Portable Speaker System help power

Discussion in 'The Projects Forum' started by hashmaster, Jun 14, 2012.

  1. hashmaster

    Thread Starter Member

    May 30, 2012
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    Kinda new to the forums, and i just started school in dec for electrical engineering so im not to far into studies yet. So i got a basic understanding of the basic laws, i can read a plan sorta, do basic formulas, and learn quick. So anyways on to what i need some help with. I am trying to build a portable sound system I have plans for a Digital volume control http://www.eleccircuit.com/digital-volume-control-by-ds1669/ a tone control http://www.zen22142.zen.co.uk/Circuits/Audio/t-ctrl.htm and the amp http://www.zen22142.zen.co.uk/Circuits/Audio/150wmp3.htm . I plan on powering it with a 12v rechargeable battery. What i want to do is add a usb power supply, solar recharge panels, and the option to run it off ac power while its charging the battery. So to clarify a bit on what i need help with is how to create a circuit that will take power from the battery to the main board, a 5v branch for the digital volume control and usb, and recharge the battery via a solar panel array and an ac source. I was planning on doing it on one or two of the large solder-able bread boards. I havent chosen a battery yet as i havent calculated my current needs yet. Any help is appreceatied if i missed anything let me know. Help, questions, comments, concerns, criticism all welcome. Thanks.
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    LA47536 Four-Channel 45 W BTL Car Audio Power Amplifier
    The LA47536 is a 4-channel BTL power amplifier IC developed for use in car audio systems. The output stage features

    - A pure complimentary structure that uses V-PNP transistors on the high side and NPN transistors on the low side to provide high power and superb audio quality.

    - The LA47536 includes almost all the functions required for car audio use, including a standby switch, a muting function, and each protection circuit. It also provides a self-diagnosis function (output offset detection). (Sanyo)

    from your link..

    150 Watts ! :eek:

    Sit back down and research on batteries and Watt/Hour Ratings vs size and weight.

    Then choose a proper 2-10 watt system and design for portability around that.

    Other than that I think you will need to tell us more about this project.

    Welcome to the forum
     
  3. hashmaster

    Thread Starter Member

    May 30, 2012
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    Well the portability part of the system is more of a 18"w x 18"d x 24"h on wheels. As far as the battery goes I was gonna use something along the lines of a AGM deep cycle battery. Im building the system for a friend of mine who manages a softball team so it needs to be a bit loud. And i know from ghetto rigging amps in the past I can have a 1000W rms 2 channel amp push 2 500W speakers for a good 6-8 hrs on a reg car battery before having to throw it on the charger.
     
  4. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    If you know it won't be "hand" portable then you are on the right track.
     
  5. hashmaster

    Thread Starter Member

    May 30, 2012
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    Yeah. My rough estimate on weight is about 15-20 lbs hence the wheels. But it should still be able to lift and tote when needed. Now that i think about it Portable Block Party might be a better title.
     
  6. hashmaster

    Thread Starter Member

    May 30, 2012
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    I plan on using a pre-built 12 VDC power supply for the ac. Scraped laptop cord or something.
     
  7. Audioguru

    New Member

    Dec 20, 2007
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    Read the details in the power amplifier's datasheet because it lies about the output power:
    1) Each channel can provide 40 PEAK Watts into 4 ohms at a horrible-sounding 10% distortion (clipping like mad) when the battery is being over-charged at 14.4V.
    2) Each channel is typically 28W RMS at 10% clipping distortion.
    3) Each channel clips at 15W per channel but is much less as the battery voltage runs down.
     
  8. hashmaster

    Thread Starter Member

    May 30, 2012
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    Well i get this wont be the most hifi amp out there. Honestly its one of the few decent plans i found. Im always open for suggestions if you know of a good 2.1 channel amp i could build im down to change it out. Nothing has been set in stone yet. Im trying to build a system like this http://www.ionaudio.com/products/details/block-rocker-am-fm which for being a single 2 channel 22 watt speaker get very loud with very little distortion.
     
  9. Audioguru

    New Member

    Dec 20, 2007
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    Don't you understand that the Sanyo "150W" amplifier IC (37.5W per channel) is Hi-Fi when it produces only 15W per channel like hundreds of other car radio amplifier ICs that are also powered by 14.4V and also have a 4 ohms loads?

    Look at the spec's for the Block Rocker, its output is also only 15W RMS (22W is phoney-baloney peak power). But since they do not mention its distortion then at 15W it might be clipping its head off with severe distortion. It is not Hi-Fi (but it is close) since its woofer misses producing deep bass sounds.
     
  10. hashmaster

    Thread Starter Member

    May 30, 2012
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    yes i realise most cars run at about 15 watt rms a speakers and it sounds pretty good even when pushed loud. and yes i realise that the block rockers 22w is bull i dont base speaker decisions on peak power as its pointless. granted im not by any means an audio expert but i do know a little mainly car audio although its more what amp and subs should i put in. so since you seem to be an audiophile in your personal opinion would this amp be pointless to build as it would just sound like crap or would it be a decent system able to push decent sound about 50 feet without sounding like someone screaming in a megaphone infront of a mic at a concert. and if the basic design of the amp is sound could i replace components with others to create a better preforming amp
     
  11. hashmaster

    Thread Starter Member

    May 30, 2012
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    And just a quick question wouldn't an ultimate hifi system produce sounds from 1Hz to 25kHz (yes I know humans can't hear all of that) with 0 distortion and 0 clipping? Just a random thought.
     
  12. Audioguru

    New Member

    Dec 20, 2007
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    Cars use four speakers at 15W each (or more if they are 2 ohm speakers 25W each like in my car) (plus a more powerful 120W sub-woofer like in my car) and the environment is closed with the speakers very close to you so of course they can play loud.
    But you are talking about only one 15W speaker 50 feet away. A HUGE difference.

    At 3' the max loudness might be 104dB.
    At 6' the loudness is 98db.
    At 12' the loudness is 92dB.
    At 24' the loudness is 86dB.
    At 48' the max loudness is only 80dB which is not loud and the average loudness is only about 70dB or less which is a whisper.

    You need more voltage to supply an amplifier that produces more power.
     
  13. Audioguru

    New Member

    Dec 20, 2007
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    Most hi-fi systems produce 35Hz to 20kHz with very low distortion (0.05%) without clipping. Clipping will destroy the fragile tweeters and your fragile hearing.
    You might find many deaf owners of hi-fi systems with the tweeters burned out.
     
  14. MrChips

    Moderator

    Oct 2, 2009
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    A simple way to create a portable sound system powered by 12v batteries is to use a car audio amplifier. Two-channel amps with power ratings from 100W to 1200W are readily available.

    btw - There is no such thing as 0 distortion and 0 clipping.
     
  15. Audioguru

    New Member

    Dec 20, 2007
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    But most are rated in WHATs instead of REAL WATTs!
    1200 WHATs is about 20 REAL WATTs.

    Some car radio amplifiers use a voltage step-up circuit so their output power is very high. Then the current from the battery is also very high and it fails soon unless it is always continuously charged.
    How do you continuously charge a portable battery??
    How do you carry a powerful battery and charger??
     
  16. MrChips

    Moderator

    Oct 2, 2009
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  17. hashmaster

    Thread Starter Member

    May 30, 2012
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    Nice little box but the problem with using a prebuilt car amp is theyre mainly to push subwoofers which dont produce vocals real well ive tried in the past. Now im not saying there isnt car amps that will produce mids and highs i just dont know of any. add to that the cost of the amp and im back in the boat of i should just buy the block rocker. but i dont really have 200+ bucks to spend.
     
  18. hashmaster

    Thread Starter Member

    May 30, 2012
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    that was part of the reason of me starting this thread. For the initial power source i planned on using a deep cycle battery just a rough guess on power needs of 12V and 12Ah. I was gonna add a ac charge plug on the back, and i was thinking of adding some solar panels to the top just because i have a bunch of 1.2v panels around (i believe they are 1.2v havent tested them yet) The main part i need help with making is where everything is controlled from. some thing to control the flow of power from the sources to the amp. heres a rough pic of what i mean.
     
  19. hashmaster

    Thread Starter Member

    May 30, 2012
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    heres the pic
     
  20. hashmaster

    Thread Starter Member

    May 30, 2012
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    it was on the news a little bit ago but some one was working on a 6400.1 or 64000.1 surround system it was insane looking. massive walls of speakers and a cost of a few hundred thousand dollars but impressive looking none the less.
     
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