BIG Bass in a Small Room - Making Infinite Baffle Subwoofers

After the very encouraging results I got from the open baffle subs experiment, I decided I'd go all in and put them directly in the wall. This is known as infinite baffle, where you are just getting output from the front of the drivers without any interaction with the back wave of the speakers.
My listening room's front wall has a utility room behind it, so it's nearly perfect for this setup. All I had to do was cut out the drywall directly behind the woofers to open them into the space. The utility room acts like an infinitely large box and completely eliminates cancellation from the back wave of the woofers.
I did have limitations on where in the wall I could put them, and this close to the floor isn't ideal. But the results are outstanding - flat bass extension down below 20Hz in the room and the woofers are neatly out of the way.
These are four 12" woofers with each pair wired in parallel (for a 4 ohm load) and driven by a 100 watts per channel Yamaha receiver that can deliver nearly 200 watts per channel into 4 ohms.
The "Mad Max" recording at the end was done on a Zoom H1 using the built-in mics from the listening position. The Zoom H1 has two mics built in for a "stereo" recording. Not the greatest mics or recorder, but close enough to give you an idea of how the room sounds.

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[IBuildIt]

After the very encouraging results I got from the open baffle subs experiment, I decided I'd go all in and put them directly in the wall. This is known as infinite baffle, where you are just getting output from the front of the drivers without any interaction with the back wave of the speakers.
My listening room's front wall has a utility room behind it, so it's nearly perfect for this setup. All I had to do was cut out the drywall directly behind the woofers to open them into the space. The utility room acts like an infinitely large box and completely eliminates cancellation from the back wave of the woofers.
I did have limitations on where in the wall I could put them, and this close to the floor isn't ideal. But the results are outstanding - flat bass extension down below 20Hz in the room and the woofers are neatly out of the way.
These are four 12" woofers with each pair wired in parallel (for a 4 ohm load) and driven by a 100 watts per channel Yamaha receiver that can deliver nearly 200 watts per channel into 4 ohms.
The "Mad Max" recording at the end was done on a Zoom H1 using the built-in mics from the listening position. The Zoom H1 has two mics built in for a "stereo" recording. Not the greatest mics or recorder, but close enough to give you an idea of how the room sounds.

[oglaz]

Woodworking audiophile, what a combination! Your studio looks amazing.

[Canadian_Eh_I]

Finally someone doing it right. This is more like how I'd build out my room if I owned my own house with a basement. Good job

[ArtturiSalmela]

That's a lot of bass.
The recording at the end did sound like being in a movie theatre, even with it coming through youtube and my open-back headphones.
The bass being inside the wall looks really cool, too! Nice job on the panels, one would not guess you had altered them like that.

[MarkAW]

Hi All - I have 4 x 15" original Adire Tempest subs in Manifolds build into the floor in my dedicated room. The floor cavity is the box.
2 Drivers in each Manifold, facing each each other to cancel mechanical vibration, with the top open into a hole in the floor. A manifold behind each main speaker, in the front corner.

Technically they are over-damped, QTS is 0.4, but Similar to John they extend well below 20hz. Rolloff stuff, F3 and all that....is irrelevant, it all happens so low it doesn't matter. As they are flat (room excluded) through the relevant frequencies, group delay is very low.

After EQ (Multiple Subwoofer Optimiser to EQ them together, then the Anthem ARC over the top), the in room response is very flat - but you will always be at the mercy of the room, and you can't move them around for a better response.

Excursion has never been a problem. At normal listening levels they barely move. There is no air spring to overcome, and loads of cone area. Therefore distortion is low.
At insane movie levels they move a bit....but the floor/room is shaking like crazy..and at ludicrous levels the floor feels like an earthquake. Power has never been a problem either, I drive them with a Rotel 200w per channel amp and have never clipped them.

But while they can go loud, it's really about a clean, articulated response that make your main speakers feel larger and opened up. Not chest-punchy car sub competition bass. (But with this much headroom, you can EQ whatever bass response you want.)

If you can do this...DO IT!

Anybody else remember The Cult of the Infinitely Baffled website?

[tgun]

A new acolyte in the Cult of the Infinitely Baffled. Very nice.

[FSXgta]

Your videos answer my questions better than digging through tons of forum posts on open baffle/infinite baffle

[Ben]

That in room response is perfect, lots of lows

[joesabato]

Welcome to the world of IB bass!

If you find that the direct wall mounting vibrates your front wall too much, make 2 more panels and build manifolds with the drivers opposing each other, with the opening where the drivers are now.

Block off 1 of the woofer holes in each panel for possible future expansion.

That setup will reduce/ eliminate any sympethetic vibrations that the drivers induce in to your wall

[GregsGarage]

I'm learning something new on every video!

[ScottGrammer]

It looks like your woofers are overdamped. This is a common problem when using conventional woofers in an infinite baffle system. A typical good quality woofer has a Qts of between 0.3 and 0.45. When installed in an acoustic suspension cabinet, the air in the cabinet acts as an additional spring to reduce the compliance of the woofer and raise the Q to a more desirable 0.7 - 1.0. Without the small volume of trapped air, the woofer's Q stays low, and so it is overdamped. This is what's causing the slow rolloff you're getting in the deep bass.

You could either try woofers made for infinite baffle, with a Qts of 0.7 - 1.0, or you could simply insert some power resistors between the woofers and your amplifier. Assuming your woofers are 8 ohms each, and the two on each baffle are in parallel, you could add a 2 ohm 200 watt resistor in series. This would waste a bit of amplifier power, but it would also raise the Qes (and therefore the Qts and Qb) of the system, flattening out the bass response. You can find such resistors for about $10-20 each, so it's worth a try.

[vikassm]

Circle cutter router jig using one threaded rod!! The idea is so simple and yet effective, cant believe I've never noticed it before in your videos! I'm gonna borrow your jig idea, thanks for the video! 👍👍

[Zarkoff]

I have been running two manifolds of six, 12" subs in my attic for the past few years and absolutely love the quality and quantity of the bass.

[ottohonkala]

Man - look at that flat response!!! 10-20Hz must feel amazing!

[JPWack]

This is beyond insanity, I love it. Consider the V8 thoroughly honored by your deeds.

[paulhirst]

What a great video and a nice finish to a huge project.

[gordiefrench]

Mr heisz
I am in new Brunswick and a friend built a infinite baffle for his theater setup
8 18" subs in a manifold mounted in his wall
Played the twister move and I was uncomfortable as in so real of a impact that I was scared.
I have never heard bass so strong smooth and extended

[michelevitarelli]

I also have an infinite baffle subwoofer setup in my theater. They are amazing. Great video. Thanks for sharing.

[BostonMike]

Your are a true craftsman and you got a lot better at speaker building

[bonzainews]

I'm glad I found this channel. Nice work.