80x25mm Fan Round-Up #1

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SILENX IXTREMA THERMISTOR FAN IX-08025-14T

Ambient noise at the time of testing was 18 dBA.

Brand SilenX Power Rating 0.07~0.09A
Manufacturer Globe Fan Airflow Rating 18~28 CFM
Model Number IX-08025-14T RPM Rating 1,400~2,200 RPM
Retail Availability Yes Noise Rating 11.8~14.4 dBA
Bearing Type Hypro? Header Type 3-pin
Hub Size 1.29" Starting Voltage 3.5V
Frame Size 80 x 80 x 25 mm Number of Samples 3
Voltage
Noise
RPM
CFM
Power
12V
33 dBA@1m
2850 RPM
42 CFM
2.52W
9V
28 dBA@1m
2310 RPM
33 CFM
1.82W
7V
22 dBA@1m
1870 RPM
26 CFM
1.40W
5V
~19 dBA@1m
1330 RPM
17 CFM
1.01W
@10 CFM (3.6V)
<18 dBA@1m
750 RPM
10 CFM
0.53W
* Much thanks to Anitec for supplying these samples *

SilenX has a reputation for selling fans with absurdly low noise ratings, and the 11.8 dBA rating for this one is no exception — it's too low to be plausible. Fortunately, SilenX also has a reputation for being fairly quiet.

Evaluating this fan is somewhat difficult because it's thermally controlled, meaning it rarely, if ever runs at full speed, but it expects full voltage nonetheless. For the purposes of this test, we short-circuited the thermistor temporarily, causing the fan to run without the thermistor slowing things down. Assuming we can take SilenX' RPM specifications at face value, the fan's actual operational range should be the equivalent of what we heard between 5~9V. Knowing the way most thermally controlled fans work, there's a good chance that the fan will spend most of its time at minimum speed, which bodes well for noise.

SilenX sells to the retail market, and this fan looks the part. It comes in a color cardboard package that includes screws, rubber grommets for soft-mounting, and a Molex to 3-pin adapter for flexibility. All in all, not a bad package.

A tiny globe logo on the hub marks the fan as being sourced from Globe Fan, most likely. However, the mention of hypro bearings — supposedly unique to Adda — makes us wonder. Have we mis-identified the logo (unlikely, as we've encountered the logo on Globe's own fans), do Adda and Globe fan have a business relationship, or is SilenX playing fast and loose with the terms in their marketing material?

The fan spins quickly and noisily at full speed. No fan we've encountered is quiet at 3,000 RPM, and the Ixtrema held true to this rule. That said, it was quiet enough at 5V, and it still pushed a decent amount of air. We had to drop the input voltage down to 3.6V (just 0.1V above the starting voltage) to achieve 10 CFM for our constant airflow test.

Noise quality was nothing too impressive. It didn't disappear into the background like the Nexus, but the papery throbbing at 10 CFM was easy to ignore as background hiss. Above 5V, motor whine quickly became a problem, but it was still acceptable at its default speed around 5V.

Noise Recordings

MECHATRONICS A8025S12D

Ambient noise at the time of testing was 18 dBA.

Brand Mechatronics Power Rating 0.075A
Manufacturer Mechatronics Airflow Rating 25 CFM
Model Number A8025S12D RPM Rating 1,500 RPM
Retail Availability Minimal Noise Rating
Bearing Type Ball Header Type bare wire
Hub Size 1.33" Starting Voltage 5.3V
Frame Size 80 x 80 x 25 mm Number of Samples 1
Voltage
Noise
RPM
CFM
Power
12V
21 dBA@1m
1570 RPM
19 CFM
0.76W
9V
~19 dBA@1m
1200 RPM
14 CFM
0.57W
7V
<18 dBA@1m
900 RPM
9 CFM
0.46W
5V
@10 CFM (7.2V)
<18 dBA@1m
930 RPM
10 CFM
0.46W

Mechatronics made its name making bearings for the Aerospace industry, so they are not well known in the electronics industry. They are headquartered not far from SPCR in a suburb of Seattle, but the "made in Korea" on the fan hub shows that they follow the common industry practise of out-sourcing their manufacturing (and design?) to Asia.

This particular fan has unusually small fins and a very low power rating. It has been on our recommended list for some time, so we already know that it's quiet. Can it retain its recommended status, or will our newly stringent test techniques reveal some flaw that was overlooked before?

The most obvious place to look for flaws is the airflow. Those small, backwards-swept blades don't push much air, and we weren't surprised to learn that the motor had to spin about 20% faster to generate the same airflow as the more conventional fans that we tested. Despite the extra speed, the fan stayed quiet enough to give the Nexus a run for its money.

We had to strain to hear the fan at 9V, and it disappeared almost entirely below this level. Straining our ears, we might catch the occasional click that could be attributed to the fan, but these would not be heard in general use.

At full speed, it produced slightly less airflow and measured slightly louder than the Nexus. The higher noise measurement can be attributed mostly to differences in noise character. The Nexus sounded slightly smoother and more tonal, while the Mechatronics had a muffled, rhythmic throbbing that made for a less constant sound.

The fan's starting voltage was quite high — above the 5V threshold that we consider failsafe. However, in this case, the noise quality is good enough that a smart builder might be able to use this fact to his advantage. In combination with a thermally regulated controller, the Mechatronics is a good candidate for use as an emergency activated fan that only turns on when the case begins to overheat. Just bear in mind that the stall voltage is considerably less than the starting voltage, so once it comes on it will probably be on for good.

Noise Recordings

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