Reduce Transistor Amplifier Gain
Budget: $10 – $30 USD
My transistor-based input stage is far hotter than I need. It drives 35 tape heads wired in series inside a Mellotron, so any hiss or overload quickly snowballs. I want to lower the overall gain—not just at one end of the spectrum, but evenly across the full audio range—while preserving the instrument’s character and noise floor.
I will share the present schematic (single-ended, discrete transistors, no op-amps) and measured rail voltages. Your task is to propose the simplest, most reliable way to tame that first stage: feedback network tweaks, input pad, emitter-degeneration—whatever keeps bandwidth flat and phase response musical.
Deliverables (PDF or KiCad preferred)
• Updated schematic with new component values and any extra parts
• Short explanation of why the chosen method maintains full-range fidelity
• Table of expected gain, input sensitivity, and noise figures before/after
• Quick test plan so I can verify the change on the bench with an oscilloscope and audio analyser
Acceptance will be based on a measured gain reduction that matches your prediction (±1 dB), no audible tonal shift, and no added hum.
I will share the present schematic (single-ended, discrete transistors, no op-amps) and measured rail voltages. Your task is to propose the simplest, most reliable way to tame that first stage: feedback network tweaks, input pad, emitter-degeneration—whatever keeps bandwidth flat and phase response musical.
Deliverables (PDF or KiCad preferred)
• Updated schematic with new component values and any extra parts
• Short explanation of why the chosen method maintains full-range fidelity
• Table of expected gain, input sensitivity, and noise figures before/after
• Quick test plan so I can verify the change on the bench with an oscilloscope and audio analyser
Acceptance will be based on a measured gain reduction that matches your prediction (±1 dB), no audible tonal shift, and no added hum.