125B · 2 knobs
Baja VH4Verified
Based on the BAJA VH4
- Category
- Preamp / Amp-in-a-box
- Build
- Perfboard
- Layout
- Verified · Effects Layouts (blog) marks it as built and working
- Tags
- Amp Emulator, Baja, Overdrive
From the post
Another drive circuit from Bajaman. He's been on a tear lately! In his words...
Here is my latest build based on the frequency response characteristics of the Diezel VH4 tube head channels 3 and 4, but scaled down into a 9v dc pedal friendly format... I got a chance to try using it on Neil Young's "Keep on Rockin' in the Free World" and needless to say it sounded awesome on very low gain setting Channel 3 - just the right amount of searing crunch and in my view one of my best pedals to date!
It will fit in either a 125B with top mounted jacks, or a 1590B with side jacks. If you go 1590B, you'll either have to offboard the pots or use long leg pcb-mount pots and populate them on the component side. I've added extra pads for the JFETs so you can use either DGS or GSD pinout transistors. Schematic can be found 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 Effects Layouts (blog). No KiCad fragment has been drawn for this circuit yet.
Parts list 33 rows
Report a wrong parseGot parts in a drawer? See what you can build with them.
| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 12 | ||||
| ×5 | 1K | 1k | read from the layout by eye | |
| ×4 | 10K | 10k | read from the layout by eye | |
| ×3 | 22K | 22k | read from the layout by eye | |
| ×3 | 47K | 47k | read from the layout by eye | |
| ×3 | 2.7K | 2.7k | read from the layout by eye | |
| ×3 | 1M | 1M | read from the layout by eye | |
| ×2 | 4.7K | 4.7k | read from the layout by eye | |
| ×2 | 1.5M | 1.5M | read from the layout by eye | |
| ×1 | 33K | 33k | read from the layout by eye | |
| ×1 | 2.2K | 2.2k | read from the layout by eye | |
| ×1 | 470Ω | 470 | read from the layout by eye | |
| ×1 | 820Ω | 820 | read from the layout by eye | |
| Capacitors 12 | ||||
| ×2 | 220pF | 220p | read from the layout by eye | |
| ×1 | 330pF | 330p | read from the layout by eye | |
| ×1 | 1.2nF | 1.2n | read from the layout by eye | |
| ×1 | 6.8nF | 6.8n | read from the layout by eye | |
| ×1 | 8.2nF | 8.2n | read from the layout by eye | |
| ×1 | 10nF | 10n | read from the layout by eye | |
| ×1 | 47nF | 47n | read from the layout by eye | |
| ×5 | 1uF | 1u | drawn as box film; read from the layout by eye | |
| ×1 | 2.2uF | 2.2u | electrolytic; read from the layout by eye | |
| ×1 | 4.7uF | 4.7u | electrolytic; read from the layout by eye | |
| ×1 | 47uF | 47u | electrolytic; read from the layout by eye | |
| ×1 | 100uF | 100u | electrolytic; read from the layout by eye | |
| Diodes 2 | ||||
| ×1 | 1N4001 | 1N4001 | read from the layout by eye | |
| ×1 | 1N4148 | 1N4148 | read from the layout by eye | |
| Transistors 3 | ||||
| Q1 | 2SK117 | 2SK117 | JFET; legend: 2SK117 or similar; read from the layout by eye | |
| Q2 | BC547B | BC547B | legend: BC547B or similar; read from the layout by eye | |
| Q3 | 2SK117 | 2SK117 | JFET; legend: 2SK117 or similar; read from the layout by eye | |
| ICs 1 | ||||
| ×2 | TL062 | TL062 | read from the layout by eye | |
| Potentiometers 2 | ||||
| Gain | B100K | B100k | Potentiometer | read from the layout by eye |
| Volume | B100K | B100k | Potentiometer | read from the layout by eye |
| Switches 1 | ||||
| Switch | DPDT on/on | DPDT ON/ON | toggle; Sw2, Sw3, Sw5, Sw6 on the board, Sw1 wired to Sw4; read from the layout by eye | |