running ic's off a single voltage vs bi-polar voltage

Anyone have information on the advantages and disadvantages of running ic chips off a single supply voltage say 36VDC vs  a bi-polar voltage of +/-18VDC?

On EEVblog I've seen a case of a low voltage OA which has way more offset running at bipolar than single supply, of course it only means that reference is no the low rail or at the half, it was a rail to rail OA, meant to work with digital stuff at 5V or less. Well implemented it should't be much problems other than more coupling caps, the cap at inverting input for example usually used a low voltage high capacitance in mic pre needs to be higher voltage so it will be bigger. I don't know, 0V is a concept, think your reference voltage as your ground and should be the same as working with bi polar... As I said before, there are opamps that likes more one thing than the other, you should check for your specific opamp, and data sheet probably won't tell you much about that.

JS

In theory no difference, but some op amps are optimized for single supply operation (like with input range including -V).

JR

Power Rails, both +ve & -ve in the usual Class B OPA output stages have really yucky current.

With single supply, you need to make sure your yucky -ve supply at 0V doesn't share your clean 0V tracks. 

JR's admonition not to put sewage in your clean water supply is appropriate.

You need to consider what happens if your earth tracks/plane has finite resistance & inductance .. cos it HAS.

You need to do this with +/- supplies too but with single supply, its easier for the unwashed masses to muck it up by assuming eg an 'earth plane' is at 0V.

Well that's just it, I have used opamps that asked for single voltage in a bipolar power configuration and they worked well and vice versa, so trying to find more information on the subject.

oh and since there are a few opamps that can run off a +/-24VDC was thinking a single supply voltage of 48VDC to run everything from phantom to all the audio IC's.

pucho812 said:

oh and since there are a few opamps that can run off a +/-24VDC was thinking a single supply voltage of 48VDC to run everything from phantom to all the audio IC's.

Click to expand...

So you can directly interface with POTS. 

pucho812 said:

oh and since there are a few opamps that can run off a +/-24VDC was thinking a single supply voltage of 48VDC to run everything from phantom to all the audio IC's.

Click to expand...

Yes, provided you are careful with your grounding, this works perfectly well. You will usually need double RC coupling to keep DC off pots and switches, however.

You could hack the "0" (as a sort of a "translation" from bipolar supply) by sacrificing one opamp and make it a rail splitter, so a virtual ground. This way it's possible to hack the pots' cold connections from real ground to the virtual "0", and keep some caps out of the signal path this way - so only using them at the circuit input and output. (IMO this is good for fast and painless "known circuits" conversion).

With the opamp rail splitter, you can be smart with the layout and position the cap (of course there will be a cap from resistive potential divider to the real ground) so that it will "listen" to the least dirty point of your layout's ground ... so the virtual "0" will be a tad cleaner as well and would reference well to the real ground which is good since your output is going to be referenced to the real ground (the "-" rail).

While full 48V seems a bit high to me, you could always hack in a capacitance-multiplier with some TO-220 darlington and cleanup the rails this way while dropping a couple of extraneous volts... or some mosfet. IRFs are good. Nelson Pass likes them.