radicchio, I am going to guess that the problem has recently shown up. If the sound inside the valve can be described as 'clicking', then you might have a defective solenoid or the current going to the solenoid is getting interrupted. This 'on/off/on/off' condition can cause the vibrating pipes in the house. Install a new or another working solenoid and if the problem goes away you will know what it was. If the problem persists then you could next find out if it is the current supply. I'd connect a suitable meter on the circuit (at the solenoid) and watch for fluctations. If this is the problem you will need to find out if the wiring is defective or the timer itself has a problem on that circuit. You can take the meter to the timer and find out or, you can connect the feed wire to another working station. If the problem is not resolved by then, I must ruefully admit defeat.

What you have is called water hammer. Some times it is caused by the sprinklers exceding the amount of water that the valve can supply. The demand is higher than the supply. Try what Ronalawn82 said, if that doesn't work then cap off on sprinkler and if it gets better then you might need to split the system. You can repair the top of the valve very simple and they still make that valve although the name has changed to Irritrol. If the valve has several screws it can be the 2711apr 3/4, 2713apr 1", if it looks like the valve has a big nut then it is the 2711dpr 3/4", 2713dpr 1".

Here is a link that might be useful: how to change the top of valve