Vibrato [sic] circuits that boost and cut evenly?

[Groover]

Opto-isolator type Fender Vibrato [sic] circuits cut the average signal level when in use. To put it another way the center of the LFO wave defines an average volume lower than the reference volume when the Vibrato is disengaged, the input signal being the same.

On the Vibro-Champ it seems like, with the footswitch set to "off", as I turn the intensity up the signal through the amp drops, and then when I click the footswitch "on" the signal swings around that reduced level as a center point, so the apparent average volume doesn't change when turning on and off with the footswitch, but it is lower than the reference volume with the intensity turned to minimum.

The Vibrato in my SFPR seems to swing the signal around a centerline that is close to if not the same as when it is turned off either with the pedal or the Intensity knob.

Do bias modulating Vibrato designs all work this way. Is this (Vibrato reference volume) an aspect that can be tweaked to taste?

[tubeswell]

Do bias modulating Vibrato designs all work this way. Is this (Vibrato reference volume) an aspect that can be tweaked to taste?

I don't think bias-vary trem makes the vol louder than what you get on the non-trem setting. It just varies the signal between the (otherwise standard) non-trem volume and a lower volume (which can be anything down to 'off' with the depth pot at max) - if that is what you are thinking about??

(But I stand to be corrected on this)