TECH2

Seeking savory sound

Examining the speaker’s plastic enclosure, I came up with no brilliant ideas for improving the sound. I thought about adding some filters to tame that fearsome treble, but I knew I’d lose a lot of output that way. I noticed a little ventilated section in the back, though, which suggested maybe the speaker was blowing sound out the rear and using the can as a resonator to boost the bass. So maybe there was something I could do with the can itself.

Then I remembered that you can buy Pringles in two sizes: the Super Stack and the Grab & Go! Stack. The former measures about 10.5 inches long, the latter only about 4.8 inches. I headed down to the 7-Eleven to grab a Grab & Go! and a Diet Coke, quickly consumed 375 calories worth of junk food, then pulled out the Clio again.

To my disappointment, a close-miked measurement showed the two cans measured almost the same in the bass, indicating that very little sound was getting out that rear vent. I did notice, though, that the little can didn’t have the big can’s nasty resonance at 740 Hz. Aha! Progress!

I then got the bright idea of stuffing the cans with absorptive material, the same way a manufacturer would fill an acoustic-suspension speaker with fiberglass to soak up the woofer’s back wave. I stuffed the large can with 1 oz of recycled-denim insulation, which translates to a density of about 3 pounds per cubic foot. Then I ran another measurement. Eureka! The 740 Hz resonance was gone, the bass peak at 280 Hz was tamped down, and the midrange was considerably smoother. It sounded better, too, because the resonances inside the can were killed and the can’s sides vibrated much less. The only downside was that the “bass” was slightly less rocking, although it sounded tighter and better-defined.

The small can benefitted just as much from 0.4 oz of stuffing, delivering a nearly identical response to the large can. I tried using just 0.2 oz, but such a low density of stuffing barely affected the performance at all.

Of course, you might not want to spend $6 on a bag of insulation to tweak a free speaker, but you could use ordinary fiberglass insulation as long as you don’t mind itching for an hour afterward.

The best free sound ever

If you’re fortunate enough to have gotten in on the Pringles can speaker deal, your solution for the best sound is simple: Stuff the can. Given that the small Grab & Go! Stack doesn’t sound or measure much different from the big Super Stack, I’d recommend going with the small one just ’cause it’ll clutter your desk less. And don’t toss the Pringles can speaker if you upgrade to something better. With Warhols now fetching as much as $100 million, you never know what the Pringles can speaker might be worth someday.