Enclosure not stated · 4 knobs
Electro Harmonix Freedom Preamp PedalVerified
Based on the Electro-Harmonix Freedom Amp preamp· 1 other board clones it
From the post
Here we have a rare bird from the early-mid 70s. A tweaked version of the the circuit found in Freedam Preamp amp found its way into some Big Muff enclosures. Original is very pricey and rare. The original ran on two 9v batteries for bipolar power supply for the op amp section but I added a bipolar voltage converter so you can use with your normal power supply. A Master control is added at the end of the circuit so you can crank the volume control to achieve overdrive at reasonable levels. Also, the trimpots value remains unknown but I would shot for 10k... The facory schematic is avaiable HERE.
Schematic
This is a board layout, a drawing of where each part goes, and the post may link the schematic it was drawn from. Open the layout at Dirtbox Layouts. No KiCad fragment has been drawn for this circuit yet.
Parts list 26 rows
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Check before you build · 1 value the reader of this layout was not sure of
- Trimmer at right (rows M-P, cols 15-18): printed as a range '1K-10K', legend says 'Trimpot value unknown'
| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 11 | ||||
| ×3 | 10K | 10k | read from the layout by eye | |
| ×4 | 4.7K | 4.7k | read from the layout by eye | |
| ×2 | 47K | 47k | read from the layout by eye | |
| ×2 | 270K | 270k | read from the layout by eye | |
| ×1 | 68K | 68k | read from the layout by eye | |
| ×1 | 1K | 1k | read from the layout by eye | |
| ×1 | 27K | 27k | read from the layout by eye | |
| ×1 | 2.2M | 2.2M | read from the layout by eye | |
| ×1 | 2.2K | 2.2k | read from the layout by eye | |
| ×1 | 47Ω | 47 | read from the layout by eye | |
| ×1 | ? | ? | LED resistor, value not given; read from the layout by eye | |
| Capacitors 6 | ||||
| ×4 | 22nF | 22n | read from the layout by eye | |
| ×2 | 10nF | 10n | read from the layout by eye | |
| ×2 | 100nF | 100n | read from the layout by eye | |
| ×3 | 1uF | 1u | electrolytic; read from the layout by eye | |
| ×1 | 10uF | 10u | electrolytic; read from the layout by eye | |
| ×2 | 100uF | 100u | electrolytic; read from the layout by eye | |
| Diodes 1 | ||||
| D1 | 1N5817 | 1N5817 | read from the layout by eye | |
| Transistors 1 | ||||
| Q1 | 2N5087 | 2N5087 | read from the layout by eye | |
| ICs 2 | ||||
| IC1 | 4558 | 4558 | read from the layout by eye | |
| IC2 | ICL7660S | ICL7660S | read from the layout by eye | |
| Potentiometers 4 | ||||
| Tone | B100K | B100k | Potentiometer | read from the layout by eye |
| Volume | A100K | A100k | Potentiometer | read from the layout by eye |
| Bite | A100K | A100k | Potentiometer | read from the layout by eye |
| Master | A100K | A100k | Potentiometer | read from the layout by eye |
| Trimmers 1 | ||||
| ×1 | 1K-10K | 1k-10k | legend: Trimpot value unknown; read from the layout by eye | |
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