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As Khron says, the 6k8 resistor in series with each leg of the phantom power supply - plus the 2k2 resistor in series with the feed to the op-amp supply - will ensure that the supply can't exceed the maximum DC for this type of op-amp.
With the 2 amps shown in OPA Alice circuit, each leg of the phantom power supply will need to supply c.2mA as a mimimum. (Probably at bit more, if a voltage multiplier is being supplied as well?).
So the voltage drop fom 48 v with 6k8 and 2k2 in series with each leg will be I X R .... 0.002A x 9K = 18v.
Thus the maximum DC supplied to the op-amps will be 30v..... Probably less in practice.

The half rail - 'center' - supply is derived from the equal value resistors - sadly partly covered by the red line in the schematic above.
The attached OPIC schematic - which doesn't use a zener - shows R6 and R7 - together with decoupling caps C4 and C6 performing that task.
Seems to work pretty well.....

[ATTACH]138836[/ATTACH]

<blockquote data-quote="rogs" data-source="post: 1173038" data-attributes="member: 3128">As Khron says, the 6k8 resistor in series with each leg of the phantom power supply - plus the 2k2 resistor in series with the feed to the op-amp supply - will ensure that the supply can&#039;t exceed the maximum DC for this type of op-amp.With the 2 amps shown in OPA Alice circuit, each leg of the phantom power supply will need to supply c.2mA as a mimimum.&nbsp; (Probably at bit more, if a voltage multiplier is being supplied as well?).So the voltage drop fom 48 v with 6k8 and 2k2 in series with each leg will be I X R ....&nbsp; 0.002A x 9K = 18v.Thus the maximum DC supplied to the op-amps will be 30v..... Probably less in practice.The half rail - &#039;center&#039; - supply is derived from the equal value resistors - sadly partly covered by the red line in the schematic above.The attached OPIC schematic - which doesn&#039;t use a zener - shows R6 and R7 - together with decoupling caps C4 and C6 performing that task.Seems to work pretty well.....[ATTACH]138836[/ATTACH]</blockquote>

[QUOTE="rogs, post: 1173038, member: 3128"] As Khron says, the 6k8 resistor in series with each leg of the phantom power supply - plus the 2k2 resistor in series with the feed to the op-amp supply - will ensure that the supply can't exceed the maximum DC for this type of op-amp. With the 2 amps shown in OPA Alice circuit, each leg of the phantom power supply will need to supply c.2mA as a mimimum. (Probably at bit more, if a voltage multiplier is being supplied as well?). So the voltage drop fom 48 v with 6k8 and 2k2 in series with each leg will be I X R .... 0.002A x 9K = 18v. Thus the maximum DC supplied to the op-amps will be 30v..... Probably less in practice. The half rail - 'center' - supply is derived from the equal value resistors - sadly partly covered by the red line in the schematic above. The attached OPIC schematic - which doesn't use a zener - shows R6 and R7 - together with decoupling caps C4 and C6 performing that task. Seems to work pretty well..... [ATTACH]138836[/ATTACH] [/QUOTE]

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