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Boombox Dynamat

My first and second generation TRC-931 boomboxes are incredibly loud, but their plastic enclosures could be improved. The outer plastic shell lacks rigidity when handled roughly, and it has a tendency to carry vibrations when bass-heavy music is played. Since using Dynamat sound-deadening material is a popular way of reducing vibrations and improving sound quality in car audio applications, I decided to evaluate its usefulness for my ghettoblasters.

Although Dynamat is by far one of the most popular sound deadeners on the market, it is by far one of the most expensive. After following some of the research posted here, I decided that Damplifier by Second Skin was an excellent choice balancing the effectiveness and cost of butyl-based sound deadeners.

I decided to use three 12"x24" sheets per boombox, and each sheet adds 0.9 lbs of mass. After opening up the first stereo, I used gift wrap to cut templates of the right size for each panel of plastic. The gift wrap was much easier to work with than the dense Damplifier sheets.

A set of precision-cut pieces was made for the first boombox using a pair of scissors and an Xacto knife. I duplicated these pieces for the second boombox since they both use the same plastic enclosures.

The pieces are laid out inside the stereo, ready to be adhered. All the sections prone to vibrations are covered: the back panel, battery cover, tape deck assembly, and all sides of the case.

Like all sound deadeners, the Damplifier sheets have an adhesive backside. Each piece is firmly pressed in place, and the boombox circuit boards are reinstalled.

A photo inside the "damplified" boombox. I added some extra pieces of deadener on the metal speaker frames and the plastic piece supporting the radio tuning indicator.

A photo of the back panel. The rear vents were left unobstructed to allow rear-firing sound waves to still escape from the back.

With the boombox open, I took the opportunity to whiten the speaker cones, which had faded to a pale yellow with age. After reading some tips on the Stereo2go forums, I used a 1:1 solution of bleach and water, along with some paper towels, to gently dab the speaker cones. Since the cones are made of a thin, brittle paper, it's important not to soak them or the black surrounds, which could damage the speaker. The photo shows the finished result, after the light layer of bleach had dried.

You don't need to remove the dust caps to clean the speakers, but I decided to re-attach the loose one on the left with super glue.

After the power and antenna wires are reconnected, the stereo is ready to be re-assembled.

A photo of both boomboxes with the sound deadener installed. Although you can't tell cosmetically that they've been reinforced, picking them up reveals that each is about 3 lbs heavier because of the Damplifier. Unfortunately, the stereos don't seem noticeably louder than before, but at least they feel much sturdier when I'm carrying them around. I guess it's up to preference whether you'd prefer lifting the extra weight or not.


6x sheets of SecondSkin Damplifier $45.00

Total $45.00