't forget the marketing team can use almost any numbers they want.
For example, if your speakers area advertized to have 99db sensitivity, it's likely at 1kHz. If you then make a crossover, make the frequency response flat, you'll see you need to pad the 1kHz down, quite a bit, so the sensitivity is only 85db or so. And this doesn't even mean the speaker can do this loud without distorting, it might be able to do something like 80db + some headroom. So it's just number games in marketing department. But the reality is physics 🙂
So, whats wrong here? The numbers. If you make 6" speaker you get some sound, perhaps plenty enough, if you make it 18" you get much more sound, even if it was less in reality than marketing team of the 6" lets you believe it has! Numbers you have seem overestimated compared to your expectations.
edit. see this:
https://www.diyaudio.com/community/threads/volume-displacement-for-spl-chart.5668/post-55869
Example: a 5" driver has cone area of roughly 85cm^2. Lets be generous and round it to 100cm^2 for easy math.
Then let's recal that ear is most linear around 80dB or so, so for example movies and studios monitor sound around that level and it's reasonable a hifi system should also be listened around 80db, which is quite loud by the way. Now, usually listening distance is few meters so sound level needs to be higher than 80db, say 86db. Then the music has some dynamics, lets say 14dB for easy math that our system should be able to do 100dB for good sound, right? Some people like bit elevated bass so you might add some, or just count on that the room provides some extra on the lows. You could come up with different numbers but this is the way you would come up with a number, calculate what is required for a system.
Now let's see from the chart how much volume displacement a woofer in a closed box needs to do to get 100db / 1m around 20Hz. That would be roughly 500cm3, bit more but lets take that. If you have 5" driver with 100cm2 cone area it would need to have p2p xmax of 50mm to achieve 500cm3 volume displacement. Not going to happen, most have perhaps 10mm, so it means you'd need 5 of them to meet your target numbers. A 12" woofer has about 550cm2 cone area so it would need to make only 10mm p2p to get there, so one would suffice, with high power or big box! To get 99db sensitivity for 20Hz really needs a huge pile of speaker.
For example, if your speakers area advertized to have 99db sensitivity, it's likely at 1kHz. If you then make a crossover, make the frequency response flat, you'll see you need to pad the 1kHz down, quite a bit, so the sensitivity is only 85db or so. And this doesn't even mean the speaker can do this loud without distorting, it might be able to do something like 80db + some headroom. So it's just number games in marketing department. But the reality is physics 🙂
So, whats wrong here? The numbers. If you make 6" speaker you get some sound, perhaps plenty enough, if you make it 18" you get much more sound, even if it was less in reality than marketing team of the 6" lets you believe it has! Numbers you have seem overestimated compared to your expectations.
edit. see this:
https://www.diyaudio.com/community/threads/volume-displacement-for-spl-chart.5668/post-55869
Example: a 5" driver has cone area of roughly 85cm^2. Lets be generous and round it to 100cm^2 for easy math.
Then let's recal that ear is most linear around 80dB or so, so for example movies and studios monitor sound around that level and it's reasonable a hifi system should also be listened around 80db, which is quite loud by the way. Now, usually listening distance is few meters so sound level needs to be higher than 80db, say 86db. Then the music has some dynamics, lets say 14dB for easy math that our system should be able to do 100dB for good sound, right? Some people like bit elevated bass so you might add some, or just count on that the room provides some extra on the lows. You could come up with different numbers but this is the way you would come up with a number, calculate what is required for a system.
Now let's see from the chart how much volume displacement a woofer in a closed box needs to do to get 100db / 1m around 20Hz. That would be roughly 500cm3, bit more but lets take that. If you have 5" driver with 100cm2 cone area it would need to have p2p xmax of 50mm to achieve 500cm3 volume displacement. Not going to happen, most have perhaps 10mm, so it means you'd need 5 of them to meet your target numbers. A 12" woofer has about 550cm2 cone area so it would need to make only 10mm p2p to get there, so one would suffice, with high power or big box! To get 99db sensitivity for 20Hz really needs a huge pile of speaker.
Last edited:
That is exactly why we are asking for wich purpose you want to do your speakers.
First of all, when 20hz is claim it is not necessary 20 and it is probably with room gain.
Next, all is compromise: If you want to match 99db sensitivity you need HUGE cabs and drivers.
This little speakers are probably near 80db. Not 99.
First of all, when 20hz is claim it is not necessary 20 and it is probably with room gain.
Next, all is compromise: If you want to match 99db sensitivity you need HUGE cabs and drivers.
This little speakers are probably near 80db. Not 99.
If you want to understand a bit more you Can imagine a bag of sand that has the same volume. One axis is efficiency second is opposite if the size and third is bass extension.
If you want to stretch your bag for the bass extension you will need to sacrify either cab volume or efficiency (or both)
In your case 99db is Big in term of efficiency.
And 20 is realy low. Hence the big sacrifice is the size of cabinet ...
If you want to stretch your bag for the bass extension you will need to sacrify either cab volume or efficiency (or both)
In your case 99db is Big in term of efficiency.
And 20 is realy low. Hence the big sacrifice is the size of cabinet ...
Could you indicate what 5" system has such specs?
If you really find such a specification it's either complete BS or a very optimistic in-room-response (in corner response) or an practically unusable extremely low efficiency/sensitivity system.