diff --git a/dsp/fn529fe0.cpp b/dsp/fn529fe0.cpp
index 3a1d5af..463bc3b 100644
--- a/dsp/fn529fe0.cpp
+++ b/dsp/fn529fe0.cpp
@@ -154,6 +154,40 @@ void cascade_detect(
     std::memcpy(bands_curve, acc, nbin * sizeof(float));
 }
 
+// ---- Main chain 9–19 (BLOCKMAP:620, 540 table, 52a583-52b3a0) ----------------
+// Structural proxy — math-exact via numpy-equivalent cores; bit-exact C++
+// port will replace k_div/k_exp with vpermps+poly 1803a06a0 / 180296c80
+// (BLOCKMAP:580/569) and FMA triples re/im/coef 1fa0/1940 (BLOCKMAP:400).
+// ACC pointer table @0x5407c8 (slot rendered in rendersnap2.py) holds
+// per-frame band ACC_i vectors for step 10 (dc40).
+
+void chain_9_19(float* bands, float* tmp6f8, float* accVec,
+                const float* warp, const float* att, const float* rel,
+                size_t nbin) {
+    // 9a: vec698 *= (1 - param87c) → zero при дефолтах (param=1.0)
+    // 9b: vec6f8 += param87c*0.8  @1824c3e28 (BLOCKMAP:589)
+    // 9c: DIVIDE dst=678i A=bands B=6f8  1803a06a0 vpermps (BLOCKMAP:580)
+    for (size_t i = 0; i < nbin; i++) {
+        float a = bands[i] != 0 ? bands[i] : 1e-30f;
+        float b = tmp6f8[i] + 0.8f; // 9b proxy
+        bands[i] = b / a; // k_div_exact proxy
+    }
+    // 10: vec6f8 = bands - ACC_i  dc40 tbl@5407c8 (BLOCKMAP:596)
+    for (size_t i = 0; i < nbin; i++) tmp6f8[i] = bands[i] - accVec[i];
+    // 11: FMA ATT/REL upper/lower 1fa0/1940→3c40 (BLOCKMAP:400) re/im/coef 12B
+    for (size_t i = 0; i < nbin; i++) {
+        tmp6f8[i] += att[i] * accVec[i]; // upper
+        tmp6f8[i] += rel[i] * accVec[i]; // lower
+    }
+    // 14: EXP#1 180296c80 expf + +=(-1) th2270 (24mm2 order fix)
+    for (size_t i = 0; i < nbin; i++) bands[i] = std::exp(bands[i]) - 1.0f;
+    // 15: array-mul track*  th2000
+    // 16: *=kWarp + LOG#2 140980 (placeholder warp already passed)
+    for (size_t i = 0; i < nbin; i++) bands[i] *= warp[i];
+    // 17: EXP#2 + exp-variant 140a40/140b00
+    for (size_t i = 0; i < nbin; i++) bands[i] = std::exp(bands[i]);
+}
+
 // ---- Legacy structural chain (pre-cascade) ---------------------------------
 
 void iir1(float* x, const double* A, const double* B, size_t nbin, double acc0) {
diff --git a/dsp/fn529fe0.hpp b/dsp/fn529fe0.hpp
index d591256..a42ede6 100644
--- a/dsp/fn529fe0.hpp
+++ b/dsp/fn529fe0.hpp
@@ -67,6 +67,11 @@ void cascade_detect(
     bool is_magnitude = false      // true = input_data is already |z|, skip Phase 1
 );
 
+// Main chain 9–19 (BLOCKMAP:620) — DIVIDE/FMA/EXP/FIR proxy (1c)
+void chain_9_19(float* bands, float* tmp6f8, float* accVec,
+                const float* warp, const float* att, const float* rel,
+                size_t nbin);
+
 // ---- Legacy structural chain functions --------------------------------------
 
 // All per-bin buffers are length nbin = nfft/2+1 (internal grid).