OPA627 vs OPA637
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iWeasel410

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So is there any difference between these two opamps? I currently use the 627s but I have a couple of 637s but I can't hook them up because I don't have an adapter.
 
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KTpG

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Gain>5, yes.... but I had that in my amp and it was still unstable. Tried AC power with LOTS of capacitance and regulators... nothing.... batteries... nothing... I think these chips are very picky. Definitely need small value bypass caps on power supply rails very near each chip... perhaps even a cap in the feedback loop.

Although, others seem to get these chips working well with little effort... but they aren't working for me.
 
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peranders

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Good pcb layout is important when the opamps become faster. Still, WHY do you want this 637?

Speaking as a professional I would never use the 637 for gians less than 10-20.
 
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jboehle

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I just built a PPA with 627 in ground and 637s in L/R. With no C2, C3, or C5s installed, it seems to be behaving ok. But that's with the default gain (11?).

As far as the differences, depending on your system, you may or may not be able to hear differences between the 627/637.

BTW, why do you think you need an adapter? Or do you mean your 627s are soldered directly to the board instead of being mounted in DIP sockets? Or do you have the SOIC version?

-Jason
 
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iWeasel410

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I got soic 627s for free and made my own homebrew adapter to dip. Anyway, I was just wondering cause I got a few 637s for free and found the data sheet for the 627 and 637s to be the same.
 
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jamont

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Quote:

Originally posted by jboehle
I just built a PPA with 627 in ground and 637s in L/R. With no C2, C3, or C5s installed, it seems to be behaving ok. But that's with the default gain (11?).


Touch them after it's been in use for a bit, how hot are they?
 
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jboehle

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I will check that tonight. Had it running for 10 minutes or so yesterday though, and I could still put my finger on them for 10+ seconds, so not overly hot. I plan on putting C2/C3/C5 in, just haven't decided for sure what I'm going to use. Some like the Black Gate Non-polars for those, I'm mulling it over.

-Jason
 
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