# im curious the advantage (if any) of tweeters that produce over 20k



## jeremy7 (Feb 7, 2008)

I was thinking that sense the range of hearing ends at approx 20k, is there a significant advantage to a tweeter that produces sound to say 40k? Ive always been curious


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## Bill Fitzmaurice (Jun 14, 2008)

jeremy7 said:


> I was thinking that sense the range of hearing ends at approx 20k, is there a significant advantage to a tweeter that produces sound to say 40k? Ive always been curious


20kHz if you're 15 years old, maybe. For the average adult 12 to 14 kHz is more like it. As for what's up at 40kHz, nothing useful. Even if instruments or voices were capable of gong that high the microphones used to record them aren't. onder:
The only compelling reason for a tweeter that goes to 40kHz on-axis is that it will probably have very good off-axis down in the range where something can be heard from it.


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## drf (Oct 22, 2006)

Bill Fitzmaurice said:


> The only compelling reason for a tweeter that goes to 40kHz on-axis is that it will probably have very good off-axis down in the range where something can be heard from it.


Wouldn't off-axis response be more related to the physical shape and the rigity the cone as apposed to its freq' limit? 

I am 32, I can hear to about 18Khz still but I don't bother with anything over 12K. Basically there isn't much point. I have a set of headphones here that some people were raving about, so I tested them and found that they didn't even go past 9Khz. Therefore I summise that for 90% of the population if you get off-axis response acceptable to 9Khz then nobody will notice the rest*. Let alone 40Khz 

*Unless they are moving slowely around the room during the movie, in which case they are no welcome in my theatre.


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## Bill Fitzmaurice (Jun 14, 2008)

drf said:


> Wouldn't off-axis response be more related to the physical shape and the rigity the cone as apposed to its freq' limit?
> .


Yes, but unless you have off-axis plots to compare you have no way of knowing how any driver will work. If you want to be sure that a tweeter works well off-axis to 15kHz without charts -6dB axial response to 22kHz or better is a good indicator.


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## BoomieMCT (Dec 11, 2006)

Bill Fitzmaurice said:


> Yes, but unless you have off-axis plots to compare you have no way of knowing how any driver will work. If you want to be sure that a tweeter works well off-axis to 15kHz without charts -6dB axial response to 22kHz or better is a good indicator.


That's a neat tip I never thought about. Thanks Bill!

I've always heard that content up to 40kHz could produce undertones in the frequency range you can hear. I'm not savvy about microphones and really have no idea how high they can typically record or if things like electronic music or movies might add in effects up in that range. 

I will also generally agree with drf - from my time doing single range drivers you'd be surprised how well a speaker can sound without that top octave. Honestly though, after months of listening you do really notice it when you add that top octave back in.


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## Fird (Sep 9, 2008)

psh, I'm 20, I can hear 18.5khz and question whether it's the tweeters or my ears that drop off above that. The real value it adds is that it won't smear transients as badly as the tweeter drops down into the audible range. Transients have infinite frequency response, and thus having a little extra range on both ends is a plus as long as the tweeter behaves as it should within the range you actually intend to hear. 

can't hear above 12khz? I'm sorry to hear that  I own a pair of M-audio IE-10's which are fantastic for bass, and smooth through the midrange, but the brick wall cutoff at 13khz really limits their usefulness as a monitoring device, the crisp clarity just isn't there.


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## thxgoon (Feb 23, 2007)

Fird said:


> The real value it adds is that it won't smear transients as badly as the tweeter drops down into the audible range. Transients have infinite frequency response, and thus having a little extra range on both ends is a plus as long as the tweeter behaves as it should within the range you actually intend to hear.


Welcome to the Shack!

I'm not sure I follow you here. Transients are dynamic in nature and contain the frequencies within the transient... As long as there is no clipping involved I can't see where these infinite extra frequencies come from.

The max frequency a CD can reproduce is 22 khz. The max frequency of any digital recording is always half of it's clock rate, as it takes 2 data points to define a max and a min. If you have a tweeter that goes to 40khz, but a medium only capable of 22khz, there's no benefit. Newer lossless codecs operate at higher clock rates, but as someone said before, who records anything higher than this? Personally, I don't see the advantage.


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## Bill Fitzmaurice (Jun 14, 2008)

thxgoon said:


> The max frequency a CD can reproduce is 22 khz.


More important, most microphones and other sound sources don't go much past 15kHz, if that. You can't hear what the engineer didn't put in there.


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## Kevin Haskins (Nov 14, 2007)

I'm working on a tweeter with bandwidth to 35K but I don't consider it important. You end up getting that kind of bandwidth with really stiff & light domes and it gets put on the spec sheet, not because it's important, but because it is one more bullet point in your marketing material. 

I'd ignore it when trying to determine which product to choose for a given application. The top octave is the least import one to worry about when doing speaker design, let alone concerning yourself with 20K-40K.

Bill is right about microphones too. The mic I use to design speakers is good to about 22K. It drops like a rock after that. 

Kevin Haskins
Exodus Audio
www.diycable.com


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## redduck21502 (Oct 23, 2008)

Bill Fitzmaurice said:


> 20kHz if you're 15 years old, maybe. For the average adult 12 to 14 kHz is more like it. As for what's up at 40kHz, nothing useful. Even if instruments or voices were capable of gong that high the microphones used to record them aren't. onder:
> The only compelling reason for a tweeter that goes to 40kHz on-axis is that it will probably have very good off-axis down in the range where something can be heard from it.



I'm glad you mentioned this. I was running test tones through my in-walls the other day and could not hear a 15KHz test tone. I am not sure of whether it is me or the speaker. I used to be able to hear it if I would stick my ear up to it on some tweeters that I used to have in my car. I could hear the 20KHz tone in my Image Dynamic HLCD in the car, but now I don't know. It made me happy to see that most do not hear that high when you get older. I'll have to get my son to listen to it just to see if there is audible sound in that range. Everything sounds fine to me, I was just worried that I may be missing something in the 15-20KHz range.


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