New SunGold Power LF-PV 18,000W Inverter, Very Loud Fan--Looking for Quieter Fan

[MWeiss]

I got my new "monster" inverter in today, hooked up battery cables and powered it on at no load to check basic operation before I wire into system. Unlike my SunGold Power 6000W inverter, the fan on this one runs on high speed all the time. It's 66 decibels at 3' which is much too loud for a recording studio. By contrast the other inverter is about 32 decibels.

So I'm searching for a reliable ball bearing fan that is designed for low noise while still moving 100 cfm or so. McMaster-Carr has one that's 43 decibels but I'd like to find something even quieter if possible.

The fan is 4.72" square frame, 1.5" thick and runs off 220 VAC, 18 watts.

I'm seeking recommendations for a fan that can be run variable speed off a thermistor, so a range of 90-240vac would be ideal. The thermistor would be thermally attached to a critical component like the power transformer frame and would control fan speed as per temperature.

 

[MWeiss]

I installed a new "34dB" noise level fan in my inverter today and it's far from 34dB.. measured 55dB from the same measuring spot. I'm 11dB better off, but $100 later and still too noisy for a recording studio. Ugh.

 

[MWeiss]

SunGold Power tech support reimbursed the cost of the quieter fan to the tune of about $100 after I showed them the invoice. Good company with solid support.
I'm getting ready to mount this 200lb monster on the wall and once in place, I will build a shroud lined with 2" OC703 fiberglass tiles. I have a piece of it near the inverter facing the fan exhaust and boy does it cut the noise way down!