Op-Amp unbalanced rail voltage?

[ftransform]

For a dual supply op-amp are they any negative effects from having un-equal rail voltages other then having a smaller output range?

I.E. If one rail is 15.5 and the other is 14.7 is there any kind of degradation of specifications, such as PSRR, noise, bias currents, whatever.

[amspire]

None at all.

[Neilm]

I've measured nA with on op-amp supplied from +15V and -8V.

No problem what so ever.

Neil

[vlf3]

Just need to keep in mind your supply rail to rail max, verses signal out, peak to peak before clipping. 

[SeanB]

I have seen many use a rail of -0.6V ( a diode drop above negative rail) and 11.6V as supply, just because this allowed an output to be very close to 0V, while allowing positive voltages in with no problem. Fails with an inverting amplifier though, but fine for many applications.

[ftransform]

I swear though once I was taking measurements once and the AC measurement from my multimeter indicated that there was less noise when I increased the rail voltage from like 5 to 15.
I don't remember the setup though.

[c4757p]

I swear though once I was taking measurements once and the AC measurement from my multimeter indicated that there was less noise when I increased the rail voltage from like 5 to 15.

Op amps can definitely have different characteristics with different rail to rail voltages across them, it's the relative location of ground between them that doesn't make a difference. -1V/11V should be the same as -6V/6V, but (obviously) not -1V/1V.

[ftransform]

I swear though once I was taking measurements once and the AC measurement from my multimeter indicated that there was less noise when I increased the rail voltage from like 5 to 15.

Op amps can definitely have different characteristics with different rail to rail voltages across them, it's the relative location of ground between them that doesn't make a difference. -1V/11V should be the same as -6V/6V, but (obviously) not -1V/1V.

ah ha i am not crazy

[c4757p]

Also, I've seen some fantastically crappy power supplies that were noisier at low voltages (presumably due to the long wires going to the voltage pot picking up noise and not being adequately filtered), so the power supply may be injecting noise as well.

[ftransform]

This is possible my PSU is old. I really should take it apart and test capacitors at least.

[rdl]

w2aew has a good video on op power supplies.