Story of Infrasonic Subwoofer (105db @ 8hz)

[RajithKumar]

It might not be clear..

Nice,is it the near field or listening position response.

 

[prateekatasniya]

Nice,is it the near field or listening position response.

Its at the listening position..
Subwoofer around 8-9 feet from the listening position.

 

[sud98]

Thats some seriously great graph. Can you please share details of the driver and the costs?

 

[prateekatasniya]

18" driver from faitalpro ( Italy)
Driver costs somewhere around 35k.

 

[oldmonk]

Hello sir

What are the cabinet external dimensions ?

Do you have a pic of the bracing and how much foam or stuffing is used to develop this subwoofer ?

 

[josealfredfernandes]

Story of achieving 105db at 8hz

I Bought genelec 8040b pair.(November 2015)

I Was awestruck by the bass it produced for its size and Felt why a subwoofer is needed for those speakers.

Later I Had the itch to experience frequencies down to 20hz, so bought genelec 7060b subwoofer after a couple of years.

"Awestruck moment again"

The depth and feel of bass with subwoofer got addictive. ( For both movies and music)
Next was the itch to build a monster subwoofer that's better than my existing sub,
Which can play with finesse when needed and satisfy both my movie and music needs.

After lot of studies on the technical front and also after studying the world class subs in the market, I understood Sealed sub was the way to go.

Performance down to single digit frequencies was my goal.

2 months of vigorous research and simulating many drivers, day in and day out, I found a way to achieve my target using an 18" subwoofer driver.

( Higher the SPL capability of a sub, lesser the strain on the driver leading to lesser distortion- no subwoofer can be overpowering in a room - overpowering bass is in the hands of the person setting the subwoofer volume)


After thorough study I understood DSP is a must to extract the best performance and to equalise to get flat bass.

As my crown xls1502 don't have on board dsp, I Bought Minidsp 2x4 ( a mistake- as Max output is 0.9 volts and I needed at least 2 volts to avoid clipping)

Spent hell lot of time trying various EQ filters.. both manual and REW generated filters.
Learning REW took time however results were breathtaking.

In this study process, I understood the importance of rock solid enclosures for best performance of sealed subs, and I built a sub enclosure as strong as possible with extensive bracing.

Another aim was to keep the weight of the subwoofer in check so that it could be moved relatively easily if needed.
Choosing driver with Neodymium magnet saved 4 kilos.
Chose 13ply 18mm birch plywood to make to cabinet more stronger,lighter and durable
Passive design meant Amplifier weight reduced and a single cable needed to connect the subwoofer.
This lead to a weight reduction of around 15 kilos.

After all this, I spent days and weeks on integrating my sub and did everything possible to get the best bass response possible.

Final result was absolutely jaw dropping performance.
I fall short of words to describe Pre and Post Calibration difference and also the difference between this 18" subwoofer and my Genelec 7060b is incomparable.
AQUAMAN is my favourite movie to test the sub or rather enjoy the real potential of the sub.
Passengers movie outside ship scenes have incredible tactile feel.
This tactile feel is a thing to experience for any audio enthusiast.

In room Max SPL at listening position -
105 db at 8hz ( limited by amp+minidsp)
120db at 30hz
Subwoofer location- corner
Room size - 16.5 x 13 feet

Will measure again once I upgrade the amplifier.
Expecting better performance.

Thank you for reading

It might not be clear..

Bro, how much will you charge to manufacture 1 unit for me?