How to Soundproof a Cardboard Box; Lower the Amp Noise!

Making a soundproof cardboard box is something they usually make you do as a school project, but soundproof cardboard boxes can have real-life applications.

The most common reason to make one is for recording music at home, especially electric guitar.

This is because in order to get the most out of a tube guitar amp, it needs to be cranked all the way up, this makes it sound a lot better.

But playing late at night with a powerful amp isn’t something your neighbors are going to like.

Here’s where the soundproof cardboard box comes into play; you can simply put the amp inside, still be able to crank it and not disturb the neighbors at the same time.

In this article I will teach you how to build a soundproof cardboard box cheaply and fast. You still will need to purchase a couple materials which I’m also going to list here.

Table of Contents

  • Materials you will need
  • Take Measurements and Cut
  • Install the Styrofoam
  • Install Mass Loaded Vinyl or Sound Deadening Mats
  • Seal the Gaps
  • Install the Acoustic Foam Panels
  • Make three holes; one in the back and two in the front
  • How to properly make the Holes?
  • Enjoy

Materials you will need

Take Measurements and Cut

The first step is to measure the box properly so you know how big the pieces of the soundproofing material should be.

Next cut the Styrofoam and the Mass Loaded Vinyl or the Sound deadening mats to those measurements.

MLV is really easy to cut with a sharp knife. Just make an incision and then you can simply tear it with your hands.

Note: Make sure to cover 100% of the inner surface of the box. Even the tinniest gap will let sound through, and quite a lot actually.

Install the Styrofoam

The first step is to install the Styrofoam which should be very easy to do since you already cut them to the required size.

To do this you should utilize the glue spray.

You could apply the glue on the box or directly on the Styrofoam, there’s not much of a difference.

After you’ve installed the Styrofoam, it’s time to move on to the next material that’s actually responsible for blocking the sound.

Install Mass Loaded Vinyl or Sound Deadening Mats

Both of these materials are excellent at blocking sound, you could purchase one or the other.

The reason I’m mentioning both is that MLV tends to be more affordable, but it requires glue to be installed, while the sound deadening mats are far easier to adhere.

Spray the blue on the back of the MLV and adhere it against the Styrofoam.

Again, make sure that every little hole and gap is perfectly sealed, there should be no open spaces between the Vinyl sheets.

Same goes for the deadening mats.

Seal the Gaps

The next step is to seal every crack and gap you can find using acoustic caulk.

Acoustic caulk works great for sealing off small gaps which could otherwise not be sealed, like the ones between the vinyl sheets, especially in the corner of the box.

You should get this Acoustic Sealant from Amazon since it’s super affordable and will get the job done, there’s no need to get a more expensive one.

I’d recommend letting the caulk dry for a couple hours before continuing with the next step

Install the Acoustic Foam Panels

Even though you could use the box like this, simply with the Styrofoam and the Mass Loaded Vinyl, adding some sound dampening materials like acoustic foam will further reduce the noise levels.

I would recommend that you don’t just buy the cheapest ones you can find, since they tend to perform wore than some of the better ones.

My suggestion would be to get these ones from Amazon which will do just fine.

Another alternative to staple some old towels to the inside of the box, since towels, believe it or not, are excellent sound absorbers.

Make three holes; one in the back and two in the front

Why is this?

Well, if you’re going to record music and place the box over the amp, you will need to find a way to get a microphone in there, and what’ s more important, a way to feed the cable to the microphone.

Since running the cable under the box means that there is now a gap beneath it, sound will be able to leak out through that space which is something we want to avoid.

So, the best solution in to make a tiny hole in the front where we can insert the cable.

The same thing goes for the guitar cable which will be plugged into the amp.

If you have cables to spare then I’d recommend caulking around the cables to seal the holes entirely.

The third hole should be in the back of the box, behind the amp, basically for the same reason since you need to plug the amp in, in order to power it.

The same thing should be done here. If you can, caulk around the cable to prevent sound from leaking out.

How to properly make the Holes?

You should be using a drill and slowly drive it inside the box, paying special attention to not rip any of the soundproofing materials out.

This could also be done with a very sharp knife.

The important thing is to not damage the Styrofoam, the MLV and the acoustic foam.

Enjoy

Now all that’s left to do is to connect all the equipment and start recording.

To do this you will need to get a small desktop microphone stand, place it in front of the amp and that’s it! You’re ready to record some awesome music.

You should notice a massive sound reduction which, hopefully, will keep the neighbors happy.

Conclusion

Soundproofing a cardboard box is affordable, easy to do and actually very effective.

If you’re struggling to record music at home properly and you’re driving your neighbors crazy at the same time, doing this might be a fantastic idea.