Making the top notch performing EVM more top notch? 
Not being MrMax, but the NJM4580 are pretty good devices. They also do in my test equipment in the pre-stage.
I wouldn't call this to bad:
shorted inputs + ADC noise:
1kHz +3dBV:
Not being MrMax, but the NJM4580 are pretty good devices. They also do in my test equipment in the pre-stage.
I wouldn't call this to bad:
shorted inputs + ADC noise:
1kHz +3dBV:
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The 3255 evm is not as well implemented or the chip does not perform as well?
Regards,
There's very little wrong with NE5532/4s. Decently low noise, very low distortion across the audio band and can deliver a decent amount of current on their outputs.
Yeah you can do better but I cannot believe for a minute that an NE5532 on the front end of the TPA3251 is going to degrade its performance in any meaningful way.
I used the dual differential LME49724 for my front end.
Yeah you can do better but I cannot believe for a minute that an NE5532 on the front end of the TPA3251 is going to degrade its performance in any meaningful way.
I used the dual differential LME49724 for my front end.
May be I mistaken. I thought you were answering the post #1094 :
"That's a great offer - so which of the TPa32xxd2evm to buy... "
Never mind.
At the risk of starting an op amp discussion which no-one wants, I don't like the 5532 cos it sounds dull, so I will be replacing it. AD8620, AD8599, OPA2132, LM4562 are my go-to dual op amps but the 1612 looks like a reasonable choice - 1/5 of the noise, triple the slew, 4x the bandwidth, and the THD... wow. Comparing specs I also found my memory is faulty since Ti's 5532 can drive better than 1612: 38 vs 30mA. However, the significant issue for me is that people say the 1612 sounds good - very subjective but given I don't like 5532, it is worth trying I think.
Cheers and happy new year.
Have you tried injecting some 4G signal either by proximity coupling or with an audio cable connected between 4g-device and amplifier?
Always this rise in distortion. What is creating it. What does it take in terms of eulution to get rid of it?
http://www.3e-audio.com/wp-content/uploads/2017/01/THDN_vs_frequency_20W.jpg
An externally hosted image should be here but it was not working when we last tested it.
http://www.3e-audio.com/wp-content/uploads/2017/01/THDN_vs_frequency_20W.jpg
I am guessing that it is similar to cross over distortion in a class AB amp. Recently Bob Cordell mentioned this phenomenon as it is caused by the way that the H-bridge fets are switched on/off. They require some dead band to prevent feedthru or both being on at the same time and acting as supply short to ground.
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I've had a quick read of the datasheets - that input circuit seems redundant. The amp has 24K input resistance so could be driven directly from most pre-amp outputs (balanced of course). Did I miss something relevant?
Has anyone measured if there is DC present on the input pins? It would be great to bypass the DC blocking caps too...
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If you have 4Vrms to drive, then the opamp can be omitted. If you use PFFB you'll need some additional gain to compensate the reduction introduced by the feedback loop.
There's DC on the inputs.
Use an input transformer - has the added benefit of allowing SE outputs to drive balanced ins. Plus a reduction in CM noise.