I did also replace the psu fan with a noctua. Doesn’t impact this discussion but makes a big difference in sound. Right now I’m about 6 ft from it running at 700 and my iPhone is reading at around 37 db. I don’t know how accurate these apps are, but it is quiet enough that my wife is able to sleep which is all that matters.
Discussion
looks like those fans do make a difference. this one runs in a room void of rugs, sitting on hardwood. 
You could try upping the target temp (mine is at 94 C) to see if the fans have to work less, but I bet this is primarily a difference in fan size 140 vs 120 and noctua vs stock for the db level.
I probably should keep it off the carpet honestly, but I have found if you stack the miner with the PSU on the bottom and add some rubber padding the ground will barely get warm from contact during normal operation. 
I have the miner rotated 90 degrees from how I normally run it above. Hopefully I’m not doing something incredibly dumb here