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My toroids buzz

catalogguy

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First it was the Creek Evo 100A amplifier.
  • I tried other outlets (with nothing plugged into the device other than AC... no speakers or sources).
  • I tried an iFi gizmo (AC iPurifier and Groundhog +) but it made no difference.
  • I tried an Emotiva line filter (CMX-2) and that made an immediate difference, but it was short-lived. I think I was just good timing the first time I plugged it in.
Usually the buzz is louder, sometimes it is softer, and occasionally the amp is silent. I have not been able to correlate it with usage of anything else in the house.

Recently, I bought a Matrix Audio Mini-i Pro 3. For the moment, it is on my desk, plugged into the wall, and buzzing while in standby mode. I had headphones plugged in, but even with no headphones or sources, it buzzes.
 

LTig

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First it was the Creek Evo 100A amplifier.
  • I tried other outlets (with nothing plugged into the device other than AC... no speakers or sources).
  • I tried an iFi gizmo (AC iPurifier and Groundhog +) but it made no difference.
  • I tried an Emotiva line filter (CMX-2) and that made an immediate difference, but it was short-lived. I think I was just good timing the first time I plugged it in.
Usually the buzz is louder, sometimes it is softer, and occasionally the amp is silent. I have not been able to correlate it with usage of anything else in the house.

Recently, I bought a Matrix Audio Mini-i Pro 3. For the moment, it is on my desk, plugged into the wall, and buzzing while in standby mode. I had headphones plugged in, but even with no headphones or sources, it buzzes.
You may have DC in your power lines. Try a DC blocker.
 

Vini darko

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Good chance there's DC on your mains line. It's the usual culprit for singing transformers particularly torroids. Unfortunately as its not constantly present (transformers noise varies alot) pinning down the amount of it will be fun. Dc blockers can help but they have limitations for the amount of dc they can block and current draw limits.
I've got the same problem at home but haven't wanted to try measuring it due to safty concerns. At some point I'll have to pay an electrician to investigate and get the numbers.
My current solution is only use equipment with E core double insulated transforms or switchmode power supplies. Torroids are just going nuts and causing all kinds of issues.
 

waynel

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First it was the Creek Evo 100A amplifier.
  • I tried other outlets (with nothing plugged into the device other than AC... no speakers or sources).
  • I tried an iFi gizmo (AC iPurifier and Groundhog +) but it made no difference.
  • I tried an Emotiva line filter (CMX-2) and that made an immediate difference, but it was short-lived. I think I was just good timing the first time I plugged it in.
Usually the buzz is louder, sometimes it is softer, and occasionally the amp is silent. I have not been able to correlate it with usage of anything else in the house.

Recently, I bought a Matrix Audio Mini-i Pro 3. For the moment, it is on my desk, plugged into the wall, and buzzing while in standby mode. I had headphones plugged in, but even with no headphones or sources, it buzzes.
Either of these will solve your problem
https://emotiva.com/products/cmx-2
https://avahifi.com/products/humdinger-dc-line-blocker
 

mSpot

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You may have DC in your power lines. Try a DC blocker.
He already did (Emotiva CMX-2).
iFi recently introduced a new DC Blocker product, but if the Emotiva didn't work, it might not help either.

I have hum from my amplifier that varies in loudness, like the OP. I tried the CMX-2 and it didn't help. I was able to reduce (not eliminate) the hum by tightening the transformer mounting bolts. Doesn't address the cause of the problem but it deadened the vibration and reduced audibility to an acceptable level.

If you Google "transformer hum", you'll find that it's a common problem but there is no single solution.
 
OP
catalogguy

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I have the tester in the photo below. What can I test with it?
multimeter.jpg

I would buy another gizmo if it works... can I daisy-chain the DC offset devices for incremental improvement?
 
Last edited:
OP
catalogguy

catalogguy

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Still buzzed in the garage on a newer outlet that is about 10 feet from the subpanel.

Looking online I see measuring DC offset at the speakers terminals of an amplifier. Also, some use an oscilloscope, but I don't know how or why one would do that. I do not think I want to measure the amp output, do I? My concern is contained to what is in the household current? Is there anything I can measure, to any benefit?
 

Haflermichi

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I have the tester in the photo below. What can I test with it?
View attachment 124716
AC voltage.
Select VAC V and insert the probes into the outlet.
You did not answer my question about trying other outlets in your residence. This is a basic troubleshooting step.
Verify if the DUT buzzes using multiple different outlets.
Can you take your devices to a different location like work or a friends house and verify if the buzzing still exists?
 

Doodski

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The best method to detect DC offset at the AC mains is to use a oscilloscope set on DC coupling to detect any DC offset on the AC waveform coming from the wall outlet. Have you attempted tightening the mounting bolt at the toroid transformer?

The DC offset that you saw online measures the slight DC offset coming from a amplifiers outputs and that can be near zero'd by using the DC offset adjustment trim pot located at the amplifier circuit board. This is not applicable with the issue you are experiencing.
 

Maki

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First it was the Creek Evo 100A amplifier.
  • I tried other outlets (with nothing plugged into the device other than AC... no speakers or sources).
  • I tried an iFi gizmo (AC iPurifier and Groundhog +) but it made no difference.
  • I tried an Emotiva line filter (CMX-2) and that made an immediate difference, but it was short-lived. I think I was just good timing the first time I plugged it in.
Usually the buzz is louder, sometimes it is softer, and occasionally the amp is silent. I have not been able to correlate it with usage of anything else in the house.

Recently, I bought a Matrix Audio Mini-i Pro 3. For the moment, it is on my desk, plugged into the wall, and buzzing while in standby mode. I had headphones plugged in, but even with no headphones or sources, it buzzes.
One of my amps had a humming toroid when I first got it, the CMX2 seemed to fix it. Later I moved it off the CMX2 and it still didn't hum. Don't know if it burned in or my neighbors got rid of their super-switcher-9000. You can try opening it up and tightening the nut that attaches the toroid to the case which may help, or replace it with a higher quality toroid if you can find one that fits and has the required secondaries. Antek is a good source. My gut tells me the more headroom you have, the less buzz you should get but I haven't personally verified this.
 

Haflermichi

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Opps, sorry. Our messages crossed in the ether...It's good that you tried the garage. But it's still possible that those are the same circuit breaker branch.
Try multiple outlets in your home.
 

Haflermichi

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You need to be systematic and not get ahead of yourself in your troubleshooting.
Tracking down DC is all well and good but the toroids are before rectification.

Verify your AC in multiple rooms. Verify that BOTH devices buzz in multiple rooms. Verify that both devices still buzz at a different residence.
The reason I'm pointing you in this direction is I recently had a house-wide AC problem that caused all sorts of wacko equipment behavior including my Nakamichi PA7 periodically buzzing.
I fixed the AC problem and all is well.
 
OP
catalogguy

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Thank you for your response. I appreciate your offering helpful suggestions. I tried the Matrix Audio devices in various circuits. Years ago, I made a list of circuits in the house, so I am confident that I tested 3 different circuits... and all caused the device to buzz.

Good result (so far): I purchased one of the above-recommended gizmos, the iFi DC Blocker. I was only able to find one US-based seller, but it arrived today after ordering over the weekend. I tried it on both the Matrix Audio device and the Creek amp and it worked. I tried it very briefly, and I recall that the Emotive device seemed to work the first time I plugged it in. But I tested for buzzing with and without the gizmo, and did so a few times for the Matrix device. For both devices, I hear the buzzing sound when I powered them up, but within a second or two the buzzing stopped. For the Matrix device, I put my ear right near the chassis, and perhaps I could hear it, but I am not sure. I will try again later when the house is quieter.
 

RayDunzl

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For both devices, I hear the buzzing sound when I powered them up, but within a second or two the buzzing stopped.

A little hum at startup, for a second or two, I'd class that as "normal".
 

Haflermichi

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If you're comfortable saying..how much did the iFi DC blocker cost?
You've pretty much confirmed the problem is house wide and not the equipment...accept for trying them at a different home or office.

I'd still be interested in knowing what you get when you use that multi-meter and measure AC.
My home had an "intermittent neutral" which caused all manner of problems including transformer hum.
I was getting a huge range of AC, all over the house, from 90 to 150 VAC.
I called the power company and they had a guy at my house in an hour, with a bucket lift truck, at 11:30 at night. On a Sunday.
 

Matias

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+1 for the iFi DC Blocker, costs about 150 euros.
 
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