Fan speed controller advice

Hi, i have recently purchased a 4" Manrose mix flow fan and need it a little quieter, i was wondering whether these fan speed controllers would work?
http://www.ebay.co.uk/itm/ELECTRIC-FAN-SPEED-CONTROLLER-CONTROL-AIR-FLOW-IN-AND-OUT-DISPATCHED-SAME-DAY-/130639931336?pt=UK_HomeGarden_Garden_PlantsSeedsBulbs_JN&hash=item1e6abf27c8#ht_587wt_906
or
http://www.ebay.co.uk/itm/1-5-AMP-FAN-SPEED-CONTROLLER-KITCHEN-HYDROPONICS-/170900853500?pt=UK_Home_Garden_Hearing_Cooling_Air&hash=item27ca7c12fc#ht_500wt_1414


As im not looking to spend a fortune i was wondering if these ebay ones are ok.


Cheers.

A 4" fan moves little going full tilt. Slowing it down may make it quieter at the expense of air flow. Play loud metal music to cover fan noise. The plants love it.

You probably want something like a Variac if you care about noise. Check the manual for your fan, it will define what type of regulation (voltage or frequency) your fan supports. Most, if not all, will respond perfectly to voltage regulation, slowing speed and therefore reducing sound. Only some support both voltage and frequency regulation, so many fans make a "hum" noise as soon as you reduce the AC frequency they are running on. Variacs regulate voltage, get one that goes 0-120+ Volts and set it beneath 120. 120 is more or less what comes out of the wall, so you use the variac to reduce it to slow your fan. http://www.ebay.com/sch/items/?_nkw=variac&_sacat=&_ex_kw=&_mPrRngCbx=1&_udlo=&_udhi=&_sop=12&_fpos=&_fspt=1&_sadis=&LH_CAds=

I have a 165 cfm fan which is quite small but it is very noisy if I want to have people over and not have them hear it. I have to have the grow in a closet within a room with the door closed and have the fan turned down all the way to be quiet enough to just barely hear it.

I use a triac type speed controller and it works great. Even with all the measures I take, you can still hear the fan but it is so low I hope they think it is just something 'normal' like a computer fan or similar.

I run Ubuntu Studio in the, well, studio, and need a non-hideous, hardware fan controller. It'll be controlling +- 7 fans on three channels (3x GT, 2x CM 230mm, 2x Multiframe). No software controllers, please; unless you've tested it yourself on Linux..