Exchanging TL072 for LM6172?

I have a question that might be really dumb, because I don’t know much about electronics.
But I’ve been told that the TL072 and LM6172 ICs are pin-compatible. So, if I have an audio Eurorack module with TL072s that cannot handle video signals, could I not simply replace those chips with LM6172s? I know the power consumption will increase. Any other potential problems or risks?

The rest of the circuit might still not be video friendly.
Also, the higher bandwidth 6172’s are more prone to oscillations and other high frequency phenomenon. - if i recall correctly they might even burn out if improperly decoupled.
Same with the rest of the circuit; your PSU might well handle the increased power draw, but depending on the number of amps replaced the internal power circuitry on the board might be a problem.


Thanks, Transistorcat, I knew it probably wasn’t gonna be that simple :slight_smile:

most audio circuits are decoupled the same as the video ones. just 2x 100nF caps
some audio circuits have high frequency filtering, which might be something you don’t want in video.
So for some circuits it would be an option to try this, you must know the circuit to know if it is possible.
Also , in my experience, video circuits are buffered on the in and outputs, audio circuits not so much, or sometimes.

What you can try is replace the lm6172’s with tl072: this will give you ‘smearing’ effects and edge softness, blurry stuff. Can be interesting! I tried it by accident when I bought fake LM6172’s on Ebay for the TFG :slight_smile:

I might even design a circuit around this !

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+1 to transistorcat and reverselandfill’s answers.

I’ve cooked LM6172 where TL072s were entirely fine! For example, directly connecting the -IN and OUT pins to create a unity gain op-amp - with a LM6172 I end up with the chip oscillating wildly and getting very hot. A resistor is needed instead…

I’ve also noticed that many audio circuits use high value resistors (10K - 100K) in series with the input, whereas the LZX circuits generally prefer low values (499R, 1K). I’m not entirely sure why this is, but it may be relevant.

That said, if you don’t mind a potential bit of melted IC adventure/cost, go ahead and see what happens! Build it up on a breadboard so you can stick a finger on the chip to check if it’s hot, and see if it starts smoking (that’s what I do :slight_smile: ).

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