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Using filters to improve speaker performance

Yameyo

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Hi all

First of all I just wanted to say thanks to ASR. I've really enjoyed using the site and reading the forums.

I was reading the review of the Q Acoustics 3020i in which Amirm describes how a sharp filter at 40hz filter helped to improve the sound, and was wondering what the consensus was around using filters this way. Does anyone take this approach as standard with their speakers, even when a subwoofer is not in use, in order to avoid sending frequencies to a speaker that have no chance of being usefully reproduced?

Link to the review.

https://audiosciencereview.com/foru...oustics-3020i-bookshelf-speaker-review.14568/
 

DVDdoug

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Does anyone take this approach as standard with their speakers, even when a subwoofer is not in use, in order to avoid sending frequencies to a speaker that have no chance of being usefully reproduced?
I've never thought about it but it makes sense. Although, I do turn-down the bass in my car if I start hearing distortion or buzzing. .. Factory Honda stereo with "limited performance". My other vehicle is a van with a "killer" system and a pair of 12-inch subs under the back seat.

Amir had the advantage of all the measurements so he had a starting point.

Most people are likely to do the opposite and turn-up the "weak bass", although if you can get good bass down to 40Hz that's not terrible. The lowest note on a standard electric bass is about 40Hz and a lot of "pro" subwoofers for live use or dance clubs are tuned for around 40Hz. As you go lower it takes more-and-more energy and larger speakers to fill a big space with strong bass so I guess 40Hz is a good compromise.

But that little Q Acoustics woofer isn't going to put-out 40Hz you can feel in your body, even in a small room... ;)
 

AnalogSteph

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It is an approach taken by a fair few active and even a few passive speakers ('90s Canton comes to mind). You can even trade off between bass extension and output level like that. In order to reproduce a given level, woofer excursion quadruples as frequency halves. So even in a closed-box speaker with its 2nd-order response dropoff down below, excursion will still remain constant for the same input in that area.
Things get more critical with the common bass-reflex (ported) enclosures, as while the port resonance will provide relief and reduce excursion in a certain area (usually just below cutoff), below that excursion starts to rise ever more quickly as a ported box cannot hold static pressure and thus has to be an acoustic short at frequency zero. Examples given here:
https://www.css-audio.com/single-post/2019/02/19/plugging-a-port-what-is-happening-to-your-speaker
So content in this critical area can make distortion go haywire very quickly.

In case of the 3020i, for example, the relief effect is noticeable in the 60-70 Hz area where distortion dips substantially. Anything much below 60 Hz really is best avoided with this speaker. If you need levels of 96 dB @ 1 m, 100-150 Hz may be more like it.

Once you filter out the critical ranges below resonance, a ported speaker can play louder than a closed-box design with the same woofer.
 
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RayDunzl

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Factory Honda stereo with "limited performance".

The base sound system in my 2019 Camry is pitiful, too, but I mostly listen to "talk" in the car, so...
 

digitalfrost

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If you use DSP for your speakers it is easy to do this, and yes I do. Any bass reflex speaker would benefit from having frequencies below the tuning freq removed, since the air suspension doesn't work there anymore.
 
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Yameyo

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Thanks all, your information was very useful. I'll try applying DSP in Jriver after my new (cheap) setup is delivered.
 
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