UPGRADED TO FOUR SUBS - Still Chasing Perfect Bass

[honestmuggle]

Hello Guys,

I have 5.4.4 home theatre system, and I'm experiencing inconsistent bass perception across different seating positions in my living room size (13 feet in width and 19 feet in length, resulting in a total area of 247 square feet.), and the bass isn't as adequate as I had intended. I remember when I first planned to own a fully set up home theater system in 2022, I couldn't have been happier . I had my demo at Topgizmo in Noida which blew me away with the performance, even with just a single subwoofer. After demoing many subs, I finalized the SVS PB1000 Pro.


I bought them and had them installed in my living room. Soon, I realized that optimizing them was much more complex than the typical consumer-grade home theaters we're used to. So, I decided to experiment with various settings, learning about frequency response behaviors, crossover points, and level matching. Thanks to hifivision community and I read you guys a lot.
After some audyssey calibration my system somewhat improved, but I was still not satisfied. This hifivision community has been incredibly helpful in my trial-and-error process, teaching me about different aspects.


Considering the larger room size, I decided to invest further in a subwoofer, acquiring a second one to create a dual-sub setup. The difference was significant, but it still didn't achieve the perfect sound my ears and brain had perceived. I learned about Room Correction EQ, and with the help of a technical friend, I managed to fix the bass response in my room. Yet, after all that, I still felt I was missing the power and punch we all desire from a pro-grade system.


I was advised to go for three or four subs, which honestly irritated me. I thought the problem lay elsewhere, something I couldn't figure out. I believed simply adding more subs wouldn't solve the issue and it would be a waste of money; in some cases, even one sub can sound amazing. But despite my reservations, I did go for dual subs. Eventually, I lost hope, got used to what I had, and focused on my daily routines and responsibilities for forgot about it.


As time passed, my mind kept ticking, and I craved to try more. got some free time from work and my mind went experimental, so I planned to add two more subs but aesthetic was a concerns at home, and, of course, I had to ask my wife. Luckily, she agreed, knowing how enthusiastic I am. So, I bought two more PB1000 Pros and added them to my system making it total 4 subs in the room, placed them all four in the corners of the room. After getting the room correction EQ done again, I'm kind of liking it, yet it's still not what I had hoped for, considering the money I've poured into this, blindly with the intention of achieving that perfect bass and get the dopamine triggered. The bass is still lacking.




Now, I have a new problem I'd like to discuss and seek help with.


Although I achieved a good bass response at the main listening position with the help of UMIK and REW, it's not consistent in other spots. In our living room, we have multiple seating positions, and our family seats at different spots when watching movies. So, if I'm getting that good bass feel at main listening position, others might be missing it in nulled zones. I tried crawling to all positions in my room, but nowhere is the bass performing as well as the main listening position, which is quite sad because that was the whole purpose of having a total of four subs – to improve bass evenness and reduce seat-to-seat variation. I'm still missing that smoother bass across a wider listening area despite sacrificing aesthetics and going for all four subs. I'm not regretting buying multi-subs, but I am somewhat disappointed with the outcome. Am I over-expecting, or do I just need to find the right solution HERE?


Few more points to note

• All subs are in a sealed mode
• Sub frqeuency at 120Hz LFE, SUBWOOFER trim level is -9db.
• Dynamic EQ is Off (though after turning it on it does improve the bass but make it slightly boomy and also ruins my surround speakers) But I use it for stereo music.

SORRY FOR THE LONG POST, BUT ANY ADVICE AND HELP IS GREATLY APPRECIATED.​

 

[edjamesx]

There are pros and cons adding multiple subwoofers. The phase of subwoofers have to be tuned accordingly to get proper aligned sound in Mutiple sub woofer setup. Some people use mini dsp to control Mutiple subs to get properly aligned LFE sound. Having more than two subwoofers looks to be slightly overloaded but You may try different things which may work better which is listed below,

• Try Changing the phase control of each sub to get aligned frequencies. Make sure the gain settings are same in all subs.
• Try adjusting the sp-level and sp-distance of subs manually in AVR settings over Audyssy settings and check.(increase slightly 1 to 5 points)
• Keep array of "two"( place one sub near another sub parallelly) subs in one corner of room , and another array of two subs in another corner. Keeping it one top of another also good , but since your sub is designed that way , it may get damaged. REL sub has array of two subs model one above other.
• If not at all above thing worked, Try keeping all subs in parallel in the front in adjacent to LCR speakers. You need to adjust phase control correctly. If you notice any cinema halls behind scenes, they will keep the subs in parallel in align with LCR speakers. This will improve the punch and thump. if the phase control not set correctly here then sub may sound too much boom.
• Finally you may need to do some acoustics in the room which does not arrest LFE sound.

For larger rooms going with 1 or max 2 no of "15" or 18" subs will be more recommended since it can go deeper and will sound better. And the more powerful it will sound tighter and punchier.

 

[ajuvignesh]

If possible try auditioning ascando sv 12. Or you can simply try jbl’s pro 18 inch sub with external amp. Or perhaps a REL subwoofer. Svs cannot give the punch you’re looking far if my guess is right.

 

[ajuvignesh]

Hardcore gamer was in similar situation. He used dirac live for his svs pb2000 pro to bring back the midbass. If your receiver supports dirac live, try giving the demo account a shot.

 

[IndianEars]

FWIW:

247 sq ft is Not a large room, especially when using 4 subs !

Corner placement of subs will add a HUGE LF reinforcement of LF via Room resonance. (Did a Knowledgeable person recommend this? )

Probably easier to get Clean (Quality not quantity) by locating a Single ( maybe 2? ) In the central axis of your room running between your Left & Right Speakers and on the arc created by your left & Right Speakers, with yr listening position as the centre of that curve....

If you must use 2 Subs, maybe the 2 Sub located on the same axis either between the the 1st Sub & the Listening position, or behind the listner.

IMO, locating 4 subs in each corner is a not a good idea.....

 

[honestmuggle]

Hardcore gamer was in similar situation. He used dirac live for his svs pb2000 pro to bring back the midbass. If your receiver supports dirac live, try giving the demo account a shot.

Thanks for the reply, unfortunately, X3700H doesn't support DIRAC, only the X3800/X4800/X6800 models do.
now I wouldn't upgrade for just DIRAC unless I am truly convinced it would be a complete game-changer for my system.

 

[honestmuggle]

FWIW:

247 sq ft is Not a large room, especially when using 4 subs !

Corner placement of subs will add a HUGE LF reinforcement of LF via Room resonance. (Did a Knowledgeable person recommend this? )

Probably easier to get Clean (Quality not quantity) by locating a Single ( maybe 2? ) In the central axis of your room running between your Left & Right Speakers and on the arc created by your left & Right Speakers, with yr listening position as the centre of that curve....

If you must use 2 Subs, maybe the 2 Sub located on the same axis either between the the 1st Sub & the Listening position, or behind the listner.

IMO, locating 4 subs in each corner is a not a good idea.....

Even I used to think a single subwoofer could deliver great bass and one has to look for quality but quantity, but assuming the room allowed for it.
Trust me, I made endless efforts to make it work. If I had that option, I would have continued with a single sub saving my wallet a lot of stress.

But in my personal experience, especially in my living room, I faced the sad reality of standing waves create significant dead zones and an uneven, and unpleasant, bass response. That's why I've learned and would recommend a minimum of dual subwoofers for anyone seeking good bass if calibrated well; three are better, and four are the best, not excessive. Regarding placement, I agree it's not always practical for everyone, If I had a dedicated theatre room, I would have think. My living room, for instance, has aesthetic limitations, restricting me to corner placements. An alternative four-sub configuration with subs in the middle of each wall was also an option to my knowledge but my main listening position is right against the back wall.

 

[caspian1985]

Thanks for the reply, unfortunately, X3700H doesn't support DIRAC, only the X3800/X4800/X6800 models do.
now I wouldn't upgrade for just DIRAC unless I am truly convinced it would be a complete game-changer for my system.

What could be a game changer is the x3800H for a couple of reasons
1. 4 independent subwoofer outs, allowing independent calibration
2. Dirac Live Bass Control ( not just Dirac Live full bandwidth ) - this does an outstanding job on averaging the impulse response for multiple independent subs across 16 different measuring positions which is what your complaint seems to be
3. Future support for Dirac ART - supposed to be game changing beyond DLBC for bass management and currently only supported on Storm Processors

You’ll likely get the 3800H for 1L, the Dirac DLBC licenses another $600 or 55k, so 1.55 ( not counting Dirac ART ).

 

[Analogous]

Since you have spent so much time and effort in choosing the subwoofer (good quality and well regarded brand and model) and in getting the room correction software adjust the subs’ output according to your preferred placement, It’s good you are pausing to take stock of what has been achieved.
My suggestion would be to understand some basic acoustic concepts like standing waves, nodes and troughs.
These happen in every room without exception and irrespective of size.
Given the significant effort you have put in so far, it may be worth considering the following:

Moving the subs from the corners to positions where they can sound better: Please read up on the “subwoofer crawl” technique of speaker placement; start with one sub connected and add more repeating this procedure. This only requires time and physical effort, no further expense.

Adding bass traps (more expense and some aesthetic considerations) in the corners

Keep in mind you have more than enough quantity (4 large subs) it’s as you have pointed out an issue of quality.
Start with “room diagnosis” - understanding your room and how sound waves behave in it and try moving the subs little by little using the technique mentioned above or any other technique to get them in positions where they sound best to you. There unfortunately will still be spots share the waves reflect back and cancel each other out (no bass or null spots) and others where they add up. But since you have 4 subs this issue could be minimised as compared to using one sub.

Start with physics.

• Wavelength: The distance a sound wave travels in one cycle.
• Frequency: The number of cycles a wave completes per second, measured in Hertz (Hz). Bass frequencies in the human audible range are usually between 20-80 or 100Hz. These waves are moving from each sub in all directions, hitting the walls and other surfaces and bouncing back and forth till the energy is dissipated.
• Speed of Sound: The speed at which sound travels through a medium (e.g., air), roughly 340 m/s at room temperature.
  
  
• Relationship: Wavelength = Speed of Sound / Frequency.

1. 20 Hz:
   • Wavelength = 340 m/s / 20 Hz = 17 meters
2. 80 Hz:
   • Wavelength = 340 m/s / 80 Hz = 4.25 meters

Good luck and take care you don’t hurt your back.

Ps: you should explore other techniques too as the subwoofer crawl technique also has it’s limitations and critics

 

[ajuvignesh]

Thanks for the reply, unfortunately, X3700H doesn't support DIRAC, only the X3800/X4800/X6800 models do.
now I wouldn't upgrade for just DIRAC unless I am truly convinced it would be a complete game-changer for my system.

Or, you can try a minidsp if one is lying around and calibrating the subs with REW software. It might restore some of the midbass punch.

 

[rainbowsong2000]

If you're not looking to make a big investment or use Dirac, there's another option you can try—get the Audyssey MultEQ Editor app and use it to calibrate your subwoofer.

The benefit of using this app is that it allows you to tweak the EQ curve. From your graph, it looks like you're missing some of that midbass punch, which I think you're aiming for—it currently looks too flat. Try setting a gentle roll-off around 18Hz and apply a small boost of around +2dB in the 30–60Hz range to follow something closer to the Harman curve, something like below.



Try to move the subwoofers away from the corners .

Here's the link to the app:
Audyssey MultEQ Editor App – Google Play

Also, without a MiniDSP, it's very difficult to achieve consistent bass response across multiple seats.

 

[devdutta]

Have u done any acoustic treatment
Have u done any acoustic treatment especially for bass. From my experience in an untreated room bass will not be even or low as expected.

I had smilar issue with my dual pb2000 in my 24*14 room. The base was very boomy and inconsistent. I had addrrsed the issue with placement of subs ( at midpoint of front and back wall) and investeting in room acoustics.
Now the bass is even and smoother, deeper and it compliments the channels... like u can say the whole system producing the bass. Subs very much blend with rest of the system(7.2.6)

The intersection point of wall to wall and wall to celling are very vonurble to low freequency.
This is my observation in my room. Covering those ares with bass traps I have achieved good bass in my room atleast. Before that bass was very irritating in my case.
I have also got minidsp 2*4 HD and Umk1 but not used them so far due to time constrains.

 

[Surrealistix]

Have you tried the OCA Room correction tool for Denon/Marantz system. If not, you should give the latest version of his free software a try.

https://www.avsforum.com/threads/acoustica-latest-and-greatest-from-oca-for-denon-marantz-only.3324025/