Here is some of my findings from this upgrade I uploaded on YouTube

My Research:

This mod uses Local Negative Feedback (LNFB) to shape the feel and response of your amp’s second gain stage. By feeding a small portion of the tube’s output signal (plate) back to its input (grid) through a resistor and capacitor, we reduce distortion, smooth out the transition into clipping, and increase clarity and touch sensitivity — all without changing the amp’s core tone.

The lower the resistance, the stronger the feedback effect.

🎵 13 Amazing Benefits

1. Tames early clipping and lets you push the amp harder before distortion kicks in.
2. Reduces Stage Gain Safely
   LNFB offers a cleaner way to reduce gain without changing cathode or plate resistor values — maintaining original voicing.
3. Smooths Out Distortion
   Makes overdrive more even and round, with less buzzy or harsh harmonics.
4. Improves Clarity
   Notes retain more definition
5. Reduces amplified noise floor (less hiss/hum etc..)
6. Widens out the sweet spot
   More of the gain stage becomes usable — smooth breakup and great tone across a wider dynamic range. Edge of break up easier
7. Reduces higher-order (odd) harmonics that are often unpleasant — makes the output more spectrally balanced.
8. Reduces Mud
   Helps tighten up the low mids, making the amp feel less boomy or congested.
9. Useful in Cascaded Gain Stages
   In multi-stage designs (like Dumble, Soldano, etc.), it pre-conditions the gain to behave more musically further down the chain.
10. Adds “Glassiness” Without Harshness
    Preserves treble detail in a sweet, musical way, not brittle or ice-picky.
11. Compresses Naturally
    Introduces a subtle compression that can make the amp feel more -polished.
12. Makes Gain More Usable
    You can run more gain without losing articulation — great for stacking or cascaded gain stages.
13. Works Well with Other Mods
    Plays nicely alongside mid boost switches, cathode bypass cap mods, and relay switching — non-invasive and modular.

🎧 Why it’s not the same as turning the gain down

✅ 1. It Changes the Shape of the Overdrive, Not Just the Level

• Turning down gain reduces the input signal hitting the tube → less clipping.
• LNFB alters the tube’s nonlinearity by feeding back an out-of-phase signal, which reshapes how the tube distorts.
• It creates a smoother, more gradual onset of clipping, more like the feel of a big clean amp being pushed.

✅ 2. It Tames Odd-Order Harmonics

• Tubes naturally produce odd-order distortion. LNFB tends to cancel or soften the harsher odd-order content, leaving the tone rounder and less harsh — something a gain knob won’t do.

✅ 3. Dynamic Response Becomes More Controlled

• LNFB acts like a “soft limiter” — loud peaks get gently reined in after amplification, not before.
• This leads to that “touch-sensitive” feel where the amp reacts more to your playing, not just signal strength.

✅ 4. It Affects Compression and Bloom

• With LNFB, there’s often a subtle increase in clarity and articulation, especially during chord decay or string muting.
• You don’t get that with a gain knob — turning down gain often just makes things lifeless or weak.

🎛️ "LNFB is like installing a smart limiter that reacts musically" — Explained

✅ Limiter

In studio gear, a limiter gently keeps the signal from going over a certain threshold.
LNFB does something similar:

• It feeds a small portion of the inverted output (plate signal) back into the input (grid),
• This opposes the incoming signal just enough to flatten the peaks.
• But it doesn’t clamp or squash it like a compressor — it still breathes.

✅ Smart

It’s "smart" because:

• It only acts when the gain stage starts to clip or become nonlinear.
• At lower levels, it mostly stays out of the way.
• The more you push it, the more LNFB gently pushes back, keeping the signal from spiralling into harsh clipping.

✅ Musically

This is where it shines for players:

• It doesn’t choke the amp — it makes it feel smoother and more controlled.
• Your pick attack, dynamics, and guitar volume still shine through.
• Notes bloom instead of splattering — and chords stay articulate.