5 channel amp for newbie

[Bob0513]

Hello,
I want to make a 5 channel surround sound amplifier for my dorm room, but am a complete newbie to amplifier design. I don't want to have to buy a kit because they are very pricey. Could you guys recommend the easiest, cheapest amp design for me? I don't need that much power, since my room is small and I don't listen to my music very loud. The front and rear speakers on each side will be driven by the same audio input (there are 2 inputs to the amplifier, left and right).

Also, could someone reccomend a realistic wattage I will want for my amp design? Again, I will be listening in a small room, and I don't need the music to burst my eardrums .

Thanks,
Robert S.

[Minion]

Well you could simply make a Basic LM3886 Chip amp useing one LM3886 Chip for each channel which will give you about 50w per channel or 250w total output.....

You could have the front and Back Left speakers run off of 2 Chips and the Front and Back right speakers run off of 2 more chips and then sum the Left and Right into a single mono channel for the center speaker running off of one more chip......


You would need a Pretty big Transformer( 2x18v at 500vA) and if you aren"t willing to buy a Kit then you will have to design the circuit yourself and then etch your own circuit boards which if you have never done before will be a experience in it"s self.....


You can pretty much go by the Datasheet for the LM3886 to find the circuit you can use but without experience in this area and without someone to help, you might find that you are a bit over your head....OR maybe not!!


Maybe someone will chime in with a better option for you....

Cheers

[Bob0513]

Don't you think 50 Watts per channel is a little excessive? I was thinking at most 25, but, then again, I am a complete newbie to audio amplifiers.

[Spasticteapot]

Originally posted by Bob0513
Don't you think 50 Watts per channel is a little excessive? I was thinking at most 25, but, then again, I am a complete newbie to audio amplifiers.

With the basic LM3886 design (check out chipamp.com), the speaker impeadance and supply voltage are what determine power. An amp with a 40VCT transformer and a 8-ohm speaker might put out 25 watts; the same amp with a 50VCT transformer, a 4-ohm speaker, and a really big heatsink can do nearly double that.


ChipAmp.com is your friend. Add a bunch of potentiometers, and you're set, providing you have the necessary outputs.

[Leolabs]

Don't you think 50 Watts per channel is a little excessive? I was thinking at most 25, but, then again, I am a complete newbie to audio amplifiers.

Depends on your environment/room.For a bedroom,25W/ch is enough.

[Bob0513]

How many transformers should I use? 1 per channel, 1 per chip, or 1 for the whole amplifier? Also, can use the same transformer for both the amplifier and pre-amp?

[Spasticteapot]

Originally posted by Bob0513
How many transformers should I use? 1 per channel, 1 per chip, or 1 for the whole amplifier? Also, can use the same transformer for both the amplifier and pre-amp?

You're going to hate me, but the answer is:

All of them.

There's many ways to build a chipamp. Some people have a fondness for monoblocks (1 transformer/rectifier per channel), and some people use really zarking big transformers for the whole thing. Two of the ultrafast 20A @ 200v switching diode modules at Goldmine-Elec (4$) and a 450VA transformer will let you drive 5 3886's at a reasonable level of power, but I'd spring for at least a 600VA transformer, and possibly use four of the diode modules. (Two in paralell for both the + and - voltage rails). 60,000uf of power filtering should be about right.

I would reccomend putting the PSU in a seperate enclosure. Less noise, less hassle, and you can stick the likely massive thing where you won't have to look at it.