Enclosure not stated · 4 knobs
Royal RP-2 Fuzz Wah MachineVerified
Based on the Royal RP-2 Fuzz Wah Machine
From the post
Another old japanese obscurity. There is a hand drawn factory schematic floating on the web but I decided to clean it up in order to build a clone. It looked like slimmed down Ibanez Standard Fuzz with a tone control. and a "Howl Adjust" control which dials in the upper octave.
And built the fuzz section only...and it wasn't any good...at all. Lacking in gain, output volume and the tone control was useless. So I had to mod it without tinkering too much Added a "gain cap" across the source of the input FET transistor and ground and subbed the ge diodes for silicon. For the tonestack I simply moved the 3,9nF cap from bass side to the treble side and the 33nF from treble side to the bass side. It now behaves like the tonestack in Foxx Tone Machine but it is not as scooped. Volume control was increased to 250k and the 2SK30 input FET was just not cutting it so I replaced it with a 2SK117 for much more gain on tap.
Much better! But still not as good as a regular Superfuzz or Standard Fuzz IMHO. But it was fun to tinker and "improve"old forgotten stuff.:-)
Fuzz section with suggested mods.
Wah section
Schematic
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 24 rows
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Check before you build · 2 values the reader of this layout was not sure of
- 3.6K (column 5, rows M-O): printed clearly as 3,6K, unusual value
- 50K trimmer (rows G-J, columns 6-9): drawn semi-transparent over links and cuts, label reads 50K; legend does not mention it
| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 8 | ||||
| ×3 | 10K | 10k | read from the layout by eye | |
| ×3 | 220K | 220k | read from the layout by eye | |
| ×2 | 1.8K | 1.8k | read from the layout by eye | |
| ×2 | 27K | 27k | read from the layout by eye | |
| ×2 | 150K | 150k | read from the layout by eye | |
| ×1 | 22K | 22k | read from the layout by eye | |
| ×1 | 1M | 1M | read from the layout by eye | |
| ×1 | 3.6K | 3.6k | read from the layout by eye | |
| Capacitors 4 | ||||
| ×3 | 33nF | 33n | read from the layout by eye | |
| ×1 | 3.9nF | 3.9n | read from the layout by eye | |
| ×6 | 10uF | 10u | electrolytic; read from the layout by eye | |
| C11 | 10uF | 10u | electrolytic; optional, for gain boost; read from the layout by eye | |
| Diodes 3 | ||||
| D1 | LF144 | LF144 | LF144 (Germanium?); read from the layout by eye | |
| D2 | LF144 | LF144 | LF144 (Germanium?); read from the layout by eye | |
| D3 | 1N5817 | 1N5817 | read from the layout by eye | |
| Transistors 4 | ||||
| Q1 | 2SK30-A | 2SK30-A | JFET; 2SK117 for more gain; read from the layout by eye | |
| Q2 | 2N5088 | 2N5088 | 2N5088, 2N3904 etc. (2SC828-S in original); read from the layout by eye | |
| Q3 | 2N5088 | 2N5088 | 2N5088, 2N3904 etc. (2SC828-S in original); read from the layout by eye | |
| Q4 | 2N5088 | 2N5088 | 2N5088, 2N3904 etc. (2SC828-S in original); read from the layout by eye | |
| Potentiometers 4 | ||||
| Howling Adjust | B10K | B10k | Potentiometer | read from the layout by eye |
| Expand | B50K | B50k | Potentiometer | read from the layout by eye |
| Tone | B50K | B50k | Potentiometer | read from the layout by eye |
| Volume | B50K | B50k | Potentiometer | 250kB suggested as a mod; read from the layout by eye |
| Trimmers 1 | ||||
| ×1 | 50K | 50k | read from the layout by eye | |