add per-oscillator coarse tune (ctune1/ctune2); add blueprint image

README.md

@@ -7,8 +7,17 @@ state-variable filter, dual envelopes, an LFO, a built-in FX unit (chorus /
 delay / space), and a factory patch bank - all edited and browsed through the
 on-screen LCD instead of a conventional panel of knobs.
 
+## Screenshot
+
 ![RMX-19 screenshot](shot.png)
 
+---
+
+## Blueprint
+
+![RMX-19 blueprint](blueprint.png)
+
+
 ---
 
 ## What it is at a glance
@@ -126,7 +135,7 @@ The interface is a small nested menu system:
 
 | Screen | Parameters |
 |--------|------------|
-| **VOICE** | OSC1 WAVE, OSC2 WAVE, DETUNE, OSC BAL |
+| **VOICE** | OSC1 WAVE, OSC2 WAVE, COARSE TUNE 1, COARSE TUNE 2, DETUNE 1, DETUNE 2, OSC BAL |
 | **FILTER** | FILTER TYPE, CUTOFF, RESONANCE, FILT ENV, KEY TRACK |
 | **ENVELOPE** | AMP ATTACK, AMP DECAY, AMP SUSTAIN, AMP RELEASE, FENV ATTACK, FENV DECAY, FENV SUSTAIN, FENV RELEASE |
 | **LFO** | LFO RATE, LFO SHAPE, LFO DEPTH, LFO TARGET |
@@ -174,7 +183,9 @@ the host map onto the factory bank.
 
 - **Voice engine** - each voice is a classic two-osc → mix → SVF filter →
   amp-envelope chain. The oscillator mix is a crossfade between OSC1 and
-  OSC2, and detune offsets OSC2's frequency (OSC1 × `2^(detune/1200)`).
+  OSC2, and each oscillator has its own tuning: a coarse tune in semitones
+  (`2^(ctune/12)`) plus a fine detune in cents (`2^(detuneN/1200)`, DETUNE 1 →
+  OSC1, DETUNE 2 → OSC2).
 - **Filter** - a stable Chamberlin state-variable filter; cutoff is modulated
   by the filter envelope, key tracking, the LFO, and the mod wheel, with a
   smoothed control signal to suppress zipper noise.