Answered 80hz vs How low the speakers can go?

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Hi guys, I have another dilemma which I cant make a decision about. I have a pair of Monitor Audio Bronze 2s and a Monitor Audio Bronze centre; through a bit of experimentation with audio tests, I found that the fronts can go as low as 30hz and the centre 40hz (however my reciever crossover can only go as low as 40). My question is should I set them like this, 40 40, or stick to the standard 80hz? Feels like if I leave em both at 40 whats the point of a sub lol. Hope that wasnt too confusing.
 
The general consensus of opinion suggests it is better to set all speakers as being small if you have an active sub within your setup and limit the frequencies you send to them to those above 80Hz. The reasoning behind this is explored to some degree in the following:


Small vs. Large
Do you have a subwoofer in your system? Great. Then your speakers are small. Before you get all upset, read on. This is one of those audio myths whose time has come to be busted. To understand why, we need to talk about Bass Management.

In the early days of home theater it was thought that in order to reproduce the full movie surround experience at home it was necessary to place 5 large loudspeakers in the room. The reason for the size was the woofers. To play at theatrical reference levels and reproduce the deepest bass available in the content requires each speaker to have 12” or larger woofers. Let’s just say that this theory didn’t get very far by the real world.

A better and more practical approach came after studying human perception. The mechanisms that we use to determine the direction of arrival of sound depend on the frequency. At high frequencies the wavelength of sound is small and so sound coming from the side is shadowed by our head. That creates a level difference between the sound reaching the ear closest to the source and the ear on the other side. Our brain analyzes these level differences and produces an estimate of where the sound is coming from. But at lower frequencies, the wavelength of sound gets longer and our head is not large enough to produce a level difference at the two ears. Instead, we analyze the difference in time of arrival of sound at the two ears. Sound arrives first at the closest ear and we use that to determine the direction. But even that ability fails us below about 80 Hz. The wavelengths get very large and it was found in listening tests that 80 Hz is the frequency below which most people can not localize the direction of sound.

Taking advantage of this apparent “deficiency” in our hearing was what made home theater practical for millions of homes. Five satellite speakers of reasonable size could now be used because they no longer required large woofers. A subwoofer (or two) can reproduce the lower octaves and it can be placed out of sight since its content is not directional.

But there is also a practical advantage: directing the bass to a dedicated subwoofer channel with its own amplifier greatly improves the headroom in the main channels. The idea behind this was proposed in a Society of Motion Picture Engineers (SMPTE) meeting in 1987. The participants could not agree on the minimum number of channels required for surround sound on film. Various numbers were being shouted out until a voice was heard from the back: “We need 5.1”. Everyone’s head turned around to look at Tom Holman. He proceeded to explain what he meant: Take the low frequency content from all 5 channels and redirect it away from the satellite speakers to the subwoofer. If we do the math, then the content below 80 Hz is 0.004 of the audible 20,000 Hz bandwidth. But 5.004 didn’t sound as catchy so Tom rounded up to 5.1. By the way, don’t make the amateur mistake of calling it 5 dot 1. It is a decimal: 5 point 1.
Fast forward to the early 90s when the first DSP powered home theater receivers started to appear. Along with progress came complexity. Some industry forces believed that Bass Management should be an option that could be turned on and off by the consumer. That’s not necessarily a bad idea, but to make an informed decision requires much more knowledge about the system than what was available to the typical consumer. So, the Large and Small rule of thumb was established. The idea was to look at the size of your speakers and decide whether their woofers were “large enough” to reproduce the lowest octaves at the required levels. It was a noble thought, but looking at it 15 years later I believe that it has led to nothing but massive confusion. The poor consumer was led to believe that Large is somehow a good thing and was then left wondering why there was nothing coming out of their subwoofer.

Redirecting the bass to the subwoofer relieves the receiver amplifiers from having to work on reproducing the low frequencies and this greatly improves the headroom. If you happen to be using Audyssey MultEQ for room correction, you will achieve much better low frequency performance because the MultEQ subwoofer filters have 8x higher resolution than the filters in the other channels.

Here is a better rule: All speakers are Small. In today’s complicated AVR lingo that just means: If you have a subwoofer you should always turn bass management on. Always. Even if your receiver clings to the past and automatically sets your speakers to Large.
 
The general consensus of opinion suggests it is better to set all speakers as being small if you have an active sub within your setup and limit the frequencies you send to them to those above 80Hz. The reasoning behind this is explored to some degree in the following:
Well I always had them small anyway, I understand that bit but, sounds like in my case, instead of setting the crossover 40 40, so basically as low as they go, I should instead select 80 because ill be give the speakers a bit more headroom?
 
It's a bit more complicated than that as film soundtracks are mixed to perform with sounds below 80hz being designed for the sub. With boomy sound, especially with floorstanders then placement is critical. Also giving a higher crossover can help to clear up the mids giving clearer dialogue on a centre speaker. It is also important that your receiver's sub setting is LFE only and not LFE + Main.
 
It's a bit more complicated than that as film soundtracks are mixed to perform with sounds below 80hz being designed for the sub. With boomy sound, especially with floorstanders then placement is critical. Also giving a higher crossover can help to clear up the mids giving clearer dialogue on a centre speaker. It is also important that your receiver's sub setting is LFE only and not LFE + Main.
So maybe 80 for the fronts and higher for the centre? I have my LPF for LFE always set to 120hz.
 
Even with large floor standers I had my AVR set to use active bass management at 80Hz with them as I found it yield by far the best AV sound for TV/movies. If you don't like the result for music, then try pure direct mode or whatever you AVR calls it for stereo music.

I have since changed the fronts back to large (because music sound is important to me as well and I much prefer the sound for music when they get to use the fronts in large mode), but it took a lot of fiddling around with room eq wizard and measuring mics and subtle re-positioning of the fronts (along with convincing my wife they hadn't moved, or if they have then the cat must have done it ;)) to get the same level of bass control and clarity as well as much enjoyable sound for music.

For most people who maybe don't have the tools and/or urge to fiddle, I would strongly suggest just go with 80Hz all round.
 
So maybe 80 for the fronts and higher for the centre? I have my LPF for LFE always set to 120hz.

Just set all the crossovers to 80Hz unless you actually know there are lulls associated with the location of some of your speakers? The higher you set the crossover above and beyonfd 80Hz then the more likely it is that the audio being redirected to the sub will be localised to the sub. The reason 80Hz is recited as being the optimum point at which to redirect is because this is the point at which it has been determined that the human auditory system starts to localise frequencies. Not everyone can locate higher frequencies up to 200Hz, but more people start to the higher those frequencies get above 80Hz.

By the way, this implementation of bass management is the same as utilised within commercial movie theatres. It is also endorsed by THX and THX certified speakers do not even need to portray frequencies below 80Hz in order to qualify for certification.
 
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Just set all the crossovers to 80Hz unless you actually know there are lulls associated with the location of some of your speakers? The higher you set the crossover above and beyonfd 80Hz then the more likely it is that the audio being redirected to the sub will be localised to the sub. The reason 80Hz is recited as being the optimum point at which to redirect is because this is the point at which it has been determined that the human auditory system starts to localise frequencies. Not everyone can locate higher frequencies up to 200Hz, but more people start to the higher those frequencies get above 80Hz.

By the way, this implementation of bass management is the same as utilised within commercial movie theatres. It is also endorsed by THX and THX certified speakers do not even need to portray frequencies below 80Hz in order to qualify for certification.
Thanks a lot, I'll just stick to 80hz then for them all. Not sure what you mean about lulls, all I know is that feeding my fronts with bass rising from 20hz to 200hz, is that my centre averaged around 40hz and the fronts 30hz.
 
Thanks a lot, I'll just stick to 80hz then for them all. Not sure what you mean about lulls, all I know is that feeding my fronts with bass rising from 20hz to 200hz, is that my centre averaged around 40hz and the fronts 30hz.


Some rooms effect certain frequencies in certain locations that result in those frequencies not being portrayed very well if a speaker is put in that location. These are termed lulls.
 
The low frequencies, bass tones, take the most amount of amplification power, so the more you offload onto an active sub, the more headroom you have on your AVR.

However, if you set them too high, you might actually hear sounds that you shouldn't coming from the sub (eg dialogue), which is not good.

If you get the Audyssey app, you can see how Audyssey measures your room, and have a play with all of the curves for the different speakers, look at the peaks and nulls, and limit the room correction frequencies. Hours of fun ;)
 
If its films then go with 80Hz, as the LFE is a dedicated channel, however with stereo (2 channel) music, then the sub is used to take over where the speakers roll off, (The subwoofer is not a separate channel) which you will need to do via trial and error if you do not have any measuring equipment.

Bill
 
The low frequencies, bass tones, take the most amount of amplification power, so the more you offload onto an active sub, the more headroom you have on your AVR.

However, if you set them too high, you might actually hear sounds that you shouldn't coming from the sub (eg dialogue), which is not good.

If you get the Audyssey app, you can see how Audyssey measures your room, and have a play with all of the curves for the different speakers, look at the peaks and nulls, and limit the room correction frequencies. Hours of fun ;)

You'll never hear dialogue coming from a sub. Subs can't handle frequencies higher than 200Hz and fialogue isn't apparent below 500Hz.


The reason you try not to direct the higher frequencies to the sub is because you shouldn't be able to localise where the sub is because of what it is outputting. It has nothing to do with preventing dialogue from eminating out of a sub. Frequencies higher than 80Hz can be localised by some people and the higher the frequency within the human auditory scale then the easier it is to locate where the audio is coming from.
 
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You'll never hear dialogue coming from a sub. Subs can't handle frequencies higher than 200Hz and fialogue isn't apparent below 500Hz.


The reason you try not to direct the higher frequencies to the sub is because you shouldn't be able to localise where the sub is because of what it is outputting. It has nothing to do with preventing dialogue from eminating out of a sub.
I have heard dialogue from my sub, which is why I mentioned it. Mainly the lower frequencies of male voices, when I was experimenting with crossovers. So, it has got something to do with that!

EDIT: Dialogue is definitely audible below 500hz!

The voiced speech of a typical adult male will have a fundamental frequency from 85 to 180 Hz, and that of a typical adult female from 165 to 255 Hz

Voice frequency - Wikipedia
 
I have heard dialogue from my sub, which is why I mentioned it. Mainly the lower frequencies of male voices, when I was experimenting with crossovers. So, it has got something to do with that!

You theoretically shouldn't be able to because humans do not create frequencies below 500Hz while speaking.
 
The voiced speech of a typical adult male will have a fundamental frequency from 85 to 180 Hz, and that of a typical adult female from 165 to 255 Hz

Voice frequency - Wikipedia


I was always lead to believe that the human voice didn't ordinarily create frequencies below 500Hz?

A voice frequency (VF) or voice band is one of the frequencies, within part of the audio range, that is being used for the transmission of speech.

In telephony, the usable voice frequency band ranges from approximately 300 Hz to 3400 Hz. It is for this reason that the ultra low frequency band of the electromagnetic spectrum between 300 and 3000 Hz is also referred to as voice frequency, being the electromagnetic energy that represents acoustic energy at baseband. The bandwidth allocated for a single voice-frequency transmission channel is usually 4 kHz, including guard bands, allowing a sampling rate of 8 kHz to be used as the basis of the pulse code modulation system used for the digital PSTN. Per the Nyquist–Shannon sampling theorem, the sampling frequency (8 kHz) must be at least twice the highest component of the voice frequency via appropriate filtering prior to sampling at discrete times (4 kHz) for effective reconstruction of the voice signal.

Voice frequency - Wikipedia


Okay, it relates to telephony, but it is more representative of recorded diaogue than measuring actual speech. What you are refering to is the Fundimental Frequency and not the voice frequency.


Maybe you are hyper sensitive to lower frequencies?
 
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Why don't you try it out? Set the centre speaker crossover high, say 120hz, then play back something with lots of deep male voices, and see if they come out of your sub?


I can and have set all my crossovers to 200Hz in the past and cannot either localise the sub or hear dialogue coming from it. Not everyone is the same though and some people are more sensitive to lower frequencies than other people are. Age is a contributing factor.

Note that some sat speakers are heavilly reliant upon a sub and need the crossovers to be set at 120Hz or higher.

Also note that the recommended crossover for Atmos speakers is 150 - 200Hz.
 
From Wikipedia....

The voiced speech of a typical adult male will have a fundamental frequency from 85 to 180 Hz, and that of a typical adult female from 165 to 255 Hz.[1][2] Thus, the fundamental frequency of most speech falls below the bottom of the "voice frequency" band as defined above. However, enough of the harmonic series will be present for the missing fundamental to create the impression of hearing the fundamental tone.
 
That is for telephony and cover the frequency range needed to make a voice easily intelligible.

For dialog production and some vocal production, its 80Hz upwards. I will typically low cut between 80Hz and 120Hz. From 120-200Hz that's a region that I will EQ for clarity and to minimise effects of the recording environment, mic positioning (proximity effect) etc and start to shape the character a bit if needed, so its a region that does matter.

Its another reason why a center channel at 80Hz makes a lot of sense. I often come across two issues with AVR center channel setups:
1. The speaker itself is sitting directly on a resonant wooden cabinet make dialog sound a bit woody or overly thick and some cases even a bit muffled - fix with gel feet, foam pads and place speaker at front of cabinet.
2. As the roll off of many center speakers is between 60 and 100hz, then AVRs auto setup might actually start boosting around here as compensation before they decide to give up and accept the lower limit. Fix is flatten out any boost at the low end. Dialog tends to be clearer when you err on the side of shelving cut below 200Hz than any boosts in that region - boosts in that region in production have to have a very good reason - I am far more likely to lower levels in this range unless the recording was too thin sounding for some reason.
 
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From Wikipedia....

Fundamental frequency. The voiced speech of a typical adult male will have a fundamental frequency from 85 to 180 Hz, and that of a typical adult female from 165 to 255 Hz. Thus, the fundamental frequency of most speech falls below the bottom of the "voice frequency" band as defined above.


And the voiced frequency listed above the fundimental frequency?
 
That is for telephony and cover the frequency range needed to make a voice easily intelligible.

For dialog production and some vocal production, its 80Hz upwards. I will typically low cut between 80Hz and 120Hz. From 120-200Hz that's a region that I will EQ for clarity and to minimise effects of the recording environment, mix positioning (proximity effect) etc and start to shape the character a bit if needed, so its a region that does matter.

Its another reason why a center channel at 80Hz makes a lot of sense. I often come across two issues with AVR center channel setups:
1. The speaker itself is sitting directly on a resonant wooden cabinet make dialog sound a bit woody or overly thick and some cases even a bit muffled - fix with gel feet, foam pads and place speaker at front of cabinet.
2. As the roll off of many center speakers is between 60 and 100hz, then AVRs auto setup might actually start boosting around here as compensation before they decide to give up and accept the lower limit. Fix is flatten out any boost at the low end. Dialog tends to be clearer when you err on the side of shelving cut below 200Hz than any boosts in that region - boosts in that region in production have to have a very good reason - I am far more likely to lower levels in this range unless the recording was too thin sounding for some reason.


This is good advice irrespective of what you determine the frequencies associated with dialogue to be.
 

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