TDA7293 and TDA7294 is a common feature of the bootstrap capacitor is not installed work as usual, which gives an opportunity for unscrupulous traders to provide fake, counterfeit goods market is the most polished printed for the TDA7294 TDA7293, from the printing on the can identify, find a few different batches of IC for your reference:
TDA7294 pin 11, pin 12 empty legs, open state is insulated
TDA7293 pin 11 (voltage amplification stage output), pin 12 (bootstrap) has a resistance:
Limit voltage 100v TDA7294
I found that some batches were TDA7294 90V breakdown in the type of IC sound like TDA2030, reaction was slow, boring sound, though not sure whether the fake, but certainly not a good thing!
The breakdown is not more than 90V, the general performance of the midrange and treble sound clear and bright, fast response! Found in different batches of test and origin of the TDA7294 sound even different!
Sound quality not as good as Legend TDA7293 TDA7294, wrong! I found a few pieces of genuine TDA7293 sample tests and found TDA7293 TDA7294 sound much better than that, the biggest feature is bright! Fast! Power foot.
Above are for reference only, are welcome to share and talk about their experiences