stk392-020 as an audio amplifier

[james007]

hi all ,this is my first time with DIY, and i'd be very happy to know if there is someone out there who could help me (if possible) to reconfigure the stk392-020 convergence IC to an audio amplifier .I have recently salvage them from a Toshiba tv. I have also the complete board assembly for this convergence section. thak you in advance. James

[pacificblue]

Step 1 is to read the datasheet
Then you could copy the amplifier section from any audio amplifier datasheet. Recommendable schematics are e. g. figure 5 on page 7 and figure 7 on page 21 in the LM4780's datasheet. I. e. you need an input resistor, blocking resistor, a feedback resistor pair. You should add DC blocking capacitors to both inputs and an RF filter. At the output you shoud use a Zobel circuit. A Thiele circuit won't hurt either.

The power supply depends on the load impedance you wish to connect and the output power you wish to achieve. The peak output current is 6 A, just like the LM3875. So you can use a similar power supply. The thermal resistance of the case is 2,1 K/W, so the transformer should be 2 x 18 V or less for 4 Ohm speakers and 2 x 24 V or less for 8 Ohm speakers.

A good thing are the separate pins 11, 12, 13, 14 for the pre-stages. Here you could use a regulated power supply for improved sonic performance.

Add a big heatsink and don't expect too much of the IC. Maybe it doesn't even sound bad, but it is obviously not designed for audio purposes. For a first time project it might be a better idea to go for a proven application like TDA2030, LM1875, LM3875 or so.

[EWorkshop1708]

I also have some STK392's.

I have the STK392-110. Two of them with a heatsink, salvaged from a Projection TV.

These chips are simple, they are just a huge triple Op-Amp!

You have the better chip. Your STK392-020 is class AB. The STK392-110 is class B.

I'm also planning on making an audio amp with these too. However, my chips being class B, they probably make good amps for bass, or alarm sirens, or any non-SQ critical application.

Your Class AB chip should work fine for any audio.

Give them a try, they may sound great. They are designed for HF operation. Follow the Datasheet for the basic hookups of power rails and grounds, and go from there.