Page 19 - Triwatt Custom Lead Amp Builder's Guide

Building an Amp

Warning: Do not attempt to build a guitar amp unless you know how to work safely with the
dangerous voltages present in a tube amp. These can exceed 700 volts.

Introduction

If you have purchased your Trinity Amp as a kit, this guide will help you build a tube guitar
amplifier. It is oriented towards someone who knows a little about electronics but is new to do-it-
yourself amps. It outlines a simple path to getting a quality amp build.

Switches and wire
Use standard UL approved switches with a 125V/3A rating for the Power and Standby switches.
Use 20 or 20 Gauge insulated solid wire with a 600V rating. It is good to get a variety of colors so
you can color code your wiring.

Use 18 Gauge stranded for mains wiring.

Physical layout

Make sure the jacks, sockets and pots mounted along the edge won't interfere with parts mounted
on the underside of the chassis. Imagine how chassis will be mounted in the cabinet and make sure
there is enough clearance for the speaker and mounting brackets. Trinity amp chassis are laid out
with serviceability and neatness in mind.

Grounding

It is recommended that you follow the layout provided with your Trinity Amp. It has been tested
and has proven reliable. If you choose to deviate, consider the following information.

Amps traditionally use the chassis for signal ground. This is not the best choice since it can create
ground loops and bad ground connections may develop over time. It is better to use star
grounding in which all of the local grounds are collected at a single ‘star ground’ point. With star
grounding there is only one connection between the chassis and signal ground.

Here are some rules for laying out a star ground. More information on grounding can be found in
the Tube Amp FAQ and the Tech Info page of Aiken Amplification.

(1) Connect the power transformer center tap directly to the negative terminal of the first power
supply filter capacitor (cap) then run a separate wire from the negative terminal to the star ground
point.
(2) Collect the ground points of each tube and its associated resistors and capacitors to a local
ground point that is not connected to the chassis. Run one wire to the star ground point from each
collection.
(3) Run exactly one wire from the star ground point to chassis.

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