Nice JFET op amps to replace TL072

[12Bass]

Can you hear the difference between the TL07x and the new Belchfire HyperAmp in actual equipment and conditions?

Or does some other issue overwhelm the differences?

FWIW, I've auditioned a large number of op amps in various circuits and been able to reliably hear the differences between them.

Here's a good resource with detailed measurements of a variety of op amps: http://www.sg-acoustics.ch/analogue_audio/ic_opamps/

[kingswayguitar]

voltage noise mostly. the datasheet doesn't seem to quote it at 1K, but 48 nV per root Hz typical at 10 and 12 typical at 10K, potentially more, is too much for mic preamps

It's shown in fig. 41, about 13nV/rtHz. It's close to 4dB quieter than the TL072 across the board.

http://www.uni-kl.de/elektronik-lager/416511

For a one-chip 200 ohm mic preamp solution, maybe the INA103?

http://www.ti.com/lit/ds/symlink/ina103.pdf

ina103
$11-$12
yes sir!

[12Bass]

ina103
$11-$12
yes sir!

INA163 is another alternative: http://www.ti.com/product/ina163

[R.G.]

> the LM381,  but it was a no-holds-barred low noise
It's long-gone. TI got the design but marks it OBSOLETE and further has mis-filed it under "battery fuel gauge".
...
LM381 is about 1uV total hiss in 20KHz bandwidth.... fine for several-Kohm uses but far from the lowest voltage-noise (OR current-noise) part around.
I keep looking at it though. It was good but far from fabulous.

I know its obsolete, but I had an experience with a 381 based preamp when it was new that left a lingering impression.
I was at a friend's house, listening to some records (N.B. for modern-day readers; these are plastic discs about 12" across, which encodes sound as wiggles in a spiral groove, read by a (usually) diamond needle tip) and he mentioned that he was using his newly-build LM381 preamp, which was very quiet. I could hear the normal background noise on the recording, and said it didn't seem all that quiet. In reply, he lifted the arm off the record and turned the volume knob to maximum. There was *no* detectable hiss out of the speakers, even listening from about a foot from the speaker cones. He then positioned the arm over the start grooves of the record and hit the lever which let the arm drift down very, very slowly.

The sound when the needle hit the record surface rattled the windows and my ears, and the second pop when it dropped into the lead-in groove did the same. The surface noise from the nominally quiet lead-in groove was too loud to talk over.

I was impressed. It was a great real-world gee-whiz demo.