How To Soundproof A Cardboard Box At Home In 8 Simple Steps

As a home theater buff, I found I had need of a soundproofed space for different applications. I built the best use of this in making a soundproof cardboard box for my guitar amplifier.

It can be difficult getting a clean recording of an amplifier by just setting a microphone in front of the amp. Room and other ambient noise can color the sound in unwanted ways.

A soundproof cardboard box presented a cost-effective and easy solution. The materials are readily available and simply assembled.

How To Soundproof A Cardboard Box

Step 1 – Start With a Box

I began with a box that was large enough for my project without being too big. I settled on one that was 24 inches wide by 18 inches deep by 24 inches high.

A box is easily obtainable from many retail merchants. If you search at their back doors you should find something close to what you need.

For a larger box like we need, an appliance store is a good bet. A furniture store may also have what you require.

If you can’t find the exact size you’re looking for, you can get the closest thing. As long as it will hold what you want to soundproof, you’ll be good.

You may also purchase the box that you need. U-Haul is a great source for various boxes such as this one that is our required dimensions.

I used this box for my soundproof box project. It is sturdy and will last for many years to come.

If you can’t find a U-Haul dealer near you with the box, you can find it online at above link. They will ship directly to you.

Step 2 – Time to Insulate

The way to start soundproofing your cardboard box is with Styrofoam sheets. These are readily available in convenient sizes.

One place to procure your Styrofoam sheets is Office Depot. Their attractively priced Office Depot® Brand White Foam Board size 40″ x 60” can be purchased in-store or online.

You will need 2 or 3 sheets of this Styrofoam to complete your project. You can easily cut it to required dimensions with a razor knife using a straight edge as a guide.

Step 3 – Styrofoam Adhesive

Cut your sheets to have sufficient pieces to cover the entire inside of the box along with two sheets for the bottom. Cut off the short top flaps of the box and make 2 Styrofoam sheets to cover the inside of the long flaps.

There are different types of Styrofoam adhesives available. The easiest to use is 3M Styrofoam Spray Adhesive (Amazon link), a spray product.

Make a protected space for using this product. Using newspapers or other suitable materials, make a safe place that will catch all of the overspray.

Using the 3M spray adhesive, attach the panels to the inside of the box. Allow the panels to set before proceeding to the next step.

Step 4 – Serious Soundproofing

The heart of your soundproofing is a material used in automotive soundproofing known as Dynamat. This will create the perfect barrier to keep the sound where it belongs.

Dynamat can be purchased at Amazon or Walmart. You will need two rolls of Dynamat 11102 Dynaliner 32″ x 54″ x 1/4″ Thick Self-Adhesive Sound Deadener (Amazon link).

Cut sheets to fit the entire inside surface of your box. Don’t forget to cut two small sheets for the top flaps.

Peel off the adhesive protector starting at one end of a panel. Position inside your box and peel the sheet as you progress, firmly pressing the panel onto the Styrofoam.

When you’re done you will have covered all four sides and the bottom of the box. You will also cover the two top flaps.

Step 5 – The Best Part

First, using your 3M Styrofoam adhesive spray, attach the final bottom Styrofoam panel to the bottom of the box. This will be the resting place for the amplifier.

Now we will use a special material to complete our project. This is available online at Amazon.

Procure the Acoustic Foam Egg Crate Panel Studio Soundproofing Foam Wall Panel 48″ X 24″ X 3″ (2 Pack) from Amazon. This will create the quiet space you need.

Cut the panels into pieces to cover the sides and top of the box. You will not need a piece for the bottom.

To attach the foam to the Dynamat you can acquire a special purpose product. Auralex FoamTak is a specially designed adhesive which give the best and longest lasting results.

Using the protected space previously created, spray the back of the panels. Carefully attach to the insides of the box and the two top flaps, remembering to leave the bottom with just the Styrofoam.

Step 6 – Final Touch

For ease of microphone access, create a port in the front of the box. This will allow easy feeding of the microphone cable to the inside.

Using a one-inch drill bit bore a hole in the bottom front center of the box. This will allow unrestricted passage of a standard XLR jack.

Drill another hole in the bottom rear center of the box. This will allow passage of the amplifier’s power cord.

Now using a razor knife, carefully trim through the Styrofoam, Dynamat and foam egg crate to complete the one-inch holes in both the front and rear of the box. You are now ready to record.

Step 7 – The Real Deal

Now place your amplifier inside the box. An amp such as the Fender Champion 20 will easily fit in the space.

Use the front port to pass the instrument cable to the amp. Your guitar is now connected.

Now you’ll need a small microphone stand. One such as On-Stage Stands DS7200B Adjustable Height Desktop Stand is perfect.

Finally, you’ll need a microphone. There is a vast selection available but one stands out for this application.

The Shure SM57 (amazon link) is ideal. This will give you all the dynamic range you need.

Step 8 – Going Live

Now set up the mic on the stand in front of the amp and feed through the mic cable. Attach the cable to the mic and your recording rig and you’re ready to go. Enjoy the clarity of your new soundproof environment.

Quick Closing Words

Well, that is how you soundproof a cardboard box at home. This soundproof cardboard box can be used for soundproofing water pumps, air compressors and other applications.

Thanks for reading! Before you go, take a minute out and check out my top recommendations for soundproofing products.