18v vs. split rail with a BB op amp: Any opinions on which is best?

[midwayfair]

I'm modding a preamp for a friend. It runs off two batteries right now and I'm changing it to a power supply with a charge pump (and a single battery instead).

So what are the pros and cons, if any, of +9v/-9v vs. just 18v?

If it matters, he uses fairly high output humbuckers, plays clean, and his guitars have a healthy amount of bass.

[culturejam]

Not sure which is better, but I think you may have to stick with the setup that is in there. If it's set up for +18v and VREF, I don't know if it will work if you run it +9v/-9v (without some modifications). There would still be voltage dividers supplying +4.5v to some of the op amp inputs, but they would be correctly biased with 0v (GND) instead.

But I might be wrong. I've worked very little with bipolar power and op amps.

[midwayfair]

Not sure which is better, but I think you may have to stick with the setup that is in there. If it's set up for +18v and VREF, I don't know if it will work if you run it +9v/-9v (without some modifications). There would still be voltage dividers supplying +4.5v to some of the op amp inputs, but they would be correctly biased with 0v (GND) instead.

But I might be wrong. I've worked very little with bipolar power and op amps.

Good point. I glanced at the resistors and there can't be a v ref in this ... there's not even a 1M to ground. at the + input.

I looked up the op amp (OPA130) to find the operating specs. The chart in the datasheet says it has a +13v/-13v operating range and that 18v is the max voltage. But then the last page has this:

"OPA130 series op amps operate with power supplies from
±2.25V to  ±18V with excellent performance. Although
specifications are production tested with  ±15V supplies,
most behavior remains unchanged throughout the full
operating voltage range. Parameters which vary significantly with operating voltage are shown in the typical
performance curves."

I'm not sure which is "more" correct, but overall I think I'd feel safer handing it back to him with no chance of blowing up the op amp if decides to get clever and run it on 12v (with the charge pump = 24v) or even 15v off a pedal power. The LT1054 is actually cheaper than the op amp and I'd rather he blew it up.

http://pdf1.alldatasheet.com/datasheet-pdf/view/56730/BURR-BROWN/OPA130PA.html

[stecykmi]

i'm fully confident that opamp will operate with a +/- 18V split supply.

[culturejam]

i'm fully confident that opamp will operate with a +/- 18V split supply.

Except for the op amps that have a max rating of +/- 15v, of course.

[jeffaroo]

look into the Burr-Brown opamps

http://tangentsoft.net/audio/opamps.html

[midwayfair]

look into the Burr-Brown opamps

http://tangentsoft.net/audio/opamps.html

The op amp I linked to is a BB.

[stecykmi]

i'm fully confident that opamp will operate with a +/- 18V split supply.

Except for the op amps that have a max rating of +/- 15v, of course.

i meant only in reference to the device in question, the opa130!

[midwayfair]

i'm fully confident that opamp will operate with a +/- 18V split supply.

Except for the op amps that have a max rating of +/- 15v, of course.

i meant only in reference to the device in question, the opa130!

I think he just misunderstood what you said at first.