Amplifier modeling

Signal processing within the modeling concept can be realized with analog or digital circuitry, or combinations of them both.

This process has the advantage of being dynamic—the amplifier settings can be adjusted without forcing the musician to re-record the piece.

A good example of a moderately complex analog modeling circuit is Peavey's "T-Dynamics" power amplifier design, which (using 100% analog circuitry) emulates complex clipping and bias-shifting characteristics of push-pull tube power amplifiers, as well as the typically high-ish output impedance of such.

Roland's earliest "Blues Cube" amplifiers employed analog tube modeling circuitry, though Roland did not model specific tube amplifiers, more so the overall characteristics of a generic tube-based preamplifier circuit.

Peavey's "Vypyr" series of modeling amplifiers utilizes analog "TransTube" circuit instead of a digital waveshaper, and Vox Valvetronix amplifiers have throughout their history presented a marriage of semiconductor and vacuum tube-based analog modeling circuitry and digital signal processing circuitry.