Off topic: Portable HiFi 13w Amp (TDA8511J)

[stonerbox]

Salvaged some small speakers (4ohm, 15w ) and two TDA8511J power amplifiers and set out to build me my first portable amp for a upcoming week long trip to the northern parts of Sweden. I found this schematic but I'm not totally sure if it is as easy as the it implies? Thoughts? Also, I will probably just be using one or two speakers so how do I go about with the not connected outputs? In similar fashion as to a usual op amp??

I know that this is far away from stompbox related things but please don't slaughter me!   


Datasheet: http://www.nxp.com/documents/data_sheet/TDA8511J_N.pdf
http://audioamplifiercircuit.blogspot.se/2014/08/4-x-13-w-single-ended-power-amplifiers.html

[Transmogrifox]

Yes, it is that simple.

Just leave the unused pins not-connected.  As you can see it's internally tied to V/2 bias on the input so everything is happy if you leave inputs and outputs as "NC".

You can get a little more headroom if you use an op amp inverting amplifier to drive inputs 1 and 2 (pins 1,3) out of phase and connect the speaker between outputs 1 and 2 (pins 6,8).

In that configuration you can get rid of the output capacitors if those amps don't have much DC offset -- they should be very nearly identical to within probably less than 100 mV, which won't damage your speaker.

If you did that actually would be better to drive inputs 1 and 4 out of phase to give physical (thermal) separation between the 2 amps.  That just gives you a little more power/headroom with lower thermal limitations.  Basically you're spreading the heat between 2 channels instead of 1.

[stonerbox]

That is great news, thanks Transmogrifox!

[stonerbox]

Hm..? I am getting a tone/squeal when I turn it on (but also music).

1 1.96
2 0
3 2.8
4 5.8
5 12
6 5.7
7 0
8 5.7
9 0
10 5-7
11 0
12 5.7
13 12
14 10.99
15 2.1
16 12
17 2.1

Missed the 100uF from pin 4 to ground. Added it and now everything is working as it should.