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Old 27th March 2015, 01:09 PM  
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Join Date: Mar 2015
Lightbulb Amp for Passive speakers

I have a pair of 2-way speakers that are for a Hi-Fi System that is very old. I was thinking if I could probably add an amp and batteries in the cabinet to make it a portable speaker. Now, I know very little about speakers so bear with me.
Here's a picture of the speakers.
aaIMG_20150327_103104.jpg

As you can see, it says 12.5 Watts on them, and from what I've read, this doesn't seem like much, which encouraged me even more to the idea of a portable set, since it wouldn't need too much power, right?

If I can't turn it into a portable speaker, what can I do with them?
Can I diy an amp circuit and put it in the box? What would the power source be?

Sorry for such naive questions
 
Old 27th March 2015, 01:33 PM  
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Location: North Derbyshire
What are you hoping to do with them? - they are simply low power (cheap) stereo speakers, not really much use for PA or instrument use.

Assuming you want a small low power 'PA' (for busking etc.) then you want far larger and more efficient speakers than these.
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Old 27th March 2015, 02:32 PM  
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They are actually loud. The Hi-Fi system isn't cheap at all.
I'm not looking for anything exceptional though. I just thought it would be a waste leaving them unused like that.
I thought I could use my phone to play some music on them when I'm out with my friends, that's why I wanted to make them portable.

Last edited by kamikaze996; 27th March 2015 at 02:50 PM.
 
Old 28th March 2015, 12:37 AM  
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a couple of TDA2030 chipamps with an adequate supply (or two so each could be independent)
might just be the ticket at 14 watts max. should be an fairly easy project to cobble together and should fit in the enclosure.
and just so you realize you posted in the wrong section of the forum.take a look through the chipamp forum.
 
Old 28th March 2015, 01:20 PM  
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Quote:
Originally Posted by kamikaze996 View Post
They are actually loud. The Hi-Fi system isn't cheap at all.
We obviously have different ideas what 'cheap' means

Simply looking at those tiny cheap Chinese speakers in plastic cabinets with a single capacitor 'crossover' screams cheap at me - it might have seemed expensive to buy, but it's only a cheap low quality system.

Do you have the model number of it?.

Quote:

I'm not looking for anything exceptional though. I just thought it would be a waste leaving them unused like that.
I thought I could use my phone to play some music on them when I'm out with my friends, that's why I wanted to make them portable.
As all you're wanting is essentially a portable radio (but without a radio ), those would probably do all you need. As turk 182 suggested, a couple of TDA2030's would be fine.
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Old 28th March 2015, 04:28 PM  
JMFahey is offline JMFahey  Argentina
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You can't say "TDA2030" and "portable" in the same phrase unless you have access to small portable 28V batteries or something

The TDA2030 can work with just 12V , sort of, very poorly, not exactly the best choice.

The OP needs an amp which can be properly powered by a 12V battery, usually chipamps designed for car use .

Search EBay for some around 15W`chipamp , ready made board, and I suggest a 12.6V 4.5AH gel cell/alarm type battery, which is inexpensive, powerful , and still reasonably portable.
 
Old 29th March 2015, 10:08 AM  
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well thanks for denigrating a suggestion. i never claimed it was ultimate just a potential way to go.
here a link to something not using a 2030 seeing how it's apparently poo...
Compact High-Performance 12V 20W Stereo Amplifier | EEWeb Community

i guess looking at old car decks an recycling the output ic would be met with the same sort philosophy so i won't offer that up.

Last edited by turk 182; 29th March 2015 at 10:16 AM.
 
Old 30th March 2015, 11:30 PM  
JMFahey is offline JMFahey  Argentina
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Quote:
Originally Posted by turk 182 View Post
well thanks for denigrating a suggestion. ........... it's apparently poo........ i guess looking at old car decks an recycling the output ic would be met with the same sort philosophy so i won't offer that up.

Boy, are we depressed today !!!!!

So no suggestions can be made different from yours?

Nice Forum spirit

FWIW I had already typed an answer suggesting the OP to recycle the boombox where those speakers came from , going straight into the power amp and bypassing the cassete deck/CD player or the FM radio or the cheesy graphic equalizer, but I refrained to avoid touching a sensitive point.

Of course no good deed goes unpunished.

By the way, I can't imagine the OP building a 12V power amp on stripboard, even less etching PCBs, so I suggested buying premade modules and a cheap but powerful gel battery ... which by the way can power both modules, instead of:

Quote:
a couple of TDA2030 chipamps with an adequate supply (or two so each could be independent)
might just be the ticket at 14 watts max. should be an fairly easy project to cobble together and should fit in the enclosure.
Straight from the TDA2030 datasheet:
http://www.st.com/web/en/resource/te...CD00000128.pdf

Quote:
TDA2030
14 W hi-fi audio amplifier
So far so good, let's see what's needed for that:
Quote:
Typically it
provides 14 WAt 14 V or 28 V, the guaranteed output power is 12 W on a 4 Ω load and 8 W on an 8 Ω load
Oops, so it needs a 28V battery for portable use.

Am I the only one which does not find it :

Quote:
an fairly easy project to cobble together
One 28V 3AH battery (84 WH energy stored) :
Milwaukee 28V Battery | eBay
Quote:
NEW MILWAUKEE M28 28V VOLT 48-11-2830 Li-Ion Battery PACK Powers V28
ONLY: $131.99

won't even comment on using two of them

vs:

one 12V 7AH battery (88WH energy stored):
New 12 Volt 7Ah SEALED Lead Acid SLA Battery 12V 7 Amp | eBay
for just: Price: US $17.40
 
Old 30th March 2015, 11:44 PM  
sreten is offline sreten  United Kingdom
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Location: Brighton UK
Hi,

A T amp and batteries would be ideal.
T amps run off basically laptop supplies.

Lepai LP-2020A+ Tripath Class-T Hi-Fi Audio Mini Amplifier with Power Supply

Note you won't get full power with a 2A supply.
And a 12V supply won't charge 12V batteries properly.

rgds, sreten.
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