Best opamp for I/V conversion? (DAC)

[tvicol]

Originally Posted by AndrewGM

So, what is the best op amp for i/v conversion ?

LME49713

Regards,
Tibi

[tiefbassuebertr]

Originally Posted by tvicol

LME49713
Regards,
Tibi

thank you - good advice.
ESS Sabre Reference DAC (8-channel) (post #1315)
LME49713, could be a killer opamp
http://audio.com.pl/testy/cary-audio...-xciter-dac:25
http://audio.com.pl/pdf/testy/przetw...ITER%20DAC.pdf
http://www.elforum.ro/viewtopic.php?...59477&start=15

Who can say the lowest possible supply voltage without loss in audible quality for +/- 2Vss output swing (the mentioned value of +/-5V from datasheet is probably too low)?

Where are to find the internal simplified schematic diagram?

[dirkwright]

Originally Posted by tvicol

LME49713

Regards,
Tibi

Keeping RFI out of that chip is going to be a challenge for anyone.

[theAnonymous1]

Originally Posted by dirkwright

Keeping RFI out of that chip is going to be a challenge for anyone.

I built a headphone amp using two of these that was powered by a DC/DC converter. No RFI problem that I could tell; excellent sound.

[SoNic_real_one]

Gosh, already TI set up the National website datasheets on their own domain...
http://www.ti.com/lit/ds/symlink/lme49713.pdf
http://www.ti.com/lit/ds/symlink/lme49710.pdf
http://www.ti.com/lit/ds/symlink/lm4562.pdf
Good bye Nat Semi!

[Extreme_Boky]

Originally Posted by tvicol

LME49713

Regards,
Tibi

1. inverting input of the current feedback OP is a poor choice for virtual ground summing

and

2. transimpedance current feedback OP cannot have a cap across the feedback resistor


Datasheet specifies the Rf value of 1.2Kohm to be optimal; this value could give less than desired voltage output level with well-regarded current-out DAC's that have only around 1mA output…. which means a second gain stage…. or…..the choice of a sub-optimal DAC (with higher Iout)… or even worse – the Vout DAC

There are OP's that can give outstanding results if used as I/V, due to very high slew rates, extremely low input bias current and very low offset voltage + they are voltage feedback OP's. The only thing to pay attention to is output oscillations, but once done right – this combination can really show what preceding current-out DAC is capable of. If the oscillations are not controlled properly the end result could be quite bad.

49713 will most definitely sound very nice (at least the oscillations would be easier to control compared to a fast voltage feedback OP) - however, the PCB trace cutting (cap should be placed at the input of the current feedback OP, in combination with the resistor for the desired cut-off frequenc, and damping) and a bit of adjustments are needed to allow this chip to be used in place of voltage feedback OP. Not many DIY-ers are ready to do this... many expect drop-in replacement should just work irrelevant of the type of the OP at hand.


Boky

[qusp]

is this series RC at the input of the CFB chip considered part of the dac output, or the opa input? ie. i take it you must know the CFB chips inputZ to enable proper choice for the size/value of the component? or does the resulting LPF rely mainly on the dac's output impedance? i expect its a combination of the 2, but which has the more profound effect? i'm on mac so cant run spice unfortunately