tda1543 overheat and distortion

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my newly built 1543x 12 distorts when it overheats. the sound is much like a tape hiss and it starts intruding into the music after a while when before it only stays on the background.

vref 68ohm
iv 82 ohm as per doede's suggestion many threads back.

lm317 6.3v
pin7 on 1543(12of them stacked btw) 1.8v

psu is a laptop dc adapter 12v 3a

the heatsinks on both 317 and 1543 eventually get too hot to touch at which point music is heavily distorted. i'll be ordering a 9v 1.5a hammond trafo but will i still require additional heatsinking, and is it normal for now for the chips to heat up so much? ive read reports that they dont wven get above warm for some.
 
my newly built 1543x 12 distorts when it overheats. the sound is much like a tape hiss and it starts intruding into the music after a while when before it only stays on the background.

vref 68ohm
iv 82 ohm as per doede's suggestion many threads back.

lm317 6.3v
pin7 on 1543(12of them stacked btw) 1.8v

psu is a laptop dc adapter 12v 3a

the heatsinks on both 317 and 1543 eventually get too hot to touch at which point music is heavily distorted. i'll be ordering a 9v 1.5a hammond trafo but will i still require additional heatsinking, and is it normal for now for the chips to heat up so much? ive read reports that they dont wven get above warm for some.

The LM317 definitely needs a heat sink.
the temp of the TDA1543 seems to vary from chip to chip. Actually I've never read about someone who could stack a few TDA1543 without additional cooling. So I'm afraid you'll have to do some work.

MArco
 
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