Making an 18V circuit from a 9V plan

You don’t have to make any notifications other than adding the 2nd battery and battery clip. You’ll just have to make sure that the components are rated for more than 18V.

Really the only thing to be careful with are the capacitors. (Standard voltage ratings for caps that you can use are: 25V, 35V, or 50V.) Anything higher is fine but they’ll usually be bigger in size.

1/4W or 1/8W resistors are fine to use.

The typical op-amps like TL06X or TL07X are able to handle the 18V. If you plan to use anything else, then read the data sheet to find the maximum supply they can handle.

Hope that helps!

 

Hi. I'm assuming this is the preamp schematic you're referencing. It's fairly straightforward to convert this to dual rail supply as I have shown by the modifications in red. I am assuming you already have this bass and just want to replace the preamp, since the wiring is already set up for +/- 9V. Otherwise you would need to replace the jack to switch both batteries.

3eq Bipolar by gerryjazzman posted Apr 12, 2020 at 1:34 PM

You could just use the existing layout with very minor modifications. Just eliminate the bias components in the lower left of the schematic (crossed out). Then the two bias points for each op amp unit would get tied to ground instead. Pin 4 of the dual op amp is tied to the -9v rail instead of ground. All this references the op amps to ground (i.e. 0V) so you can also eliminate the 10 uF output coupling cap by replacing it with a jumper. Should be fairly easy to do with the existing layout.

 

You are most welcome!

 

Sure.

 

Looks right to me. At least the changes required to use a bipolar supply. BTW, what kind of jack are you using two switch both batteries? Standard stereo / TRS jack won't work in this situation.

 

Doubling the supply voltage won't increase the gain, only the headroom before clipping. Most pickups don't exceed a volt or so, so a 9 volt supply with a fresh battery will allow for approximately a 4 volt peak signal before clipping.

 

Have you had instances of clipping your preamp? Often people go to great lengths to cure a problem where there isn't any.

 

"If it ain't broke, fix it anyway."