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AX84 4-4-0 Studio Amplifier

4-4-0 Studio Amplifier Project

[classic projects] [current version] [testing version] [old versions]


Overview

The 4-4-0 Studio is a 2W, push-pull amplifier with a single channel preamp.  This amp is very responsive to the player and cleans up will by just backing off on the guitar's volume.  As with the other Studio projects on AX84, should this amplifier be coupled to a AX84 Core Cabinet loaded with an efficent 100dB or better speaker, and then cranked to 10, it will make your ears ring.

This project is intended for those who have built amps before.  The circuitry, while deceptively simple, yeilds an amp that is at the threshold of stability, and as such, it is very sensitive to things such as component choice and wire placement.

Tone goes from sparkling clean, to smoothly overdriven, to semi-saturated distortion, depending on pick attack and guitar volume setup. Responds very well to common pedals yet still and retains your guitars tone.

Features

  • 3 stage hi-gain 12ax7 based preamp.
  • Bass, Mid, and Treble tone controls.
  • 12AX7 long-tailed pair type phase splitter.
  • Complete NFB loop that includes a Presence control.
  • 6SN7GTB dual triode in class AB push-pull configuration providing approximately 1W of power clean, and 2W at full tilt.

Skill Level: intermediate --- Status: Ready to Build.

Before using these materials, please read our terms and conditions.


Current Materials

4-4-0 Studio 10.02.16
Schematic, bill of materials, board template and chassis layout for the 10.02.16 version of the AX84 4-4-0 ~ Studio.
BrianS_4-4-0.mp3
Brian Schmittling's build.  This is what we mean by clean to distorted with the twist of your guitar's volume.  8-)
TomN_4-4-0_Clean.mp3

Alan Olson's build, Guitarist Tom Northfield with a PRS Guitar.  These clips are clean with the 4-4-0 setup as follows:
Vol=4, TMB=544, Pres=6, Bright=Low. The cabinet is an Avatar 1x12 closed back with a Celestion G12H30
TomN_4-4-0_Clean2.mp3 Alan Olson's build, Guitarist Tom Northfield with a PRS Guitar, and the cabinet is an 4x12 closed back with a Celestion Blues.
TomN_4-4-0_Crunch.mp3

Alan Olson's build, Guitarist Tom Northfield with a PRS Guitar.  These clips are dirty with the 4-4-0 setup as follows:
Vol=9, TMB=544, Pres=8, Bright=High. The cabinet is a Marshall 2x12 closed back with stock speakers.
TomN_4-4-0_Crunch2.mp3 Alan Olson's build, Guitarist Tom Northfield with a PRS Guitar.  These clips are dirty with the 4-4-0 setup as follows:
Vol=8, TMB=345, Pres=8, Bright=Low. The cabinet is an Avatar 1x12 closed back with a Celestion G12H30.
JonA_4-4-0.mp3 Jon Anderson's clip of Alan Olson's build at the Minnesota Amp Fest.

Older Version Materials

4-4-0 Studio 08.11.15 Schematic, bill of materials, board template and chassis layout for the 08.11.15 version of the AX84 4-4-0 ~ Studio.
4-4-0 Studio 08.11.10
Schematic, bill of materials, board template and chassis layout for the 08.11.10 version of the AX84 4-4-0 ~ Studio.
4-4-0 Schematic 08.10.17
Schematic for the 08.10.17 version of the AX84 4-4-0 ~ Studio.
4-4-0 Schematic 08.10.02
Schematic for the 08.10.02 version of the AX84 4-4-0 ~ Studio.
4-4-0 Schematic 08.09.27
Schematic for the 08.09.27 version of the AX84 4-4-0 ~ Studio.
Preliminary 4-4-0 Schematic 08.08.03
This is the preliminary, developer's 4-4-0 schematic.


Is this area looking a little skimpy? Looking for older materials and soundclips from previous version? Check out [the older versions]


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