Enclosure not stated · 4 knobs
Runoffgroove Thor
Based on the Run Off Groove Thor· 3 other boards clone it
- Category
- Preamp / Amp-in-a-box
- Price
- see vendor
- Also as
- Vero layout · Perfboard layout · from Revolution Deux
From the vendor
Runoffgroove's Thor emulates a Marshall 100W Super Lead preamp with their Fetzer Valve technique: two common-source JFET stages biased to clip like tube stages, then a JFET mu-amp that mimics the odd-order harmonics of a push-pull power amp. It keeps the small Bright cap of the JTM and early Super Leads and the later 470k/470pF filter before the second stage. A TL071 stage at the end adds the Bottom switch, a bass boost that mimics a 4x12 cabinet's resonance.
Schematic
The schematic is in the post. Open it at Revolution Deux. No KiCad fragment has been drawn for this circuit yet.
Parts list 41 rows
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| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 16 | ||||
| R1 | 1M | 1M | read from the schematic by eye | |
| R2 | 33K | 33k | input; read from the schematic by eye | |
| R3 | 390 | 390 | read from the schematic by eye | |
| R4 | 470K | 470k | read from the schematic by eye | |
| R5 | 1K | 1k | read from the schematic by eye | |
| R6 | 220K | 220k | read from the schematic by eye | |
| R7 | 390 | 390 | read from the schematic by eye | |
| R8 | 390 | 390 | read from the schematic by eye | |
| R9 | 10K | 10k | Vref divider; read from the schematic by eye | |
| R10 | 10K | 10k | Vref divider; read from the schematic by eye | |
| R11 | 1M | 1M | read from the schematic by eye | |
| R12 | 120K | 120k | read from the schematic by eye | |
| R13 | 56K | 56k | read from the schematic by eye | |
| R14 | 39K | 39k | read from the schematic by eye | |
| R15 | 100K | 100k | read from the schematic by eye | |
| R16 | 33K | 33k | read from the schematic by eye | |
| Capacitors 14 | ||||
| C1 | 220p | 220p | read from the schematic by eye | |
| C2 | 1n | 1n | read from the schematic by eye | |
| C3 | 470p | 470p | bright cap; read from the schematic by eye | |
| C4 | 470p | 470p | read from the schematic by eye | |
| C5 | 100n | 100n | read from the schematic by eye | |
| C6 | 100n | 100n | read from the schematic by eye | |
| C7 | 100u | 100u | electrolytic, power filter; read from the schematic by eye | |
| C8 | 100u | 100u | electrolytic, Vref filter; read from the schematic by eye | |
| C9 | 100n | 100n | read from the schematic by eye | |
| C10 | 470p | 470p | read from the schematic by eye | |
| C11 | 22n | 22n | read from the schematic by eye | |
| C12 | 22n | 22n | read from the schematic by eye | |
| C13 | 1n | 1n | read from the schematic by eye | |
| C14 | 100n | 100n | read from the schematic by eye | |
| Transistors 4 | ||||
| Q1 | 2N5457 | 2N5457 | drain biased near 6.4V; read from the schematic by eye | |
| Q2 | J201 | J201 | drain biased near 4.5V; read from the schematic by eye | |
| Q3 | 2N5457 | 2N5457 | read from the schematic by eye | |
| Q4 | 2N5457 | 2N5457 | read from the schematic by eye | |
| ICs 1 | ||||
| U1 | TL071 | TL071 | or equivalent; read from the schematic by eye | |
| Potentiometers 4 | ||||
| Q1 drain trim | 5K | 5k | Potentiometer | trimmer VR1, set for about 6.4V on Q1's drain; read from the schematic by eye |
| Q2 drain trim | 20K | 20k | Potentiometer | trimmer VR2, set for about 4.5V on Q2's drain; read from the schematic by eye |
| Gain | A1M | A1M | Potentiometer | drawn 1M-log; read from the schematic by eye |
| Volume | A100K | A100k | Potentiometer | drawn 100k-log; read from the schematic by eye |
| Switches 2 | ||||
| Bright | SPST | SPST | read from the schematic by eye | |
| Bottom | SPST | SPST | read from the schematic by eye | |
Other boards based on the Run Off Groove Thor
- Runoffgroove Thor Dirtbox Layouts
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