Scott Dorsey has made many posts regarding the use of the INA103 on rec.audio.pro which you can find on deja.com.
Basically, the unbalanced output is the source of most of the distortion that this IC produces, and as a result the higher the gain on the thing the lower the distortion spec (as the output stage just idles, apparently).
In addition to a +/- 24-volt supply voltage for higher headroom and lower distortion he also recommends the following for anyone using the INA103 for a preamp design:
1. Supply decoupling. Use tantalums _and_ ceramic bypass caps _and_ massive electrolytics on board.
2. Use external gain-setting resistors and do _not_ rely on the internal resistor even if you are just using it at 40 dB.
3. Use a follower after the thing if you need to drive a 600 ohm load.
4. Use 150 pf caps between each leg of the input to ground. This will improve stability on weird source impedances like you wouldn't believe. Yeah, I know, 20 pf should be enough, but it's not.
5. Be very careful about the leak resistors from the input to ground. They should not contribute too much to noise and they shouldn't screw up the rejection too much since they are very small compared with the source impedance, but they are the primary load presented to the mike, and some dynamic and ribbon mikes change in sound radically depending on the load.
Also, with regards to the inverted outputs available at pins 7 and 11, this is the way many manufacturers (Grace, etc) use this IC. They take the output from 7 and 11 and use another output stage.
Joel
