How Boomboxes Got Badass (2013)
collectorsweekly.com
collectorsweekly.com
Pianos have the same effect for the lowest notes, they will not reproduce the bases directly because the soundboard simply isn't large enough to accommodate the waveform. But the harmonics do fit and again your brain will interpret the harmonics pattern in such a way that they conclude the low tone is actually present.
This is called the 'missing fundamental' and is one of the more interesting psycho acoustic phenomenon.
It works like this: instead of playing A0 directly (27.5Hz) you'd play 110, 137.5, 165, 182.5, 220 etc all the way up to say 2 KHz in diminishing fashion as you go higher. For a piano you'd have to keep track of odd/even harmonics and ensure they are in the right relation to each other to get the right timbre. The brain then is apparently capable of determining the distance between those harmonics and make you believe that you are hearing A0 even though that frequency is not at all present in the output.
I remember being in some kind of demo truck as a kid, where they were showing a scene of Jurassic Park (from a Laserdisc!) and they had these big speakers left and right in front and small ones behind, and were blasting the audio at pretty high volume so you would think "surely the thick base is coming from those big speakers up front". Then, half way into the demo, they would open up the "speakers" in front of the audience, revealing the surrounding wood to be fake and the actual speakers inside the fake housing being just the same tiny ones as those located in the back.
I remember being very impressed by that demo. By the speakers, but actually even more by that Laserdisc ;-)
Everything is better on a Laserdisc!
Whatever happened to the Laserdisc?
Laserdisc!
I saw that demo too, though it was in a store and I don't remember a JP scene being used. Bose were always shite at accurate sound reproduction, but great at making things sound good. And nothing noise-cancels like a pair of QuietComforts.
But probably they had multiple variants of the demo.
Take your small bass or midrange speaker (something with large excursion of the speaker diaphragm) and place it between two "tubes" that are in a 3:1 ratio. The tube on the front-side of the speaker should be the longer of the two.
So - grab a cheap 4-5" woofer and a carpet tube. Cut the tube into a 3 foot length and a 1 foot length. Put the woofer between the tubes, sealing it up well, with the front of the woofer firing down the longer tube.
That's it. It actually works well. I built one myself using junk as a kid back the late 1980s, after reading the article. What Bose did was then "fold" the tube so it could easily fit into a box. There is probably a ratio also between the volume of the tubes and the width of the driver, among other things, but the basic idea described above will work rather well. You could even do the folding trick with an actual wood enclosure if you can calculate the lengths and such thru the curves properly.
It's similar to a bass reflex or other ported style speaker, and it scales up and down rather well (see the Bose Wave radio - IIRC, it used either a 2.5" or 3.0" single driver for the bass). The downside is that it doesn't work over a wide range of bass; the bandwidth is somewhat narrow (it is possible to offset this, though, with an EQ and amplifier, to boost those lower frequencies - plus midrange speakers in the "satellites").
Every note an instrument makes is composed of a sine wave at the fundamental frequency of the note plus a number of sine waves at integer multiples of the note, called overtones. The amplitudes of those overtones determine the timbre or sound of a particular instrument. The difference between a guitar playing A2 at 110Hz and clarinet playing A2 is in the relative loudnesses of their different overtones.
So an A2 will be composed of sine waves at 110Hz, 220Hz, 330Hz, 440Hz, 550Hz, 660Hz, 770Hz, and so on. The amplitudes diminish as the overtones go up in frequency and it eventually peters out.
Notes an octave apart are also integer multiples. An A3 is at 220Hz with overtones at 440Hz, 660Hz, 880Hz, etc. As you can see, there are a lot of overlapping overtones. So it seems like you shouldn't be able to fake a lower note by shaving off the fundamental. If you take an A2 and remove the 110Hz fundamental, you're left with 220Hz, 330Hz, 440Hz, 550Hz, 660Hz, 770Hz. That looks quite a lot like an A3.
However, our brains are smart enough to note that there are extra overtones in there that are not integer multiples of A3's fundamental 220Hz. The presence of 330Hz, 550Hz, 770Hz, etc. are enough for our brain to realize there must be a lower fundamental that we aren't hearing that leads to all of these extra overtones. Another great example of how our brains that fill in missing data by perceiving patterns in the data it receives.
This is an important technique in dance music production. On a good sound system, especially in a club, you want the bass to have a deep low fundamental that users can feel in their chest, lower than 100Hz even. But listeners are often using earbuds, in their car, or in other places with smaller speakers that can't reproduce that fundamental. So when doing sound design for the bass, you ensure the note has some overtones above that will still be preserved.
In practice, the user experience in many synthesizers goes in the other direction where they pick a fundamental that is in the reliably audible range and then add in a "sub" oscillator that makes a clean sine tone an octave below.
Also, by playing all of the harmonics except one, could the missing harmonic actually be induced somewhere along the way?
I like how they all had some kind of "turbo bass" switch - like a kid carrying around a boombox would ever not want turbo bass. The worst is when you accidentally turned it off and didn't realize for hours or sometimes days.
Of course those did have a purpose. You would run in Turbo mode all the time, except when you were running bad old software like I wrote, that used timing loops assuming a 4.77 MHz clock rate.
Back to the article: I owned a JVC-100 in red, just like the one pictured. I never took it out much because it seemed so fragile and my memory is that it sounded like crap compared to a hunk of plastic durable Sony that I also owned. I have no idea where either of those boomboxes got off to. Probably sold in a garage sale at some point.
Funny you mentioned that. I've watched that movie when I was a kid and, very impressed. I wanted to watch it again but I never knew its name to start with. Yet an internet stranger just blurts it out and makes my day. Thanks stranger.
Near my office, kids gather all the time and play music really loudly on small Bluetooth speakers. I don't even dare to imagine the experience if they had one of these bad boys.
The ones that are sort of sold for use as a PA speaker have much larger speakers than most boomboxes.
Yet there was a decent selection from the likes of Hitachi, Sony and Grundig and possibly others that were more mini hifi with handle and detachable hifi(ish) speakers you could separate properly. It's where the whole bookshelf hifi thing started as far as I can tell.
Course you may still hate the kid's music taste. :)
Now common/cheap BT speakers made public music listening en vogue again. Just right for me to enter my grumpy old man phase, but interesting nonetheless. (And to be honest, it beats the sheer cringe level of someone carrying around a vintage portable record player)
This also seems to make it more acceptable to listen to music/videos on your smartphones external speakers, so I'm willing to bet that having better ones will be a factor for current/future development.
People just set up in the park or on a street and start blasting club volume music. It's getting harder to not be the grumpy old guy.
I didn't carry it around though, it was my home stereo until I was able to afford something bigger. Since it has an aux input, I've continued to use it over the years as computer speakers and such.
Rock on!
P.S.: Of course we all know this movie scene, right? https://www.youtube.com/watch?v=BHyPS1boeuI
Boombox was a name that came from US TV and film, and only started to be the name retrospectively looking back. I don't remember anyone here actually using boombox back then.
I remember in the early 80's the transition from all-analog to LCD display boxes, which allowed more precise FM tuning, and programming for copying tapes or an alarm clock.
And that the #1 item in terms of interest and sales volume at a lot of consumer electronics retailers was the boombox.
Their size really did get ridiculous - carrying one around was a workout.
Nowadays you can be fairly certain that just about every set of somethings will be ‘collected’ by a set of aficionados whose number of members is or exceeds two.
I was lucky.. there was a Tower Records 1/2 mile (1 km) from my house, the one where Metallica played that concert in the parking lot. And somehow I acquired a 1990 West German The Doors - The Doors CD.