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ASTRA SILICON FUZZ

2

TABLE OF CONTENTS

1

Project Overview

7

Drill Template

2

Introduction & Usage

8

Enclosure Layout

3-4

Parts List

9

Wiring Diagram

5

Build Notes

10

Licensing

6

Schematic

10

Document Revisions

INTRODUCTION

The Astra Silicon Fuzz is a clone of the Astrotone Fuzz, also released as the Sam Ash Fuzzz Boxx (yes, 
there are three Z’s and two X’s!). It was manufactured by the Universal Amplifier Company in New York 
City from 1966-1968.

The Astrotone was one of the first silicon fuzz units, developed in an era when germanium transistors 
were still widely used. It’s also one of the first effects pedals to feature a tone knob, although it’s not 
particularly effective in this circuit (at least not without some modifications) and later fuzz pedals such 
as the 3-knob Tone Bender greatly improved upon the concept.

Analogman released his version of the Astrotone, conveniently also called the Astrotone since the 
original trademark had expired. It has the exact same topology, but has several component values 
changed out to round out the tone and remove the thinness of the original. It’s not an exact clone, but 
it’s still very highly regarded. A parts list for the Analogman version is provided in the documentation 
alongside the original version.

The updated version of the Astra includes a toggle switch to select between three different sets of 
clipping diodes. Since the circuit uses hard clipping with no volume recovery stage afterward, the 
clipping diodes will directly impact the maximum available volume.

USAGE

The Astra has the following controls:

• 

Attack

 is an input volume control that reduces the gain before the transistor amplification stage, 

acting as a drive control.

• 

Tone

 cuts the treble after the clipping stage.

• 

Level 

controls the overall output of the effect.

• 

Clip

 (toggle switch) selects between three sets of diodes: 1x silicon (stock), 2x silicon, and LEDs.

Summary of Contents for ASTRA SILICON FUZZ

Page 1: ...NT VERSION Astrotone Fuzz An early silicon fuzz from 1966 that was also sold as the Sam Ash Fuzzz Boxx One of the first drive circuits to include a tone control Silicon fuzz 1 0 1 2021 04 27 BUILD DIF...

Page 2: ...ed his version of the Astrotone conveniently also called the Astrotone since the original trademark had expired It has the exact same topology but has several component values changed out to round out...

Page 3: ...film resistor 1 4W LED current limiting resistor Adjust value to change LED brightness C1 47n Film capacitor 7 2 x 2 5mm Analogman version uses 470n here C2 47n Film capacitor 7 2 x 2 5mm C3 47n Film...

Page 4: ...D 5mm LED 5mm red diffused IN 1 4 stereo 1 4 phone jack closed frame Switchcraft 112BX or equivalent OUT 1 4 mono 1 4 phone jack closed frame Switchcraft 111X or equivalent DC 2 1mm DC jack 2 1mm pane...

Page 5: ...most diodes Therefore while DO 7 silicon diodes are rare today this would not be uncommon to see in 1966 The other evidence in favor of them being silicon is more practical since they re hard clipper...

Page 6: ...kB 100kB GND 47n 2N3565 2N3565 1M 22k 470k 1M 1k8 1k8 47n 47n GND GND GND GND 47n VA VA VA GND 100R 1N914 1N914 1N914 1N914 1N914 1N914 GND IN OUT D1 C5 C6 LEVEL 1 2 3 TONE 1 2 3 ATTACK 1 2 3 C1 Q1 Q2...

Page 7: ...of closed frame jacks like the Switchcraft 111X If you d rather use open frame jacks please refer to the Open Frame Jack Drill Template for the top side LED hole drill size assumes the use of a 5mm L...

Page 8: ...ASTRA SILICON FUZZ 8 ENCLOSURE LAYOUT Enclosure is shown without jacks See next page for jack layout and wiring 125B...

Page 9: ...125B IN V GND N C N C OUT PCB IN GND V V JACK GND JACK OUT IN GND GND PCB OUT Shown with optional 9V battery If battery is omitted both jacks can be mono rather than one being stereo Leave the far ri...

Page 10: ...ojects may be used for commercial endeavors in any quantity unless specifically noted No attribution is necessary though a link back is always greatly appreciated The only usage restrictions are that...

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