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ever wanted to have a powerful speaker system for those inpromtue garden parties/field raves. many will say this is a redundant Instructable, as there are many boombox style radios from days gone by cheaply available, or these cheap ipod style mp3 docking stations that run on batteries.
I strongly disagree with this statement, boomboxes are huge and eat batteries, docking stations are weak and sound poor. so for the best of both worlds, I present to you my portable rave speakers.
I built these speakers to meet these specifications:
-compact, for easy, in a back pack transport
-powerful, for punchy clear audio to get those outdoors raves going
-long run time, who wants to stop raving ?
I strongly disagree with this statement, boomboxes are huge and eat batteries, docking stations are weak and sound poor. so for the best of both worlds, I present to you my portable rave speakers.
I built these speakers to meet these specifications:
-compact, for easy, in a back pack transport
-powerful, for punchy clear audio to get those outdoors raves going
-long run time, who wants to stop raving ?
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Signing UpStep 1
First step as always is, what do you need?
Components:
-speaker cones (take them out of a couple of sets of computer speakers)
-amplifier chip (see next step for details)
-1Mohm potentiometer
-3.5mm audio jack
-2 * 470nf capacitors
- a 220 micro F capacitor
-2 5kohm resistors
-high capacity set of batteries (12-18v 4000mah+)
-the best heatsink you gan get
tools:
-soldering iron
-dremel (or equivalent)
-wire cutters
Other materials:
-lots of assorted shrink tubing (electrical insulation)
-solder
-small project box (altiods tin would suffice)
-a good length of good quality wire.
-battery connectors of choice (I chose deans "t" connectors)
-thermal greese
Components:
-speaker cones (take them out of a couple of sets of computer speakers)
-amplifier chip (see next step for details)
-1Mohm potentiometer
-3.5mm audio jack
-2 * 470nf capacitors
- a 220 micro F capacitor
-2 5kohm resistors
-high capacity set of batteries (12-18v 4000mah+)
-the best heatsink you gan get
tools:
-soldering iron
-dremel (or equivalent)
-wire cutters
Other materials:
-lots of assorted shrink tubing (electrical insulation)
-solder
-small project box (altiods tin would suffice)
-a good length of good quality wire.
-battery connectors of choice (I chose deans "t" connectors)
-thermal greese
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I have a set of 2 2.7Ohm speakers (with two tiny tweeter disc things attached in parallel) gotten out of a boombox. The label on the boombox itself says 50W.
I'm planning on disposing of the (broken) Boombox and making a new one out of a briefcase, but aside from scaling up to a suitable amplifier chip, how much higher capacitors/resistors/potentiometer should i use?
Thank you!
In parallel, the impedance is half (as long as the two speakers are the same) and the power use goes up for the same reason.
The tradeoff is loudness vs. battery life.
Up to the point of the chip's and battery's minimum load and maximum current capabilities.
Too low of an impedance will:
If you're lucky, put the chip into protect mode
If you're not, fry the chip with too much current even with a proper heatsink OR
the battery won't be able to deliver current fast enough and cause "clipping" where the audio waves can't be reproduced properly and you get distortion.
Electric guitarists often want this effect but for music playback, it's ugly and causes ear fatigue.
The resistance (impedance)varies depending on which frequency feeding the speaker, the resistance value is measured at 1kHz(?, not entirely sure).
Btw i'm also working on a portable amp or two, and in about a week or so i'll post my design as well. (it isn't very big, but weighs about 2-3 KG with speakers that's it's only disadvantage... The good thing is it lasts about 1-2 days on full power non stop playing and it's 2x10 W ...)
I think you are likely to be missing some information some where (look at my very long post to someone about output power) according to you, I will be generous and 24 hours at 2*10W. this means you have 480Wh of stored energy. If you are using lead acid batteries that would weigh (480Wh) /(41wh/Kg) =11.7kg, that's a big battery.
If you used a good lithium ion battery (480Wh)/(128Wh/Kg)= 3.75 kg (this would be quite expensive)
That is just battery weight, plus cones and enclosure a speaker that could last even just one day at that power would weigh at least 5kg if you are incredibly clever about reducing weight. 2 days - obviously allot more than that. So you are likely over estimating the power you are actually using and probably the time that they will last as well. If your speakers do actually weigh 2-3kg and contain more than 480Wh of energy - call the patent office now - because you are going to be a rich person. ;p
That post was made 4 months ago, the amp from then is long dead (It could play about 17h or so on a full charge (on full power around 12h.)
The weight of the amp and speakers was >500g (good ol' AlNiCo magnet speakers) the rest of the weight was the battery (and case, tho the case couldn't have been more than 200g)
So, the 17h run was made with old cell-phone(look like cell phone batteries, but i don't think they are) batteries (nothing beats good ol' industrial batteries, the ones i used were 4.2V ~2110mAh (don't ask where i got them from) ) a total of 15 (...) batteries were used (and are still in use).
From what i calculated the brick was around 10Ah 12-13V
(Also, don't start calculating weight and stuff, these are not ordinary li-ion batteries they're Russian li-ion batteries, lol)
Also the weirdest thing was the batteries were(are) as light as a feather. If you took 3 batteries from these they would weigh as much as a BL-5C battery (aka the battery EVERY NOKIA phone uses today) don't have a good thing to compare to.
One last thing, the amp. I don't exactly remember it ( there were a lot of modifications to it), but from what i remember it was transistor based (when i say transistor based i mean it had a lot of bipolar and FETs) and was almost as big as the box, the output power was around 2x4-5W (10W speakers) it took 4 books and a lot of stupidity to make, but the end results were insane around 0.00042% THD made the sound crystal clear ....
That's all i remember
ask away if you have any questions.
About the amplifier - I would be interested in seeing the schematic/source of that - never have I seen a distortion figure that low for a practical audio amplifier. That is at least an order of magnitude better than ones I can find on the internet. Did you measure the distortion characteristics? or are you guessing ?
The case, less than 200g, was it made of cardboard? on my newest speakers my case weighs around 1Kg and it is too flimsy (partially my lack of skill I am sure, but I would think 1/5th of the weight would be horrific :P)
What size speakers were you using, 500g for 2 would be limiting you to some quite small ones, a decent single 4" driver is about 1kg (750g would be a little skimpy). if they are much smaller bass is going to go out of the window (especially if the box is not rigid enough).
anyway I would be interested in your answers from the sound of it you might have an interesting setup :)
The case is made from a plastic-like substance(a friend gave it to me, but it got lost about 1 month ago....damn...)
The speakers were small, yet powerful, not sure bout the dimensions and i think they were about 10W each... They're full range speakers with awesome highs and pretty clear lows (but when you run everything from one speaker sometimes the bass craps up the highs a little) also they're not that light one is about 300g, wasn't thinking when i wrote 500g overall.... pic related.
The amp, Actually me and a friend from Resprom(a Bulgarian audio company that made some of the best sounding amps and speakers I've ever heard.) developed/build the amp. He made most of the amp I just helped with the output stage(fun thing is after i made the output stage the dude gave me some weird looking transistors that turned out to be pretty fast/powerful) and filter.
Also he measured the THD with something like an oscilloscope.
All i remember from the schematic is....hmm.......well nothing.
Twas a great amp.
I can see that you are very ambitious, so if you wanna build some much more louder BOOMBOXES i can send you all the shematics, i have done some of it and when i came to school even the profesors were impressed how loud and how clear it was and how simple the amplifier was. It has 2*45Watts RMS on 12V battery. You can check the datasheet of IC it is called TDA7375A that one is stereo version, if you want to go quad there is TDA7386 i reccomend these two they are very simple to build and the quality of sound is amazing.
BTW. Sorry if my english is bad because im from Croatia.
So everybody is happy - apart from your battery, and this is where the class of amplifier you are using lets you down. Yours is a class A/B. There is lots of information around about what that specifically means but the issue is that this class of chip usually uses more power than is necessary when there is no output (actually it is much better than a lot of classes). Yours uses around 150mA just sitting there, or 2.16W (0.15A * 14.4V) that is allot of power not doing anything useful to us. Seeing as a major component of music is silence in-between sounds or low level sounds (in between bass thumps for example). So where am I going with this? is there a more efficient amplifier that is clearer? of course there is otherwise I wouldn't have written such a long post. Look at this amplifier http://shop.41hz.com/shop/item.asp?catid=42&itemid=43 . The output power at comparable distortion is the same as your amplifier but the power drawn quiescently (no sound) is much lower (64mA*13.4V = 0.86W) and in fact the measurement on my sample is actually 0.5W. so this is around 4 times the efficiency of yours when there is no sound, this matters less and less as you put the power up - at maximum power (15W if you want it to sound nice) there is little difference I expect, but the AMP6 will sound clearer generally. So if you find you use your speakers for BBQs/just chilling allot (rather than booming and raving) I would recommend you use an AMP6. If however you are using it exclusively for raving I would advise buying two Amp6's or one AMP9 and building the speakers in the style of http://www.diyaudio.com/forums/class-d/104402-boominator-another-stab-ultimate-party-machine.html . That link is probably to the most professional DIY boombox on the net. sorry for the very long post - hopefully we can inspire each other:)
i need to know so i can get some :]
Im kinda n00b to building speakers and thought you could help me with it...
I have two 4watt, 4Ω speaker elements and want the build a portable speaker/boombox.
If you consider helping me I'll make sure your name will be written on the front of it. :D
So basicly i want a list of components, and a "blueprint".
I would appreciate it alot!
excuse me for bad english, im from sweden.
And, don't overlook scrapped CRT TVs as a source of speakers. Also, if you're a real scrounger, an amplifier: on one Sony I found in the woods, the audio amp chip was on a corner of the circuit board and I was able to break off that section with my bare hands.
I suggested a T-amp because if you order a TDA7057AQ from someplace, it'll cost almost as much as one of the TDA2024 amp boards. And the TDA7057AQ doesn't appear to be rated to drive 4 ohm loads, which limits the choice of speakers and means that 2 per side (as shown) may not be a good idea.
Don't mistake my correction negativity. This a VERY cool instructable! If you would like to figure out your actual gain values, (without crunching all the numbers of the individual ICs, you could always input a SMALL voltage (like 0.2v DC) and measure the actual output. Would be cool to see some real numbers! Great job!
great ible though ! :)