diff --git a/crap/tube.h b/crap/tube.h
index 741878e..ff4e20b 100644
--- a/crap/tube.h
+++ b/crap/tube.h
@@ -11,7 +11,8 @@
 #define COPYRIGHT "MIT"
 #define PARAMETERS 2
 
-#define HIST_SIZE_2 (2 + 2*11)
+#define OVERSAMPLING 6
+#define HIST_SIZE_2 (2 + 2*8)
 #define HIST_SIZE   (HIST_SIZE_2*2)
 
 typedef struct {
@@ -55,35 +56,31 @@ distort(double x)
 	h[i*2 + 1] = h[i*2 + 0]; \
 	h[i*2 + 0] = x;
 
-// b2 is always b0 with lowpasses
-// a0 is already factored into the rest of the coefficients
-#define LOWPASS(i, b0, b1, a1, a2) \
-	y = b0*x + b1*h[i*2 + 0] + b0*h[i*2 + 1] \
-	         - a1*h[i*2 + 2] - a2*h[i*2 + 3]; \
+// b0 and b2 are equivalent and factored out
+// b0 and a0 are factored out as overall gain
+#define LOWPASS(i, b1, a1, a2) \
+	y = x + b1*h[i*2 + 0] +    h[i*2 + 1] \
+	      - a1*h[i*2 + 2] - a2*h[i*2 + 3]; \
 	BQSHIFT(i); \
 	x = y;
 
 static double
 oversample(double h[HIST_SIZE_2], double x)
 {
-	/* designed with <https://coewww.rutgers.edu/~orfanidi/hpeq/>
-	fs = 44100; OS = 4; Gs = -120; f2 = 18544/fs/OS; f2s = 22050/fs/OS;
-	N = hpeqord(-Inf,0,Gs,-6,2*pi*f2s,2*pi*f2,2) % 21.9986847697467
+	/* Fp = 20000.62
+	   os = 6; N = 8*2; Gp = 0.0135; Gs = 120;
 	*/
 	double y;
-	LOWPASS( 0,+0.68211844,-0.96291784,-1.54972173,+0.95104078);
-	LOWPASS( 1,+0.64259794,-0.89367078,-1.46615406,+0.85767914);
-	LOWPASS( 2,+0.59754712,-0.80432534,-1.37570293,+0.76647184);
-	LOWPASS( 3,+0.54606830,-0.69425498,-1.27603271,+0.67391434);
-	LOWPASS( 4,+0.48770451,-0.56343052,-1.16582052,+0.57779902);
-	LOWPASS( 5,+0.42283783,-0.41357065,-1.04538942,+0.47749444);
-	LOWPASS( 6,+0.35328311,-0.24971266,-0.91771844,+0.37457200);
-	LOWPASS( 7,+0.28296589,-0.08195448,-0.78962026,+0.27359756);
-	LOWPASS( 8,+0.21832227,+0.07351444,-0.67243388,+0.18259286);
-	LOWPASS( 9,+0.16778186,+0.19566401,-0.58109077,+0.11231849);
-	LOWPASS(10,+0.13979560,+0.26348229,-0.53059324,+0.07366673);
-	BQSHIFT(11);
-	return y;
+	LOWPASS(0,-1.7310964991540,-1.7686201550064,+0.9924894080401);
+	LOWPASS(1,-1.7228987922703,-1.7591070571963,+0.9756664940293);
+	LOWPASS(2,-1.7030928294094,-1.7508784553758,+0.9530819894740);
+	LOWPASS(3,-1.6623628189757,-1.7420481292930,+0.9206849371458);
+	LOWPASS(4,-1.5767803723821,-1.7314029454409,+0.8755898544307);
+	LOWPASS(5,-1.3754954625889,-1.7189289035735,+0.8193999703446);
+	LOWPASS(6,-0.7934216412437,-1.7066722500921,+0.7627918423024);
+	LOWPASS(7,+1.1176227011686,-1.6987049565355,+0.7256338727337);
+	BQSHIFT(8);
+	return y*0.000005162322938;
 }
 
 static double
@@ -100,11 +97,13 @@ process_os(personal *data, double x, int right)
 	double y;
 
 	#define doit(SAMP) \
-	oversample(h1, process_one(4*oversample(h0, SAMP), \
+	oversample(h1, process_one(OVERSAMPLING*oversample(h0, SAMP), \
 	    smooth(&data->drive), smooth(&data->wet)))
 	    doit(x);
 	    doit(0);
 	    doit(0);
+	    doit(0);
+	    doit(0);
 	y = doit(0);
 	#undef doit
 
@@ -186,8 +185,8 @@ adjust(personal *data, param *params, unsigned long fs_long)
 	data->wet.desired = params[1].value;
 	data->drive.actual = data->drive.desired;
 	data->wet.actual = data->wet.desired;
-	data->drive.speed = 1 + 20/fs/4;
-	data->wet.speed = 20/fs/4;
+	data->drive.speed = 1 + 20/fs/OVERSAMPLING;
+	data->wet.speed = 20/fs/OVERSAMPLING;
 	data->drive.log = 1;
 	data->wet.log = 0;
 }