Selmer Treble 'n' Bass 50 Mk III - Normal preset

Verified · 88/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Mk III revision of Selmer’s Treble ’n’ Bass 50 keeps the two-channel layout: Bass and Normal channels each have two inputs and their own ECC83 with a treble/bass network and volume. New for the Mk III is an Echo send and return after the channel mix, followed by an ECC83 recovery stage. An ECC83 long-tail inverter drives two fixed-bias EL34s into 15 and 7.5 ohm taps, with BY128 silicon rectifiers replacing the earlier GZ34.

• Made in: UK
• Wattage: 50W
• Channels: 2
• Preamp tubes: 4× ECC83
• Power tubes: 2× EL34

Tags: british, vintage, el34, mid-wattage, two-channel.

Schematic-derived preset files for 16 Fractal and Line 6 modelers: Axe-Fx II/XL/XL+, Axe-Fx III, FM3, FM9, and the full Helix family (Floor, LT, Rack, HX Stomp, HX Stomp XL, Native).

Gridleak extracts amp parameters from original circuit schematics using AI vision — component values, gain staging, tone stack topology, tube types — then generates native preset files for every supported modeler. Every extraction is scored 0–100 and the score is published.