Author Topic: Setting LPF of LFE to anything lower than 120Hz....a cure for muddy bass?!  (Read 1223 times)

Offline desray

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As you guys are aware, I have sold my Anthem MRX Receiver and jumped back to Audyssey (again) after almost 1 year. My last Audyssey AVR was the Denon X7200WA flagship. So it is not something alien to me when it comes to calibrating using Audyssey. While there is only so many things you can do to adjust the settings on a AVR with Audyssey - like playing with the crossover setting, distance and level (none of these will affect the EQ filters, so no worries and play till your heart content!)...there is "one" particular setting that is rarely been touched. Something which most of us regarded as a "sanctity". Yes, I'm talking about the Low Pass Filter (LPF) of LFE. This is NOT to be confused with the crossover setting and bass management system which exist between the speakers and the subwoofer(s). The LPF for LFE is related to the Low Frequency Effect (LFE) of the authored content of a movie or music being played. This is NOT system dependent (unlike crossover setting) but "content" dependant. This is the "tricky" part...for the most part, 120Hz is the default filter for this LPF of LFE. The risk of setting a lower filter than 120Hz for the LPF is that any LFE content present in a movie or music track "may" not be able to reproduce, thus "losing" some of the "intentional" bass (LFE) that the studio sound engineers intended.



I have been reading and experimenting with this LPF of LFE for the past 1 week or so since I got the new Denon Flagship, the AVC-X8500H. Apart from the mandatory Audyssey calibration that we must performed, there is always this somewhat "imperfection" that existed that some of us can't put a finger to. Some hated Dynamic EQ (DEQ) to the core as it makes the whole system sounded "boomy" which tends to muddle the whole soundstage to say the least. So many choose to either turn off the DEQ completely or worse, turn off the Audyssey Curve (Reference) completely off! This is definitely NOT a viable solution imo. What we wanted to achieve here is to have Audyssey Curve (Reference) turned on as well as DEQ.

Let's take a look at DEQ...how does DEQ "screw-up" my bass response?! Well, to put it simply, UNLIKE LPF of LFE, every change effected by the DEQ will affect the whole speakers in the array - e.g. 7.2.4 or the typical 5.1/7.1. Now this is going to be a problem as DEQ will "dynamically" analyze every sound tracks within a scene and altered its filter to conform to the Audyssey Target Reference Curve which naturally has a roll-off at about 4KHz. This is good and bad...the "bad" part is any appreciation in bass response will ultimately affect the entire 7.2.4/7.1/5.1 speaker arrays which ultimately contribute to that "muddiness" in bass.

So is there a way to "tame" it?
Well, there might be a "way" but it ain't perfect. Yes, some might have guessed it by now, that is to adjust the LPF filter from 120Hz to somewhere in between 110Hz and 80Hz. DO NOT go lower than 80Hz as this is minimum threshold for most movies and music content. Take note there is absolutely not mandatory for you to set the LPF for LFE to anything <120Hz. This is for those who faced "boomy" bass that just simply can't get it to work right if DEQ is engaged. For me, this I've set the LPF at 100Hz which provides me with the "right" amount of mid-bass slam and also "tightens" up the bass response in the process. It may also helped with dialogue intelligibility as well. For some of the movies, I do found the default 120Hz to have a bit more "omph" but for the majority of the movies I have had played which ranged from Jurassic Park (DTS:X) to Lord of the Rings (DTS-HD MSTR) which are all bass-heavy, I find the deep end of the bass (20Hz - 40Hz) to be just fine but mid-bass is the most "tricky" part as it may robbed you of that mid-bass slam (for me is around 70Hz - 150Hz) for certain movies. But I've read that majority of the Hollywood movies are authored with a LFE (.1 content) of 80H and below. Interestingly. I've also found that with LPF set at 80Hz, it sounded even better than the default 120Hz!



Caveat
Take note that, you will need to play around with your crossover settings for your speakers and the subwoofer(s) while you make changes to your LPF setting. What I will do is to play some familiar movie scenes or music tracks while you make the adjustments. Take note this DOES NOT preclude the fact that you STILL need to ensure a proper Audyssey calibration has been performed. Hence I would say this is more of a compromise rather than a complete antidote to "cure" that "less-than-stellar" bass response after Audyssey calibration.

Do report back your findings if you decide to give it a try. :)
« Last Edit: July 13, 2019, 14:47 by desray »

Offline ronildoq

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💪🏻💪🏻

I have this LPF for LFE at 100hz as well, u r absolutely right with your experiment work above, for me I’ve also liked to focus on content from 10-70hz, this is where most of the special effect action happens, especially 30-70hz. It’s never good to have a null at this region

The ones below 30hz down to 10hz, is where it sets the entire system apart from the pack...

Setting it at 100hz means it starts to roll off early about 95hz or so, depending on the filters use, if I recall correctly, the avr filters uses a 12db octave slope, it starts to roll off by -3db by 100hz ,so on and -12db by 200hz. it’s no different from a shelving filter... it doesn’t eliminate content by setting it to 100hz, just reduces volume -6db at 150hz and -12db as u approach 200hz, in layman terms

That is why I always advocate using a house curve for the target curve, this house curve, should ideally be in line with the lfe target curve as well, and the rest of the speakers, then the whole set up will be seamless

By the way, why did u sell the anthem ? I thought u loved the anthem?

Offline desray

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💪🏻💪🏻

I have this LPF for LFE at 100hz as well, u r absolutely right with your experiment work above, for me I’ve also liked to focus on content from 10-70hz, this is where most of the special effect action happens, especially 30-70hz. It’s never good to have a null at this region

The ones below 30hz down to 10hz, is where it sets the entire system apart from the pack...

Setting it at 100hz means it starts to roll off early about 95hz or so, depending on the filters use, if I recall correctly, the avr filters uses a 12db octave slope, it starts to roll off by -3db by 100hz ,so on and -12db by 200hz. it’s no different from a shelving filter... it doesn’t eliminate content by setting it to 100hz, just reduces volume -6db at 150hz and -12db as u approach 200hz, in layman terms

That is why I always advocate using a house curve for the target curve, this house curve, should ideally be in line with the lfe target curve as well, and the rest of the speakers, then the whole set up will be seamless

By the way, why did u sell the anthem ? I thought u loved the anthem?

Some correction there...the filters is using 24db octave, so the decrease will be much steeper at -6db at 100Hz and -12db at 120Hz. And yes, you are right that it does not "eliminate" LFE content in this case. Using the Audyssey MultEQ Pro Editor App to add some boost in the region of 70Hz - 150Hz will help with the mid-bass slam.

The reason I'm selling off my Anthem is always the same reason which I always believe in...nothing last forever. I love Anthem ARC Genesis more than Audyssey and till this day, I still standby my claim on that...but reality sets in, Anthem MRX x20 series has reached its 3rd year already and I'm expecting to see Gen 4 coming soon, likelihood next year or so...so as a rule of thumb, it will be wise to let go while it is still the "current" flagship model to fetch better resale value. Chances are, I may switch to Anthem again or try something else (maybe Dirac Live built-in like AudioControl series) in the near future. For AudioControl, it is also in the same conundrum as Anthem MRX series AVR - i.e. coming to 3 years and furthermore it is only a 9 Channel amp which requires additional power amp to power an extra pair of Atmos speakers...I've sold off my Emotiva and Parasound Power Amp after I got the Denon AVC X8500H.

Offline ronildoq

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Oh, so the avr is using a steeper filter, that’s better then.

I see your point, buying a new product that has already been in the market for 3 years , at a premium $ will need justification

Dirac live is definitely the way to go... it’s ever evolving and has some very nice improvements  with the recent upgrades.. worth taking this route

Offline desray

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Just curious, anyone try lowering the LPF for LFE content to 80Hz/100Hz range? Any effect?

Offline sevenz

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I used  110hz after this thread started. So far so good. Bass seems cleaner. Hehe...

Offline desray

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I used  110hz after this thread started. So far so good. Bass seems cleaner. Hehe...

Have you try 90hz?


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Offline sevenz

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Have you try 90hz?


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Not yet...

My untested worry is lose too much lfe effects if it's set below 100hz.... ha... Cos I love lfe.

How's everyone findings so far if u set it below 100hz.... ?

Offline desray

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Not yet...

My untested worry is lose too much lfe effects if it's set below 100hz.... ha... Cos I love lfe.

How's everyone findings so far if u set it below 100hz.... ?

I set mine at 120hz (default). The reason I created this thread is for the benefit of those who find Audyssey DEQ is causing their bass to go awry.



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