Just resurrecting this topic...!
I finally fitted the Focal IS 165 VW speakers at the weekend. My notes, from my attempt to fit:
- The Focal speakers use a 4-pin connector, which I didn't have. Fortunately I had some small spade connectors which I could just use to attach the speaker wires directly to the terminals on the speakers.
- The original Skoda Octavia Mk3 (Estate, if that makes any difference) has two pairs of wires in the loom(s) in the door - one to the tweeter and one to the woofer. The Focal IS 165 VW woofer seems to take one connector, which then has a pair of wires which go up to the tweeter. So I disconnected the original tweeter cable, knotted it round itself and tethered it safely against the door skin, in case it was needed in future, and wired the Focal tweeter in parallel with the woofer.
- I removed the Skoda 2-pin connector from the woofer wires so I had two bare ends. I removed the Focal spade connectors from one end of the paired tweeter wires. Each wire pair had one with a black stripe, so it was easy to make sure polarity (positive and negative) was kept the same throughout. And the Focal speaker has a - and a + on the plastic moulding, so it's easy to see what should connect where.
- I tested and experimented with the wires - it seems the four terminals on the Focal connector are two -ve, two +ve, in pairs next to each other. In other words, the two terminals near the "-" symbol are connected in parallel, and so are the two terminals nearest the "+" symbol on the speaker.
- I twisted and soldered the Skoda loom feed wire and the Focal tweeter wire together and connected them to a spade connector, then covered them up with heatshrink. They gripped the speaker terminals well.
- Drilling out the plastic clips that held the original speaker in was fine. HOWEVER the rivet / screw holes in the door panel are around 8mm diameter, so the nice Focal rivets that come with the speakers didn't work - they expanded and popped, but hadn't expanded wide enough to hold the speaker in, they just rattled out! I run a bicycle shop, so I used bottle cage rivnuts. They were a bit of a faff to fit, but meant I had tidy nuts held in place, so I could use M5 bolts and washers, with Loctite 243, to really hold the speakers securely in place.
- the tweeters were actually way less hassle than I expected. The Focal tweeters come with a removable ring; once that's removed, the diameter of the tweeter is the same size as the original. To remove the original tweeter, you just need to cut the three pins off the plastic housing with a sharp knife, then pull the tweeter away. I then cleaned up the cylinder in the door housing so the new tweeter fitted neatly onto it. I then used a hot glue gun and plenty of glue to glue the new tweeter in place, making sure the wires fitted neatly through the retaining clip.
- the original rubber ring to fit between the woofer and the door panel _doesn't_ fit the Focal speakers. But it's very close - so, again with the sharp knife, I trimmed off the small plastic moulding lumps around the outside of the ring and made it as close to a uniform circle as I could, then offered it up against the Focal woofer... it fitted around outside the moving parts of the speaker, so I held it in place and wrapped some PVC insulating tape around it a couple of times (pull it slightly and it stretches, to hold the ring firmly in place) then fitted the door panel, checking that it hadn't been dislodged and it wasn't fouling the actual speaker.
...I think that's it! With a completely flat EQ profile on the OEM sound system, the new speakers sound clear, the range is great, the definition is superb and I'm very happy with them so far.
(I just wish I'd taken photos!)