Outdoor stereo helps your neighbors learn to issue noise complaints

Backyard parties are going to rock over at [Effin_dead_again's] house. That’s because he just finished building this outdoor stereo. It carries its own power supply so you can take it on the road with you, and we don’t think you’ll have trouble hearing it with the 240 Watt amplifier hidden inside.

He shared the equipment details in his Reddit conversation. A 12V lawn mower battery sits in the base of the wooden enclosure. One of the commenters mentioned the dangers of hydrogen off-gassing from that power source, but [Effin_dead_again] thought of that and included venting around the lid. The subwoofer is an 8″ Alpine, and speakers are out of a Hyundai car. The head unit has Bluetooth built in for easy connection to your smart phone. It of course has the ability to play CDs and MP3s too, and we’d bet you can tune the radio if there’s an antenna connected.

Need similar power but a bit more portability? Check out this stereo built into a cooler.

Comments

  1. danman1453 says:

    Looks like a nice build. I am working on a work site version with some protective covers over the speakers. Do you have anything set up to run the system from wall power? Or, is the fun over when the battery dies?

  2. fartface says:

    Lawnmower battery = 15 minutes of music at 240 watts.
    I’m guessing that he is silly and believes what is printed on that Cheezy car stereo.

    25 watts is probably realistic, and maybe an hour from the tiny lawnmower battery. He needs to add two Optima deep cycle sealed batteries in the bottom for real power and life.

    • mur1010 says:

      Yeah, damn PMPO and its fake power measuring. 240 Watt out of a car stereo…lol…unbeliveable.

    • Oliver Heaviside says:

      Good Job! I suspect that this will play for some time, and likely several days at normal levels if the battery is fully charged.

      Peak audio ratings don’t have much to do with normal volume levels. A single watt or two of audio power is pretty good, and few people ever listen to music at anything over five watts anyway.

      When you see the 9000 watt ratings on stereos, it’s all BS – lately, on chinese imports, that means 240 watts into a dead short, calculated by multiplying all the audio channels by 2 and then adding it up.

      The calculations are done in a fictional sense, by basing the capability of the amplifier on the circuit’s (fictitious) theoretical limit, or maybe just the maximum instantaneous power drawn by the cable connecting to the battery if it shorted out.

      Then they multiply by 10 for marketing purposes.
      The same nonsense is found on import power tools. You know, 6.5 hp motors with 60cc displacement or the 1.5hp electric tree trimmer that can’t reach those numbers without being supercooled, and even then can only sustain it for 10msec.

      But nobody will buy a 15W amp when they can buy a 240W amp. I had some real 350W amps, and that was 350W into a 2 ohm or less load. They weighed a lot, and were rack mounted with a champagne finish. Not suitable for much.

      • Danny says:

        Sorry had to reply :p. Please tell me how to get power into a dead short xD?

      • Oliver Heaviside says:

        Hi Danny – You asked how to get power into a dead short?

        Rather than blah blah blah calculus, I present you with the real world example: The Toaster.

        In fact, real world examples abound:
        If you have a length of bare (solid) 10 ga copper wiring, you could use it to short across an ac outlet by sticking one end into each side of the plug. You might want to use insulated pliers – being electrocuted sucks, and fire will shoot out of the outlet.

        Let’s assume the breaker fails to trip, and lets assume that the low resistance of the copper is close enough to zero to be called zero. That basically makes it a bare short.

        As the copper is heated from the current source doing it’s job, it will start to melt. The place where it starts to melt will get very hot, and a section of copper will be converted into a ball of plasma ejecting hot gasses, copper and various by products directly into the face of the person doing it. Fiat Lux, as they say, followed by a visit to the emergency room.

        That ball of plasma represents all the power available under the circumstances. Most car stereos aren’t really that capable, so it won’t be creating little balls of plasma.

        However, it is possible to turn the knobs to 11, put a .001 ohm load between the leads and then measure the peak current flowing in the few msecs before the amp goes into thermal protection mode and shuts down.

        If the stereo was made in china, the output transistors will suddenly realize that die size means something after all, and sudden feelings of inadequacy will lead them to immediately commit suicide to protect the thermal overload stage.

        This number represents the most power the amp can put out, ever, for some period of time before dying. It is measured in milliseconds, and is never declared on a specification sheet.

        The duration is so brief that it must be captured by a poorly calibrated storage scope. Then the number is rounded up to the next graticule, or simply to whatever sounds good. For example, 1.1 will become 2, or 5.

        That is how they spec the peak music output power of the amplifier. Then marketing will round it up to the next significant digit, or order of magnitude, and then give that adjusted value to whomever writes the spec sheet.

        The old ways of taking these measurements had too much information, and didn’t even help sell stereos once people stopped bothering to do math and read graphs.

    • effin_dead_again says:

      No, the Sony amplifier I used for the project is 600 watts PMPO, 240 watts RMS. (I am the builder of this thing, I’d like to think I know a thing or two about what I’m doing.)

      • Oliver Heaviside says:

        Yay! I do like the cut of your jib.
        You might also enjoy seeing the somewhat more ambitious build circa 1994 – when your stereo can bring you a beer:

        Back to audio – once upon a time, it was quite common for the soldering-iron set to fall into one of two camps: Ham Radio and/or Audio.

        The audio guys consisted of three types: Folks that knew how to use an oscilloscope and a function generator and do math, Folks who liked it really loud, and finally, the slightly gullible Folks who spent a lot of money buying crap from the first two groups.

        Almost all that’s left of group three are the people who buy monster cable instead of cheap 14-18 ga wire bought in bulk. However, a new generation is coming up to repopulate their ranks, and these people are the ones for whom the recently coined unit of measure “PMPO” was designed. Peak Music Power Output – and look, I’m on a horse.

        Sadly, from looking at various amplifier chip specs, PMPO seems to generally works out to about 15 * RMS, or 600/15 = 30W RMS power. Of course, if they decide to sum up each channel, it’s about 15W RMS. Most car audio products are only linear up to about 10W anyway, and then they degrade.

        I don’t say this to bash your amp or your project, but seriously, 30W is a lot of power. A 25W stereo amplifier can leave your ears ringing for a long time, and make you one of those old guys who can’t understand people very quickly.

        The other side of the equation is the impedance of your speakers. A 2 ohm effective load speaker is going to be much better than a 16 ohm speaker at converting that power into sound pressure, which is what you perceive as loudness.

        But seriously – there’s nothing wrong with your setup. I will admit that I’ve switched to “high” quality ($$$) all-in-one media receivers and bookshelf speakers. It works fine, and I can fill my home with everything from Lupe Fiasco to Stan Getz to Tricky to Bach and back again and it sounds fine.

        I will say this: One day a couple years ago, I set up my old audiophile gear for a week or so before I gave it away to a kid who raved about planar speakers, and used it every day.

        After it was gone, I turned on my all-in-one to replay a cd, and within minutes I was ready to cry. There is no comparison.

        It was like spending a week with a friendly super model, a $60k limit credit card and a jag XKR in LA, and then going home to a run down single wide trailer under an underpass in Hoboken, N.J. to scrape for quarters so you can buy a hot dog and a big gulp at the 7-11.

        Actually, it was worse… imagine now that when you come back from the store, you discover that your wife’s mother-in-law met your girlfriend and tipped over your motorcycle in anger.

        Luckily, after four or five days, the all-in-one sounded fine again. I’ll never listen to high end audio gear again.

  3. randy says:

    where is the stereo amp in a volvo 740gl?

    • Rob says:

      If it’s the factory unit you’re asking about, it’s part of the radio assembly… you can add an aux line-in to it, but trying to break it out would be a bit more challenging. you’re better off with a “class D amp” (such as a Topping or something similar) that uses modern circuitry and runs far more efficiently than the amp in a Volvo 740GL stereo could ever dream of doing.

    • Rob says:

      This project is full of win! Use it wisely. :-)

  4. barryronaldo says:

    I have a couple of Velodynes and a Moogslayer EX800 for when the homies think they got something. Fixed my neighbor from coming in from his evening bar-closing coke sales at 3am with Fabulus or whatever blaring. Took two applications, but they got the idea. Nice job and the car battery keeps it portable and no cables for imbibing folks to trip over :) Nice work.

    • Oliver Heaviside says:

      240 Watts? Snicker.

      I had a neighbor like this. For weeks the guy started playing his frat rock from his porch at 5pm, and my requests to back it off a tad went the “it’s a free country” route. I’m not hard to get along with.

      Many neighbors complained.

      One day I asked him if he minded if I turn my radio up a bit so I didn’t have to hear it. “It’s a free country, man!” was the reply. I know he’d heard my jukebox playing before from the garage and he probably figured that was where this was going.

      I was never a golden ear guy, but I had a couple of pounds of circa 1979 top of the line audio gear that I never used. These amps could double as spot welders – true 350W+ per channel amps, and I had a quad setup. Bought it cheap, assuming I’d use them as servo drivers.

      Out onto the porch came one of the speakers – towering monsters that had been gathering dust. A little strategic placement of a foot locker to rest the speaker on, and we were ready for action.

      I went through the start up sequence (audiophile gear is a pain in the ass) and warmed it up. I put an LP of ragtime music and adjusted the music until I knew he’d be able to hear it.

      He cranked the volume up, but consumer stereos aren’t known for infinite gain and the sound quality went from mediocre to poor. After this, I turned my music down and feigned defeat. His girlfriend and drunken buddies clapped.

      After an hour, I put on “Winter” from the four seasons, and went to “3”. He brought his speakers onto the porch and cranked it up more. I turned mine down again, as I didn’t want to pester the neighbors.

      Best of all, he started playing music I liked, so I backed off and took my gear inside. I’m not a grudge holder.

      Come Saturday at 4PM, he started at it again, and he and his drunken friends started subjecting the entire neighborhood to his tastes in music.

      Mind you, I love every kind of music – apart from celine dionne and a few other artists (certain types of hip-hop in 4/4 time, most ballads and ballad singers, anything with autotuning), I can listen to anyone’s music.

      This time I put all four speakers out, arranged in a parabola and focused on his front door and porch, where they sat and drank beer.

      I could have played many things, but I wanted something that would grate. They were not expecting Der Ring des Nibelungen. It’s almost as rare as the spanish inquisition, and always grabs your attention.

      Naturally, I went for the most popular bit from that little series, das Ritt der Walküren – aka the ride of the valkeries. You’ve heard it.

      The police later informed me that it could be easily heard from the city park roughly four blocks away. I didn’t take sound pressure readings, but I was wearing ear protectors and eventually the lights of my house were dimming on the trills.

      The song is eight minutes long.

      I just turned it up slowly, and then left it at a level that didn’t sound too bad to me. I cracked a window on the porch window, but it was simply vibration – the sub woofers projected both ways.

      It was a long – but thrilling – eight minutes.
      Luckily, the song had finished by the time the cops showed up, and I had already taken the equipment back inside. I was given a verbal warning.

      However, the neighbor kept the music turned down at polite levels after that. And though I may have been an ass about it, it was a vast improvement over the silenced match rifle dispatch of a boom box committed by an army buddy in a neighboring high rise a decade previously.

      Age mellows people.

      • esbi says:

        That amused me almost as much as the page title. Once I worked at a very disturbing stamping facility where more people than not were deaf from thousands of tons of steel pounding all day long. 4000 watt (peak) systems with a second alternator and battery and all that were not uncommon in the parkinglot at breaktime. Nobody thought much of it.

        Noise so loud you put earplugs in, then muffs, and will probably still vomit till you are used to your innards shaking. As fun as it is scary.

      • Chris C. says:

        Well played sir!

      • wholostwhat says:

        Where is the “Report comment – poster deserves a medal” link? I have considered doing similar to an obscenely bothersome neighbour, but with The Ying Tong Song (classic Goon Show) or perhaps some Tuvan throat singing. Unfortunately I passed my powerful hifi gear to my nephew before I moved countries.

        I may have other geeky ways to deal with him though :)

      • effin_dead_again says:

        You sir get a gold star! I like to be respectful of my neighbors. If any of them ever asked me to turn it down I would gladly do so. But stories like this make me smile :-)

        I didn’t build this thing to get massively loud. I built it so I could listen to my tunes in the backyard without having to endure the grinding lack of sound quality of a crappy boombox.

        The sound quality of this box is pretty good all things considered. The Hyundai OEM speakers sound miles better in this enclosure than they did in the car.

  5. whizbo says:

    Great Build!

    I built something similarSimilar project in a box with external speakers and battery. http://lackof.org/john/projects/projects/rufus/index1.html

    When I wanted something portable I built a smaller all in one system, that takes it’s input from anything with a headphone jack. Based on these directions: http://stories.parts-express.com/stories/2444-en_us/category/Speaker/story/16637/redirect.htm

  6. Rob says:

    (Meant to post this in the main thread, but it got stuck beneath a sub-reply… derp.)

    This project is full of win! Use it wisely. :-)

  7. echodelta says:

    No wires to trip over, just the unit to tip over if you push at controls. Better to make it long and low. Might get more spread and boundary zone boost. The cooler deal is well suited to worksite and party.

    • effin_dead_again says:

      The sheer weight of the box keeps it from tipping over, plus it’s pretty easy to just put it next to a wall or in a corner to prevent that from happening.

  8. Mike says:

    A friend and I made a similar build years ago for a shop stereo we could bring from job to job. We were just high school kids trying to make beer money fixing cars over summer vacation and our unit caused quite a stir. We mounted an old 289 oil pan on the front of an old speaker box and mounted a car cassette player and a pioneer booster/eq in cutouts on the pan. next I cut speaker holes on the sides for some good ol’ 6×9 triax’s I picked up at western auto and mounted them in. Then I wired it all together with an old crossover so we could use the original speaker in the box for a sub. in the bottom of the box we mounted 2 sealed marine batteries wired parallel so we’d have plenty of juice to crank it, then I mounted some huge casters off of a lumber cart on the bottom for mobility. recharging was handled by use of cig lighter plugs with a long wire. It’s still sitting in his dad’s shop in vegas, although his dad listens to Hooked on Classics and not Def Leppard like we did.

  9. matt says:

    why is this here. this isnt really a hack, new or novel, its just some guy who built an enclosure for a car stereo. it isnt even particularly powerful or loud.

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