Leo Fender crafted guitar amplifier masterpieces without the assistance of computers, software or the Internet... In 1959 "graphical methods" meant drawing Bode plots with a pencil and ruler... Times have changed. ● Master the basics ● Design your amp ● Know it works Amp Design for the 21st Century

Guitar Amp Technology

Analog Technology

Mesa/Boogie Duo-ClassTM Power
A push-pull transformer operates in single-ended mode with zero net plate current through the transformer core.
Mesa/Boogie patent drawing


Power Amp with Variable Harmonic Distortion
The balance of the power amp input signal is user-controlled to vary the harmonic content of the power amp.
Peavey patent drawing


Mesa/Boogie Solo ControlTM
footswitchable volume boost to enable the guitar player to "step forward in the mix for a spotlight feature in any mode"
Mesa/Boogie transistor switch


Soldano SLO Global Feedback Controls
"The combination of the Depth and Presence controls provides a powerful EQ section that goes well beyond a typical tone stack."
Soldano SLO frequency response for depth control and presence control settings


Davoli Bootstrapped Phase Inverter
The circa 1965 Davoli Model 207 guitar amplifier from Parma, Italy has an unusual phase inverter with a split plate load.
Davoli bootstrapped phase inverter


Danelectro Differential Amplifier
Many players have rediscovered the lo-fi bristle of Danelectro and Silvertone amps.
Danelectro system design


Ampeg Plate Follower Phase Inverter
"It carries a mix-and-match bundle of ingredients found in a couple variations of a highly desirable blues and rock amp from another maker." -Dave Hunter
Ampeg plate follower circuit


Guild Parallel LTP Phase Inverter
Here is something not often seen in a guitar amp: a four-triode phase inverter!
load and grid lines


Hughes & Kettner Relay Control
Hughes & Kettner uses microcontrollers and relays to create a switched-channel, MIDI-controlled performance powerhouse.
relay coil driver


Mesa/Boogie Switchable Grid Bias Supply
The Dual Rectifier has a grid bias supply that is switchable to support EL34 power pentodes or 6L6 beam power tetrodes.
percentage output voltage graph


Magnatone Model MP3 Fixed Bias Preamp
The first stage adds a strange 220kΩ resistor between the 140V plate supply and the cathode.
Magnatone fixed bias circuit