Even if you underclock and lower freq with original fans it's not what I would consider quiet (IE one I would want in a room I use much). Some have switched fans to much nicer and quieter ones that is really needed if you want more quiet not just bearable.
Avalon 4.1's still are king as far as quiet miners that are not to old. But they do cost more to get and only from used market.
At 2600 RPM i find them quiet enough. And soon i will be able to run them at the minimum, i think the firmware will let me run is 20% which should be about 1800 RPM. Which for me is very quiet.
Can't hear them at all in the next room. But keep in mind that for 2600 and less rpm i need outdoor temp of 5-10c fed strait into them. They're running at 387.5hz though, i didnt try underclocking them as well.
Temps are low too, 48c~ at 17c outdoor but 3000 RPM. I could probably lower them further but i like this target of 50c.
What I find quiet is having trouble hearing it in same room. I don't enjoy hearing miners to be honest.
That is part of reason I got a area just for mining. I might bring the Avalon 4.1's in during winter to heat a room or two. But most will remain in my mining area so I don't have to hear them.
I see, i would call that silent. The only miner i have that is "silent" is S1 in a cold room, with their fan under 1k RPM. For winter i'll remove their fans, downlocked them further and make a rack of them in my room to keep it warm.
I've heard of how awesomely quiet the Avalon 4.1 are but i never found a single one for sale. Except on ebay at ridiculous price. And now they are starting to be less interesting with the price/hash and low-ish efficiency so i may never get to check one out.
Sadly they did not lower prices when SP20 and S5's were. Avalon 4.1 kept their price high. So sadly it leads to them still costing more on after market (they no longer make new). But they are the quiests miners I've ever had with zero mods. So good for those who own them but bad for someone wanting to buy one.
I hope on next gen they don't go with premium pricing but likely they will.