Would you be taking the sound readings with the fan fixed to the 'box'? The reason I ask is that I think I can hear resonance. Also, and this was while you were still focused on the fan controller there was a lot of background hiss that disappeared as soon as you switched the fan on. I don't believe the hiss was being drowned out by the fan noise.
Fair - yeah they look well wedged in there. Ah, nice work dude Ah, yes, that makes sense. I do have some old 0-60pa (0-6mmH2O) Magnahelic gauges that I salvaged a couple of years back, they look like this (not stainless steel): It may help you with going off scale on the manometer. Let me know if you want me to post one over to you Not to take away from your manometer at all - as a liquid gauge you gain some damping. Diaphragm gauge's have a tendency to bounce (although Magnahelic are magnetically damped) Nice one on the video - no worries I understand how these things go when prototyping. Looking good indeed
@Big Elf you're right, there's a lot of resonance from the box. My plans with the sound level meter are to measure the fan noise (at various speeds for the faster fans) against a heatsink, fan filter, case side panel etc. The video above was just raw from the camera, so the sound is pretty bad; I'll be using the Tascam to record audio when I do it for real - I'll hopefully get a chance to do a quick preview this evening when the kids are in bed! @cobalt6700 thanks! I'd be well up for borrowing one of the gauges - looks like a serious piece of kit!
@LennyRhys No problems at all, drop me your address. Hoping to pop in for some other bits this week so will grab it.
PM sent - thanking you! @Big Elf here's a cheeky wee preview video for you just to give you an idea of the sound quality to be expected from the Tascam, and this is just mono for now. Youtube will mulch the audio a little bit but it's still far superior to what the camera mic can achieve. When I have a proper setup organised, I'll include the SPL meter in the shot as well. For this test, the Tascam was about 20cm from the front of the fans, just out of shot at the bottom. I switched literally everything in my room off at the wall, and it was so quiet it was actually quite eerie. One interesting take-away from this video is that there is literally no extraneous noise from the Gentle Typhoon, which means no bearing noise. You can tell this pretty clearly when the fans are switched off. Another note about the Noctua is that it is utterly inaudible at its lowest speed, but at 260rpm you're going to need sixteen of them on two 480 rads to achieve anything lol.
I'm going to be curious to see that a12 vs the GT, as I ran 3 1800rpm GT's for years and they were always bery quiet, and the specs say they're air pressure is very close to the A12's. Still rumblings about the A12's in black any time now... Also, probably worth changing the thread title now, as the discussuion has changed
Yep I was the same - I ran two GTs on my CPU cooler at around half speed, and they were amazing. If the Noctua wasn't so ludicrously expensive (just shy of £27 on Amazon), it would probably be worth it in my book. It's worth noting that as a product, the Noctua is in a different league from the Gentle Typhoon because of all the accessories you get with it, including a really nice rubber gasket that fits over the whole fan frame. I got the Gentle Typhoon from Amazon for £21 and it's no longer available, so I'm glad I got it when I did! I'll be acquiring / obtaining more fans along the way, and as Bloody_Pete says I'll have to get the thread title changed.
Today's update: I've got a couple more bits and pieces coming at various points this week, and I decided to... well, have a little bit of fun. If anyone's familiar with Bernoulli's principle and the ongoing debate about how planes actually fly, you'll probably have heard of the barn door analogy. Having disassembled one of the crappy 120mm fans in my collection, I decided to salvage the hub and make a new impeller for it, using barn doors. Simple. I sprayed the old impeller with matt grey primer to make the contours a little more evident, and it's interesting to note the near perfect aerofoil shape of the blades. By contrast, my impeller is made from sheet styrene. I used 1mm sheet for the blades, and I've not refined or modelled them at all. Their placement on the hub is reinforced with thin strips of 0.5mm styrene, and as you'd expect, it's not very well balanced. Performance numbers are interesting. I'm using one of my Delta AFB1212M fans as a substitute, and I get the following: Max speed in free air: 2,410rpm Max speed on the box: 1,890rpm Max static pressure: 4mmH2O (significantly higher than the Gentle Typhoon, and at lower speed) I haven't measured the sound yet, but I will. The Delta motor is really buzzy and annoying but the impeller seems pleasantly whooshy and not at all loud. The impeller is from (I think) an NMB fan, which is unusual in that it rotates clockwise. The rest of the fan is history, but I'm using the hub with the ring magnet inside.
You should have tested the fan first as a comparison! Interesting though! Thats some nicely engineered styreen, I was expecting something really janky!
Thanks - I've been building with styrene for years and it's my go-to medium for side projects like this. A pencil and a utility knife is all you need. I wasn't sure how the styrene would manage with it being so thin, but I don't see any warping at all even after running it at 2,400rpm for a while. The original fan was a really low speed thing, not really worth testing - that's partly why I broke it for the hub. I now have a Barn Door Fan™ that will be pitted against the best fans currently available!
Here's what I was up to yesterday evening. Courtesy of @cobalt6700 I have on loan two very cool Magnehelic gauges, one with high resolution for low pressure (increments of 1Pa / 0.1mmH2O) and the other for higher pressure (up to 250Pa / 25mmH2O). As you can imagine, these gauges are far superior to my u-gauge, so it'll be nice re-testing the fans and getting "proper" measurements. More importantly, I now have the means to test low speed fans and compare sub-max static pressure with a very high degree of accuracy, which is fantastic. I'm still waiting for more flexible tubing to arrive in the post, so I decided to fashion my own connector for the gauges, keeping it as tidy and simple as possible. The styrene tube is thin enough to push-fit onto the spurs, and I reinforced and sealed all the welded connections with Milliput, a very durable epoxy putty that hardens like concrete and is airtight. With the gauges secured to the wall and vertically aligned, all I need to do now is zero them and they'll be good to go. Hopefully the tube arrives by the weekend and I'll be able to make a video showing the gauges in action - they are very cool pieces of kit indeed! (For some reason, the 60Pa gauge didn't seem to like my M3 bolts very much so I've given it some extra security with insulating tape!)
Fun. The styrene tube with the putty makes look like it been in a plant for a while and just got a fresh lick of lead based paint. A thought on screw issue, as those meters are American, then probably are using silly American machine screw sizes. The #6 screw notable the 6-32 fails between an M4 and M3, thus an M4 is too big and will not fit in the hole and an M3 will loosely thread into a #6. I remember when hard drive switched from 6-32 to M3s, I ended up messing up a bunch of screw holes trying to fit a 6-32 screws in to a M3 holes.
I was thinking that same thing, watercooling rad used to have the same problem and be a massive pain!
Hey folks, sorry for the radio silence - I've been really tired this past week and haven't managed to do much other than work, work, work. I took the opportunity this evening to make another test video, this time featuring two 3-wire fans which I have to control by voltage adjustment, and measuring the relationship between voltage, current, and sound level. This is just a test so it's not super polished, but I'm happy that the meters are all readable and everything makes sense. For sound level measurements I'm going to do what Nidec do, which is to measure from the side of the fan at 25cm, and then subtract 15dB to adjust for 1m, As you can see from the video, the San Ace is so quiet at 4.5v that the meter barely picks up the sound, maybe half a decibel above ambient. I'm using a simple DIY controller with a Micrel adjustable low-dropout regulator (iirc it's MIC29302WT), and you can see that the max voltage with both fans is above 11.5v, which is pretty good. The ever-popular LM317 has a significant dropout and tops out at around 10.5v. I also bought a couple of "cheap" fans on amazon just so that I have representatives from both ends of the spectrum, and I'm curious just how bogus these so-called "pressure optimised" fans are. I now have a radiator and a fan filter that I will use when measuring sound level, and I'll probably use the fan filter on the pressure box too. Finally, I managed to get the Magnehelic gauges properly set up and zeroed, and they are absolutely spot on. I'm getting 2.8mmH2O for the Gentle Typhoon, which is 100% on the money, and I'm now able to measure extremely low static pressure levels with a resolution of just 0.1mmH2O. This will come in handy when measuring low power fans with the dampers open. As before, big thanks to @cobalt6700 for the gauges and to @Big Elf for sponsoring the Tenma meter.
Utterly brilliant work! I love how you've lashed the meters together with an elastic band! I can't wait to start seeing some of these fans getting tested! If you weren't the opposite end of the country (and we're in a pandemic) I'd offer to come help do the testing to takesome of the work off you!
Thanks Pete It could turn into a lot of work but it's fun (as long as my wife doesn't kill me... once again it's 9:30pm and I haven't really come out of this room since 8am!). I managed to do quite a bit of thermal testing this evening after getting things organised and set up for repeatable measurements. I won't go into any details at the moment but suffice to say I used a selection of fans set to 1,250rpm so that I could see what the real-world difference in performance is... and the answer is, not very much at all. Even the Barn Door Fan managed an entirely respectable bottom place effort, only a fraction of a degree behind the Arctic P12. What's most interesting to note is how the each fan's maximum static pressure performance doesn't necessarily translate into cooling performance - for example, the Arctic is one of the better fans of the bunch on the graph, but it's second bottom in the cooling tests. The same goes for the Barn Door Fan. And it has to be said that I'm really surprised and disappointed by the poor cooling performance of the Noctua, which is by far the most expensive fan of the bunch (currently £27 on Amazon). Yes, it's really quiet... but so are all the other fans, including the ones that cost less than a quarter of its price. Obviously the Gentle Typhoon takes the performance crown, but my personal choice would be the Arctic P12 - it costs £6, it's really, really quiet at 1,250rpm, and it's within a degree of the Noctua.
Depending on what you're using, airflow is more of an indication than pressure I think. So I'd be interesting to see how airflow compares to thermals. Also can you do a higher RPM, something like 2000rpm, as thats when the A12 'should' show off its performance more
