Fake BB OPA2604 Chips???

[Enchilada]

Hi guys,

I've re-chipped my Tascam M3700 console with a mixture of chips. I used OPA2132 chips that I got from the USA in the master section, NE5532 chips that I got from China (eBay) and BB OPA2604 chips that I got from China.

I'm a bit concerned that they might be fakes. If they are, what does this mean for me? The chips seem to sound better than the stock ones but I've read that sometimes the Chinese BB OPA2604 opamps are often just rebadged NE5532s. If that are rebadged then it makes sense that the would still sound better seeing as the NE5532 is a faster opamp however I was really keen for some Burr Brown goodness in my console.

Is there anything I can test on them to see if they are just rebadged 5532s?

Thanks guys,

Kris

 

[JohnRoberts]

Hi guys,


Is there anything I can test on them to see if they are just rebadged 5532s?

Thanks guys,

Kris

Actually there is.. the 5532 a bipolar input will have much higher input bias current than the JFET input 2604.  So 2604 will have  typical 100 pA of bias current, vs. 200nA in 5534. So with high impedance input and feedback resistors you can calculate the input bias current from the voltage drop.

JR

 

[Enchilada]

Hi guys,


Is there anything I can test on them to see if they are just rebadged 5532s?

Thanks guys,

Kris

Actually there is.. the 5532 a bipolar input will have much higher input bias current than the JFET input 2604.  So 2604 will have  typical 100 pA of bias current, vs. 200nA in 5534. So with high impedance input and feedback resistors you can calculate the input bias current from the voltage drop.

JR

I'm sorry, you may have lost me there. So what you're suggesting is that I test if it is bipolar or not? So this will test if its a 5532 or not, are there any other ways I can test the chips to see if they're actually 2604?