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Solving Bass Nulls with DSP or not ?

HarmonicTHD

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I don't have good news for you either. I have the same problem as you, sitting in the middle of the room and have huge dip between 40 and 60hz. Take a look at my EQ
View attachment 216656

However, this 12dB boost doesn't do miracles. It only mitigates the dip for 6dBs

View attachment 216657
See the comment from DonH56 above. Dont boost Nulls. Especially Not by a whopping 12dB. It’s futile due to the cancellations, stresses your speaker and even increases distortion. See the thread above plenty of good advice eg sub location, multiple subs (MSO) all the way to bass traps

Edit. Typo
 
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See the comment from Dough above. Dont boost Nulls. Especially Not by a whopping 12dB. It’s futile due to the cancellations, stresses your speaker and even increases distortion. See the thread above plenty of good advice eg sub location, multiple subs (MSO) all the way to bass traps
Thank you for your advice, but boosting narrow dip (7Q bandwidth) is not that "deadly" for the amplifier and/or speakers especially in the sub bass region where the speakers roll off naturally. Also, you can see on the second picture it does help a bit but does not solve the problem completely. Btw I have 1 subwoofer as well
 

HarmonicTHD

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Thank you for your advice, but boosting narrow dip (7Q bandwidth) is not that "deadly" for the amplifier and/or speakers especially in the sub bass region where the speakers roll off naturally. Also, you can see on the second picture it does help a bit but does not solve the problem completely. Btw I have 1 subwoofer as well
Can’t cheat physics. Again read the very detailed and expert explanation by DonH56. You are introducing distortions by boosting your sub by that much and can clip your amp as well. Do you know how much more power 12dB is?

But hey your system. Do want you want. It’s just real bad advice

Edit. Typo.
 
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levimax

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Thank you for your advice, but boosting narrow dip (7Q bandwidth) is not that "deadly" for the amplifier and/or speakers especially in the sub bass region where the speakers roll off naturally. Also, you can see on the second picture it does help a bit but does not solve the problem completely. Btw I have 1 subwoofer as well
After I create a strong corrections like this I like to play a 0 dB sweep (you can generate them with REW) and listen for digital clipping, which is obvious. I have had corrections that were supposed to take everything into account result in strong digital clipping at certain frequencies. Analog clipping can sound bad but digital clipping sounds way worse.
 
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After I create a strong corrections like this I like to play a 0 dB sweep (you can generate them with REW) and listen for digital clipping, which is obvious. I have had corrections that were supposed to take everything into account result in strong digital clipping at certain frequencies. Analog clipping can sound bad but digital clipping sounds way worse.
Ofc. I've activated the roon headroom manager and the signal clipping indicator. The overall gain is adjusted to -4db, otherwise I would clip the signal
 

levimax

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Ofc. I've activated the roon headroom manager and the signal clipping indicator. The overall gain is adjusted to -4db, otherwise I would clip the signal
Interesting... I found I had to lower overall gain by 4 dB in addition to all the "automatic gain managers" ( I use Foobar 2000) as well to eliminate digital clipping. I wonder if in order to preserve headroom the "automatic" tools allow for some digital clipping.
 
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atoprak

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Btw....
This is my current setup without sub....
1657056399633.png



And this is with the sub...

1657056772051.png


I still have some dips here and there but at least have some low end with the sub... this is of course within my listening position ...

I am trying to get some sensible positioning for the possible second sub .. but couldn't figured out yet.
May be I should get the mic and try to import real measurements instead of simulation.
 

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Interesting... I found I had to lower overall gain by 4 dB in addition to all the "automatic gain managers" ( I use Foobar 2000) as well to eliminate digital clipping. I wonder if in order to preserve headroom the "automatic" tools allow for some digital clipping.
I don't think the "automatic" headroom tools will allow some digital clipping, otherwise they'll be useless
 

levimax

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I don't think the "automatic" headroom tools will allow some digital clipping, otherwise they'll be useless
Foobar2000's convolution plug in definitely allows digital clipping with "automatic level control" on with a 0 dB sweep. I have to add -4.5 dB of gain to prevent it.
 

DonH56

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12 dB boost = 16x additional power relative to 0 dB.

Sound waves at a boundary will ideally exhibit zero velocity and maximum pressure (for any frequency).
 
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ppataki

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After I create a strong corrections like this I like to play a 0 dB sweep (you can generate them with REW) and listen for digital clipping, which is obvious. I have had corrections that were supposed to take everything into account result in strong digital clipping at certain frequencies. Analog clipping can sound bad but digital clipping sounds way worse.

I personally use volume control as the first item in the audio chain (Jriver's internal 64-bit volume control), ensuring there is no clipping further down the chain

I have elaborated that in the below thread:


Btw this thread also contains a good example of successfully correcting bass nulls with EQ.....
 

levimax

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I personally use volume control as the first item in the audio chain (Jriver's internal 64-bit volume control), ensuring there is no clipping further down the chain

I have elaborated that in the below thread:


Btw this thread also contains a good example of successfully correcting bass nulls with EQ.....
Digital clipping and analog clipping are completely different things. If a "room EQ filter" causes digital clipping at a boosted frequency it will sound bad regardless of the volume control position. In general it is better to error on the side of analog clipping and avoid digital clipping at all costs.
 

ppataki

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Digital clipping and analog clipping are completely different things. If a "room EQ filter" causes digital clipping at a boosted frequency it will sound bad regardless of the volume control position. In general it is better to error on the side of analog clipping and avoid digital clipping at all costs.
If you lower the signal before any room EQ filter (or any filter for that matter) well enough then it will be impossible for any filter to cause digital clipping
I apply boosts of up to 22dB and there is zero digital clipping all along the chain since the volume is adequately lowered at the start of the chain
It is all about headroom management
 

levimax

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If you lower the signal before any room EQ filter (or any filter for that matter) well enough then it will be impossible for any filter to cause digital clipping
I apply boosts of up to 22dB and there is zero digital clipping all along the chain since the volume is adequately lowered at the start of the chain
It is all about headroom management
If you are talking about lowering the "level of the digital signal" before any digital filters are applied then you are correct but that is not how all media players work. Most rely on some type of automatic analysis of the filter that hopefully reduces digital volume pre-filter by enough to prevent digital clipping. I thought they always worked but they don't. Have you every run a recording of a 0 dB sweep through you system and listened for digital clipping? With a 22 dB boost headroom management is obviously important but it comes at a huge cost.... if you had 1,000 watts per channel with 22 dB of "headroom management" you now have a system that plays as loud on average as a 6.3 watt system.
 
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With a 22 dB boost headroom management is obviously important but it comes at a huge cost.... if you had 1,000 watts per channel with 22 dB of "headroom management" you now have a system that plays as loud on average as a 6.3 watt system.
I don't think your are right here. The sentence above will apply only if you boost whole frequency spectrum for a 22dBs. I don't say its harmless, but once again, boosting narrow region where the music doesn't have much energy is not a tragedy.
 

ppataki

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Here is another example where extreme heavy corrections were applied and it just works fine:


On one of the pages there is a part where I am showcasing the bass null corrections too

I would say that in general people refrain from doing these kind of things since they hear from everywhere that 'it is from the devil'....
I believe that one shall give it a try, it might work or it might not in a given room with a given gear
 

Hipper

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Hello everyone,

I am having a bit of trouble with my setup in my new living room.
I have a pair of Monitor Audio RX6, driven by Creek Audio Evo50 amp. I use Bluesound Node and a Marantz CDP as the source components.
I have also added BK audio XLS 200 subwoofer to mitigate bass null point in my listening room.

Before the addition of the subwoofer I had very tiny bass output on my listening position. The reason is just because of the listening position as it is almost middle of the room ... (just bit close to front wall... ). I also seen that on REW simulation without sub .. and seen some dips around 60h-80hz and 110hz region ... I have added this sub to get bit more low end push and I actually did... now I get decent bass from where I sit but the other places even standup, I get bit boomy sound ... so the balance is not there ...

I am just wondering If I can fix these issues with an addition to miniDSP (with or without dirac) to system or not....

I am also keen on some changes.... may be switching to active speakers .... or event the streaming ones....

What I am looking for is general improvement on balance (with or without sub) and bit more fines .... I am listening on low to mid volumes in general..

Unfortunately changing listening position is not option since both wife factor and the general design of my living room.
Btw... I dont know how but my new Sony TV has a very tiny sub behind the panel which sound very good for the size even on my problematic listening position .. I dont know how but It does.... crazy

What do you think .. which direction should I follow ?

Thank you
You say that you get 'decent bass where you sit'. That's all that matters - where you sit. If it sounds bad in corners, at the ceiling or floor, anywhere else, it doesn't matter.

Generally your options to improve the sound are positioning, room treatment, DSP/EQ, and subs, or any one or combination of these. If you can have a dedicated room you can do what you like but of course in a family room your are limited.

Positioning. You might consider good positioning, of speakers and listening position, on a temporary basis, storing in more practical locations at other times.

Proper room treatment is usually big (especially to deal with the lowest frequencies) and ugly. You could buy smaller decorated panels to help control the higher bass.

I've never used subs but two or even four placed around the room should do good work. They need careful positioning and setting up.

DSP/EQ. I use an equaliser (a Behringer DEQ2496) and for me it finishes things off after careful positioning and lots of room treatment. I had a large wide null at 50Hz and tried everything to find what and where in the room it was but failed. As a last resort I used the Behringer and it filled it in. To this day I don't know why! I suggest you try and fill in any large null by adding a few dB to see what it does. Most people say that narrow nulls aren't usually an issue.

DSP/EQ is great at reducing peaks. Getting the peaks reduced will go a long way to enable you to play the music louder without annoying neighbours. Another thing that will reduce the volume your need to listen at is sitting closer to the speakers.

One thing room treatment does that I'm not sure DSP/EQ can do is reduce decay times. Reducing decay times gives tighter clearer sounds. Reducing reflections off walls, side front and rear, can also improve the crispness of the sound but some claim doing this reduces 'envelopment'.

Other factors can also affect the sound. Just moving your head slightly, backwards or forwards, or tipping your head downwards so you look to the floor, can give you more or less percussion for example. So does putting your hands behind your ears, or bending your ears forward!
 

Willem

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I still have some dips here and there but at least have some low end with the sub... this is of course within my listening position ...
Please realize that these are not measurements but simulations. Such simulations are a nice starting point, but no more than that, particularly if your room is not as regularly shaped as the simulation presupposes. My advice would be to get a Umik-1 measurement microphone, and measure actual response using REW, and investigate alternative locations for the sub. Try to decorrelate the subwoofer location from the location of the main speakers.
 

Andysu

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get lots of plasterboard sheets timber and need few guys to assist that all understand the same thing .
take all the sub bass speakers of same make model outdoors . set them up on the surface in same way as the room .
next play the sine wave tones and run the frequency sweeps for overlay graphs .
next start placing the timber frame plasterboard walls up piece by piece while still doing the sine and frequency sweeps or pink noise filtered on the REW while all the microphones placed within the area and some on the outside of the area and see what actually happens, while making hours worth of videos otherwise no one will believe ?

you'd then see what is actually happening with the sub bass or bass wavelengths spl dB , whatever . i'd chose open desert like that area-51 alien encounter desert that is wide open for miles for sub bass testing .
 
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atoprak

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get lots of plasterboard sheets timber and need few guys to assist that all understand the same thing .
take all the sub bass speakers of same make model outdoors . set them up on the surface in same way as the room .
next play the sine wave tones and run the frequency sweeps for overlay graphs .
next start placing the timber frame plasterboard walls up piece by piece while still doing the sine and frequency sweeps or pink noise filtered on the REW while all the microphones placed within the area and some on the outside of the area and see what actually happens, while making hours worth of videos otherwise no one will believe ?

you'd then see what is actually happening with the sub bass or bass wavelengths spl dB , whatever . i'd chose open desert like that area-51 alien encounter desert that is wide open for miles for sub bass testing .
Sounds like a summer project :D
 
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