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Author Topic: subwoofer distortion  (Read 4976 times)

Raj Sookraj

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subwoofer distortion
« on: October 08, 2012, 09:56:39 pm »

How does distortion make a sub sound louder? Specifically what's generating the distortion?
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Ivan Beaver

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Re: subwoofer distortion
« Reply #1 on: October 09, 2012, 07:21:39 am »

How does distortion make a sub sound louder? Specifically what's generating the distortion?
Distortion is basically extra harmonics added to the original signal.  They will be in multiples of the base freq.

You can easily see this using most any measurement system.  Evan an RTA (to some extent)-but something like Smaart-Systune etc is better/easier.

Simply put in a single tone freq-say 60Hz.  Now as you turn up the level-look at the level of 120-180-240Hz etc (multiples of the original 60Hz).  As it gets more distorted-you will see those levels come up-in relation to the increase of level at 60Hz.

These "free sound" will make it sound louder-since there is more energy appearing at your ear.

The distortion is generated by the non linearity of the cone-caused by movement.  Basically the cone will start to "warp" or change its shape from what it was at a low level.  The move the cone moves-the more distortion will be generated.

Drive it hard enough and the distortion components can equal or actually be louder than the original signal.

Of course some people prefer this sound.  It is often funny to hear people talk about a specific loudspeaker and they like the way it "sounds"-and then they talk about how accurate it is.  HUH?????

How can it change the sound and be accurate at the same time?  Whatever makes them happy I guess-------------------------------

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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

John Roberts {JR}

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Re: subwoofer distortion
« Reply #2 on: October 09, 2012, 10:41:03 am »

There is one mechanism related to how we perceive loudness at low frequencies, where lower frequencies need to be louder than mid frequencies to sound the same loudness. This means the distortion overtones at higher frequency than the LF fundamental note are easier to hear.

Another perceptual clue, which may not be the dominant one for woofers, in nature when we make louder sounds they are more complex (more distortion overtones).  A singer at low level can make almost pure notes, while that same singer singing louder will make more complex sounds, with more overtones present. From experience we associate distorted with loud, because it usually is.

Finally an observation... Woofers have been making so much distortion for so long, that many system operators have become accustomed to that as their normal baseline. The distortion in woofers is not as nasty sounding as distortion in other frequency ranges, and actually supports the lower notes that may not be reproduced very strongly. Many in the audience hear the distortion and just consider that part of the original sound. Sometimes even thinking the speaker has response lower than it really does, because of the distortion that is present.

This must be extremely annoying to a company like Danley, that makes low distortion woofers since operators accustomed to the previous high distortion "normal" may now think something is missing.  ::)

The customer is always right, even when wrong. Note: they do make add-on effects units that introduce LF distortion (to make speakers sound like they go lower), so you can make Danley speakers sound like other speakers by adding distortion ( but why?).  8)

System operators need to be aware that all that old school distortion is not part of the original signal, and learn a new normal. While I can imagine a scenario where a club meeds to keep SPL down, so faux bass is better than real bass, kind of like the loudness knob on your hifi receiver.
[edit] OK, not exactly, loudness is an EQ contour not added distortion, but more perceptual trickery to compensate for Fletcher-Munson constant loudness curves. [/edit]

JR
« Last Edit: October 09, 2012, 10:44:35 am by John Roberts {JR} »
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John Chiara

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Re: subwoofer distortion
« Reply #3 on: October 09, 2012, 02:11:37 pm »

This is the concept that the Waves Maxxbass operates on... Creating a controlled version of these harmonics.
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Ivan Beaver

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Re: subwoofer distortion
« Reply #4 on: October 09, 2012, 06:53:29 pm »

This is the concept that the Waves Maxxbass operates on... Creating a controlled version of these harmonics.
While the Waves unit can trick the brain into hearing something that it is not-it cannot trick the body into feeling the impact of deep low freq that you experience with subs that truly reproduce those freq.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

ProSoundWeb Community

Re: subwoofer distortion
« Reply #4 on: October 09, 2012, 06:53:29 pm »


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