opa637 parallelled or what?

[umut1001]

Hi.There is a chinese man sells opa637 opamps.I am not sure that they are geniune or not.I bought opa627 from him and i think they are geniune.
There are 2 pieces of opa637 on a dual to mono socket.What is the purpose of them?I asked that is it paralleled or not and if can be used for lm4562.He said you can use it for a replacement op lm4562.Is it parallelled opa637?Is it for reducing distortion of opamp?Thank you
Here is the link
Dual to Mono Opamp OPA2604 NE5532 TL072 to OPA637 - eBay (item 320516209779 end time Aug-10-10 05:52:58 PDT)

BR
Umit

[analog_sa]

Slightly surprised that you are asking this. It's just a convertor which allows two single opamps (higher quality) to be used instead of a dual one. No paralleling. His answer that it can replace an LM4562 should make this clear.

[umut1001]

Oh sorry i see.I misunderstood sth.And let me ask a question to you.Some say opa637 have better specifications than opa637.But opa627 is the most sold opamp(more sold than opa637).Why?I heard opa637 have better PSRR.So i will use them at the output of tda1541 chip.My friend used opa627 but Nazar BL (He is a designer as you know) said opa637 is better.

[analog_sa]

Originally Posted by umut1001

But opa627 is the most sold opamp(more sold than opa637).

Only because it's unity gain stable and many applications require this.

[umut1001]

I have a Denon pma495r amplifier.I replaced its njm2068 opamps with opa627au on mono to dual adaptor.The sound improved but I do not have a service manual and i can not find it.How can i know that opa627 or opa637 is better?.I do not know its gain.I do not have an oscilloscope

[abraxalito]

Originally Posted by umut1001

How can i know that opa627 or opa637 is better?

You'd better know the gain if you want the OPA637 to work without oscillation. The OPA637 is the better specified part as its decompensated, but it seems quite a few people shy away from using it as they don't know how to make it stable. If you're interested in understanding that, ask Google to find you the datasheet for the LMV793 - its another decompensated amp and in the data there's a wealth of helpful hints about applying it.