# LFE, LPF of LFE, crossover, Large/Small, main/main+LFE, confused about settings



## THX-UltraII

I have a Teufel Theater 8 THX-UltraII 5.1 speaker setup (http://www.areadvd.de/hardware/teufeltheater8.shtml). Am I correct with the following statements:

1. If I set the *Crossover Frequency *to 70Hz everything that contains bass in the signal that is send to the fronts, center and rears gets cut of and played by my subwoofer.
2. If I set the* LPF of LFE* on 120Hz all content in the (5).1 (LFE signal) up to 120Hz is produced my my subwoofer. Condition of this is to set the crossover on the subwoofer to OFF. 
3. THe LPF of LFE setting has nothing to do with crossover of frequencies of the main speakers.

If my above statements are correct, I still have remaining settings that I m not sure what to set them too. 

1. the setting *LFE* or *LFE+MAIN*
and
2. speaker setting *Small* or *Large*


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## JBrax

THX-UltraII said:


> I have a Teufel Theater 8 THX-UltraII 5.1 speaker setup (http://www.areadvd.de/hardware/teufeltheater8.shtml). Am I correct with the following statements:
> 
> 1. If I set the Crossover Frequency to 70Hz everything that contains bass in the signal that is send to the fronts, center and rears gets cut of and played by my subwoofer.
> 2. If I set the LPF of LFE on 120Hz all content in the (5).1 (LFE signal) up to 120Hz is produced my my subwoofer. Condition of this is to set the crossover on the subwoofer to OFF.
> 3. THe LPF of LFE setting has nothing to do with crossover of frequencies of the main speakers.
> 
> If my above statements are correct, I still have remaining settings that I m not sure what to set them too.
> 
> 1. the setting LFE or LFE+MAIN
> and
> 2. speaker setting Small or Large


You sound as though you have a pretty good handle on it. For your first question by selecting LFE+main all bass below the crossover point will be sent to both the sub and the mains. My experience is this produces over exaggerated bass and does not sound good to me. I prefer all bass going to my sub as that's what it was designed for as well as relieving my AVR's amp of the workload. As for question number two small or large I personally set all of my speakers to small with a crossover of 80. I have found this to sound the best on my system but to each his own. Tinker with it and take notes and choose the settings that sound best to you.


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## hearingspecialist

Crossover with a THX setup should be set at 80hz and your LPF set at 120hz. Based on the THX processing this should provide you optimum enjoyment. Saying that, to each is own and whatever sounds best to your ears in your room is what you should follow. Depending on your room correction setup/program, some processors will ask if THX and automatically set points for best high level listening, i.e. THX reference level.


Brian in Bakersfield...


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## Jungle Jack

Hello,
I am in agreement with the above Posts. Definitely set the LPF of LFE to 120hz. As your Speaker System is THX Ultra2 Certified, definitely set them to an 80hz Crossover which corresponds to a Small Setting on the AVR/SSP Bass Management. I would not do LFE+Main as it would set your Mains to Full Range whereas they are not Full Range Speakers. Truth be told, a tiny portion of Speakers can honestly go down anywhere close to 20hz and those that are cost as much as a very nice Automobile. So I would simply have the Subwoofer handle all frequencies below 80hz. I love Areadvd.de and spend a great deal of time there. Google Translate is a beautiful thing.
Cheers,
JJ


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## hearingspecialist

Subs look super cool and very interesting, would love to hear a set of those paired monsters :T


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## THX-UltraII

thxz for all replies guys. Really helpfull.

I now have the following settings:
- Small for all speakers
- Crossover freq. 80Hz
- LPF of LFE 120Hz
- setting LFE+MAIN/LFE set on LFE only

Last thing I need to know is my subwoofer setting. On what freq. do I put my subwoofer rotation button?


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## Kal Rubinson

THX-UltraII said:


> thxz for all replies guys. Really helpfull.
> 
> I now have the following settings:
> - Small for all speakers
> - Crossover freq. 80Hz
> - LPF of LFE 120Hz
> - setting LFE+MAIN/LFE set on LFE only
> 
> Last thing I need to know is my subwoofer setting. On what freq. do I put my subwoofer rotation button?


What button? Level? Crossover?


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## phreak

Since the only rotating "button" on a sub that affects frequency is normally the low pass crossover, set it to its highest frequency (or off/bypass) and all bass management will be done by the receiver.


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## Kal Rubinson

phreak said:


> Since the only rotating "button" on a sub that affects frequency is normally the low pass crossover, set it to its highest frequency (or off/bypass) and all bass management will be done by the receiver.


Ah. I missed the "freq." in the post.


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## phreak

Kal Rubinson said:


> Ah. I missed the "freq." in the post.


It's not often that I get to chime in where such an illustrious sharpshooter misses a minor detail, but I thought I would give it a shot. It was probably in one of Kal's informative technical posts in the past that I learned this stuff anyway.


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## Kal Rubinson

phreak said:


> It's not often that I get to chime in where such an illustrious sharpshooter misses a minor detail, but I thought I would give it a shot.


I shoot myself in the foot often because I read too fast.


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## THX-UltraII

Another question about this:

I bought a 'new' receiver, the Onkyo TX-SR876. This receiver has no SMALL/LARGE speaker option to choose from. I can however set the Xover frequency for each (FR, FL, CC, SR and SL) speaker individually. Does this mean if I set this Xover on 'FULL RANGE' (which is an option in the settings) the speakers are on 'large' and when I choose ANY Xover frequency (let s say 80) that this is the same as 'small'?

Also, there is a 'THX-subwoofer' option in the receiver which can be set on YES or NO. What does this do in both YES or NO?


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## Jungle Jack

THX-UltraII said:


> Another question about this:
> 
> I bought a 'new' receiver, the Onkyo TX-SR876. This receiver has no SMALL/LARGE speaker option to choose from. I can however set the Xover frequency for each (FR, FL, CC, SR and SL) speaker individually. Does this mean if I set this Xover on 'FULL RANGE' (which is an option in the settings) the speakers are on 'large' and when I choose ANY Xover frequency (let s say 80) that this is the same as 'small'?
> 
> Also, there is a 'THX-subwoofer' option in the receiver which can be set on YES or NO. What does this do in both YES or NO?


Excellent AVR you just got. 80hz on the Crossover is considered the Small Setting on THX AVR's. Provided you are not using tiny Bose Cube's or the like, 80hz is a good setting for a speakers. What Speakers are you using? Also change the LPF of LFE from 80hz to 120hz. Newer Onkyo AVR's now use 120hz as the LPF of LFE.


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## THX-UltraII

> 80hz on the Crossover is considered the Small Setting on THX AVR's


thxz. Thats all I needed to know.

You also know what the THX UltraII subwoofer YES/NO settings does?


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## Jungle Jack

Sorry. Do not use it unless you have a THX Certified Subwoofer as it engages BGC (Boundary Gain Compensation) Also, THX Subwoofers must match the I/O (Input/Output) characteristics of the THX Controller (AVR/SSP) Long story short, set it to no unless using a THX Subwoofer.


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## THX-UltraII

Jungle Jack said:


> Do not use it unless you have a THX Certified Subwoofer as it engages BGC (Boundary Gain Compensation) Also, THX Subwoofers must match the I/O (Input/Output) characteristics of the THX Controller (AVR/SSP) Long story short, set it to no unless using a THX Subwoofer.



I know the manual states to use it when you have a THX cert. subwoofer but what I want to know is WHAT is actually done by the AVR when selecting YES (or NO). Does something happens with the EQ, PHASE or TIME ALIGNMENT and if so, what happens to this? etc.

You can select THX Cert. Subwoofer YES and bound.gain comp. OFF so there must be a difference between NO and YES(with bgc off)


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## Jungle Jack

I covered that when I discussed THX Subwoofers matching the I/O characteristics of the THX Controller. THX Subwoofers. That is they have higher voltage levels to ensure the THX mandated 20db of additional Headroom for the Subwoofer over the THX Certified Loudspeakers. This is because THX Loudspeakers do not go much lower than 80hz by design as THX strongly recommends an 80hz XO for all channels and thus the Subwoofer is tasked with handling both the Bass for LFE and all speakers.


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## THX-UltraII

Jungle Jack said:


> I covered that when I discussed THX Subwoofers matching the I/O characteristics of the THX Controller. THX Subwoofers. That is they have higher voltage levels to ensure the THX mandated 20db of additional Headroom for the Subwoofer over the THX Certified Loudspeakers. This is because THX Loudspeakers do not go much lower than 80hz by design as THX strongly recommends an 80hz XO for all channels and thus the Subwoofer is tasked with handling both the Bass for LFE and all speakers.


My subwoofer IS thx-ultraII certified indeed (Teufel M11000SW) but I looked at it s specs and the voltage seems about average (about the same as eg. the SVS PC13 Ultra). 80% of home cinema people have their [email protected] so they all have the same 'problem' that their subwoofer has to handle both the LFE signal and freq. from the satelites under 80Hz.

I still think there is something more about this setting. The best to find out is take measurements with THX subwoofer YES and NO and compare them. I ll do this this weekend.


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## THX-UltraII

Guys, I need to know something (I know what the LPF of LFE setting does):

What if my AVR (Denon 2808) DOES NOT have a LPF of LFE setting? What will happen with the LFE content from 80Hz and up? Will I lose it or does it mean that when a AVR does not have the LPF of LFE option it sends all the LFE signal by default to the subwoofer without a upper filter?


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## phreak

THX-UltraII said:


> does it mean that when a AVR does not have the LPF of LFE option it sends all the LFE signal by default to the subwoofer without a upper filter?


Yes


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## THX-UltraII

phreak said:


> Yes


ok, but it is not expected that there will be much information above +-110Hz on a movie track is there? Because I would not like it if my subwoofer plays eg 250Hz tones.


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## Moonfly

THX-UltraII said:


> My subwoofer IS thx-ultraII certified indeed (Teufel M11000SW) but I looked at it s specs and the voltage seems about average (about the same as eg. the SVS PC13 Ultra). 80% of home cinema people have their [email protected] so they all have the same 'problem' that their subwoofer has to handle both the LFE signal and freq. from the satelites under 80Hz.
> 
> I still think there is something more about this setting. The best to find out is take measurements with THX subwoofer YES and NO and compare them. I ll do this this weekend.


Dont forget the LFE channel is hotter than the standard channels, so the redirected bass really just gets 'lost', though its not actually lost. 

To the THX guy. You might find you DVD/BR player has a LPF setting you can use if you like. Probably worth checking. The LFE channel is only encoded upto 120hz, so your subs is never going to player higher than that anyway, and IIRC, many films dont actually bother to use the 80 - 120 hz range anyway, though I stand to be corrected on that.


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## THX-UltraII

Moonfly said:


> Dont forget the LFE channel is hotter than the standard channels, so the redirected bass really just gets 'lost', though its not actually lost.
> 
> To the THX guy. You might find you DVD/BR player has a LPF setting you can use if you like. Probably worth checking. The LFE channel is only encoded upto 120hz, so your subs is never going to player higher than that anyway, and IIRC, many films dont actually bother to use the 80 - 120 hz range anyway, though I stand to be corrected on that.


thanks, but why do many AVRs these days have a 250Hz LPF of LFE option then?


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## Moonfly

I cant give up a definitive answwer on that. Some subs built in filters also go that high. I suspect its to cater for those who might run multiple subs in more music orientated setups or studio's but still run low level connections


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## imtiaz

I have been reading (and learning!) with great interest the opinions by the experts. I would request somebody to help me on my set up.

AVR: Onkyo TX-NR609 THX Select2Plus

Fronts: PSB Image T55 Tower 
Center: PSB C40
Sub: Polk Audio DSW Pro 600
Surrounds: Polk Audio 
(Speakers and sub are not THX certified)

Settings: Fronts and Center - 80Hz
LPF of LFE: 100Hz 
Low Pass on Sub: 120Hz

Can some please advise me if this looks OK? It doesnt sound too bad though!


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## Jungle Jack

imtiaz said:


> I have been reading (and learning!) with great interest the opinions by the experts. I would request somebody to help me on my set up.
> 
> AVR: Onkyo TX-NR609 THX Select2Plus
> 
> Fronts: PSB Image T55 Tower
> Center: PSB C40
> Sub: Polk Audio DSW Pro 600
> Surrounds: Polk Audio
> (Speakers and sub are not THX certified)
> 
> Settings: Fronts and Center - 80Hz
> LPF of LFE: 100Hz
> Low Pass on Sub: 120Hz
> 
> Can some please advise me if this looks OK? It doesnt sound too bad though!


Nice setup and looks great. Only thing I would do is change LPF of LFE to 120hz as there can be information up to 120hz in the LFE Channel and setting it lower could cause a gap.


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