As pointed out by jerryfreak, conversion from 6V to 12V inside the V2/V3 only affects calibration of the
low-battery indicator and
low-voltage shutoff point. Low-battery indication is inconsequential as everyone these days typically monitors voltage of their non-SLA battery packs at the battery itself. However,
low-voltage shut-off point is not inconsequential. 9V is below the typical low-voltage shutoff point for 12V operation, meaning that if setup that way without recalibration of the shutoff voltage potentiometer the preamp will not power on from a 9V source.
Resources:
Thread documenting procedure recalibrating the V2 (V3 is presumably identical)-
https://taperssection.com/index.php?topic=161217.msg2027239#msg2027239Quoted in that thread:
The 6V/12V jumper inside the V2 is for setting the auto-shutoff and low battery indicator. This was necessary for sealed lead acid type batteries where their voltage would slowly drop as they became discharged. The battery you are considering is a Lithium Polymer type that has a regulated voltage output and built in low battery indicator/auto-shutoff, so there is no need to adjust the voltage settings inside the V2. A 6V V2 will run with any voltage from 6-15V without a problem. The only caveat with running higher voltages is that the battery won't last as long and the unit will run slightly warmer, nothing to be worried about.
I would suggest using a 6V battery if you can since it will run longer, but if you want to use that 12V battery you can do so without worrying about changing the settings inside the V2.
Please let me know if you have any questions!
Take care,
Alex Vallejo
Grace Design Customer SupportFrom the
V3 operation manual:
Power Consumption
6-12VDC 600-1000mA
(depending on A/D settings and microphone type)The V3 is set at the factory to run at 6 or 12V. The current drain is the same at either voltage, but
the total power consumption will be twice as high for the 12V system. Also, it is normal for a 12
Volt V3 to run warm to the touch.DC SUPPLY VOLTAGE JUMPERS Jumpers J26 and J27 select the operation Voltage to be 6 or
12 Volts DC. These jumpers should be moved ONLY by a qualified technician. Consult the factory for
voltage change information. Figure 5 on page 9 shows the V3 INTERNAL JUMPER LOCATIONS and the locations of the calibration potentiometers
Potentiometer VR7 adjusts the low-voltage indicator threshold
Potentiometer VR8 adjusts the low-voltage cutoff threshold