Room Correction Filter for <500Hz, and Only Gain Reduction above

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philmwchan
Posts: 2
Joined: 08 Feb 2021 16:03

Room Correction Filter for <500Hz, and Only Gain Reduction above

Post by philmwchan » 08 Feb 2021 16:36

Hi:

Is there a way to create a digital room correction filter in Acourate that only corrects the lower frequencies i.e. below 500Hz, and applies a gain reduction above 500Hz? It could be 500Hz or other frequency to be selected. I would like to correct the bass response, and have a slope gain reduction from 1kHz to end with a 6dB reduction at 20kHz with the capability to also add a BBC dip at 3KHz. I would like to generally retain the higher frequency characteristics of my passive crossover speakers, and have a general 6dB tilt and option to add BBC dip.

Regards,

Phillip
In-Ear
Posts: 47
Joined: 02 Jan 2020 18:41

Re: Room Correction Filter for <500Hz, and Only Gain Reduction above

Post by In-Ear » 08 Feb 2021 16:51

Hi Phillip,

so what exactly is it you do not want to correct above 500Hz? Reducing gain and adding a dip is also a correction and can easily be done by the target curve designer. If you want a smoother correction choose a a small value for the second value (heights) in Macro 1 and/or for excess phase correction in Macro 4.

The BBC dip could also be applied by e.g. a pre-filter.

Best regards,
Jörn
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UliBru
Posts: 434
Joined: 19 Oct 2019 13:58

Re: Room Correction Filter for <500Hz, and Only Gain Reduction above

Post by UliBru » 08 Feb 2021 16:58

philmwchan wrote:
08 Feb 2021 16:36
Is there a way to create a digital room correction filter in Acourate that only corrects the lower frequencies i.e. below 500Hz, and applies a gain reduction above 500Hz? It could be 500Hz or other frequency to be selected. I would like to correct the bass response, and have a slope gain reduction from 1kHz to end with a 6dB reduction at 20kHz with the capability to also add a BBC dip at 3KHz. I would like to generally retain the higher frequency characteristics of my passive crossover speakers, and have a general 6dB tilt and option to add BBC dip.
Yes, there is a way. Please try the following manual steps:
1. Macro1 as usual
2. create the desited target as usual. Drag the target by the left marker to a position where it crosses the measurement. Everything above the target will be corrected - keep this principle in mind when you set the target height.
3. Apply FD-Functions - Amplitude Difference and compute Target minus Pulse48Lmp and Pulse48Rmp - linearphase!
4. Apply FD-Functions - Amplitude Limiter - 0 dB to both results
5. Now search a position around 500 Hz where both curves are 0 dB. Right-click with mouse in the chart to set a marker
6. Apply TD-Functions - Phase Extraction - minphase with below=0 and above = marked frequency (button RM takes the marker frequency) to both left/right results. This will limit the correction to 500 Hz, only peaks get corrected.
7. Save the results as Pulse48Linv and Pulse48Rinv
8. Proceed with macro 4 as usual
Stay well tuned
Uli

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Acourate system: JRiver/Roon -> AcourateConvolver -> miniDSP U-DIO8 -> TacT M/S2150 amps -> DIY horn speakers
philmwchan
Posts: 2
Joined: 08 Feb 2021 16:03

Re: Room Correction Filter for <500Hz, and Only Gain Reduction above

Post by philmwchan » 08 Feb 2021 17:40

Thanks for the replies. Will try.
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