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Old 7th October 2003, 04:34 PM   #1
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Default Noob in need: passive speaker amp???

Hey, first post here cause i'm not a huge AV fan, but need some help/advice/flaming

Just brought some passive speakers for my Ipod (mp3 player for everyone outta the loop). They are very quiet, and I would like to make a small amp between the Ipod and the speakers.

The speakers have a sticker on the bottom saying:

impedance = 8 ohms
rated output power = 2x500mW
maximum output power = 2x1W

I have at my disposal:

# Soldering Iron + solder
# Old sound card
# wire
# rechargable battery (9V)

Can also buy compenents. I guess what i'm really askin is can i bodge something together to make an amp, or do i need to buy some stuff and make a circuit (need a circuit diagram if that is the case).

Any help appreicated

Ben

PS: class smiley
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Old 8th October 2003, 03:19 AM   #2
ir is offline ir  New Zealand
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try one of these http://www.national.com/pf/LM/LM1877.html

(MDIP version)

2W per channel

as you can see if you look at the datasheet, contructing it requires hardly any parts. Probably best to base it directly on the "Stereo Amplifer with Av=200" design on page 6

runs of 6 - 24 V

i've built a couple of small amps based on other model chips in this range (ie NatSemi low power Overture amps) a 1W version (sounds really good) and a 5W version (even better)

so i'd say this chip should be pretty sweet
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Old 8th October 2003, 03:29 AM   #3
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It sounds to me like the speakers you already have are amplified with a maximum of 1 watt power. My suggestion (if this is correct) is to rip out the existing 1w amp inside the speakers and replace it with a slightly higher power version. One such as IR suggested.
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Old 8th October 2003, 06:31 AM   #4
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Just opened it up, and the wire comes straight through the case and into the speaker "cone". Doesn't look like theres any kinda amp in either speaker. WIll have a go at ir's suggestion. Still open to others tho.

Ben
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Old 8th October 2003, 11:15 AM   #5
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Well if theres enough room jam one in each channel

Only external mods required would be a power jack and a small pot.

Thats if you cant control the volume from the ipod efficiently, cause you could just change the volume from the unit.

Do you have a link to these speakers with pic's?
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