Assistance taming transformer hum

barbz127

New Member
Jun 4, 2022
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Hi all

I'm working through the steps of taming physical transformer hum and wanted to confirm I was on the right path.

Setup consists of a ps audio p12, antipodes k30, Holo may, nimbus us5 and Ampsandsound nautilus - outputting to nearfield speakers and headphones.

In my current setup I have a physical hum from the Holo may and the nautilus (and previously a bifrost 2). The hum is not audible through the sound chain and only physically from the unit.

I've tried with and without the p12, with and without a DC blocker (both too the effected unit and also to the whole system by placing it inline with the p12 source). The transformers hum day and night so I can't tie it back to the solar inverters.

My next steps are to install a dedicated line but I don't think this will help as I have the same problems from other points in the house, and from there an isolation transformer (something cheap to verify it works before considering a permanent fixture for the dedicated line)... And the other option on the table is to borrow a stromtank s1000 from the dealer but that is a $$$ solution.

Do I have any other options to consider/test?

I'm located in Australia so 230v.

Thankyou
 

AMR / iFi audio

Industry Expert
Aug 21, 2019
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Hi all

I'm working through the steps of taming physical transformer hum and wanted to confirm I was on the right path.

Setup consists of a ps audio p12, antipodes k30, Holo may, nimbus us5 and Ampsandsound nautilus - outputting to nearfield speakers and headphones.

In my current setup I have a physical hum from the Holo may and the nautilus (and previously a bifrost 2). The hum is not audible through the sound chain and only physically from the unit.

I've tried with and without the p12, with and without a DC blocker (both too the effected unit and also to the whole system by placing it inline with the p12 source). The transformers hum day and night so I can't tie it back to the solar inverters.

My next steps are to install a dedicated line but I don't think this will help as I have the same problems from other points in the house, and from there an isolation transformer (something cheap to verify it works before considering a permanent fixture for the dedicated line)... And the other option on the table is to borrow a stromtank s1000 from the dealer but that is a $$$ solution.

Do I have any other options to consider/test?

I'm located in Australia so 230v.

Thankyou
If DC blockers and the P12 didn't help with the hum, my guess would be on the transformers themselves. Can you try your devices at somebody's house? that would help us determine if the issue is in them, or in your electric grid.
 
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barbz127

New Member
Jun 4, 2022
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If DC blockers and the P12 didn't help with the hum, my guess would be on the transformers themselves. Can you try your devices at somebody's house? that would help us determine if the issue is in them, or in your electric grid.


Thankyou
I have tested these elsewhere and they are silent.
 

Badge

Well-Known Member
Mar 29, 2019
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Have you tired lifting the ac ground on one or more components.? Simple AC adaptors at most hardware stores will be worth a try.
 

barbz127

New Member
Jun 4, 2022
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Have you tired lifting the ac ground on one or more components.? Simple AC adaptors at most hardware stores will be worth a try.
Thankyou
I have not tried this as I was worried about the safety aspect
 

jerrybj

Active Member
Feb 28, 2022
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Hey babz127

I'm in NZ.
I have a similar issue with my Perreaux amp.
Had it recapped last year, and the technician heard no hum at his place.
Same issue of it humming upon its return to my house.

Have a dedicated line for audio.
Have ferrite chokes through my house on fridges, SMPS etc.
Bought an Audiolab DC Block a couple of months ago, which has had a small effect.

Last week had an electrician in to complete some small jobs.
Had read that light dimmers are very noisy.
So got him to replace the 'cheap as chips' dimmer I had installed in 2009.
That has made a difference.
Still have the hum, but not nearly as pronounced.
 
Last edited:

barbz127

New Member
Jun 4, 2022
15
1
3
38
Hey babz127

I'm in NZ.
I have a similar issue with my Perreaux amp.
Had it recapped last year, and the technician heard no hum.
Same issue for me upon its return.

Have a dedicated line for audio.
Have ferrite chokes through my house on fridges, SMPS etc.
Bought an Audiolab DC Block a couple of months ago, which has had a small effect.

Last week had an electrician in to complete some small jobs.
Had read that light dimmers are very noisy.
So got him to replace the 'cheap as chips' dimmer I had installed in 2009.
That has made a difference.
Still have the hum, but not nearly as pronounced.
Thankyou
Electricians are coming out next week so I'll have the bifrost dac with me so they can easily hear it and see if they have any ideas
 

AMR / iFi audio

Industry Expert
Aug 21, 2019
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ifi-audio.com
Thankyou
Electricians are coming out next week so I'll have the bifrost dac with me so they can easily hear it and see if they have any ideas
I was thinking about noise on your mains, but P12 should take care of that. Maybe there is a ground loop? Can you try to power on your devices without connecting them with cables together? Just power in.
 

barbz127

New Member
Jun 4, 2022
15
1
3
38
I was thinking about noise on your mains, but P12 should take care of that. Maybe there is a ground loop? Can you try to power on your devices without connecting them with cables together? Just power in.
Sorry I didn't mention it but I have tested without any interconnects and the sound is still there.

I've also confirmed the polarity on the power cables/p12 is correct.
 

AMR / iFi audio

Industry Expert
Aug 21, 2019
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Sorry I didn't mention it but I have tested without any interconnects and the sound is still there.

I've also confirmed the polarity on the power cables/p12 is correct.
Is every piece of equipment connected to the P12? Have you checked the polarity of every power cable?
 

barbz127

New Member
Jun 4, 2022
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Is every piece of equipment connected to the P12? Have you checked the polarity of every power cable?
Yes all to the p12 and I've checked maybe half of my power cables but not the p12 itself.

The cables jnto the effected units have been tested but I didn't go nuts with the others (yet).

Thankyou
 

AMR / iFi audio

Industry Expert
Aug 21, 2019
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ifi-audio.com
Yes all to the p12 and I've checked maybe half of my power cables but not the p12 itself.

The cables jnto the effected units have been tested but I didn't go nuts with the others (yet).

Thankyou
Then, I'm afraid we need to wait for the electricians to do the measurements and tests. Can you keep us posted? I would love to know what is the issue here.
 

barbz127

New Member
Jun 4, 2022
15
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Circling back on this one to close it out.

Dedicated line in - slight lowering of noise across the board with no power filtering etc connected and slight change to the transformer hum.

Some of my gear was boxed while the new line was installed so there was clear access for the electrician and while running in a condensed setup for whatever reason I leaned over the amp pressing on the top of it with one hand while I reached back with the other and low and behind silence..

So next steps from here are some weights to sit on the transformer housing and ponder an isolation platform to see if that helps.

Turns out Ive been fighting the problem from the wrong angle all along.
 

sbayne

Member
Nov 18, 2020
4
4
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59
We use alternating current (AC) so the magnetic field the transformer creates changes the dimensions of the transformer’s iron core. The core expands and contracts with the AC, which causes a humming sound. As the transformer ages, or perhaps damaged, the layers within the core of the transformer begin to break apart and separate from one another. This causes the vibrations to get louder. Since taking DC off the line didn't help much It makes sense your pressing on it reduced the vibration. I would suggest you put some dampening material under the transformer and then tighten the center bolt (don't over tighten since it might cause further damage).
 

Alrainbow

Well-Known Member
Dec 12, 2013
2,592
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385
NYC , USA
I dont think messing with the trannys are a good idea unless there loose and you proved to me it’s nit them in another location
if the ELECTRICAN has not solved it yet or is still around he can try this
make a use very large ground wire from your. Water main not just a rod in the yard and attach it directly to the two items humming
while it’s a regen it still has a common ground as such common mode noise is still passing through
if the ground wire line 4 gauge or so works do this as fix
buy a balanced iso transfomer
say 2k watt use this to feed the ps audio snd all front end stuff
let us know
 

Atmasphere

Industry Expert
May 4, 2010
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St. Paul, MN
www.atma-sphere.com
Circling back on this one to close it out.

Dedicated line in - slight lowering of noise across the board with no power filtering etc connected and slight change to the transformer hum.

Some of my gear was boxed while the new line was installed so there was clear access for the electrician and while running in a condensed setup for whatever reason I leaned over the amp pressing on the top of it with one hand while I reached back with the other and low and behind silence..

So next steps from here are some weights to sit on the transformer housing and ponder an isolation platform to see if that helps.

Turns out Ive been fighting the problem from the wrong angle all along.
You found the problem. The transformers are actually quiet; but they do vibrate and the panel is resonating. Some extensional damping compounds, applied to the inside of the panel (don't block any cooling holes or slots) will sort it right out. EAR here in the US makes a nice material for this (its blue and about 4mm thick) that has a nice peel-off sticky back. Tricky to find in small quantities or at all with all the supply shortages.
 

AMR / iFi audio

Industry Expert
Aug 21, 2019
1,825
795
200
41
UK
ifi-audio.com
Circling back on this one to close it out.

Dedicated line in - slight lowering of noise across the board with no power filtering etc connected and slight change to the transformer hum.

Some of my gear was boxed while the new line was installed so there was clear access for the electrician and while running in a condensed setup for whatever reason I leaned over the amp pressing on the top of it with one hand while I reached back with the other and low and behind silence..

So next steps from here are some weights to sit on the transformer housing and ponder an isolation platform to see if that helps.

Turns out Ive been fighting the problem from the wrong angle all along.
Car audio damping mats are excellent for damping chassis vibrations, and they have adhesive on from the box. Super convenient and inexpensive solution.
 

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