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W A R N I N G !

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Tuesday, March 29, 2011

Measured current draw of some op-amps

As I was going to use my cMoyBB on a regular basis, I was curious as to which op-amp to use for maximum battery life.

Of course I can search the datasheets, but what's the fun in that. Also, I want to try to find clues that can tell me whether my OPA627BP's are fake.

LM4562 10.1mA
OPA-Earth 49.1mA
OPA627 14.0mA for two
LM6172 >60mA (error)
OPA2604 10.0mA
OPA2227 7.3mA
JRC4580 5.1mA
OPA2132 8.8mA

Yup, the numbers are as the datasheets say, mostly. LM6172's is over 60mA and increasing, and it was getting warm fast. It still has a very high DC-offset (>100mV!) despite the unity-gain mod - LM4562 dropped from 20 to 2.3, JRC4580 from 40+ to 10+, and OPA2227 from... I forgot from how high/low, but now it is 0.1 and 0.3mV.

OPA627 taking 7mA each as according to the datasheet, low DC-offset of... 0.0 and 0.0mV which was expected when reading the datasheet too. Things are looking better for these unknown-authenticity chips, some THD and load tests (to test the 45mA output current) later will wrap things up.

Subjective listening yielded good results too - particularly the bass, which is powerful yet clean, as though all the other op-amps I've tried so far have difficulty driving the 32-ohm MS1 (I haven't tried high-current ones like AD8397. And the background instruments come out more too. The main instruments are also more forward and wider but less deep soundstage which is not to my liking.

I wasn't specifically listening for anything nor having any expectations so it pleasantly surprised me. But hey, I've demonstrated to myself that I can hear tweaks even before doing them, so take these results with a pinch of salt. I've also failed a recent "Name that op-amp in the dark" test, although I have more confidence of identifying this OPA627 but these are not possible to do that test with.

Well, these chips are looking to look like the real stuff, pity I sold off two pairs cheaply at SGD25 per pair because I wasn't sure if they were real.

1 comment:

Mike said...

Nice test, I can see why JDSLabs chose the OPA2227, among many other reasons, is the fairly low current draw.

I was at calico's house today (the woody guy) and he told me that he bought fake 627BPs that exploded when he went and installed it.