It may not be the gate voltage, it could be the slope of the gate envelop.
You could try using the square wave LFO. This can be set to 10v output if you use the MIDI Control Centre software.
Remember, as the output is an LFO. If you set one step to 50% on a quant of 1 note it should trigger a gate for 50% of the step. It is an LFO so if you want steps without gates you need to set the LFO to 0% for the quiet steps.