diff --git a/Sources/ECGSynKit/ECGSyn.swift b/Sources/ECGSynKit/ECGSyn.swift
index ac8e634..35d68b5 100644
--- a/Sources/ECGSynKit/ECGSyn.swift
+++ b/Sources/ECGSynKit/ECGSyn.swift
@@ -23,10 +23,9 @@ public enum ECGSyn {
     public static func generate(params: Parameters, rrSeries: RRSeries<Double>) -> [Double] {
         var rng = rrSeries.rng
         let srInternal = rrSeries.timeParameters.srInternal
-        let dt = 1.0 / Double(srInternal)
 
         // adjust extrema parameters for mean heart rate
-        let hrFact = 60.0 / rrSeries.timeParameters.hrMean
+        let hrFact = sqrt(rrSeries.timeParameters.hrMean / 60.0)
         let hrFactSqrt = sqrt(hrFact)
 
         let ai = params.a
@@ -37,6 +36,7 @@ public enum ECGSyn {
 
         let nt = rrSeries.count
 
+        let dt = 1.0 / Double(srInternal)
         let ts = (0 ..< nt).map { Double($0) * dt }
         let x0 = SIMD3<Double>(1.0, 0.0, 0.04)
 
diff --git a/Sources/ECGSynKit/ECGSynKit.swift b/Sources/ECGSynKit/ECGSynKit.swift
index 038ccd5..fb7448a 100644
--- a/Sources/ECGSynKit/ECGSynKit.swift
+++ b/Sources/ECGSynKit/ECGSynKit.swift
@@ -21,7 +21,7 @@ public struct TimeParameters {
     let hrStd: Double = 1.0
 
     /// RNG seed value.
-    let seed: UInt64 = 10
+    let seed: UInt64 = 8
 }
 
 public struct RRParameters {