Need a good amp for a pair of 4ohm, 40w nominal fullrange speakers

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zinblade19

Member
Joined 2009
Hi,
I'm planning to make an amplifier for a pair of 4ohm, 40w nominal fullrange speakers (mostly for PC use).........
.......can anyone please suggest me a good one??
I don't want it to be to costly or a hard to find one (most importantly I'm a novice,so I don't want it to be a very complex one either)
PCB designs or images are very much welcome.:confused:
 
A

AndrewT

R.I.P.
Joined 2004
your 18-0-18 3A transformer has a VA rating of 108.
This will work for power amps with a maximum total output of 54W to 108W.

You could run one channel from this transformer or you can choose to run two channels if you wish.

Calculate the smoothing cap voltage from the AC specification.
Use that DC voltage to read off the maximum output power declared in the chipamp datasheet.

Check the size of heatsink recommended in the datasheet. Double it for cooler operation.
 
star882

star882

Member
Joined 2007
If you're using them with a PC, pure digital is the way to go. However, pretty much all the digital chipsets are SMD, which is not recommended for a beginner. (There might be kits with the SMD components already soldered onto the board, but I'm not aware of any.)
 
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zinblade19

Member
Joined 2009
Thank u very much AndrewT :angel:

I shall use one transformer each for the two separate channels
(afraid of burning out the transformer)

I see there are lots of pcb layouts for lm3886 in this forum, I don't know which one to choose. Can you link me to one that you prefer most (have to be simple though).

Please keep helping, thanks.:hot:
 
ionomolo

ionomolo

Member
Joined 2007
ionomolo said:


Won't this hum?
Click to expand...

Andrew has made me notice that this post wasn't clear.

There is a problem when wiring two amps to the same psu and source because this introduces a ground loop:

........ --> AMP 1.. -->
PSU.. ---. LOOP.... --- SOURCE
........ --> AMP 2.. -->

While there are tricks to get the hum lower, they aren't 100% effective, so it's best to avoid such wiring. The two solutions are: Using a single board for both channels (With a single signal ground) or using two separate power supplies.

Two supplies will obviously give much better results because there will be no interaction between channels but it's not in your line of low complexity.

EDIT: :smash: replaced spaces with dots... what happened to them??!!
 
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