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If you've spent weekends stuffing corners with oversized bass traps, measuring, shifting panels around, but that 70Hz crater still glares back at you from the frequency plot, then this is for you.

Here's the question I got from an email subscriber: "I know absorption can reduce peaks in the bass response, but will it also remedy nulls? How can I target dips when selecting DIY acoustic treatment for my room?"

He's basically asking whether he can really fill that 70Hz dip with absorption somehow, or if he's stuck with it.

I totally get that. I used to think this as well.

Let me flip the script on what you've probably been told about peaks and dips.

Peaks and Dips Are Two Sides of the Same Coin

Here's what most people miss: that dip at 70Hz and the peak at 140Hz (which you haven’t even looked at) aren't separate monsters you need to tackle individually.

They're dance partners.

Whether created by standing waves, room modes, or reflection-induced interference, these acoustic effects always come in pairs. When you add deep absorption in the right spot, something interesting happens:

• Peaks come down
• Dips come up
• Both move toward neutral

It's like pushing down on one end of a seesaw—the other end has to move.

The Real Question Nobody's Asking

But here's where it gets tricky (and where most acoustic advice falls apart).

The question isn't "Can absorption fix my null?"

The real question is: "What's actually causing this null in the first place?"

Because here's the thing—there are three completely different acoustic effects that can create that same 70Hz dip on your measurement:

1. Standing waves/room modes - Low frequency waves bouncing between parallel walls, creating interference patterns
2. Mirror point reflections - Sound bouncing off a surface back to your listening position, creating comb filtering
3. Speaker boundary interference (SBIR) - Reflections bouncing back to the speaker itself, not your ears

They all look similar on a frequency plot. But they require completely different solutions.

Why Chasing Individual Dips Is a Fool's Game

I used to spend hours trying to identify which effect was causing which dip. Move the mic here, measure. Move it there, measure again. Check the impulse response. Calculate time delays.

You know what I discovered?

In real rooms, all these effects sit on top of each other like layers of paint. By the time you've identified one, three more have complicated the picture.

That's why I switched to what I call the "shotgun approach."

Instead of playing acoustic whack-a-mole with individual problems, you treat based on first principles:

1. Place deep absorption where you expect to hit those three acoustic effects
2. Cover enough surface area
3. Then measure to see what's left

By the time you've done this properly, any remaining issues stand out clearly—and are much easier to identify.

The Uncomfortable Truth About Bass Absorption

Here's what nobody wants to tell you about fixing bass nulls:

You need 12 to 20 inches of total absorption depth to effectively treat frequencies between 50-100Hz and upwards.

I know. That's a lot more than the 4-inch panels everyone's selling.

But physics doesn't care about our room dimensions or budgets. Low frequencies have long wavelengths, and they need that depth to be absorbed.

(Yes, air gaps can help you cheat this a bit—I've got a whole video on maximizing air gap effectiveness if you want to go deeper.)

The Order That Changes Everything

Before you start ordering rockwool by the truckload, here's the hierarchy that will save you time, money, and frustration:

First: Nail your listening position and speaker placement. This is free treatment that most people skip. If you haven't found your room's "low-end sweet spot" yet, you're trying to fix problems that proper placement would eliminate.

Second: Add treatment based on first principles. Don't chase individual problems—create a comprehensive treatment plan that addresses the room as a system.

Third: Use EQ as the final polish. Yes, it works. No, it's not cheating. But it should be your last step, not your first, because it comes with compromises (latency, reduced headroom).

The bottom line: Stop thinking of peaks and dips as separate problems to solve. They're symptoms of the same acoustic effects, and when you treat the cause properly, both improve together.

Ready to stop guessing and build bass traps that actually work? My "Build A Better Bass Trap" course shows you exactly how to construct absorption that reaches down to 40Hz while keeping your room lively. Check it out here: Build A Better Bass Trap