Low pass filter outside hearing range

[SorenTyson]

Hi all,

Inspired by this thread:
Thread 'What's the highest frequency you can hear?'
https://audiosciencereview.com/foru...ats-the-highest-frequency-you-can-hear.45701/

I wonder if it would make sense to low pass speakers so that they don’t have to produce frequencies that I would not hear anyway?

Idea being for the tweeter to perform better in the range that I can hear (this is just an assumption from another statement, that a bookshelf woofer would perform better if offloaded by a subwoofer).

I hope this question is generic, in my application I would use an avr with dirac.

Br

Soeren

 

[DVDdoug]

You are correct.

You can end-up wasting energy on sounds that your speaker can't reproduce and/or that you can't hear. You can end-up driving your amplifier (or speaker) into clipping/distortion with sounds the speaker can't reproduce, and if you have too much amplifier power you can even burn-out the woofer with low or subsonic frequencies.

Most amplifiers have a high-pass filter, mainly to block DC (zero Hz). You can get DC from defective hardware or some "home recordings" have "DC offset". (Digital can go down to zero Hz.)

In the vinyl days, you could often see the woofer flapping or pumping in-and-out from record warp and a lot of amps & receivers had a "rumble filter" to filter it out.

Most digital music doesn't contain much very-low or subsonic frequencies. Even bass-heavy dance music rarely goes down to 20Hz because you have to take-away loudness or headroom, making everything else quieter, and you can get stronger-sounding bass by focusing the energy a little higher where it sounds louder.

With the movies and the separate "point one" LFE channel, the bass isn't "competing" with anything else, and you've usually got plenty of digital headroom. If you've got an active subwoofer, it may have a built-in subsonic filter customized to the driver & cabinet so you don't over-drive it with frequencies it can't reproduce.

For similar reasons, "pro" subwoofers used live and in dance clubs are usually tuned down to around 40Hz. (The lowest note on a standard electric bass guitar is around 40Hz). That's low-enough for bass you can feel in your body. If you tune the sub to go lower you tend to lose efficiency and you need more subs and bigger amplifiers to fill a large venue with strong bass. (This isn't as much of a problem at home and many home & studio subwoofers do go down to 20Hz.)

 

[SorenTyson]

You are correct.

You can end-up wasting energy on sounds that your speaker can't reproduce and/or that you can't hear. You can end-up driving your amplifier (or speaker) into clipping/distortion with sounds the speaker can't reproduce, and if you have too much amplifier power you can even burn-out the woofer with low or subsonic frequencies.

Most amplifiers have a high-pass filter, mainly to block DC (zero Hz). You can get DC from defective hardware or some "home recordings" have "DC offset". (Digital can go down to zero Hz.)

In the vinyl days, you could often see the woofer flapping or pumping in-and-out from record warp and a lot of amps & receivers had a "rumble filter" to filter it out.

Most digital music doesn't contain much very-low or subsonic frequencies. Even bass-heavy dance music rarely goes down to 20Hz because you have to take-away loudness or headroom, making everything else quieter, and you can get stronger-sounding bass by focusing the energy a little higher where it sounds louder.

With the movies and the separate "point one" LFE channel, the bass isn't "competing" with anything else, and you've usually got plenty of digital headroom. If you've got an active subwoofer, it may have a built-in subsonic filter customized to the driver & cabinet so you don't over-drive it with frequencies it can't reproduce.

For similar reasons, "pro" subwoofers used live and in dance clubs are usually tuned down to around 40Hz. (The lowest note on a standard electric bass guitar is around 40Hz). That's low-enough for bass you can feel in your body. If you tune the sub to go lower you tend to lose efficiency and you need more subs and bigger amplifiers to fill a large venue with strong bass. (This isn't as much of a problem at home and many home & studio subwoofers do go down to 20Hz.)

Thanks for answering. I was actually thinking at the other end of the frequency scale. If I anyway cannot hear above for instance 13,000 Hz, then to cut those frequencies and offload the tweeter.

The woofer is already offloaded by a subwoofer.

Br

Soeren