First op-amp...

[1843]

Hi all,

Why in some PIs, the pin3 of their first op-amp is fasten to the gnd by a resistor( generally 1k )?????

I cut the track of IC6 pin3 in my HH and then added an 1k resistor between that pin and gnd. I didn't see any effect on my HH...!? If I remember good, the op-amp output became out of saturation a little bit.

Best regards

[Carl-NC]

When designing for low offset, you normally want to load both inputs in the same way. So if the inverting side has a 1k input resistor, put a 1k on the non-inv side. For the PI preamp, it has almost no effect.

- Carl

[1843]

When designing for low offset, you normally want to load both inputs in the same way. So if the inverting side has a 1k input resistor, put a 1k on the non-inv side. For the PI preamp, it has almost no effect.

- Carl

Ok, Thanks!