Manual Linkwitz-Riley filter

I'm trying to implement a manual linkwitz-riley filter, here's what I've done so far:

[x, fs] = audioread('nobody.wav');
 
[b0 a0]=butter(4,500/(fs/2));
[b1 a1]=butter(4,2000/(fs/2));
[b2 a2]=butter(4,500/(fs/2),'high');
[b3 a3]=butter(4,2000/(fs/2),'high');
 
lpL = filter(b0, a0, x);
lpH = filter(b1, a1, x);
 
lo = lpL+lpH;
 
hpL = filter(b2, a2, x);
 
 
mid = hpL + lpH;
 
apL = lpL + hpL;
 
hpH = filter(b3, a3, x);
 
hi = apL + hpH;
 
newsig = hi + mid + lo;

It kind of works, but doesn't sound like the original signal. I'm wondering whether any of you could help me out with implementing this a bit better.

I tried to follow this guideline:

.       +---+  +---+
.    +--|apL|--|hpH|-- Hi
.    |  +---+  +---+
.         |
.    |  +---+  +---+
.  --+--|hpL|--|lpH|-- Mid
.    |  +---+  +---+
.    |
.    |  +---+  +---+
.    +--|lpL|--|lpH|-- Lo
.       +---+  +---+