The Vaccum:Boost is based around an ECC832 tube (12DW7) dual vacuum triode. The high gain triode amplifies the incoming signal and takes care of equalization, while the low gain triode provides further gain, compression and output drive.
With output at maximum and boost set to desired signal amplification, it stays quite clean, even for loud input signals. Approaching maximum gain, the pedal will gently compress signal before in the end, overloading and adding grit. This is not meant to be a standalone overdrive pedal, so there is not much “smooth tube overdrive” inside. It’s designed to push your amplifier into doing what it does best(?), overdriving your signal.
We have 40dB of boost in here… this is 10 times more voltage gain than a “normal” 20dB boost pedal. Add in another 5 dB equalization range in mids (600hZ) or trebles (1.2kHz shelf) and you really have a lot of possibilities. And it’s all done in-phase so it won’t screw up phase relations in a multiamp setup.
Since it’s using tube amplification, at high voltage, output signals can greatly exceed those found in normal 9volts powered pedals. Actually, it can theoretically toast inputs if they are not over-voltage protected (boutique pedals anyone?), so run it just before your amp, not your unprotected NOS-germanium or mosfet overdrive!