I am building a large sound system with active crossovers to use for djing, and i used some math to figure out the exact frequencies a crossover should be, or at leat i think i have. I decided maybe i could help some people by sharing my info, or if i was totally wrong, i would be set straight. Most people break crossovers down into what their drivers are capable of handling, and i realized, tht could mess around with sound reproduction. I broke it down by octave and used an exponent sytem. I decided that nice subwoofer speakers (large diameter) can safely go to 20 hz, so thats where i started my scale. Decent tweeters can go up to 20,000 hz, and that is also the limit of human hearing, and a silly number to excede, so that is the top of my scale. This adds up to exactly 10 octaves, meaning, it doubles ten times, so i decided, why shouldn't i try and work the same amount of octaves into each crossover frequency? i assumed that an even distribution would prevent distortion in one region when trying to perfectly reproduce a sound. I did the math for 3 way and 4 way crossovers.
a 3-way crossover should have crossovers from bass to midrange at 20x2^3.3hz, or 200hz, and a crossover from midrange to treble at 20x2^6.6hz, or 2030hz.
a 4-way crossover should have crossovers from bass to midbass at 20x2^2.5hz, or 115hz, a crossover from midbass to midrange at 20x2^5.0hz, or 650 hz and a crossover from midrange to treble at 20x2^7.5hz, or 3675hz.
either design requires high order cutoffs at 20hz and 20,000hz to maximize efficiency, thts a given with any system though. When i build these crossovers i will use 2nd order filters for all crossover points (unless someone suggests something better.)
I hope the math is self explanatory, i just divided 10 octaves by the number of ranges in my system, and then used that number of octaves in each system to determine, using expnonents, just what frequencies to include.
If you are building a sound system, i would suggest finding speakers to fit these ranges witha little room to spare in either direction (obviously thats hard with a subwoofer, but look for one that can handle close to 20hz, if you are willing to invest in a beastly 21 inch sub its worth it)
I really hope this helps at least one person... (i DO know its gonna help me drop some crazy beats 😀 )
a 3-way crossover should have crossovers from bass to midrange at 20x2^3.3hz, or 200hz, and a crossover from midrange to treble at 20x2^6.6hz, or 2030hz.
a 4-way crossover should have crossovers from bass to midbass at 20x2^2.5hz, or 115hz, a crossover from midbass to midrange at 20x2^5.0hz, or 650 hz and a crossover from midrange to treble at 20x2^7.5hz, or 3675hz.
either design requires high order cutoffs at 20hz and 20,000hz to maximize efficiency, thts a given with any system though. When i build these crossovers i will use 2nd order filters for all crossover points (unless someone suggests something better.)
I hope the math is self explanatory, i just divided 10 octaves by the number of ranges in my system, and then used that number of octaves in each system to determine, using expnonents, just what frequencies to include.
If you are building a sound system, i would suggest finding speakers to fit these ranges witha little room to spare in either direction (obviously thats hard with a subwoofer, but look for one that can handle close to 20hz, if you are willing to invest in a beastly 21 inch sub its worth it)
I really hope this helps at least one person... (i DO know its gonna help me drop some crazy beats 😀 )
What you have stated may be a reasonable starting point.
However, the final crossover frequencies and slopes very considerably, depending on the driver capabilities, number of drivers, physical layout, and the target acoustic space.
For example, using Metal cone midranges demand a lower crossover and steeper slopes to keep the driver resonances in check, while a "wide range" driver may need a 10K first order to help it in the top octave, and a 100 Hz LP crossover to keep excursion to a minimum.
All of the choices are compromises, and depend on many factors.
Just My 2 cents.
Doug
However, the final crossover frequencies and slopes very considerably, depending on the driver capabilities, number of drivers, physical layout, and the target acoustic space.
For example, using Metal cone midranges demand a lower crossover and steeper slopes to keep the driver resonances in check, while a "wide range" driver may need a 10K first order to help it in the top octave, and a 100 Hz LP crossover to keep excursion to a minimum.
All of the choices are compromises, and depend on many factors.
Just My 2 cents.
Doug
robotnation said:
It is pretty easy to show the fallacy of that. We may not hear single sine waves above there (for me not even that) but you can hear when it is missing, because an intruments can produce HF sound that produces beat frequencies you can hear.
The logic of your analysis seems flawless, but leaves out practical considerations & the sensitivity to the ear-brain system. Crossovers are nigh-on impossible to get perfect (new digital systems show promise, but sampling rate is still too low), and putting them where the ear is most sensitive is, IMHO, not a good idea.
For a 3-way a bass-mid XO 80-250 Hz, and mid-hF at 5-12kHz. This puts the onus on the mid to be a stellar performer (and i suggest the best place to go looking is in the full-range section).
In a 4-way, the extra driver can be added to handle the lowest bass, and the higher part of the range for the bass-to-mid choosen. Think of the purpose of the woofer to be relieving the driver one up from large excursions. ie i've always held that the biggest benefit of adding an active woofer is the improvement in the midrange.
When i'm doing a multi-way system, i like to find a mid that is musically satisfying all on its own, and then adding help (& relief) on one or both ends. (ie a 2-way should have an XO between 200-350 Hz or 7-12 kHz).
Your approach can produce a speaker with excellent measured FR, dispersion, and power distribution, but in most cases sounds like it has had the life sucked out of it.
And in the end, it is all about enjoying the music.
dave
Telephone bandwidth is from 300Hz to 3.4kHz because that's where the important stuff is. Anything else is icing on the cake. In other words, we'd really like to avoid having a crossover within that region. Traditionally, 8" drivers could be made to stagger up to 3.5kHz and 1" soft dome tweeters didn't distort too horribly if pushed that low, so that's where the crossover was. Three-way systems tended to leave the 3.5kHz crossover and use a better midrange, then put the other crossover frequency at 300Hz.
These days you can get drivers that almost cover the entire range and just need a little help at the top and the bottom. They make excellent midrange drivers. As planet10 says, a trawl of the full range forum will be rewarding.
These days you can get drivers that almost cover the entire range and just need a little help at the top and the bottom. They make excellent midrange drivers. As planet10 says, a trawl of the full range forum will be rewarding.
Your idea is nice, but it seems to me like you are trying to stuff hexagonal shapes into round holes because they are more logical. (lol I sound like Spock!) At the end of the day, a drive unit will have a bandwidth that must be observed and there is no getting around that.
Just a caution on the range determined for telephones. This was to cover speech only.
Music limited to this range sounds horrid.
I agree with previous comments that the mid range is critical, and should cover as much as possible. Removing the demands of the bass from this driver cleans the sound up no end. The treble end seems much less critical, and getting the crossover above 3.5KHz seems adequate.
Moving the crossover a few KHz upwards does not seem to improve matters significantly, and tends to cause beaming with most drivers large enough to go low, say to 100-200Khz. Hence the tendency to use "helper" tweeters.However the most recent drivers are better in this regard, and a 3 or 4 inch "full" range crossing high about 10K could be the thing.
Although I am using a fullrange as my main speakers at present, I find most have limitations. After all like all speakers they are a compromise. I particularly dislike those that use a whizzer cone, although I have not heard the latest Lowther with the damped edge, which may remove my objection to the previous units.
A further comment- cone materials all have their own "sound" and mixing materials brings a further set of problems.
Music limited to this range sounds horrid.
I agree with previous comments that the mid range is critical, and should cover as much as possible. Removing the demands of the bass from this driver cleans the sound up no end. The treble end seems much less critical, and getting the crossover above 3.5KHz seems adequate.
Moving the crossover a few KHz upwards does not seem to improve matters significantly, and tends to cause beaming with most drivers large enough to go low, say to 100-200Khz. Hence the tendency to use "helper" tweeters.However the most recent drivers are better in this regard, and a 3 or 4 inch "full" range crossing high about 10K could be the thing.
Although I am using a fullrange as my main speakers at present, I find most have limitations. After all like all speakers they are a compromise. I particularly dislike those that use a whizzer cone, although I have not heard the latest Lowther with the damped edge, which may remove my objection to the previous units.
A further comment- cone materials all have their own "sound" and mixing materials brings a further set of problems.
I just wanted to put forward the thought that since your speaker is relaying sound to a human ear rather than a spectrum analyzer you may want to start from the viewpoint of the ear. It's a quirky little thing, perhaps you can find places in it's repsonse where a crossover is better hidden than others.
wow these are all good ideas... but i was wondering, do all of these little factors change considering the music being played? I am going to be playing techno and using speakers with range limits that are hard to push and break (the drivers i'm looking at are pretty nice.) Another thing, when i dj i have a mixer with EQ settings and i can control what gets sent to my amps. If i have the crossovers i was suggesting, couldn't i bend the music around to be more pleasing before sending it to the amps?
p.s. my crossovers are going to be active not passive
p.s. my crossovers are going to be active not passive
The type of music will have no influence whatsoever on the bandwidth that the speakers are capable of producing. You may choose however, that if you like a big vocal picture to run the midrange up a bit higher than normal at the expense of reduced directivity and also possibly some breakup.
Maybe some of the responding people overlooked the fact that he was talking about high-power systems for DJing.
In this case recommendations for 4" fullrangers and softdomes and their usual crossover frequencies don't help much here.
In this case I would say that:
1.) The original poster's proposal is a good starting point (look at it as a flexible design target). 20 kHz is high enough for this purpose BTW.
2.) But there is no way around designing the crossovers matching the driver responses etc.
3.) Higher than 2nd order is recommended for high-power applications of than kind in order to reduce IMD and THD.
Regards
Charles
In this case recommendations for 4" fullrangers and softdomes and their usual crossover frequencies don't help much here.
In this case I would say that:
1.) The original poster's proposal is a good starting point (look at it as a flexible design target). 20 kHz is high enough for this purpose BTW.
2.) But there is no way around designing the crossovers matching the driver responses etc.
3.) Higher than 2nd order is recommended for high-power applications of than kind in order to reduce IMD and THD.
Regards
Charles
i've been running a techno night ( www.pure-filth.org ) for the last 5yrs using my own system
if i may suggest a few things born out of my experience...
what you've suggested above is a nice idea and in anything but the real world of high decibel soundsystems would be a lofty goal to aim for
however put simply it ain't gonna work
for starters our tunes are all about the kickdrum and you need maximum output between 60Hz and 90Hz as that's where it's main meat is located
in order to get this the best thing you can do is have at least 4 per side of something like the HD15 playing between 50Hz and 120Hz with at least 500w across each driver
trust me this is techno we're talking about here!
you don't need a sub but if you play alot of stuff with b-lines you might feel that you need to go down that area
the X1 is perfect for this role and at a ratio of 1 sub to 2 HD15's crossed at 60Hz and playing down to 30Hz works perfectly with no less than 1.5Kw across the driver
above 120Hz you should be looking at a single horn loaded 12" to about 300-500Hz
from there to about 3 - 5KHz a single 6" or 8" again on a horn and above that a 1" or 1.5" compression driver upto it's roll-off around 15 - 16KHz
you don't need to go below 30Hz or above 15KHz as that's the range in which vinyl is cut besides which by the time we reach adults only the lucky ones can hear above 14KHz
outside the above range all you are doing is wasting amplifier power trying to achieve something that is doing no more than damaging your speakers
you'll need a Loudspeaker Management System (LMS) (behringer DCX is a budget one) to xover and time align your speakers so you don't get phase cancellations and lose parts of you tune
i'm afraid you can't use your mixers EQ to do this as you still only have one stereo ouput
all crossovers should be at least 4th order to maximise the power available to the bandwidth
some people might suggest going with a longer horn and doing without the sub but for techno i disagree believing a concentrated bandwidth to get the punch of the kickdrum is more the style to look for
do all the above and i promise you you'll kick *** and have people wanting to hire your system for their own nights just how it happened with us!
if i may suggest a few things born out of my experience...
what you've suggested above is a nice idea and in anything but the real world of high decibel soundsystems would be a lofty goal to aim for
however put simply it ain't gonna work
for starters our tunes are all about the kickdrum and you need maximum output between 60Hz and 90Hz as that's where it's main meat is located
in order to get this the best thing you can do is have at least 4 per side of something like the HD15 playing between 50Hz and 120Hz with at least 500w across each driver
trust me this is techno we're talking about here!
you don't need a sub but if you play alot of stuff with b-lines you might feel that you need to go down that area
the X1 is perfect for this role and at a ratio of 1 sub to 2 HD15's crossed at 60Hz and playing down to 30Hz works perfectly with no less than 1.5Kw across the driver
above 120Hz you should be looking at a single horn loaded 12" to about 300-500Hz
from there to about 3 - 5KHz a single 6" or 8" again on a horn and above that a 1" or 1.5" compression driver upto it's roll-off around 15 - 16KHz
you don't need to go below 30Hz or above 15KHz as that's the range in which vinyl is cut besides which by the time we reach adults only the lucky ones can hear above 14KHz
outside the above range all you are doing is wasting amplifier power trying to achieve something that is doing no more than damaging your speakers
you'll need a Loudspeaker Management System (LMS) (behringer DCX is a budget one) to xover and time align your speakers so you don't get phase cancellations and lose parts of you tune
i'm afraid you can't use your mixers EQ to do this as you still only have one stereo ouput
all crossovers should be at least 4th order to maximise the power available to the bandwidth
some people might suggest going with a longer horn and doing without the sub but for techno i disagree believing a concentrated bandwidth to get the punch of the kickdrum is more the style to look for
do all the above and i promise you you'll kick *** and have people wanting to hire your system for their own nights just how it happened with us!
i think it reminds a lot of people of old turbosound bins ;-)
still it's a proven design that does exactly what it says on the tin and we've been using them for 5yrs loaded with PD154's and have nothing but praise for them
it's only in the last few months that we've added subs to the rig and we've been hiring it out to d&b nights as well as house nights
no complaints from the d&b but the house boys wanted us to make it a little less kickdrummy!
still it's a proven design that does exactly what it says on the tin and we've been using them for 5yrs loaded with PD154's and have nothing but praise for them
it's only in the last few months that we've added subs to the rig and we've been hiring it out to d&b nights as well as house nights
no complaints from the d&b but the house boys wanted us to make it a little less kickdrummy!
Pray tell where can I find any "Pro Audio" metal cone drivers like this?? With the exception of maybe MCM or Bugtussel(sp), who makes Pro audio drivers in anything but paper? (Selenium Quartz I've seen)
Cheers,
AJ
I was thinking Seas L18. I guess pro drivers are called for here. Neither of us should post on our lunch hour. 😉
Doug
Robotnation
>Crossover at 200 and 2030 Hz.
I arrived at about the same values, 160 and 1600 Hz, but it is only incenditally that each speakers deals 3 1/3 octave (16-160 Hz, 160 Hz --1600 Hz, 1.6 kHz - 16 kHz). My thought was that there must exist values of crossover frequencies which may be much preferable to others.
1600 Hz was choosen because the localisation by the ear between 1500 and 2000 HZ is not good. I found many examples of speakers crossing medium and tweeter at these frequencies which had a sound which "escape" from the baffle.
Selecting a bass crossover frequency was more difficult. I ended with 160 Hz because a box at very low frequencies must be very rigid but not so at medium frequencies. Starting at 300 Hz, the energy must be dissipated in the walls of the box which can be rather thin but must be very well damped. These conflicting requirements are solved by using boxes for bass and medium having a very different kind of construction. My bass will also have a kind of MFB which usually require a steep lo-pass filter at less than 200 HZ.
A second idea of mine is that the loudspeaker units must be chosen according to the crossover frequency and not the contrary, where one adapts the crossover frequencies to the loudpseakers units.
So my crossover is of the Bill Hardman's variety (bass not built yet) :
http://www.diyaudio.com/forums/showthread.php?s=&threadid=6655&highlight=
The very steep slope enables the use of many kinds of loudspeakers, provided that the medium has a resonance of less than 100 Hz and the tweeter, less than 1000 Hz.
~~~~~~ Forr
§§§
>Crossover at 200 and 2030 Hz.
I arrived at about the same values, 160 and 1600 Hz, but it is only incenditally that each speakers deals 3 1/3 octave (16-160 Hz, 160 Hz --1600 Hz, 1.6 kHz - 16 kHz). My thought was that there must exist values of crossover frequencies which may be much preferable to others.
1600 Hz was choosen because the localisation by the ear between 1500 and 2000 HZ is not good. I found many examples of speakers crossing medium and tweeter at these frequencies which had a sound which "escape" from the baffle.
Selecting a bass crossover frequency was more difficult. I ended with 160 Hz because a box at very low frequencies must be very rigid but not so at medium frequencies. Starting at 300 Hz, the energy must be dissipated in the walls of the box which can be rather thin but must be very well damped. These conflicting requirements are solved by using boxes for bass and medium having a very different kind of construction. My bass will also have a kind of MFB which usually require a steep lo-pass filter at less than 200 HZ.
A second idea of mine is that the loudspeaker units must be chosen according to the crossover frequency and not the contrary, where one adapts the crossover frequencies to the loudpseakers units.
So my crossover is of the Bill Hardman's variety (bass not built yet) :
http://www.diyaudio.com/forums/showthread.php?s=&threadid=6655&highlight=
The very steep slope enables the use of many kinds of loudspeakers, provided that the medium has a resonance of less than 100 Hz and the tweeter, less than 1000 Hz.
~~~~~~ Forr
§§§
i forgot to add in my previous post that for the most part providing the drivers are aligned in the time domain so that an impulse reaches the front face of your stack at the same time and the phase is correct through the crossover point you'll never know it was there (it's here your LMS comes into its own)
as such you can put the crossover anywhere and being able to do that means you can place it where your dispersion is equal therby creating a much more favourable off axis response allowing you to array horrizontally as your system grows
i'm well aware vertical line arrays give the best response and that comb filtering is there in vertical or horizontal arrays but on a small to medium system a well controlled dispersion on a horizontal array is by far the easiest solution
as such you can put the crossover anywhere and being able to do that means you can place it where your dispersion is equal therby creating a much more favourable off axis response allowing you to array horrizontally as your system grows
i'm well aware vertical line arrays give the best response and that comb filtering is there in vertical or horizontal arrays but on a small to medium system a well controlled dispersion on a horizontal array is by far the easiest solution
wow, thanks for all the information, synergy. I will definatley do something liek taht in the future, but i have to build my way up to that. Right now i am sort of incapable of building complex speakers with my lack of tools, and i don't know the volume my subwoofers take up so taht i can calculate how to get the exact volume of my enclosure, for the purpose of adding ports. Right now, however, i am working on building two unvented subwoofers with my 21" madison executioner X speakers. I know i'm eventually going to need serious power and vented speakers (and hopefully one day people will rent my system,) but i need to build up to it. I still need to know abit more though. I have two 1000 watt subwoofers, but i don't know how much power to buy in other ranges. Whats a good ratio for me distribute my power in each range? i don't want to underpower or overpower one frequency range (waste of money and all.) If i have 1 100 watt speaker for low range (jsut to make the math easier) how many watts of speakers power should go to midbass, mid, and highs?
oh yea and i also want to know... how much power for subwoofers? I will be doing some DNB myself (or having friends do it) and its almost ultimate dishonor to spin drum n bass and not have speakers that can handle those drones and grinds in the low frequencies.
a typical 18" is about 7L basket side and contains about 3L of air in the cone
for a 21" i'm guessing but i'd say probs 9 - 10L and 4 - 4.5L
for seal/vented boxes you can allow yourself about 10% tolerance and it won't make much difference
power distribution...
http://www.diyaudio.com/forums/attachment.php?s=&postid=709830&stamp=1124895971
for a 21" i'm guessing but i'd say probs 9 - 10L and 4 - 4.5L
for seal/vented boxes you can allow yourself about 10% tolerance and it won't make much difference
power distribution...
http://www.diyaudio.com/forums/attachment.php?s=&postid=709830&stamp=1124895971
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