Engine Noise Help

So this weekend I tackled doing my head gaskets. When i got everything put back together and started my car up the engine was a bit rough sounding and realized the timing was off. I fixed the timing last night and the rough sound is now gone but now I have this sound:

 

https://www.youtube.com/watch?v=T3v3sRyh65s

 

Its a 2002 Subaru Legacy 2.5L SOHC with 106000 miles. I have already replaced the timing belt and pulleys a few months ago and now the head gaskets. The water pump is still the one the car came with. The knock sound is there at idle but goes away at 1000 RPM and does not come back until 3000 RPM. It is much louder at 3000 RPM and I did not want to go above 3000 for fear of breaking something.

 

I cannot tell where the sound is coming from, the timing belt/water pump area or from the block. I wedged a screw driver between the timing belt tensioner and the block and the noise did not go away so it is not that.

 

Any help diagnosing this would really be appreciated since this is my only car and I love my Subie.

Could the timing being off initially caused a bent valve? If the noise wasn't there before you changed the head gaskets, that would be my first guess.

You have a dropped valve or rod knock

Sounds a bit like the noise I have. Does it only happen when at low revs? (sounds like it goes away when you rev it in the clip) I would assume if it was a bent valve it would happen at any revs. I would say piston knock/slap.