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Why do subwoofers have better bass than large speakers?

Eetu

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Regardless of the bass content any astounding record might have, you have been insisting in how tiny your room is.

Listen to this interview, if you please, where a loudspeaker maker warns about spending any money on their flagship product if it is to be placed on a 3x3 meters room...

They mention the Acoustics Insider channel on the podcast and it happens the topic gets adressed by Jesco here, around 4.13

In short, bass frequencies below the modal region can be reproduced. The wave length does not have to 'fit' the room.
 
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Georgios

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Link worked and it’s eye-opener to see 6" drivers achieve 17Hz +-1.5db.
 

F1308

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They mention the Acoustics Insider channel on the podcast and it happens the topic gets adressed by Jesco here, around 4.13

In short, bass frequencies below the modal region can be reproduced. The wave length does not have to 'fit' the room.
Thank you.
A loudspeaker maker that doesn't understand how sound works, and doesn't want to sell his products, is that it ?
 

dasdoing

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the problem with small rooms and low extension is the first room mode, which has an incredible boost. without EQ it really wont work. but with eq there is actually no problem (excluding the ringing, but many here can't hear that)
 

Sancus

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rofl, that guy is so fragile he has links with a referrer from ASR blocked. Amazing.
Link worked and it’s eye-opener to see 6" drivers achieve 17Hz +-1.5db.
Extension has no meaning in active speakers, it can be pretty much whatever you set the internal EQ to.
 

gnarly

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Extension has no meaning in active speakers, it can be pretty much whatever you set the internal EQ to.
Well, i guess that can be said if the idea of at what SPL is thrown away...
I mean, even a 3" full-ranger cab produce 15Hz.....albeit at minuscule SPL.

SPL needs to be equal across the spectrum. If active boost is applied to produce very low freq extension, then the SPL at that very freq low extension, is the limit of what the driver has to offer throughout the spectrum.

Hey, bottom line on why subs have better bass than large speakers is pretty stupid-simple.....subs are more likely to have a larger driver producing the low freq extension.
Why overthink something so obvious?
 

Sancus

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Well, i guess that can be said if the idea of at what SPL is thrown away...
I mean, even a 3" full-ranger cab produce 15Hz.....albeit at minuscule SPL.

I think you missed the point. If you have internal EQ available, extension can be set to whatever the manufacturer wants. So only output matters, and most don't give you a useful spec for output. What I'm saying is, the extension spec of an active speaker is only useful for knowing how it will perform at very moderate SPLs, and it's not comparable to the extension of passive speakers at all. It's basically a different thing entirely.

Yes, boosting low frequencies with EQ eats headroom. It makes sense to do it anyway if it makes your speaker bassier at 75dB.
 
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Georgios

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Well, i guess that can be said if the idea of at what SPL is thrown away...
I mean, even a 3" full-ranger cab produce 15Hz.....albeit at minuscule SPL.

SPL needs to be equal across the spectrum. If active boost is applied to produce very low freq extension, then the SPL at that very freq low extension, is the limit of what the driver has to offer throughout the spectrum.

Hey, bottom line on why subs have better bass than large speakers is pretty stupid-simple.....subs are more likely to have a larger driver producing the low freq extension.
Why overthink something so obvious?
If you look close enough I actually asked why subs with same size driver produce better bass frequency than large speakers having the same size driver.
 

polmuaddib

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why subs with same size driver produce better bass frequency than large speakers having the same size driver.
Do they, really?
Subs are made to compliment main speakers and have only bass frequencies. So, when you turn up the volume, the bass is louder, where on regular speakers, when you turn up the volume, all frequencies get louder.
In the end, you could compare the spl of the 20 to 120 Hz region of a regular speaker and a sub (both having the same driver, which is hard to find) and whould those results mean anything? Because, you adjust the sub volume to match the mains.
Theoretically, you could find that they both produce the same amount of bass frequencies, but still have advantage of having a sub, because you can put them in different places and make their volume louder and eq-ed as needed.

Another thing is how the crossover is setup in a speaker. They usually have only a low pass filter for bass and maybe some attenuation to match the other drivers. Subs might have a low pass filter, but no attenuation. Mind, I am no expert in loudspeaker design and this is just my lame opinion.

My point is that you can't compare a regular loudspeaker to sub and you don't need to. Different devices with different goals.
 

Prana Ferox

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If you look close enough I actually asked why subs with same size driver produce better bass frequency than large speakers having the same size driver.
This got explained earlier in the thread but in different words, so here goes:

A driver's diameter is only one stat that determines its performance. Another big one is its Xmax, or, roughly, how far the surface (usually a cone) can move back and forth in a controlled manner. Xmax (the distance the cone can move) times Sd (the surface area of the cone) gives you the volume of air the driver can push around, and you need to move a lot of air if you want to generate SPL at low frequencies. To work well at low frequencies the speaker generally also needs to be built with lower resonant frequency (which usually means heavier and stiffer). To move that bigger, heavier stiffer cone you need a much stronger motor, which will naturally be less efficient. The whole thing will tend to have a natural rolloff at a lower frequency than a conventional woofer, and even if that isn't an issue, the general construction optimized for LF tends to result in breakup and other nastiness fairly low in the frequency band.

You can see this in these examples of 5 1/4" driver:
264-850_HR_0.default.jpg
264-917_HR_0.default.jpg


The woofer driver is built to supply some bass. so it has a reasonably flexible surround, etc, but it also has features to help it control output up to where it can cross with a tweeter. The subwoofer driver has a much more exaggerated surround, spider (not visible) and greatly enlarged motor.

Alternately, adding surface area to the low-frequency driver of a speaker boosts efficiency. (It's easy to make higher-frequency drivers more efficient so the LF driver tends to determine total speaker efficiency.) But then optimizing it for lower frequencies lowers that efficiency back down. So dialing for these two factors becomes a big part of the speaker design. You can have speakers with large (12-15") woofers without much LF extension at all, because they're optimized way on the efficiency side.

This is what the posters earlier talking about Thiele-Small parameters were getting at. So within the bounds of Hoffman's Iron Law, you shouldn't assume that 'small driver' = 'little bass' or that 'big driver' = 'lots of bass'

That doesn't get into cabinet construction either, just because a speaker is large doesn't mean it's particularly tuned to put out a lot of LF, and a full-range speaker does have to dedicated internal volume to other stuff.
 

gnarly

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If you look close enough I actually asked why subs with same size driver produce better bass frequency than large speakers having the same size driver.
My apologies. Yes, you asked specifically about the KH750 sub which has 18 Hz =/-3dB, vs the KH420 monitor which has 26Hz +/-3dB.
The driver appears to be the same size in those based on cabinet dimensions..... could not find exact info. I'll just assume it's the same as I offer my explanation....

They were built for a different purpose.
The sub is a sealed design that is meant to reach as low as possible, which your thread title deems 'better bass'.
The monitor is a ported design that is meant to reach a higher SPL than the sealed sub, albeit at the expense of not reaching as low in frequency. Some folks might define the higher SPL in an acceptable range as 'better bass'.
Who's to say which is better bass ? other than having both SPL and lower reach :)

Neumann's specs point out that design difference.
KH420 Bass capability: Max. SPL in half space at 3% THD at 1m (averaged between 50 Hz and 100 Hz)109.9 dB SPL
KH750 Bass capability: Max. SPL in half space at 3% THD at 1m (averaged between 50 Hz and 100 Hz)105.0 dB SPL

A nearly 5 dB difference is quite significant ime/imo.
Hoffman's iron law tradeoffs in action....flow freq vs SPL vs size....
 
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gnarly

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I think you missed the point. If you have internal EQ available, extension can be set to whatever the manufacturer wants. So only output matters, and most don't give you a useful spec for output. What I'm saying is, the extension spec of an active speaker is only useful for knowing how it will perform at very moderate SPLs, and it's not comparable to the extension of passive speakers at all. It's basically a different thing entirely.

Yes, boosting low frequencies with EQ eats headroom. It makes sense to do it anyway if it makes your speaker bassier at 75dB.

Yes, i think i took your post the wrong way, as it seems we see things much the same.

I've often felt manufactures should show the EQ curve applied to active driver sections as part of their specifications. Or provide both raw and processed response curves, from which the applied EQ curve can be easily determined.
Some prosound companies like Fulcrum Acoustics do that, and it makes it relatively clear what max SPL will be.
 

F1308

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That’s why I’m reasonably choosing KH750 over KH810 or other ported subs. Link doesn’t work btw.
Link not working if you simply click on it.
But if you right click on it, copy the link address and paste it on another tab, it will open.

Listen from 44:00 if you are in a hurry or just want to access the comments on room size.

 
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Georgios

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This got explained earlier in the thread but in different words, so here goes:

A driver's diameter is only one stat that determines its performance. Another big one is its Xmax, or, roughly, how far the surface (usually a cone) can move back and forth in a controlled manner. Xmax (the distance the cone can move) times Sd (the surface area of the cone) gives you the volume of air the driver can push around, and you need to move a lot of air if you want to generate SPL at low frequencies. To work well at low frequencies the speaker generally also needs to be built with lower resonant frequency (which usually means heavier and stiffer). To move that bigger, heavier stiffer cone you need a much stronger motor, which will naturally be less efficient. The whole thing will tend to have a natural rolloff at a lower frequency than a conventional woofer, and even if that isn't an issue, the general construction optimized for LF tends to result in breakup and other nastiness fairly low in the frequency band.

You can see this in these examples of 5 1/4" driver:
View attachment 235309View attachment 235308

The woofer driver is built to supply some bass. so it has a reasonably flexible surround, etc, but it also has features to help it control output up to where it can cross with a tweeter. The subwoofer driver has a much more exaggerated surround, spider (not visible) and greatly enlarged motor.

Alternately, adding surface area to the low-frequency driver of a speaker boosts efficiency. (It's easy to make higher-frequency drivers more efficient so the LF driver tends to determine total speaker efficiency.) But then optimizing it for lower frequencies lowers that efficiency back down. So dialing for these two factors becomes a big part of the speaker design. You can have speakers with large (12-15") woofers without much LF extension at all, because they're optimized way on the efficiency side.

This is what the posters earlier talking about Thiele-Small parameters were getting at. So within the bounds of Hoffman's Iron Law, you shouldn't assume that 'small driver' = 'little bass' or that 'big driver' = 'lots of bass'

That doesn't get into cabinet construction either, just because a speaker is large doesn't mean it's particularly tuned to put out a lot of LF, and a full-range speaker does have to dedicated internal volume to other stuff.
Have to that’s the best reply I’ve ever received in my internet life:)
 
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Georgios

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My apologies. Yes, you asked specifically about the KH750 sub which has 18 Hz =/-3dB, vs the KH420 monitor which has 26Hz +/-3dB.
The driver appears to be the same size in those based on cabinet dimensions..... could not find exact info. I'll just assume it's the same as I offer my explanation....

They were built for a different purpose.
The sub is a sealed design that is meant to reach as low as possible, which your thread title deems 'better bass'.
The monitor is a ported design that is meant to reach a higher SPL than the sealed sub, albeit at the expense of not reaching as low in frequency. Some folks might define the higher SPL in an acceptable range as 'better bass'.
Who's to say which is better bass ? other than having both SPL and lower reach :)

Neumann's specs point out that design difference.
KH420 Bass capability: Max. SPL in half space at 3% THD at 1m (averaged between 50 Hz and 100 Hz)109.9 dB SPL
KH750 Bass capability: Max. SPL in half space at 3% THD at 1m (averaged between 50 Hz and 100 Hz)105.0 dB SPL

A nearly 5 dB difference is quite significant ime/imo.
Hoffman's iron law tradeoffs in action....flow freq vs SPL vs size....
Thanks for pointing out spl by finding and quoting the actual specs, I totally ignored this important factor.
 
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Georgios

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Ok, now I'm inclined to have one Rythmik F12 partnered with KH310. So I have to use DRC or miniDSP?
 

Head_Unit

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I know BagEnd was using a JBL 18" in their one sub which did not spec down low at all. It was a 80Hz Guitar speaker. It was all EQ and DSP to get down to 18hz.
Yes, their idea was to use the driver entirely BELOW resonance, in what theoretically would be a 12 dB/octave highpass characteristic which could be compensated by the usual lowpass filter made as 12 dB/octave. With enough power it can work.

Back to the original question of the thread, I'd note subwoofers for home use are generally not that large-even the big ones aren't huge compared to the size of their woofers. To reproduce low frequencies without massive EQ in relatively small boxes you more or less have to use pretty heavy cones (like car audio subs as an extreme example). In a full range speaker this would mean really low efficiency across the audio band-but that doesn't matter for a sub.
 

olbobcat

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Yes, their idea was to use the driver entirely BELOW resonance, in what theoretically would be a 12 dB/octave highpass characteristic which could be compensated by the usual lowpass filter made as 12 dB/octave. With enough power it can work.

Back to the original question of the thread, I'd note subwoofers for home use are generally not that large-even the big ones aren't huge compared to the size of their woofers. To reproduce low frequencies without massive EQ in relatively small boxes you more or less have to use pretty heavy cones (like car audio subs as an extreme example). In a full range speaker this would mean really low efficiency across the audio band-but that doesn't matter for a sub.
Fostex 31.5 Super Woofer. You can order that driver on Madisound for $5909.

GQ1022_FinalShot_01.jpg
 
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