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Thread: Quiet 12v Power Supplies for LED strips

  1. #1

    Default Quiet 12v Power Supplies for LED strips

    I am having a lot of difficulty in getting what seems a good quality 12v power supply. I wondered weather to ask here or on headfi as I also use them for audio stuff too.

    The problem I have is that I am incredibly sensitive to sound. I find the high pitched buzz emitted from a lot of power supplies almost unbearable even if it is pretty quiet. The issue with using them with LEDs is that dimming only makes the noise change and generally get louder. I have bought many from different places, some of which turn out to be suitable if the LEDs are used on full power, but produce a horrible noise when dimmed. It also brings the noise of the power supply to the dimmer itself, making it even harder to hide the noise. Interesting thing is that some old 12v power supplies i had lying around seem to be really good quality. For example an LG 12v 2A power supply that came with an optical drive for a PC, this one makes no audible noise what so ever, even when dimming. I tend to find that the sort with an mains lead to the transformer tend to be better built and emit less noise, but that is not always the case. All of the good ones I have are what happened to not be needed as the device they came with either no longer worked or was not used. As I find is the case with most things built these days including power supplies, they used to be built better. This LG one will probably be nearly 15 years old.

    Out of all the ones i have bought being over 3a in the last few years have been noisy in some way. Either the whole time or when the LEDs are dimmed.

    https://www.amazon.co.uk/gp/product/...?ie=UTF8&psc=1

    https://www.ebay.co.uk/itm/DC-12V-1A...215588c9688679

    I bought a couple from ebay and probably should have known better. I usually notice suspicious things in pictures, but i didn't until I received it and found out that the earth pin was sleeved. That surprised me as they are selling something that is illegal to ship from this country. Anyway, I tried the transformers with my own IEC leads, and they both did the job, but were so noisy. I'm going to request a refund for both anyway as they shouldn't be sold.

    So far, going cheap or expensive, I can't seem to find any new 12v power supplies that don't make any audible noise. I just have to keep looking around and using ones from dead equipment that used them as branded ones (that are not sold separately) seem far better.

    I have the same problem with 12v audio amplifiers. The amount of noise most power supplies send to the speakers is awful, but it amazes me how good a dirt cheap amplifier can sound if you use a good supply like my LG one.


    Any advice on where to buy good 12v power supplies would be appreciated, Thanks.

  2. #2
    Unenlightened
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    Default Re: Quiet 12v Power Supplies for LED strips

    Mean Well generally makes quality power supplies. You can buy from amazon or digikey or mouser.

    Alternatively, you could take a computer power supply brick and use a step down converter to get the voltage you want.

  3. #3

    Default Re: Quiet 12v Power Supplies for LED strips

    Sorry for the late response. I will see if i can look more into some power supplies from the brand that you mention. From what I have seen so far, it tends to be more the open sort rather than enclosed in a case. Regarding computer power supplies, I either have some old ones lying around or should be able to get one elsewhere. But they are pretty large and may seem a bit inappropriate for powering a simple 12v light in a bedroom for example, especially if you have to use a step down converter. But I may remember to use something like this for other purposes. For power supplies in general, the most ideal sort is just a simple 12v brick, just a quiet one. I have seen quite a few Mean Well supplies that are around the right current output but are open so for the area I would use them, they will need to be put in some case. I'm not good at making things myself so are there cases that you can get that could fit them? Although then I would run into the issue of needing to create a cable grip (or an IEC input or something similar), especially on the mains input side. I can picture all of this from power supplies i have opened up, but don't know how easily I could put together myself.

  4. #4
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    Default Re: Quiet 12v Power Supplies for LED strips

    It sounds like what you need is an old-fashioned linear supply with electrolytic caps. Most modern supplies are switchers, (including the ones you linked) because they've gotten cheaper to build than linears.

    While the switching frequencies are almost always well above the audio range (50 kHz would be quite low, some are over 1 MHz), the PWM frequencies are usually right in the audio band, 200-5000 Hz. Ceramic caps that are so popular now can have a piezoelectric effect, where they change shape with applied voltage. Inductors can have electromagnetically induced mechanical motion as well. I once designed an LED driver that had to have the caps switched from ceramic to more expensive electrolytic ones to eliminate the whine from the caps.

    A computer power supply might be okay as well, if the noise from that doesn't bother you. AT type ones have a pretty beefy 12V output and probably electrolytic caps.

    Another possibility is to put a filter between the power supply and the dimmer, to reduce the audio frequency load on the power supply. Even a couple of low-impedance electrolytic caps across the output might help.

  5. #5

    Default Re: Quiet 12v Power Supplies for LED strips

    EDIT: This doesn't seem to let me split my post in to paragraphs or start on the next line despite me editing and previewing with it looking correct several times, so sorry if it looks a mess. Starts here >> Interesting. When I think about it, this 2A LG power supply came with an external optical disk drive from 2007. I have plenty of other power supplies that I am not aware of what they came with that seem to be just as good as this one noise wise and I assume they are also pretty old. They also have a good weight to them. That is another think i notice. If they don't weigh much, they usually are more noisy. I don't know enough about the components inside to know why though. I have always been into my sound and have extremely sensitive hearing. I am in my early 20s and I can still hear just over 17khz. Interestingly, using the same site with the test tones and same headphones, I can remember a few years ago, I could hear up to 19khz, so it obviously has dropped off a bit. But I still think I am far more sensitive than the average person. For example, a lot of the time I go into shops that happen to be using an old CRT display for their CCTV images, I can usually hear them and often find it painful to be near just because of how high pitched it is. I'm not sure what it is that is in old monitors that cause this noise, but I notice it virtually every time i am anywhere near one. Very few are inaudible to my ears. Power supplies that i notice buzz usually are much lower pitched than this so are not painful, just very irritating. Just seems so difficult to find the sort that I'm after that is fully enclosed. I think I will just keep a look out for old equipment getting thrown out that still has a proper 12v power supply by a good brand - which often are not sold separately. It is strange just how variable the noise of these things can be. I've been through a lot of power supplies by Netgear for network switches, some of which have been almost silent and others have made a high pitched squeak the second they get plugged in, even without any load on them. This is sometimes the case even if the design and label looks identical. The main problem is that when I dim LED strips, the power supply almost always gets louder apart from on the good ones. The only use I will have for these will be for LEDs or audio systems. With audio, any noise from the supply gets fed through the amplifier to the speakers and then amplifying it obviously makes it worse.
    Last edited by TheGiantHogweed; 03-11-2020 at 06:07 PM.

  6. #6
    Flashaholic* DIWdiver's Avatar
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    Default Re: Quiet 12v Power Supplies for LED strips

    I had a problem years ago where the forum wouldn't acknowledge when I pressed the enter key. I used to open notepad, copy a carriage return to the clipboard, then paste it when I needed to. Eventually I found out that it was a combination of the software used to host the forum and Internet Explorer. I switched to Chrome, and haven't had the problem since.

    The reason some power supplies are heavy is that they use a laminated steel core transformer that operates at line frequency (50 or 60 Hz, depending on where you are), while the lighter ones use a high frequency transformer that can be MUCH smaller and lighter for a given power level. Line frequency transformers are usually coupled with linear regulators, and are dead silent unless there's something loose in the transformer, which can buzz at 50 or 60 Hz. There's lots of harmonic content to this noise, but even the 30th harmonic of 60 Hz is only 1800 Hz.

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