Power Supply Whine

[tanno1]

Hi all, mechanical engineer here building a speaker and I am hoping to get some clarification on my design. Currently, my speaker plays music, but there are a few issues...

Overview of my active, powered speaker build components:

1. Peerless by Tymphany SDS-P830657
2. Dayton Audio ND25FW-4 1" Tweeter
3. LRS 150 24 PSU
4. XKitz LR 2 Way Active Crossover
5. Amp, Wondom AA-AB32174

My questions:
1. You can see this in the attached video file, but there is a horrible whine that plays when the speaker turns on. I powered the system using a desktop power supply at work, and there was no whine at all, so I am sure it's coming from the power supply. Im hoping to get some EE explanation on where this comes from and what I can look for in other power supplies to fix this problem.

2. Currently, I am just feeding in a RCA audio source from my record player. There is no volume control on the speaker itself, but I would like to add that. Can I just take a Potentiometer and smack it in-between the RCA input and the RCA input to the crossover? I have the hardware to do that, I just wasn't sure if that's valid or if it will introduce some similar noise issues.

Video Link

Looking forward to chatting about this!

Edits:
Added Amplifier to component list

 

[alex-z]

That usually means your power supply has insufficient output filtration, noise from the switching process is leaking out. The datasheet indicates there is 200mV of ripple and noise.

Just find a power supply with better performance. Switch mode power supplies with 50mV ripple or less are common. Linear power supplies are often under 10mV, efficiency is poor so the industry moved away from them. Running directly from a battery is the ultimate solution but inconvenient.

 

[tanno1]

That usually means your power supply has insufficient output filtration, noise from the switching process is leaking out. The datasheet indicates there is 200mV of ripple and noise.

Just find a power supply with better performance. Switch mode power supplies with 50mV ripple or less are common. Linear power supplies are often under 10mV, efficiency is poor so the industry moved away from them. Running directly from a battery is the ultimate solution but inconvenient.

Very interesting, thanks for the response!

 

[mcochris]

That sounds like a bad power supply. I’d replace it if possible.

Another possibility is coil whine, which occurs when one or more inductors in the power supply vibrate under load. Coil whine can also be triggered if the PSU is being pushed near or beyond its rated capacity, causing higher current draw and increased magnetic forces in the coils.

You can try to locate the source by removing the PSU cover and pressing on each coil with a non-metallic tool (e.g., a wooden stick or plastic tool). If the noise changes when you apply pressure, you’ve likely found the offending coil. Check nearby coils as well, as more than one can vibrate.

A possible fix is to pot (encase) the coil(s) in silicone glue. Once the silicone cures, it mechanically damps the coil and can reduce or eliminate the noise.

Search for “how to pot a whining coil” for detailed instructions.

 

[mcochris]

Using a potentiometer alone as a volume control is possible, but it’s generally frowned upon because it can create impedance-matching issues. In addition, a turntable produces a very low-level signal that requires amplification by a phono preamplifier. You also need a power amplifier to drive the speaker crossover and speakers.

 

[OldHvyMec]

I powered the system using a desktop power supply at work, and there was no whine at all, so I am sure it's coming from the power supply.

Use that power supply and buy a second one just like it. I'm really not understanding the problem; you already answered your own question. I'm no EE, but I can spot a fix without too much of a problem. No, I'm not trying to be rude either, I'm just pointing out the facts.

Regards.

 

[Sokel]

Something is amiss here.
Meanwell are supposed to be on the quality side of PSUs (don't know about their budget line as this one though, looks too cheap to be used this way)

I would check all grounds (including main sockets) , grounding scheme for the tied components, etc along with the usual sanity measurements with a simple DMM.

 

[mcdn]

Hi all, mechanical engineer here building a speaker and I am hoping to get some clarification on my design. Currently, my speaker plays music, but there are a few issues...

Overview of my active, powered speaker build components:

1. Peerless by Tymphany SDS-P830657
2. Dayton Audio ND25FW-4 1" Tweeter
3. LRS 150 24 PSU
4. XKitz LR 2 Way Active Crossover

My questions:
1. You can see this in the attached video file, but there is a horrible whine that plays when the speaker turns on. I powered the system using a desktop power supply at work, and there was no whine at all, so I am sure it's coming from the power supply. Im hoping to get some EE explanation on where this comes from and what I can look for in other power supplies to fix this problem.

2. Currently, I am just feeding in a RCA audio source from my record player. There is no volume control on the speaker itself, but I would like to add that. Can I just take a Potentiometer and smack it in-between the RCA input and the RCA input to the crossover? I have the hardware to do that, I just wasn't sure if that's valid or if it will introduce some similar noise issues.

Video Link

Looking forward to chatting about this!

There’s no preamp or power amp in your list…

 

[solderdude]

Im hoping to get some EE explanation on where this comes from and what I can look for in other power supplies to fix this problem.

1: do you also hear it when the RCA is NOT connected ?
2: do you also hear it when the connectors to the internal amp are disconnected ?

Could be wiring issue, could be a ground loop, could be radiation from the power supply being picked up somewhere, could be a faulty power supply.

2. Currently, I am just feeding in a RCA audio source from my record player. There is no volume control on the speaker itself, but I would like to add that. Can I just take a Potentiometer and smack it in-between the RCA input and the RCA input to the crossover? I have the hardware to do that, I just wasn't sure if that's valid or if it will introduce some similar noise issues.

You could but certainly not the linked one. You would have to use a 'normal' logarithmic stereo volume potmeter (5kohm or 10kohm) wired the correct way.
Sort the unwanted sounds first (it certainly isn't coil whine as that is a mechanical issue coming from one (or more) inductors inside the power supply.

 

[Roland68]

Hi all, mechanical engineer here building a speaker and I am hoping to get some clarification on my design. Currently, my speaker plays music, but there are a few issues...

Overview of my active, powered speaker build components:

1. Peerless by Tymphany SDS-P830657
2. Dayton Audio ND25FW-4 1" Tweeter
3. LRS 150 24 PSU
4. XKitz LR 2 Way Active Crossover

My questions:
1. You can see this in the attached video file, but there is a horrible whine that plays when the speaker turns on. I powered the system using a desktop power supply at work, and there was no whine at all, so I am sure it's coming from the power supply. Im hoping to get some EE explanation on where this comes from and what I can look for in other power supplies to fix this problem.

2. Currently, I am just feeding in a RCA audio source from my record player. There is no volume control on the speaker itself, but I would like to add that. Can I just take a Potentiometer and smack it in-between the RCA input and the RCA input to the crossover? I have the hardware to do that, I just wasn't sure if that's valid or if it will introduce some similar noise issues.

Video Link

Looking forward to chatting about this!

The Mean Well LRS power supplies are good and have been proven industrial power supplies for years. I've run many TPA3251/55 amplifiers on them, and they've been absolutely silent. Of course, it could have a defect, but that's extremely rare with these power supplies.

Are you aware that you're currently running the speaker at full volume?
Depending on the amplifier's power output, this can damage your speakers, and also your hearing.
It's no wonder there's a whistling sound.
I would advise you not to use it anymore until you've connected a preamplifier, a source with a volume control, or a potentiometer for volume adjustment.

What kind of source did you test it with in the office?

I would also twist the connected positive and negative leads together.

 

[tanno1]

The Mean Well LRS power supplies are good and have been proven industrial power supplies for years. I've run many TPA3251/55 amplifiers on them, and they've been absolutely silent. Of course, it could have a defect, but that's extremely rare with these power supplies.

Are you aware that you're currently running the speaker at full volume?
Depending on the amplifier's power output, this can damage your speakers, and also your hearing.
It's no wonder there's a whistling sound.
I would advise you not to use it anymore until you've connected a preamplifier, a source with a volume control, or a potentiometer for volume adjustment.

What kind of source did you test it with in the office?

I would also twist the connected positive and negative leads together.

Hi, I do have an amplifier inside of the speaker.
My audio chain is: Source (audio-technical at-lp70x playing a record -> RCA input -> crossover -> wondom aa ab32174 amplifier -> tweeter / woofer. Why would I need a preamp in here somewhere?

I am not aware the speaker is full volume, I thought it has a set gain on the amp board, so whatever audio I send in, is amplified by that audio gain.

The source I tested in with the office was a my MacBook Pro playing at 1-2 of the volume bars. The power supply in this case was the SPD3303X-E by Siglent.

 

[tanno1]

There’s no preamp or power amp in your list…

Sorry, I forgot to link it. I put it in the list now. It is a Wondom AA-AB32174

 

[tanno1]

1: do you also hear it when the RCA is NOT connected ?
2: do you also hear it when the connectors to the internal amp are disconnected ?

Could be wiring issue, could be a ground loop, could be radiation from the power supply being picked up somewhere, could be a faulty power supply.


You could but certainly not the linked one. You would have to use a 'normal' logarithmic stereo volume potmeter (5kohm or 10kohm) wired the correct way.
Sort the unwanted sounds first (it certainly isn't coil whine as that is a mechanical issue coming from one (or more) inductors inside the power supply.

Testing these suggestions right now.

1. When the input audio RCA is not connected, I still hear the whine
2. When the RCA connectors from the crossover to the amp are not connected, I do not hear the whine. There is a small amount of audible noise, but it sounds about similar to when I turn on my M1 active Alesis speakers. I put a video recording the sound from my iPhone here

That second point is interesting. I experimented a bit in this video by unplugging the RCA's a few different ways. The noise is only there when the crossover RCA's are connected to the amp. Could this be a grounding issue?

 

[solderdude]

Try feeding the XO board from a separate power supply as a test with the amp connected to it.

Seems like a grounding issue and wiring of the power supply.

Almost safe to say the power supply is O.K.

 

[tanno1]

Good idea. I'll have to do that a bit later today. I attached a quick diagram of my wiring for the amp and crossover. Just wired one of the two sets of +/- outputs to the XO and the Amp. Seems pretty straight forward so not sure where I could be running into an issue here.

Good news about the power supply.

 

[mcdn]

The two things you've changed are:
1. the environment (work vs home, especially the mains power and RF environment)
2. the power supply (bench vs mean-well)

If it were me, I'd take the mean-well to work and try that. If it sounds fine there then you probably have some nasty noise on your safety earth at home, which the XO/Wondom aren't handling well when you link them via the RCAs. The mean-well -Vout is connected to safety earth, but the siglent says it's fully isolated, so one way to check my theory would be to bring the siglent home (I'm a very nice boss so I would let you, but yours may not!)

If you can't bring the siglent home, I'd recommend getting a mini bench power supply for $50 like this one: https://www.aliexpress.com/item/100...order_list.order_list_main.105.4ce51802beD54s, which can be powered over USB from your laptop, so you can create a fully isolated setup with the laptop battery providing all the power. I've lost count of the number of times doing this has solved a noise issue for me, and the mini bench supply is super useful for all sorts of things.

Oh one more thing: try making a separate ground connection from the XO to the Wondom, literally a wire from various ground points on each to the other, and see if that does anything. Audio ground, power ground, other points marked as ground, but obviously not anything else! A bench supply is useful here as well to limit current/magic smoke.

 

[tanno1]

The two things you've changed are:
1. the environment (work vs home, especially the mains power and RF environment)
2. the power supply (bench vs mean-well)

If it were me, I'd take the mean-well to work and try that. If it sounds fine there then you probably have some nasty noise on your safety earth at home, which the XO/Wondom aren't handling well when you link them via the RCAs. The mean-well -Vout is connected to safety earth, but the siglent says it's fully isolated, so one way to check my theory would be to bring the siglent home (I'm a very nice boss so I would let you, but yours may not!)

If you can't bring the siglent home, I'd recommend getting a mini bench power supply for $50 like this one: https://www.aliexpress.com/item/100...order_list.order_list_main.105.4ce51802beD54s, which can be powered over USB from your laptop, so you can create a fully isolated setup with the laptop battery providing all the power. I've lost count of the number of times doing this has solved a noise issue for me, and the mini bench supply is super useful for all sorts of things.

Oh one more thing: try making a separate ground connection from the XO to the Wondom, literally a wire from various ground points on each to the other, and see if that does anything. Audio ground, power ground, other points marked as ground, but obviously not anything else! A bench supply is useful here as well to limit current/magic smoke.

Gotcha, I will try grounding various points on the XO and amp together to see what that does tonight. When I was at work, I tried using the mean well and I had the same noise. I unplugged the fan on the amp which reduced the noise a bit,but it did not fully subside until I switched to using the sigilent supply.

Thanks for the link to the desktop psu! I have been looking for something like this to have at home.

 

[mcdn]

Gotcha, I will try grounding various points on the XO and amp together to see what that does tonight. When I was at work, I tried using the mean well and I had the same noise. I unplugged the fan on the amp which reduced the noise a bit,but it did not fully subside until I switched to using the sigilent supply.

Thanks for the link to the desktop psu! I have been looking for something like this to have at home.

When you use the siglent, are you connecting the amp and the xo to the same output or different outputs?

 

[tanno1]

Here is an image @mcdn. I have the +/- leads of both XO and amp on the same output of the Sigilent.

 

[solderdude]

Try to feed both the amp and XO via a separate power supply.