I'v tried both, and it is real, they sound different!!! Test setup is my AK4458 DAC analog filter, LM3886 amps and LXmini speakers. Can only confirm the orher experiences before, the 49720 sounds more warm and has somehow not a lot of details like the 4562. The bass is not as good with the 49720. Something is simply missing and sounds flat... I'll give a litte time still, but I think I'll change them back... (the ICs are from DigiKey!)
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Still they are the same due to business reasons. I recommend that you perform a blind test with some golden ear people.
Thanks, but I do not need blind testing, the differences are obviously. The LM49720 sounds "laidback", similar to the OPA2134. Not bad, but not the LM4562 level at all... I leave some burning-in time yet, but I don't think that opas really need that...
Sorry to inform you, but sighted testing is no testing at all. You seem to avoid blind testing, because it would show that there is no difference between the two chips.
You could rule out self biasing if you let somebody else do the modification without telling you. Would you then pick the difference? Refuse blind testing is the same as admit that you are wrong, meaning you can't pick the difference.
If i can trust your ears, i'm sure the lme is fake or just low quality. We have Philipine made, Thailand, Taiwan, China... Many low quality lme in the market. Post the ic picture.
If I wanted some confidence in a difference or lack of it, I'd wire up both parts in the same configuration, feed them the same signal, and do a differential measurement between the outputs. It would probably be wise to try several configurations, inverting and non, different gains and different supplies. I'd probably do square wave tests, response and thd over a reasonably wide bandwidth and at different amplitudes. Not really tough or time consuming to do.
The pic looks cheap. Are you sure USA fabs produce products with such build quality?
The IC looks good, like a normal DIP-8 IC. The picture I've made has a poor quality (hand made with high ISO value)...
Again the urban legend (fake news?) surfaces. This has been dispelled by people employed by NS and TI -- back then and currently. The LM4562 and LME49720 are IDENTICAL except for the ordering number and marking. The LM4562 was introduced first. Then National Semi, for marketing reasons, decided to create a new part number. My suspicion is that they needed more 'space' in the part number universe for the family of audio-oriented parts and came up with the LMExxxxx numbering scheme.
The most difference you are likely to find is lot-to-lot variations, and I expect that is not what's going on here.
The most difference you are likely to find is lot-to-lot variations, and I expect that is not what's going on here.
What do you mean normal. In my country, the cheapest is $1.6. More expensive is $1.7 with build appearance similar to yours, only the printing is slightly worse. Mine are $5.1 with bigger circle at the back stating the origin like 'Philippines'.
The can version also has various builds. I have seen 2 actually, with the cheapest being $10.3. The good one is much more expensive and solid build.
You don't think they all sound the same, do you?
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