I've always liked the OPA2604 too but sometimes its very difficult judging differences. I find you have to listen for a long time to get a true opinion.
Why do opamps colour the sound... well I guess when you think in terms of the discrete circuit each opamp represents and how different they all are then its no real surprise sonic differences exist, even though the specs suggest they should be very similar.
Why do opamps colour the sound... well I guess when you think in terms of the discrete circuit each opamp represents and how different they all are then its no real surprise sonic differences exist, even though the specs suggest they should be very similar.
New thread on the AD844 I/V
http://www.diyaudio.com/forums/digital-source/227677-using-ad844-i-v.html
Well, due to my own stupidity, I blew up two LM6181's yesterday. Sigh. I should have read this app note before playing with a current feedback amplifier:
http://cds.linear.com/docs/Design Note/dn46fa.pdf
The filter caps in the feedback loop of my IV converter made the LM6181's oscillate and get so hot that I burned my finger on them. I'm sure they are dead now.
It's not easy as far as I can see to limit the bandwidth of a current feedback amplifier. Some kind of prefilter is needed according to the app note. So, using current feedback amplifiers for limited bandwidth audio DAC's appears to be a difficult thing to do.
http://cds.linear.com/docs/Design Note/dn46fa.pdf
The filter caps in the feedback loop of my IV converter made the LM6181's oscillate and get so hot that I burned my finger on them. I'm sure they are dead now.
It's not easy as far as I can see to limit the bandwidth of a current feedback amplifier. Some kind of prefilter is needed according to the app note. So, using current feedback amplifiers for limited bandwidth audio DAC's appears to be a difficult thing to do.
if your I/V R is larger than the min stable feedback R then you can add a series RC in parallel to give a shelving low pass - its a start
"noise gain" series RC to gnd at the input lets you use a smaller feedback
R, lowering, pushing out the "shelf"
in fact a quick sim showed a low enough Z "noise gain" input network stabilizes a LT1227 with pure feedback C - but that is in sim - depends on op amp output Z modeling which is often poor at CFA in/stability frequency
"noise gain" series RC to gnd at the input lets you use a smaller feedback
R, lowering, pushing out the "shelf"
in fact a quick sim showed a low enough Z "noise gain" input network stabilizes a LT1227 with pure feedback C - but that is in sim - depends on op amp output Z modeling which is often poor at CFA in/stability frequency
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