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Topic: Is there a component that lowpass or bandpass filters the lfe channel? (Read 1673 times) previous topic - next topic
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Is there a component that lowpass or bandpass filters the lfe channel?

Ive recently started using foobar on a windows based pc as my main audio player and am generally a happy chap but have run into a problem

I play a lot of multichannel music (from 4.0 to 7.1, although not yet atmos) often from isos of sacds or dvdas. The problem Ive run into is that many of these discs are authored with fullrange content in the lfe channel and rely on the bass management settings of the player/decoder to remove the unwanted audio. The sony bdp-s6500 I was previously using as a media player did this for me but was too clunky and limited to use in other regards. Annoyingly, there doesnt seem to be a way to make my decoder (Emotiva UMC1) apply bass management to the hdmi multi pcm input so I need another solution

I use the subwoofer component to filter the low end of the 7 main channels to the lfe channel but it doesnt remove the >80hz content already present on the lfe channel

Ive tried the crossover component but it isnt the right tool for the job

Is there a foobar component that does what I'm looking for?
Are there any other vst options?
Obviously I can put a line level low pass filter between the decoder and amp as a last resort but Id rather keep all the processing in the pc if possible

with advance thanks for your input

Re: Is there a component that lowpass or bandpass filters the lfe channel?

Reply #1 –
Convolver can do this. Important thing about convolver: impulse must be of the same samplerate and the same channels count, as signal to which processing is applied.

As for VSTs, there is free multichannel EQ Voxengo Marvel GEQ, for example https://www.voxengo.com/product/marvelgeq/ If used multiple instances in row, equlizer can act as lowpass.

Re: Is there a component that lowpass or bandpass filters the lfe channel?

Reply #2 –
Thanks for that.
Ive installed convolver but have no idea what to do beyond that. Ive a feeling that as I playback media with a variety of samplerates, bit depths and channel counts, having to change this on a track by track basis will be too inconvenient to be useable

Ive installed a vst host but the only multichannel lpf I can find is the waves one which seems to only be available as part of a very expensive bundle.

Cascading GEQs is just too much of a blunt instrument. I need much more control of the cutoff frequency and slope than that can achieve

Is there any way to route a mono/stereo vst to the lfe channel using the matrix mixer?
 

Re: Is there a component that lowpass or bandpass filters the lfe channel?

Reply #3 –
Quote from: godathunder on
Ive installed convolver but have no idea what to do beyond that. Ive a feeling that as I playback media with a variety of samplerates, bit depths and channel counts, having to change this on a track by track basis will be too inconvenient to be useable
You can automatize DSP presets switching with foo_dynamicdsp - https://hydrogenaud.io/index.php?topic=96094.0 Latest version - https://hydrogenaud.io/index.php?topic=108904.msg988324#msg988324
Also you can use resampler in DSP chain before convolver.
Here are 2 impulses for convolver to do 80 Hz lowpass on LFE in 5.1 signal  - one for samplerate 44100 Hz and second for 96 kHz - https://www.dropbox.com/s/wgoun6wc5sg529u/5.1%20lowpass%20lfe.zip?dl=1
Disable "Auto level adjust" in convolver settings.

Quote from: godathunder on
Is there any way to route a mono/stereo vst to the lfe channel using the matrix mixer?
No.

Re: Is there a component that lowpass or bandpass filters the lfe channel?

Reply #4 –
Thank you very much for that, it's been a great help, a few albums that were unlistenable due to the fullrange info in the lfe channel are now listenable

Do you have a link to a resource where I could find more info about creating my own impulse files (for dummies) - Id like to try a few tweaks to better tune it to my system.

Is it possible to route the audio from vlc, media playing from my internet browser etc through the foobar processing? If not, do you know of any software that can apply similar processing globally to the pc's hdmi audio output?

I should probably just replace the emotiva processor with alternative hardware that does all of this but unfortunately my bank manager would currently be unhappy with that solution

thanks again for your help rollin

Re: Is there a component that lowpass or bandpass filters the lfe channel?

Reply #5 –
Quote from: godathunder on
Do you have a link to a resource where I could find more info about creating my own impulse files (for dummies)
"Empty" impulse is just one sample with maximum amplitude, surrounded with silent samples. It can be created, for example, in Audacity with Generate silence and then using Draw tool to "draw" one sample with maximum amplitude. Then apply to impulse the same affect you want to be applied to audio signal. This can be done in any audio editor.
Some questions about convolver are asked by wcs13 and answered by me in this and this threads.
To correct some of my statements in that threads , i should note that sometimes impulse needs to be pretty long to get high accuracy in lower frequencies. As you can see, impulses that you have downloaded, are long - ~500ms.

Quote from: godathunder on
Is it possible to route the audio from vlc, media playing from my internet browser etc through the foobar processing?
It is possible, using foo_record component and virtual audio card, but audio will be delayed, so not synced with video.

Quote from: godathunder on
do you know of any software that can apply similar processing globally to the pc's hdmi audio output?
Equalizer APO - https://sourceforge.net/projects/equalizerapo/ GUI for it - https://sourceforge.net/projects/peace-equalizer-apo-extension/