125B · 5 knobs
EWS Tri-Logic Bass Preamp IIVerified
Based on the EWS Tri-Logic Bass Preamp II
- Category
- Preamp / Amp-in-a-box
- Build
- Perfboard
- Layout
- Verified · Effects Layouts (blog) marks it as built and working
- Tags
- Bass, EWS, Preamp, Xotic
From the post
Here's a pretty simple but effective bass preamp from EWS. It's a 3-band EQ being pushed by a MOSFET gain stage. Looks like EWS made a version for Xotic with the same name. Not a lot different between the two other than some value changes laid out in this schematic on FSB. I've laid it out for a 125B with top mounted jacks. It runs off an 18v supply so use your favorite charge pump if you want to include that in the pedal.
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
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| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 11 | ||||
| ×2 | 2.2K | 2.2k | read from the layout by eye | |
| ×1 | 3K | 3k | read from the layout by eye | |
| ×2 | 1K | 1k | read from the layout by eye | |
| ×2 | 2.4K | 2.4k | read from the layout by eye | |
| ×1 | 1.8K | 1.8k | read from the layout by eye | |
| ×1 | 270K | 270k | read from the layout by eye | |
| ×2 | 10K | 10k | read from the layout by eye | |
| ×1 | 10M | 10M | read from the layout by eye | |
| ×3 | 100K | 100k | read from the layout by eye | |
| ×3 | 24K | 24k | read from the layout by eye | |
| ×1 | 1M | 1M | read from the layout by eye | |
| Capacitors 11 | ||||
| ×2 | 33nF | 33n | read from the layout by eye | |
| ×1 | 15nF | 15n | read from the layout by eye | |
| ×1 | 150nF | 150n | read from the layout by eye | |
| ×3 | 47nF | 47n | read from the layout by eye | |
| ×1 | 1nF | 1n | read from the layout by eye | |
| ×1 | 220nF | 220n | read from the layout by eye | |
| ×2 | 100pF | 100p | read from the layout by eye | |
| ×1 | 100uF | 100u | electrolytic; read from the layout by eye | |
| ×4 | 10uF | 10u | electrolytic; 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 | |
| Diodes 2 | ||||
| ×1 | 1N4001 | 1N4001 | read from the layout by eye | |
| ×1 | 9.1V | 9V1 | zener; read from the layout by eye | |
| Transistors 1 | ||||
| ×1 | BS170 | BS170 | MOSFET, named on the wiring diagram; read from the layout by eye | |
| ICs 1 | ||||
| ×1 | NE5532 | NE5532 | read from the layout by eye | |
| Potentiometers 5 | ||||
| Gain | B250K | B250k | Potentiometer | read from the layout by eye |
| Bass | B50K | B50k | Potentiometer | read from the layout by eye |
| Mid | B50K | B50k | Potentiometer | read from the layout by eye |
| Treble | B50K | B50k | Potentiometer | read from the layout by eye |
| Volume | B5K | B5k | Potentiometer | read from the layout by eye |
| Switches 2 | ||||
| A/P | SPST | SPST | active/passive; read from the layout by eye | |
| Hi/Lo | SPDT on/on | SPDT ON/ON | read from the layout by eye | |