Enclosure not stated · 5 knobs
Fred Briggs EQ Booster (prototype)
Based on the Fred Briggs EQ Booster
- Category
- Boost
- Price
- see vendor
From the vendor
A 2009 prototype by the author of a coloring booster: a 2N5457 gain stage with a Bass control in the input network and a treble control after it, followed by a second 2N5457 stage into the Level pot. He says it sounds best at 18V and the treble control values still need tweaking.
The values in the treble control need tweaking to find the best response. The 100K drain trimmer can probably be replaced with a 10K trimmer; set both drains to 5.5V.
Schematic
The schematic is in the post. Open it at Revolution Deux. No KiCad fragment has been drawn for this circuit yet.
Parts list 23 rows
Report a wrong parseGot parts in a drawer? See what you can build with them.
Check before you build · 3 values the reader of this schematic was not sure of
- The 33K input resistor's label is scribbled over on the drawing.
- A first-stage 500KA Level pot at point A is hatched out; the second stage and its 47KB Level pot replace it.
- The second stage's output coupling cap has no value written.
| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 8 | ||||
| R4 | 2.2M | 2.2M | input pull-down; read from the schematic by eye | |
| R5 | 24K | 24k | read from the schematic by eye | |
| R6 | 33K | 33k | label scribbled over; read from the schematic by eye | |
| R7 | 2.2K | 2.2k | source; read from the schematic by eye | |
| R1 | 10K | 10k | read from the schematic by eye | |
| R2 | 47K | 47k | read from the schematic by eye | |
| R8 | 2.2K | 2.2k | source; read from the schematic by eye | |
| R9 | 47K | 47k | read from the schematic by eye | |
| Capacitors 7 | ||||
| C2 | 3.3n | 3.3n | input; read from the schematic by eye | |
| C3 | 10u | 10u | electrolytic, source bypass; read from the schematic by eye | |
| C4 | 1u | 1u | electrolytic; read from the schematic by eye | |
| C1 | 2.2n | 2.2n | read from the schematic by eye | |
| C5 | ? | ? | electrolytic, output; value not written; read from the schematic by eye | |
| C6 | 4.7n | 4.7n | across R9; read from the schematic by eye | |
| C7 | 47u | 47u | electrolytic, supply filter; read from the schematic by eye | |
| Diodes 1 | ||||
| D1 | 1N4007 | 1N4007 | polarity protection; read from the schematic by eye | |
| Transistors 2 | ||||
| Q1 | 2N5457 | 2N5457 | read from the schematic by eye | |
| Q2 | 2N5457 | 2N5457 | read from the schematic by eye | |
| Potentiometers 5 | ||||
| Trim 1 | 100K | 100k | Potentiometer | drain trimmer, set 5.5V; read from the schematic by eye |
| Trim 2 | 10K | 10k | Potentiometer | drain trimmer, set 5.5V; read from the schematic by eye |
| Bass | A1M | A1M | Potentiometer | read from the schematic by eye |
| Treble | B100K | B100k | Potentiometer | R3; read from the schematic by eye |
| Level | B47K | B47k | Potentiometer | read from the schematic by eye |