Infineon MA12070 Class D

I'm also running this for >1400Hz so no immediate need.

tA1...

  • If I would first like to not change the op-amps and keep the pot - what would you do?
  • in a second stage, remove the pot all together - what to do then? Losing 10 dB gain no problem - rather, its desired...
Is it possible to short out the pot? The mechanical implications of removing it seems bothersome.

Also, I'm on DSP EQ so a dB here or there, if the quality is still good, don't matter in the end. Using EQ makes pure FR "problems" irrelevant.

I hesitated a bit yesterday as I was ready to dig in to it. I felt I didn't really had a good plan... better not heat up the iron before one do...

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@TNT In the proposed mods picture, do what is shown and also remove the blue 22k resistor and short the 1k resistors near the red input caps. There is no way to bypass the pot without removing it, but that's not a deal breaker. It will act like a linear level control instead of a volume control, which I think is what you're after anyway?

The attached picture shows the original circuit, the proposed mods with TL072, and proposed mods with OPA1642.

Sorry if the way I explain and present things seems a little chaotic. Welcome to the mind of someone with ADD and SCD 😵. Never claimed to be good at this stuff.
 

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I did the mods. Felt good about it. Looked clean except one resistor that wasn't perfectly lined up but measured fine. But.... nope - I heard already when power on without the "hood". I heard a very faint short noise burst every second. AVO on the output confirmed - there was sometime coming out of the amp every second. Not so much so I briefly hooked up one compression driver - there was like a klick every second. Fail.

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Well, I did not find my ESD mat / clip. But I secured an environment and procedure to reduce the risk. But it could very well be that I fried it.

I measured its output with respect to content and levels and made the assumption that it would not hurt a professional high power driver. It didn't.

It seems like the amp has gone in some sort of protection mode and tries to start up again after a while but the error persists. As I write this I come to think about a few more fault tracing efforts that I could do...

Thanks for the offer JP - I will give it a serious consideration.

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The MA5532MS has potatoes...😮
The price of this card is only 55 euros...
The RQP is huge, much better than the low coast TPA cards...
The sabaj A20 is pulverized in terms of power, but not at the expense of quality.
The MA5332 has a natural analog sound that's a bit tubed...maybe.
For a 7mm chip ... It's crazy!
No breath, there must be a noise gate inside ...
I look forward to Texas Instrument's response.

By the way.. The sound is better than my IRF2092 based amp.
Assimilated the design of the MA5332MS to that of the IRF seems very reductive. I think that the PWM modulator must be identical to the MA12070 chip, only the output stage is different.

This is just my opinion as a handyman...and Sunday musician!🤗🤗🤗🤗
 
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