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Addressing mid-bass null by adding sealed sub to existing ported sub

Sceri13

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If there is another thread discussing the successful use of mixing a ported sub (for low extension) and using a second sealed sub for mitigating a mid-bass null at the listening position with extreme room acoustics and placement issues, please direct me.

In short, I have a primary mid-bass frequency response issue with many variables and limitations I would like to address.

I currently have a single HSU VTF3 mk5 (15” ported) in the front right corner of the front stage wall (only placement option for a large ported subwoofer in the room). I have a ~6 db null in the 50 to 80 hz range, relatively strong output from 30 to 50 hz, and then a fairly steep progressive drop at 35 hz and below at the listening position. 30 hz may be the best I can ultimately hope for in terms of meaningful extended low frequency output.

I would like to address the 50 to 80 hz null to make music sound better, for now. I do not have the space to add a second VTF3. I would like to use a sealed subwoofer (such as the HSU ULS15 or SVS SB3000), with a high pass filter at 40 hz or so, to fill in the mid-bass region by utilizing strategic subwoofer placement of this second sub. Both listed sealed options have similar output to the ported VTF3 in the mid-bass region.

Room is huge given open floor plan and large opening to other areas. ~17,000+ cubic feet counting main and connected open areas. I know. My seating position is also the middle 40% of the room relative to the front stage wall. Nothing in this room is ideal and I accept the reality within the limitations.

I will only use two subwoofers total. I will use Audyssey XT32 Multi EQ (with Audyssey app) on a MARANTZ SR 8015 and any applicable subwoofer eq setting functionality for room correction.

I cannot utilize room treatments to any meaningful end given main living area aesthetics.

I know the common sentiment is that one should not mix ported and sealed subwoofers, but given I am only interested in addressing the mid-bass null, this seems a practical, if an imperfect approach at an attempt to retain the lower frequency response of the ported subwoofer in my problematic room.

Use is 50% music, 45% TV /movies, 5% gaming.

My goals are:

—Maximize subwoofer placement options via a smaller enclosure to achieve primary goals. 15” to 16” (18” max) width and depth.
—Mitigate the mid-bass null.
—Even bass frequency response. Yes, I know to properly pressurize my room and meaningfully increase frequency response down to 20 hz levels, I would likely need multiple Marty Subs. When I finish the basement….

Budget is $1200 to $1,500 for the second sub.

Given the above, would adding a second sealed sub-woofer such as the SB3000 (or ULS15) be worthwhile, in this scenario, to achieve my goals? I almost prefer the SB3000, only because it provides for the most placement options given its smaller dimensions. In the future, I may try dual sealed (and omit the ported) to see if the ability to strategically place both subs (instead of just one) improves anything in lower extension.
 
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Sceri13

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Disregard, the crossover switch on the back of my subwoofer somehow was flipped to in instead of out. That coupled with a 40 hz crossover setting on the sub vs 80 hz on my receiver was wrecking havoc on my frequency response.

I plan to stick with the one sub given I am now getting good enough results, all things considered.
 

JeremyFife

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Kudos for the posts. We learn, if we are first open to learning.

Glad you got it sorted :)
 
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