I love this spell except the damn loud sound it makes. It seems like a caveat to make sure that only rogues really have a shot of stealthily unlocking a door without the key. I think it's a good homebrew to have to roll how quiet/loud the spell is, because 300ft is just excessive. Especially for a 2nd level spell. If it was a cantrip I could understand it. But it really does just feel like a way to make sure the only ways to quietly unlock a door is to A) have the key or B) pick the lock.

Quote from Psytama >>

Because of the verbal component in silence it will be unable to be performed at all

Knock has a 60ft range. You can cast silence on the lock and cast Knock from outside the Silence  AOE, assuming the party has both spells available. . 

Quote from Psytama >>

Because of the verbal component in silence it will be unable to be performed at all

 What if it was cast with Subtle Spell? If you bypass the verbal requirement for spells, can you cast in an area of silence?

A target that is held shut by a mundane lock or that is stuck or barred becomes unlocked, unstuck, or unbarred. If the object has multiple locks, only one of them is unlocked.

No.. it's not a mundane lock

if an artificer uses knock, isn't that just them blowing up the door, box, chest, manacles, or padlock

Blast, this would have been perfect to hand my cleric npc for my murder mystery! 

Quote from FluffiusTheGreat >>

Does Knock also open the object or just unlock it.

 Only unlock it, but honestly it should open it as well if the caster wants it to

I call BS on the spell causing a sound audible from 300 freaking feet away.  I understand that Wizards were considered far too much the "Batman" class, and judged overly powerful, but 5e went WAY too far with nerfing them and magic in general.  Magic is supposed to be both magical and powerful.  It's a massive turn off for me to see magic being made into a series of gardening implements.  (Full admission I've become more and more irked with the state of Wizards and the way magic is usable in general)

Wouldn't casting silence before casting knock be more effective if trying to be stealthy?

Quote from FluffiusTheGreat >>

Does Knock also open the object or just unlock it.

 Only unlock it, but honestly it should open it as well if the caster wants it to

that's what mage hand is for

The 300ft sound blast is hilarious. As far as a football field in every direction the sound can be heard. That is beautiful and hilarious. Definitely fun hijinks to pull when trying to break out of a prison. How much noise can we make? All of them.

Makes me wonder how loud fireball is in comparison and should you just pull a classic Fizban nuking the lock instead.

i found a druid spell that can create fey and so i made a giant feymouth that can summon grimlins that have this spel it's amazing i haven't got to put it into play in a campaign yet tho

Silence is a ritual so if you aren't in a rush there is no reason the sound is an issue.

Quote from Psytama >>

Because of the verbal component in silence it will be unable to be performed at all

 Subtle spell forever.