Building a portable speaker system...from scratch.

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Hi. Im brand new here. I stumbled upon this place when I was trying to gather as much information as I could on a project I want to do. From the title you can see what I want to do.

I dont mean "portable" in the sense of small, but portable in the sense of a portable power supply in a cabinet with working speakers.

The design is going to sound crazy but just try to stay with it:

My plans were to have 5 speakers total. One large one in the center, and 4 smaller ones with one in each top and bottom corners. But I also wanted this to be portable and easilly moveable by having wheels on the bottom, and an on-board battery power supply.

If I havent lost you yet to either how stupid this sounds or impossible, I thank you for that. Now, the real kicker for me is that I know next to nothing about speaker systems. I hear all these terms and have no clue what they mean. So my first order of business is learning what terms I need to know.

The second part is knowing which parts I actually need. Based on the sizes I wanted I chose this speaker for the center one: GRS 15PF-8 15" Paper Cone Foam Surround Woofer 292-415

The ones I chose for the corners are 4 of these: Pyle PDMR5 5" Sealed Back Midrange 292-200

I dont know anything about these to be honest. Im trying to keep the price down in as many ways possible since I might need to buy alot of things. Im not looking to produce sound that is going to put anyone within earshot into some trance or anything either. Just normal quality sound to keep the price down. I also have no clue how to plug everything together as one unit and make it all work.

Now that I got what speakers I wanted out of the way, I need to know every single last piece I need to make this actually possible. Im talking about EVERY piece because im starting from scratch here. Since I dont know much about any of this, I see how it might be a huge undertaking. But im up for the challenge because this is something ive been thinking about for some time now. Money really isnt an issue but like I said before im trying to keep it down.
 
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I think he is asking what will you be feeding the speakers to give you music, an iPod, a CD player or...
Another thing to consider is that with same speakers (the midranges) you wish to have them as close together as possible or you end up with cancellation issues. You'll notice an odd sound to it, trust me placing them further apart such as in the corners is not a good idea.
By stereo, they are asking if you want to have to two separate speakers, as most recordings are stereo.
The woofer you chose is fine, the sealed back midranges will not provide the rest of the music, you still need tweeters to get all the sound like cymbals and such. A sealed back mid is convenient but there are drawbacks with the quality of sound.
If you are set on building something yourself you really have two choices. Either do a lot of reading on how this whole thing works, and I do mean a lot of reading, or maybe think about a kit speaker. They won't resemble what you have in mind but they are designed by someone who knows what they are doing and remove all the unknowns and guesswork.
 
Do you want surround sound? I have just designed a pcb (printed circuit board) based on a TDA 1557 chip amplifier. There is a way to connect extra speakers to decode the rear channel sound without fancy decoders. Unfortunately I have put this project on hold but it will be run off 12v and be portable. My thinking was what would happen when our power grid goes for a loop as we have had a lot of blackouts recently. I have also designed a pcb for the TDA 1558Q with subwoofer etc.
Mac

http://www.diyaudio.com/forums/vendors-bazaar/215967-diy-loudspeaker-construction.html

http://novelbooks.weebly.com/index.html
 
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Thats what I thought he meant by "sound source". I would use and Ipod Touch. I also see how getting one to build is easier but I would still like to pull off my idea. I also understand your point of the weird sound because of the mid-range ones to far apart. Would there possibly be a way to make that design actually possible? If you have a better idea on speakers that will work better with that feel free to reccomend them too me. As for surround sound I wasnt interested. I just wanted it to be a system like portable ipod speakers but just on a larger scale.
 
I chose 4 tweeters (Let me know if thats to many or not enough):Goldwood GT-1005 Wide Dispersion Piezo Tweeter 270-011

Ok so I started to do more research but still have a few questions. Would I also need a crossover? Could I just use a pre-assembled Passive crossover instead of building my own? How many "ways" (2 or 3) would I need on it to work properly? If I need a 3 way I would take this one: Crossover 3-Way 8 Ohm 800/5,000 Hz 100W 260-210

If I needed a 2 way I would take this one: Dayton Audio XO2W-2.5K 2-Way Crossover 2,500 Hz 260-142

Im not sure if either of these are powerfull enough or to much. If anyone knows of ones that are cheaper and still get the job done, please reccomend those too.
 
Hold on there Bubba Louie,

It appears you are heading down a path that I suggested wouldn't work. Ok, I understand individuality so I'm going to say it straight this time:

No. What you are suggesting is wrong in so many ways that I don't know where to start so I'm won't bother. Now, understand I deem this brutal approach necessary as it appears your desire comes from an aesthetic approach, rather than a desire to make things work.

I think you really ought to consider doing this: Go to your local thrift shops, find some suitable sized speakers and do some experimenting with them, the amps and batteries. Once you are happy, consider getting some kit speakers and replacing the thrift shop ones.

You are heading down too many wrong roads at once with your current approach and are never going to be happy. Please take the time to consider my words, it is not meant to discourage you they are meant to get you going in the right direction before you go and buy parts you can't use.

Like my Dad used to say: You can't cut grass with a blender.
 
kind of like this?
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Buy a TA2020 or TA2024 T-amp board from eBay (under $10), or be a big spender and get one in a case with volume knobs and all that for around $20. They'll do about 10 real RMS watts into 4 ohms, which happens to be almost exactly the same as a "high power" car head unit (which usually claim 30 to 40 "watts" where "watts" are not precisely defined).

For speakers, use the first quality pair of 4 ohm car speakers you find at a thrift store, yard sale, or abandoned Honda Civic in a gravel pit with bullet holes in the doors that miraculously missed the speakers.

Power this with 12V from a 7AH sealed lead acid battery (commonly used in computer UPS, some ride-on toy cars, emergency lighting), bunch of NiMH cells in series, or some cordless tool battery in the 12V to 14.4V range. I'd be tempted to add some frills like a cheap LED voltmeter module from eBay wired with a push switch to allow checking battery voltage, a lighter jack for powering other 12V accessories, and something that can charge the battery and/or run the unit from 120V AC.

If light weight is a concern, with some luck or perseverance you may find car speakers that have neodymium magnets and composite frames. (I found a pair like this at a thrift store: looks like an OEM speaker, but no identifying brand. It's slightly possible that asking around at car stereo installers will get you a pair that have been pulled from a new car.) OEM car speakers don't have a great reputation, but if you put them in a box that doesn't rattle or buzz, has stuffing to prevent internal resonances, and maybe add a tweeter, it could sound good.

For a lightweight but stiff enclosure that's strong enough to sit on, try a plastic foam-insulated picnic cooler. Those can be very cheap at thrift stores. I've also seen some plastic water-resistant boxes at a hunting/fishing supply store that resembled ammo boxes, like this one: http://www.amazon.com/Action-Products-Sport-Utility-Dry/dp/B001DZLL5Y
 
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For speakers, use the first quality pair of 4 ohm car speakers you find at a thrift store, yard sale, or abandoned Honda Civic in a gravel pit with bullet holes in the doors that miraculously missed the speakers.

Power this with 12V from a 7AH sealed lead acid battery (commonly used in computer UPS, some ride-on toy cars, emergency lighting), bunch of NiMH cells in series, or some cordless tool battery in the 12V to 14.4V range. I'd be tempted to add some frills like a cheap LED voltmeter module from eBay wired with a push switch to allow checking battery voltage, a lighter jack for powering other 12V accessories, and something that can charge the battery and/or run the unit from 120V AC.

Dont mean to hi-jack the thread... But I figure it'd be best to ask the relative questions here than start a new thread.. I'm new to this stuff too, but have some understanding...

My questions are
1) Why do you reccomend 4ohm speakers as opposed to 8ohm? Price? Avaiability?

2) The most confusing part to me now is power. What do you need to do to get a power source from the wall to both charge a battery as well as power the system... Do you simply wire the battery in series with the power source and then to the amp? Would that be fine to charge the battery? Or would you need to make up a circuit or add a component to "trickle" charge the battery

Thanks
 
All things being equal, 4 ohm speakers will draw twice as much power from the amp compared to 8 ohm speakers. Car speakers are nearly always 4 ohms. "Twice as much" isn't a lot when expressed in dB, though, so if you stumble over a nice pair of 8 ohm speakers, give them a try.

SLA batteries like to be charged at about 13.8 to 14.4 volts, but the charging current should usually be limited to less than C/5 (where C is the ampere-hour rating of the battery). The battery would be wired in parallel with the charger and with the load. At low to moderate listening levels, the charger would supply current to the amplifier, but with the volume cranked, the battery would do the work. But if the voltage sags when the bass hits (from 13.8 to 12V), that could have audible effects, or possibly confuse a smart charger.

Maybe it's safer to run the amp from a separate 12V supply while the battery is being charged. 12V switching supplies don't cost much from eBay or a thrift store. On the other hand, if T-amps will tolerate 15V, a 15V laptop supply could run the amp, and the 15V would be dropped (using a series diode) and current limited (resistor?) to charge the battery.

Or, a switching supply could boost the 12V from an AC adapter to charge the battery. That would have additional benefits: you could charge the battery from a car lighter jack, or use the boombox battery to boost a flat car battery.
 
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I wanted something similar. I bought a Lepai TA-2020+ and a pair of the cheap Dayton B652 speakers to start with. I then bought a piece of 1x8 pine board and some threaded rod to clamp it all together. I screwed the amplifier to the center of the bottom board. Then I used those rubber furniture leg pads to cushion the speakers. The threaded rod goes through the top board and screws into blind nuts attached to the bottom board. I put a handle on top.. and that is about it. All in, about $70 and it sounds pretty decent. I am going to make a place to mount a battery once summer comes.

An externally hosted image should be here but it was not working when we last tested it.


I also plan on tinkering with the Daytons to try to make them sound a bit better.. although that it not the real purpose of the rig. The purpose was to make something portable, that I could also disassemble and use as a near field system if the mood strikes me.
 
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