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-   -   How can I power my amp (200w) to make it portable (away from the car) (http://www.diyaudio.com/forums/power-supplies/82914-how-can-i-power-my-amp-200w-make-portable-away-car.html)

samsunnyuk 10th July 2006 02:17 PM

How can I power my amp (200w) to make it portable (away from the car)
 
Hi,
I have a small 200w amp, and i would like to power it so i can carry it around (in a rucksack, with some small "6 speakers. little project im working onv:D)

So basically some sort of battery design and I have no idea where to start :dead:

Any help appreciated, Thanks

N-Channel 10th July 2006 08:21 PM

I don't know of any 200W amps that are "small", but you could try one of several routes:

1) If it is a car amp, simply pack a good sized gel-cell or suitable AGM battery, and let 'er rip;

2) If it is a home amp, then you could use a DC-AC Inverter (of appropriate size), and the aforementioned battery;

3) Determine the operating voltages, and replace the bipolar supply with a bipolar battery of equivalent voltage, charging it when you are back near a source of AC power

-or-

4) You could try doing an SMPS DC-DC converter, stepping the voltage up from 12V to whatever +/- voltage(s) your amp will need. There are quite a few threads on the Forum regarding SMPSing for Audio.

Hope this helps,

Steve

AndrewT 10th July 2006 09:33 PM

Hi,
increase your speaker sensitivity by 10db and you only need 20W of amplifier power.

Go for 20db more sensitive speakers and you only need 2W of power.
A 4Ahr Nicad might just do if the amplifier is designed for efficiency.

samsunnyuk 11th July 2006 01:09 AM

thanks for the replies people. How can I find out what the operating voltages are?

N-Channel 11th July 2006 02:31 AM

Is this a home- or car-amp? first, It ould help to have a schematic. See if you can ordere the service manual, complete with schematics.

Second, without any more info on the amp, it's darn-near impossible to say where. I would look for the BIG power supply capacitors

N-Channel 13th July 2006 07:07 PM

BIG power supply capacitors.................
 
Wow! I must've fallen asleep during my last posting- I just noticed I stopped in mid-sentence.

I think I was saying something finding the operating voltage(s) in the amp, by looking for the BIG capacitors and perhaps a BIF inductor.

You still haven't answered the big question: Is this a home- or car-amp? The difference between the two is the voltage(s) you will find inside them, and the types of safety protocols you will need to observe.

If it is a home amp, BE ADVISED: You will be dealing with LETHAL voltages: like 120VAC, 220-250VAC, 320-350VDC, etc. etc. Anything over 60VDC is considered lethal. In Europe, 50VDC is considered the threshhold for lethality. If you want to take it portable, try constructing a DC-DC Converter from 12V to whatever the amplifier's +/- operating voltages are. Insert it into the amplifier circuit tapping at the (+) and (-) bus bars. THen, whenever you're at home, you will be operating off the AC mains, and when you're on the road, you can use the battery.

If you have a car amp, you might not be dealing with high voltages, (though +/-45V to get 200W into 4 Ohm isn't exactly considered low voltage :D), but you will be dealing with very large currents. Like, on the order of 30A & up. While not lethal, shorting one of them out CAN yield a pretty spectacular fireworks show!

Typical operating voltages you should see for a 200W amp would be +/- 60-65V for 8 Ohm operation, and +/- 45-50V for 4 Ohm operation.

Let us know what type of amp it is (home or car) and we can give you more specific advice.

Steve


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