https://community.element14.com/technologies/open-source-hardware/What is the connection between Open Source Hardware and traditional engineering companies. How can professionals & hobbyists learn from each other. What can hardware developers learn from Open Source Software.en-USTelligent Community 12https://community.element14.com/technologies/open-source-hardware/f/forum/56877/the-pam8403-amplifier-is-very-noisy/235358Tue, 05 May 2026 15:01:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:bb70ce50-e172-468c-9249-347553ee2c79me_CrisOf course, you can see in the post.https://community.element14.com/technologies/open-source-hardware/f/forum/56877/the-pam8403-amplifier-is-very-noisy/235320Mon, 04 May 2026 16:31:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:70367b99-d0ed-4de3-9ef4-b493a39dce12geraldsCan you make photos of your assembled amp., that show us details about your built?https://community.element14.com/technologies/open-source-hardware/f/forum/56877/the-pam8403-amplifier-is-very-noisy/235319Mon, 04 May 2026 14:35:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:446a7cc5-80ca-486c-924e-fd099621f452me_CrisI did a test, I used the 5V power supply from the board to power another circuit also with addressable LEDs, and the noise is reduced (not by much) than when using LEDs that are already on the speaker. The noise source (addressable LEDs) being further away has some positive effect.https://community.element14.com/technologies/open-source-hardware/f/forum/56877/the-pam8403-amplifier-is-very-noisy/235318Mon, 04 May 2026 14:29:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:5baad642-d413-492e-a077-ddb1d4d5e2b2me_CrisI'm waiting for the PAM8406 version which should not be so noisy. I didn't achieve much using the ferrite bead + capacitors filter.https://community.element14.com/technologies/open-source-hardware/f/forum/56877/the-pam8403-amplifier-is-very-noisy/235317Mon, 04 May 2026 14:27:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:8aa13adc-450b-4225-885a-4493b3fc026bme_CrisI experimented a little by inserting a filter, I didn't use the same speakers (it's more difficult than it seems) but I noticed some reduction in "noise". Waiting for my PAM8406 version to arrive which should be improved on this side.https://community.element14.com/technologies/open-source-hardware/f/forum/56877/the-pam8403-amplifier-is-very-noisy/235204Tue, 28 Apr 2026 15:29:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:c8050f99-12bb-4550-af9b-c1dc3d23127ame_CrisNot really, but maybe I don't need to go that far. I can also try other 5V powered circuits.https://community.element14.com/technologies/open-source-hardware/f/forum/56877/the-pam8403-amplifier-is-very-noisy/235203Tue, 28 Apr 2026 15:26:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:314e7a40-44eb-4abb-a168-c2bed60cf84cme_CrisThank you, I will check that filter circuit. The PCB version is a bit homemade, so I can't make any claims.https://community.element14.com/technologies/open-source-hardware/f/forum/56877/the-pam8403-amplifier-is-very-noisy/235202Tue, 28 Apr 2026 15:22:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:2d890532-151d-4c49-bfcd-3784b07fc023me_CrisThe PAM8403 module of this type is a little noisy (it's not for nothing that it costs very little), but it's clear to me that the LEDs produce a very sharp sound (I would describe it as a very annoying mosquito sound, I know it sounds strange what I'm saying ).https://community.element14.com/technologies/open-source-hardware/f/forum/56877/the-pam8403-amplifier-is-very-noisy/235201Tue, 28 Apr 2026 15:17:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:13f47e8a-6060-45b8-817b-2085e9726ffame_CrisHi, I'm a little late with the reply, I don't have much time during the week. I added pictures to the post. I'll experiment with the USB power supply part. I think LEDs (there are 7 per speaker) of this type consume enough mA (tens), and since I want to create some visual effects, I'm basically witnessing a "symphony" of noise.https://community.element14.com/technologies/open-source-hardware/f/forum/56877/the-pam8403-amplifier-is-very-noisy/235176Mon, 27 Apr 2026 15:03:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:25993dc0-3ab8-4b11-b9ce-2826657b6599geraldsYou're welcome. Oh, yes me too - I also have toys I can't remember why I have it. :) You mentioned the Vref _pin and -capacitor: It is important to know that this pin is a bi-directional pin. In the datasheet is descripted you need a X7R cer. cap. between 470n to 1u. >>> Analog Reference Bypass Capacitor (CBYP) The Analog Reference Bypass Capacitor (CBYP) is the most critical capacitor and serves several important functions. During start-up or recovery from shutdown mode, CBYP determines the rate at which the amplifier starts up. The second function is to reduce noise caused by the power supply coupling into the output drive signal. This noise is from the internal analog reference to the amplifier, which appears as degraded PSRR and THD+N. A ceramic bypass capacitor (CBYP) with values of 0.47μF to 1.0μF is recommended for the best THD and noise performance. Increasing the bypass capacitor reduces clicking and popping noise from power on/off and entering and leaving shutdown. >>> But on the EMB is mounted a 100n X7R cap. This value is too small. This pin, Vref can modulate the signal through the signal path if that Vref value is not stabile. Noise and popping noise signals are going to the amplifier. This cap. must be mounted very close to the pin and the GND must be a polygon field. - The polygon should be around the IC as well.https://community.element14.com/technologies/open-source-hardware/f/forum/56877/the-pam8403-amplifier-is-very-noisy/235175Mon, 27 Apr 2026 14:20:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:1a153218-f9f4-4565-b9d6-241cdd96ecefshabazHi Gerald, Thanks for the info, that part looks much better than the 8403. No reason to use that old part anymore. I can't recall the reason I had the 8403 board, I think I got it several years ago.https://community.element14.com/technologies/open-source-hardware/f/forum/56877/the-pam8403-amplifier-is-very-noisy/235174Mon, 27 Apr 2026 13:17:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:75660980-d202-4288-b38d-cd836077dd7egeraldsHi shabaz Here are the datasheet and an app-note. The PAM8403 is obsolete, the PAM8406 is recommended. community.element14.com/.../PAM8403-_2800_1_2900_.pdf community.element14.com/.../PAM8403_2D00_User_2D00_Guide.pdf community.element14.com/.../PAM8406_2D00_User_2D00_Guide.pdf community.element14.com/.../PAM8406.pdf As I mentioned you will need filtering on the output to the speakers. Also, the PCB needs improved routing. In the PAM8406 schematics BOM list you have the values of the components. A huge problem is a GND loop, -ringing and -bouncing. -> Poweranalog is now part of Diodes: https://www.diodes.com/search?q=pam&action_results=Go&start=20 Regards Geraldhttps://community.element14.com/technologies/open-source-hardware/f/forum/56877/the-pam8403-amplifier-is-very-noisy/235172Mon, 27 Apr 2026 11:34:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:ee6d0de2-6131-423f-8bed-456902dd390dshabazDecided to quickly try that amp board, my results won't necessarily help at all since my setup is completely different and I don't have LEDs/microcontroller attached. I'm not near 'scope so I couldn't grab any traces. I'm using a very high quality audio cable (double shield), but there is about 3 cm bare at the board end. Speaker is 8 ohm (I only wired to the right channel). For the power supply, I plugged into an Anker mains-to-USB adapter. It's quite a noisy amp, there's reasonably noticeable hiss. With the 3.5 mm plug unplugged, I hear mains buzz; it needs to be shorted for that to go away, leaving just the hiss. Then I plugged the audio cable into a battery-powered MP3 player. It sounded fine. However, then I attached the audio cable to my laptop instead, which was powered from another port on the same Anker adapter. It was intolerable, lots of electronic noise sounds. If I unplugged the laptop and let it run on batteries, then the sound became acceptable again. I tried a few things; additional decoupling (220uF electrolytic cap on the power rails, no difference. Then added a choke preceding that (a 1 mH common-mode choke with the windings wired together to be a normal single choke), still no difference. Then removed the electrolytic and re-soldered the choke as common-mode, then tried two of them : ) and also tried adding it to the audio connections too. Still no difference. Then I remembered I was not using the official laptop charger - I attached the laptop to the correct charger, and the amplifier remained on the Anker one. Noises gone. The official laptop one has 1k resistance from the USB shield to the earth pin. The Anker one doesn't have an earth connection (i.e. SELV). I'm guessing perhaps the laptop puts enough noise into the charger, that it egresses on all the other ports (common-mode or differential or both - don't know, guessing both!), and the filtering I was doing wasn't sufficient - I should have tried both differential and common-mode simultaneously but I didn't get a chance.https://community.element14.com/technologies/open-source-hardware/f/forum/56877/the-pam8403-amplifier-is-very-noisy/235169Mon, 27 Apr 2026 09:11:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:2d5a3417-04b9-4989-b1ae-a10f1f54d7e6michaelkellettDo you have an oscilloscope. It will be much easier to fix the problem if you know what it is causing it. Since the noise happens when the LED is on it should be easy to see what is changing on the amplifier when that happens. MKhttps://community.element14.com/technologies/open-source-hardware/f/forum/56877/the-pam8403-amplifier-is-very-noisy/235168Mon, 27 Apr 2026 08:48:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:44452ced-abbd-44a2-abef-afcd502f4407geraldsHi, please take a look in this datasheet. https://www.alldatasheet.com/datasheet-pdf/view/246505/PAM/PAM8403.html -> page 10, figure 2: here is a description about an EMI filter, which helps to reduce EMI. It seems your amp_PCB is not RF stabile; its layout is not optimized as well. Its GND trace is very small. As well your PS_PCB please reroute for low noise and low impedance. -> short traces as you can do, separate in-going from out-going, signal traces need pairing (parallel going) with GND not with V+. 3W output at 5V supply produce a relatively high and fast impulse current into the speakers, separate is it from input traces.https://community.element14.com/technologies/open-source-hardware/f/forum/56877/the-pam8403-amplifier-is-very-noisy/235166Mon, 27 Apr 2026 07:04:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:5ceaba93-4ba6-4cac-a60b-591f697e428eshabazIt's difficult to completely remove noise when a lot is outside of your control; even some so-called hi-fi products get noise artifacts when things are interchanged in setups the manufacturer didn't expect. Are you sure you're not expecting too much; what is the noise level in comparison to the audio level, and what does the noise sound like? Could you record it? I happen to have one of those PAM8403 boards here, but I've never used it. I've buzzed out pin 8 which needs to be connected to a bypass capacitor according to the IC datasheet, and confirmed it's present, so the basic minimal circuit is at least implemented on that module. I will try to power it up sometime, but no guarantee I can do that this week. Not sure it would be all that useful to you anyway, since I don't have the same setup as you. If you can power-down everything else (LEDs/microcontroller), and remove the input (and maybe even short the inputs) then check to see if the noise is reduced a lot. Then try to add in the audio cables, and feed in audio from something completely separate and battery-powered to begin with, such as a portable MP3 player. Just take baby steps, and see what affects the noise. I suspect that you may eventually reach a point where the noise is low, but still noticeably there, unless you're prepared to change things a lot, e.g. say switch from USB power to battery, or not use the LEDs/microcontroller if not required, and so on.