Bluetooth Boombox For That 80s Nostalgia

Sure, anyone can go buy a bluetooth speaker for their portable music needs. But for something a little more unique, at least in this decade, [Daniel] aka [speedfox] went with an 80s-style boombox and outfitted it with a bluetooth module.

The retro boombox was delivered with a few scratches and a broken radio, but the tape decks were still in decent shape so it was ready to be hacked. [speedfox] tied the Bluetooth audio output to the tape reader on one of the boombox’s tape decks, but this revealed a problem: the bass was overwhelming the rest of the sound. [speedfox] fixed this by adding a filter which worked until the power was tied in to the Bluetooth module and produced a lot of RF noise in the audio output. THIS problem was finally resolved with an audio transformer on both sides of the stereo signal. Finally!

After putting all of the new electronics in the case (and safely out of the way of the 120V AC input!) [speedfox] now has a classy stereo that’s ready to rock some Run-D.M.C. or Heavy D. He notes that the audio filter could use a little tweaking, and he’d also like to restore the functionality of the original buttons on the boombox, but it’s a great start with more functionality than he’d get from something off-the-shelf!

23 thoughts on “Bluetooth Boombox For That 80s Nostalgia

  1. Thanks for featuring it! One small correction: Tape deck A was fine, but tape deck B was broken (mechanically, not electronically). I think had it not been I would have tried to keep both decks working and add in bluetooth. Maybe that’s something I should look into if I build a V2.

  2. “Nostalgia” for boom boxes? I hated them. I recall riding a commuter train from JFK into Manhattan. The kid next to me had one blaring away a local radio station. When we approached a tunnel I thought, “Good, there’ll be no radio signal inside.” Wrong, he just switched his boom box to play a cassette.

    Some people seem so terrified by their own thinking, they keep up a constant flow of music to prevent it. The only good news is that now they numb their minds with headphones rather than boom boxes. They leave the rest of us alone.

    I hope this Daniel has the courtesy to only play his Bluetooth boom box only when he’s not bothering others.

    1. >”Some people seem so terrified by their own thinking, they keep up a constant flow of music to prevent it.”

      What kind of lifeless childhood did you live to develop such a twisted, psychopathic view of music and how people enjoy it? I’m not even being a troll here, I’m serious.

      Not enjoying music is one thing; that’s personal preference and totally okay. Going a couple steps further, and inferring that ALL people listen to music because they’re terrified of their own thinking and want to numb it?

      What the fuck, dude?

    2. I used to feel that way about other people’s music until I realized that if there’s a beat that you can recognize just start tapping your foot and do your best to enjoy it. If I ever am subject to a PSYOPS music attack, I’ll do my best to sing along or make up lyrics for 72 hours straight. “Resistance is futile.” “Hit me with music.” Etc. Etc.

  3. I’ve been thinking about doing something similar. I am thinking that a RPi would offer more functionality, as I can wifi to get music streams. Sound is find, but some of the other things don’t work or just aren’t useful anymore. It sits in my garage for listening to music when I am working out there. No need for cassettes or CDs…

    Nice work.. perhaps I will tackle mine soon!

  4. I have converted several old boom boxes in this manner. Instead of using the tape deck input and bothering with filtering, I just poked around until I found the either the radio or CD input. To silence the radio I just cut the traces and soldered to the amp side of the cut traces.

    1. I’ve been doing pretty much the same, except I use Raspberry PIs with WiFI to stream from my home server. Plenty of romm in those old boxes. It’s no loss cutting into the radio leads – there’s nothing worth hearing on FM anymore anyway…

  5. i will solve your problems assuming you dont mind ruining one of the decks/wiring.

    preamp connected to tapehead has WAYYYYYYYYYYYYYYYY too much gain, spelling of “way” to scale. also, some tape preamps are balanced. some are UNbalanced but with a floating reference voltage DC, and some are both. due to the tape’s bass and treb not being normal the preamp also tends to screw up line-in’s cuz it tries to compensate for this, much like with LP records… also tape heads are inductive…

    once the EXTREME excess gain is cut and bypassed and the power trace of the preamp also cut, your RF pickup wont be as nearly as big of an issue. at this point you might actually need more signal, VERY UNlikely as your getting it from a BT module and is probably fairly-enough. more likely you have still too much, reduce this down with a resistive divider andor new, extra, variable-resistor

    i’d say have a look at the radio input err i mean connection but in this case sounds like a ghost chase as it might be broken :P

    PS: your filter is on the right track but i find a coil shorting the bass works better then using caps to block the bass. this would have to be kept as far as possible from other components like power transformers, i usually do it when its on batteries anyway.

    PPS: you should not have anymore interference problems, or at least they should be a lot less. your power problems are related to running the grounds the way people usually feel is better. i cant really offer much advise on this when using unbalanced connections (LeftRightGround) but i do reccomend reading around on this. BT is after-all a two-way radio (plus modem). after i remind you that ground-lifting on 120vAC power entry of an appliance is deadly-deadly, illegal, and causes other nasty stuff too, buuut; inside of a stereo where you are ONLY lifting internal ground of ONE END of a LOW-VOLTAGE audio cable that still share safety ground and still have the grounds connected somewhere else (power/main ground) miiight make a difference if the interference is being created inside device.
    you’d be suprised at how much RF is present in a ground of a radio TX

    also try a grounded metal shield between BT and STEREO, and try changing where the shield ground attaches.

    and lastly, your 7805 miiight be oscilating! your 7805 usually doesnt need or like 100uF on its output, but it DOES need a cap with very low ESR, electrolytics have higher ESR. a high ESR with no other caps can make them oscillate! bigger cap doesnt not always help here. put a 0.1uF aka 100nF non electrlytic cap and then you can put a parallel 1uF or 10uF cap for your surge hungry BT. the input cap also NEEDS a non-electrolytic cap paralleled with the electro. THESE TWO SMALL 0.1uF CAPS NEED TO BE AS CLOSE TO THE 78xx AS POSSIBLE. the distance of the electros barely matter.

    now your stereo should be your little b___(toy), and do exactly what you want it to :)

    1. if you dont believe the 78xx oscillating thing there is a schematic diagram floating around the web of how to use a 78xx as a switchmode powersupply, apparently it does work, just not very efficently as other methods (high-dropout i think)

      1. Thanks for all of that. As it stands at the moment I think it sounds as good right now as it would if I played a pre-recorded tape on it, so I’m pretty happy with it but if I build another one I will look into connecting the BT receiver past the preamp. I guess I was just being a bit cowardly in not wanting to mess with the board too much. Also, i didn’t think the 7805 would be oscillating. Again, something I will check if I build another.

  6. Level mismatch. As stated above you’re going through a tuned pre-amp that would give segmented amplification to the parts of the audio that tape never reproduced well.

    Go upstream in the signal path and bypass the amps, signal would be much better and interference almost nil.

    1. The first thing I was thinking when reading the article was pretty much what you said. My question was pretty much ; Why bother use the impedance coupled preamp input circuits when you got a line level input at the input selector switch bank? With that switch bank you can also add other inputs say even from an aux jack some place hidden or even add a WiFi based network radio setup. I mean that is pretty much the basic idea with any hacked ghetto-blaster and finding any thing better is finding ways to keep it looking stock while still using newer media with the amp circuits of a re-purposed device. I like the idea of replacing the batteries with a bank of 15680 cells. With no motors running and perhaps a few radio circuits using the power too, it would last a good deal of time.

  7. Great idea, I am putting a San-pod in an ’80s pocket cassette unit. It plays flac and has direct coupled amps to headphones. It’s hard to put big enough blocking caps in a tiny device. The deck buttons will operate the failing buttons on the pod that fits in tape well.
    Bluetooth doesn’t even sound OK on telephone calls I get from users. It sounds dull in it’s stereo music mode.

  8. Interesting. I was going to do a similar project but wasn’t sure about RF noise myself. I just stuck with a tape-to-3.5mm adapter and called it a day. I did however do the same to the tape deck in my car but added a cheap USB powered Bluetooth module built for receiving BT and sending it through a 3.5mm jack. My results yielded low bass however. This was corrected through software by means of a third party equalizer app.

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