Homemade Projector Silencer - How to reduce fan noise on a loud projector

[@teatimewithja]

Does anyone have any suggestions on improving the design? I want to do make an upgraded version some day.

[@marcuspedrosa9742]

Maybe put inside a cooler and just make a hole.

[@teatimewithja]

@pt265 Nice! Yeah, I would not expect a barrier like that to do a lot more than 2 dB overall, but at high frequencies it can make a big difference. I am curious - how did you measure the sound? (Also, I am just seeing your comment, for some reason.

[@extaza555]

i do.. mod it internal and make cooling better. change the ventilators for more silent ones.

[@teatimewithja]

@@extaza555 That would seem worthwhile for a nice projector that I paid good money for, but the price of this one (free) makes major modifications not worthwhile.

[@extaza555]

@@teatimewithja in the meantime I got myself a Sony VPL-HW50 and I couldn't be happier

[@jackmorningstar24]

This is a brilliant piece of unintentional satire, well done.

[@teatimewithja]

I am afraid I don't understand your comment. Can you explain? @jackmorningstar24

[@elyk46]

@@teatimewithja That dude probably exclusively owns TVs and can't fathom why someone would want to use engineering skills to perfect an already superior product.

[@djangosoftwaredeveloper]

🤔 interesting. Has got me thinking. Could you/will you recreate this with 3d printer?

[@MrSnowmobilefreak]

good job and great work. big thank you for posting graphs on before after. lot of how to's didnt demonstrate effectiveness. Bonus points for doing it with things you could find around the house.

[@teatimewithja]

Thanks for the feedback! I would like to make one out of a bit more substantial material eventually, but this proof-of-concept silencer actually helped a lot.

[@bartekjedrzejewski7594]

:D I'm loving your video! Thanks for the help, especially I appreciate the charts at the end

[@teatimewithja]

Thanks Bartek! I am happy to help and am glad you enjoyed it.

[@DeSireeAlicea19]

Does this do anything for the heat levels that the unit might produce?

[@teatimewithja]

I am afraid I only have subjective information for you - but I hope it is helpful: I do not think this silencer drastically increased the temperature of the projector, but I was a little bit warmer with both the silencer and the enclosure. I have not had any issues so far, but I image that moderate increase in temperature could reduce the lifespan of the projector (or at least the bulb). I do not think there is any fire danger, but I can not guarantee that.

[@orbitalpunk]

How did you kill those high frequency tones? Also what mic did you use?

[@teatimewithja]

Thanks for the questions. The enclosure helped some with the high frequency tones, but the silencer brought them down more significantly. Of course, the combination was the most effective. It was a combination of the barrier effect (shielding of the enclosure) and absorption (the foam in the silencer). If you are working on something similar, make sure to seal all the cracks and deal with all the flanking paths.

[@teatimewithja]

I was using a couple PCB 378A06 free-field mics (which is the 377A06 condenser microphone combined with the 426E01 preamp), because they perform well at high frequencies, but more often I use the more-typical PCB random incidence mics. PCB makes good stuff, but it is not cheap.

[@deusdat]

The silencer introduces a pneumatic resistance that reduces the airflow. So the fan will have to work harder (turn faster) and... produce more noise. Or the lamp will get hotter and die soon.

[@teatimewithja]

Agreed - both are potential results of a silencer. If you are dealing with high air flow (I am not) there is also the potential problem of self-noise from turbulent flow caused by the tortuous path in a silencer. For this application though, I did decrease the overall SPL so, even if the fan got a little louder the silencer provided even more reduction with a net decrease in noise. Also, I tried to make the cross-sectional area of the flow through the silencer as big or bigger than the original outlet so back pressure should not be significant. Finally, the bulb may die sooner, but I will enjoy the quiet until it does. Thanks for the thought-provoking comment!

[@adrianzhang7985]

Excellent! That is what I m looking for. I have to find a way to reduce noise from fan of a DIY humidifier. And this video gives me a lot ideas! Thank you very much. And a comment, how about using foam as baffles directly?

[@teatimewithja]

Hey Adrian. Thanks for the feedback and good luck with the DIY project! My results were not perfect, but it definitely helped. Foam baffles alone will still get you some noise reduction, but the foam alone has very poor Transmission Loss so a good bit of the sound will be able to travel directly through the foam which effectively shortens the noise path to the exit and reduces the number of times it interacts with (and is attenuated by) other foam. I would recommend using something a little bit thicker than the notebook I used for the walls to increase transmission loss. Also, make sure to seal all the cracks/holes/leaks. Duct seal/putty works great (duct tape has terrible Transmission Loss). So, a couple warnings/disclaimers: Make sure you are not causing any heat issues by adding the silencer. Also, if the silencer is in the humidity flow-path, keep in mind the potential for mold if the foam is constantly damp.

[@denisrempel9200]

Did you try replacing the fan?

[@teatimewithja]

I did not try to replace the fan. I am assuming you could buy a quieter fan but my concern is that you would have to pay a good bit to get a fan that was significantly quieter, and then you might be paying a good portion of the cost of this budget projector. I might have tried that if I had a really nice expensive projector. Have you had any good luck with fan replacements?

[@peter2160]

What could I do to reduce the noise of airplanes flying over my house? Really it’s only about 44 decimals at the loudest when ones loud one flies over a bit lower than normal, but still annoying. Considering thicker curtains in my bedroom since I assume much of the noise is through the windows.

[@teatimewithja]

That is a great question, but you are not going to love the answer. Noise from an airplane has a lot of low-frequency energy which makes it difficult to do much about unless you want to make major changes to the structure of your house. If you have a long wavelength (low frequency) you need a lot of thickness and/or mass to do get decent transmission loss performance. For sure, windows are often the weak point but to get any reduction in noise you would have to have VERY substantial curtains AND make sure there are no gaps around or between the curtains that you can see light through. Instead, I would recommend looking for cracks/leaks around windows, doors, ceiling fans, and other penetrations to outside. Thicker curtains may help some, but I would guess you will not be able to tell the difference. You may be better off with white noise (a fan?) and ear plugs.

[@peter2160]

@@teatimewithja yeah that’s not great news. Fan it may be then

[@harj-spp8547]

I've got a similary type of LED based projector, recently acquired and noisy as hell. I've been looking for solutions too. I've opened mine up and found two very cheap fans inside. One is a blower chamber type that pushes air around and normally louder by design and the other is a normal 80x80mm fan, that pushes air out through the ventilation. I did think about reducing the air speed of fans but thought overtime, the LED may die from overheating. The fans are simple and not thermally controlled, which would have been better, though perhaps still noisy due to the cheap fans. As the exhaust fan is quite generic, I'm looking into replacing it with a better quality and quieter PC fan. The only problems is finding out how much air flow the original pushes, though I'm not sure if it needs to be as much, I'll try for similar. The blower mayber harder to replace as its somewhat custom, though replacing that would be great too. Or I was thinking to reduce the exhaust fan speed and attach a slim low speed fan to the exterior grill. This will suck out the heat more efficiently, as the internal is about 30mm away fro m the grill so the sir is directly going out. It's going to be a lot of experimenting.

[@teatimewithja]

That is great that you pulled your projector apart - going to the source of the noise and trying to fix that is often a better option than just treating the noise after it is made. I agree that a slower RPM, larger fan that moves the same amount of air would most likely make less noise than the smaller faster fan, so that does seem worth trying (if that is what you were saying for the external fan). Also remember though that convection heat coefficients are a function of air velocity so if you are decreasing the velocity you might decrease the heat transfer from the projector to the air. Replacing a fan with a nicer quieter one also seems like a good thing to try. Sadly, while what I did helped some, and I am guessing you can get some decrease in noise, a lot of the things I tried are only incremental improvements, not true fixes. Good luck with the experimenting!

[@MrBorkie]

Have you found a quieter blower? I'm stuck in the same situation

[@harj-spp8547]

@@MrBorkie Unfortunately no, there are some similar but the projector would need some modification for them to fit. I did change the exhaust fan to a PC noctua fan, which I had laying around. Even though definately quieter it was a few rpms slower, the temperature increased significantly inside that there was screen burning after about 5 minutes, so put the original fan back in. I also temporarily connected variable resistors to the fan lines, and played around reducing speed. The blower has the most impact on heat expulsion, reducing it only a few 100 rpms, didnt make much impact on noise reduction but again caused screen burn within a few minutes. The exhaust fan has worst design, as the heat is not pushed put enough and efficiently, gets trapped and affects further back in the air flow. I think if the exhaust section expells more air, less restricted and directed out better. You could theoretically reduce the blower speed safely. The other idea would be make a box for the projector, fit two large fans for in/out, with low rpm and will push large volume of air MAY be an option. OR/ALSO increase size of LED lamp heatsink with the fan externally mounter but slower RPM. OR like in cinemas, setup the projector in another room, projecting through a glass panel. All this for a cheap/badly designed projector! Good luck

[@teatimewithja]

Thanks for sharing all the details - it sounds like you have done some good experimenting. I like the idea of a bigger box with larger slower fans, though if were going to do something like that I would make sure to put the fans on the side opposite the audience because that could get you a bit of a barrier affect, and also not have a direct opening on the audience-side. How are you measuring the temperature?

[@ArsenicShooter]

Another solution would be to replace the noisy fan with a quieter one. Only thing is to make sure it has a better airflow, so it doesn't have to turn too high rpm.

[@teatimewithja]

That is a good idea. I think I might have done it that way if it was a bigger and more expensive projector. Do you have a success story with replacing a projector fan?

[@ArsenicShooter]

@@teatimewithjaUnfortunately I didn’t try, but I read several posts on different forums about replacing the noisy beamer fan. I’m pretty sure that on this kind of beamer it must not be very difficult to replace it. The only thing that can happen is that the fan’s rpm is checked by the motherboard’s software and if too slow, it triggers a « security shutdown » to avoid overheating, as sometimes it can monitor not only the temperature, but also the fan speed. It could be a very interesting thing to do. The first thing would be to check the fan size and connector type. Then to find a silent brand with the same size like Noctua, Arctic or Noiseblocker. They make great fans. The only thing I am wondering about is: is the fan rpm fixed or does it change depending on the temperature? If fixed, you need to make sure to get a silent fan when running at max speed.

[@teatimewithja]

That sounds like a reasonable approach and some good details to keep in mind.. Even if it may not be the simplest fix, it does sound like a fun project. I do think my projector has two different speeds at least, depending on the temperature - tricking or re-setting the rpm sensor would probably be beyond me, especially if it is all circuitry, but a combined approach (reducing the noise at the source, AND treating the noise path) may be a good approach as well.

[@ArsenicShooter]

@@teatimewithja I did something on my laser tv ust projector that has a noisy fan. It looks not terrible, but does miracles. I "attached" my air filter (that has a HEPA filter) air output to my beamer’s air input so it pushes filtered fresh air in it. It prevents noise as fresh air is pushed through it and it also filters the air from dust so no or pretty much no dust cleaning is required anymore. It runs at lowest level so I can barely hear the filter, but still has a pretty high amount of cfm and air pressure going through the system. Biggest advantage in the whole thing is that I’m not married, so nobody says anything about how it looks 😄

[@teatimewithja]

I love it. It sounds like you are solving several problems (restricted air flow, noisy projector, dusty air, etc.) at once. There definitely can be cost savings from living alone!

[@nischaltimila3184]

Does this really works?

[@teatimewithja]

It really does work. I have an education and professional experience in acoustics and the measurements I took were with NIST-traceable calibrated equipment. At the same time, the reduction I got was only a few decibels in the overall a-weighted sound pressure level - not very much. I do have to admit that my y-axis in my plots look a little funky, but if you look at the relative differences the real performance I got form the combined silencer and enclosure was in reducing the level of individual high frequency tones. This silencer build was more of a proof of concept though. To really get good performance you would need to 1) use more dense/thicker material with higher transmission loss, 2) carefully seal all gaps and leaks, 3) treat all the air openings on the projector, 4) probably use a foam with measured absorption values if you wanted mid-frequency performance, 5) not use duct tape, 6) address any flanking paths such as noise coming through the plastic projector case.

[@UniversalDirt]

We added an external fan to our projector to increase cooling, but that of course only added to the noise.

[@teatimewithja]

My projector hasn't melted yet with the extra silencer and enclosure, but it is always possible. Sounds like an silencer would not help you, but maybe an enclosure around the projector AND the extra fan (open at the front)?

[@PongoXBongo]

@@teatimewithja This is what I was thinking of doing. A big, foam-lined enclosure box with one or two super quiet computer fans (big, low RPM).

[@teatimewithja]

@@PongoXBongo I like that idea. It seems like you still may hear the big fans, but the lower frequency hum should be less annoying than the wine of a higher rpm fan. Also, remember that the lower frequency noise will, generally, be harder to absorb or attenuate with mass. I assume the computer fans would be on the front of the enclosure on the side facing away from the audience?

[@PongoXBongo]

@@teatimewithja Well, in my case, the projector is directly above the audience (wall behind couch), so fan placement for noise wouldn't matter too much. . I'm thinking more like a fan on each side (not front or back) to create cross-flow (like a PC case). Or maybe solid sides and a fan or two on top? No audience floating above the unit, lol.

[@teatimewithja]

@@PongoXBongo It sounds like you have thought through this a good bit. In that configuration, on top seems to make the most sense to get the largest barrier affect between the audience and outlets (unless roof reflections become an issue). Let me know how it turns out and if you learn anything along the way - I love acoustics stuff.

[@gurqhan]

dude sound will escape from open spaces of any dimensions, you either need an oversize hush box or replace the fan with a bigger one via a fan duct (risky to disassemble)

[@teatimewithja]

You are right that sound will get out any opening. Like I said in the video, I am treating the shoe box as more of a barrier and less of a full enclosure, because I need openings for the intake airflow. It does help reduce the sound at the listener location behind the projector.

[@HisshouBuraiKen]

$0 spent on projector, $0 spent on silencer = Infinite bang for the buck ratio.

[@teatimewithja]

I like this math.

[@heikopeifer1204]

Who is Abraham Maurice Twain? I find nothing in internet.

[@teatimewithja]

Hello Heiko. That is a good question. The quote that I put at the end of the video has been attributed to MANY different people at different times. Some say it was Mark Twain, some say that Abraham Lincoln said it first. But it may have originated in a 1907 book called “Mrs. Goose, Her Book” by Maurice Switzer. I was not really sure which name to use, so I just combined them all together into one name that, as you found, does not exist. Thanks for asking!

[@1987Redfield]

Perfect way to kill your projector. It's gonna suffocate. Fan and heat gonna have a very hard time to move around. Just replace your fans

[@teatimewithja]

It has not died yet! Some day it will, but I am not worried about it. Also quiet fans would cost a lot more then I paid for the projector ($0), and probably as much as the thing is worth.

[@1987Redfield]

Well, if it works for you, than OK:)

[@iinrohaya2920]

build enclosure from pc almunium case make a hole for 2 extra fan. blanketing with wool fabric, glue them on to outer enclosure. works for me.

[@teatimewithja]

I like the idea! Do what works for you. Are the extra fans that you added quieter than the projector fan? Also, did you put the insulation inside the PC case, or on the outside? Insulation on the INSIDE of the case will help reduce the noise inside the case which means there will be less noise to escape. Putting insulation on the outside will only help a little bit since most insulation materials do not have great Transmission Loss performance (unless they are really dense).

[@iinrohaya2920]

@@teatimewithja youp, already make one. inside side plate case. forgot to mention, extra fan usefull for vacuum hot air inside the closure. nonthe less i use processor fan lga 775 whick more quiter than regular fan

[@teatimewithja]

There is someone else commenting about the possibility of using a larger, lower speed, quieter fan. I like the idea. How did your pc-box work? Was it a good bit more quiet?

[@iinrohaya2920]

@@teatimewithja yeah so so. but now im using literaly pc case, the humming more like cpu now, and also blanketing the wall with yoga matras. last part is acrylic or transparant plastic or maybe a glass to sweeten the case overall appearance. . if you have whatsapp i'll give you the pic or video

[@teatimewithja]

I have definitely used couch pillows on my walls for temporary absorption while doing some voice recording - you've got to use whatever you have and whatever works.

[@islomboynazarov6035]

I prefer sell mine and get a silent one

[@teatimewithja]

That is not a bad option - I think spending some money to make your environment pleasant and quite is often worthwhile. Do you have a specific recommendation of a quiet projector?

[@blakespower]

geez just buy noise cancelling headphones

[@teatimewithja]

I do have some good headphones, but that only works for one person watching at a time (and good noise-canceling headphones cost several times as much as the projector). What is your typical setup for watching movies or playing video games?

[@blakespower]

@@teatimewithja i have a cheapy rokonia projector, its ok only 1080p it is loud, i played it only a few times for games, usually just use it for streaming movies and use a 25 inch monitor for gaming. I am just messing with you, i do think projectors are better for your eyes, if i watch a movie on a 4k tv its hard to see for a few minutes if its night, but with the projectors your eyes adapt faster say if you leave the room without turning on lights

[@teatimewithja]

@@blakespower I had not thought about projectors being better for the eyes - but that does make sense. I also am not sure if I would survive without my noise canceling headphones.

[@marcuspedrosa9742]

I hope will don't get your house on fire

[@teatimewithja]

I hope not as well! So far I have not had any issues, but if I do I also have a fire extinguisher.

[@dariomedinelli3769]

Spend some money and buy a less noiser projector

[@teatimewithja]

The projector was a gift and the silencer was a fun project. Money is often helpful, but it is not always the best solution.

[@DoubleMonoLR]

There are a lot of older projectors that are cheap with very good quality. It would be wasteful to just buy something new instead of reducing noise.

[@teatimewithja]

For me, it is about balance. Some things (e.g. headphones) are worth spending some money on since I listen so much. I don't watch a lot, or game at all, so a really nice quiet projector is not worth the money for me. That decision will be different from someone else. But I often agree that a bit of effort or ingenuity can save me some money.

[@teatimewithja]

Amusing - if you are saying that ALL projectors are noisy, you are probably right. Do you prefer a big screen instead?