Transformers humimg........again


Yes I'm starting a new transformer hum thread. I read through most of the others, but did not find the info I was after, sorry.
Let's start. I have a dedicated 20A line for my audio gear. Gear consists of a BPT 3.5 Signature ac isolator, Jolida JD9 II phono pre, Naim 5i-2 int. amp., two REL T-5 subs, and a Clearaudio Concept TT. Now the important part, ALL components that utilize a transformer (BPT, Naim, REL's) all have transformer hum. And yes, it is transformer hum, NOT sound from the speakers. I had a buddy, who's an electrician, over last night, and we tore everything apart from the main box to the outlet, no results. Tried many other outlets in the house, with and without the BPT unit. No difference, all transformers still humming, whether alone or not. Unfortunately, my power is fed to my house from overhead lines, but so be it. I can't change that unless I move.
Question to answer, "what can I do to stop the transformers from humming?" The hum is not overwhelming, fairly subtle actually, but nonetheless, it is something I would like to eliminate.
Can anyone offer experienced or educated replies?

Thanks :)
shawnlh
You can install a balanced power transformer outside by your electrical panel to feed the 20A dedicated line. Although not to code (JEA48 can fill you in on the details ) it will cure the problem.

For more details on balanced power look up Bryson's Tourous products and Equitech they offer sub panels with balanced power transformers.

Good listening

Peter
You can minimize the effects of transformer hum by isolating the transformer from the chassis and from the circuit boards. Remove or loosen the bolt(s) holding the transformer to the chassis and place 1/8" cork under the transformers. That should help.
Emotiva CMX-2
Pbnaudio,

The BPT 3.5 Signature ac isolator is a balanced power transformer unit. It is good for 2400Va / 20 amps FLA at 120V.
http://www.6moons.com/audioreviews/bpt2/flagship.html

>>>>>>>>>>>>>

Shawnlh,

Now the important part, ALL components that utilize a transformer (BPT, Naim, REL's) all have transformer hum. And yes, it is transformer hum, NOT sound from the speakers.
Shawnlh

First off all transformers hum to some degree, some more than others, that is normal. Now if you can hear them while seated in your listening chair that is not normal.

Tried many other outlets in the house, with and without the BPT unit. No difference, all transformers still humming, whether alone or not.
Jmho that rules out DC on the mains. Had you said with a piece of equipment plugged into the BPT the transformer of the piece was quieter but the BPT was noisy, then I could have considered DC on the mains as a possibility. An isolation transformer will not pass DC from the primary winding to the secondary winding. A piece of audio equipment plugged into the BPT output would not be affected by DC on the mains feeding the primary winding of the BPT toroid transformer.

I see you live in Canada. I believe your generating and distribution power system is the same as here in the US.

Just a few things your electrician friend should check. Have him check the mains voltage at the main service electrical panel. Make sure the voltage is the normal voltage for your area.. Have him check hot L1 to hot L2.

Then check hot L1 to neutral, and then hot L2 to neutral. The two readings should be within a couple of volts of one another.
The combined voltage of L1 to neutral + L2 to neutral should equal the L1 to L2 voltage reading.

Next thing he needs to check is the Hz. It should be 60Hz possibly 59Hz.

Next have him check the voltage at the receptacle the audio equipment plugs into unload, nothing powered up, then check the voltage again with everything powered up. The voltage should not vary more than a couple volts.

As for an overhead electrical service, there is nothing wrong with them imo.

I assume the service feeding your home is single phase 120/240V nominal.

Post back your findings
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Thanks Pbnaudio, your reply is copied, pasted, and printed. I will have electrician buddy check these points. I will report back.

Thanks muchly :)
Shawn,

Jim (jea48) is the author of the post above, he is always very knowledgable and informative about matters as your current perdicerment ( pun intended / or not 😄)

Jim points out that you already have balanced power from you power conditioner, so one question comes to mind do all your components transformers hum if plugged in by them selves or as a whole, if as a whole one of your components may have a faulty power supply which cause the other components transformers to hum.

Best of luck

Peter
Look around (no longer made) for a PS Audio Humbuster III...I found one and it works.
My experience is with toroidal transformers only. They're the circular ones. I had the same problem - hum coming from my amplifier's transformer (toroidal Plitron). Got an AVA HumDinger, hum is gone. Cost ~$125. I don't have any affiliation, and I don't sell anything.
"My experience is with toroidal transformers only. They're the circular ones. I had the same problem - hum coming from my amplifier's transformer (toroidal Plitron). Got an AVA HumDinger, hum is gone. Cost ~$125. I don't have any affiliation, and I don't sell anything."

But you must do your leg work and make sure you really need an AVA HumDinger or they will not sell you one... I tried to purchase one from AVA but he was not willing to sell me one. Told me to do all this other electrical work instead. I appreciate that somewhat, but at the same time, it would of worked on something in my office system and did not understand being rushed off the phone with no willingness to sell me an available product they offer. My guess is they build them as needed and AVA did not want to build one at the time... SO just make sure you need one or know how to explain your needs or you may be turned away... Or just go with the PS Audio Hum Buster.
You should bring one of the culprits over to a friends house and see if it has a hum problem in another house. It might not be your house wiring causing the problem!
I had taken a couple of the pieces down to my local hifi shop. We plugged them in, no hum. And that was straight into the wall socket, no filtering of any kind. I just happen to be cursed with bad ac into my home. I will take all suggestions here, apply them, and hope for something to work.
I'll also suggest an AVA Humdinger. They have a 30 day return policy, and maybe giving AVA a call would be a good call.

If they for some reason also don't want to sell you one, shoot me a message and we can see about having you try my Humdinger out in your system.
PS Audio AC regenerator. PS Audio P-5 or P-10.
Should get it, I'd think.
There are two things that cause transformers to hum, both on the AC line.

This BTW is especially true if you have toroidal power transformers.

The first is what is often called 'DC on the line' which is usually caused by a heater of some sort operating on half power so it is only drawing power when the line goes positive. This causes one half of the AC sine wave to have slightly less voltage.

This can be blocked by a fairly simple circuit- a diode and capacitor arrangement (several members have mentioned one already on this thread), that blocks the DC and thus corrects the waveform. Toroids saturate fairly easily so only a very small amount of DC (less than 1/4 volt) can make them pretty noisy. It is possible to install the DC Blocker on the line that feeds the audio room.

The second thing that can cause transformers of all types to become noisy is the 5th harmonic on the line- in the US we use the 60Hz line frequency so this would be 300Hz. The harmonic is caused by a transformer that is being used above 1/2 of its full rated capacity. This might be a transformer on a telephone pole that you and your neighbors all use. There are two solutions- have the utility replace the transformer (good luck with that, but I've seen that happen) or get a power conditioner that can block the 5th harmonic.

In regard to the latter I don't know of a 'high end audio' conditioner that can do that (OK the regenerator types can but you have to be really careful with their use to not re-introduce the same problem), but there are commercial/industrial units made that can. Elgar used to make such some years back and they are quite effective. You can find them used on ebay (the series 3000 and 6000 are the best examples). BTW they can block DC on the line too.

I had taken a couple of the pieces down to my local hifi shop. We plugged them in, no hum. And that was straight into the wall socket, no filtering of any kind. I just happen to be cursed with bad ac into my home. I will take all suggestions here, apply them, and hope for something to work.
03-29-15: Shawnlh
Shawnlh,

Did you have the electrician check the mains voltage measurements as I asked?

To high of a mains voltage can cause transformer to hum louder than normal.

As Atmasphere said in his post odd harmonics can also cause a transformer to hum louder than normal. Where your BPT 3.5 isolation transformer unit will not pass DC on the mains from the primary winding to the secondary winding it cannot block odd harmonics from the primary to the secondary.

You need to first isolate the things in your home that may be causing the problem.

Quickest way to do so is turn off every branch circuit breaker at the electrical panel except the 20 amp dedicated circuit feeding your audio equipment.
****Caution**** If the electrical panel is a bulldog or ITE pushmatic panel where you push in to turn off the breaker and then push it again to reset do not perform this test. Pushmatic breakers are notorious for not being able to reset.

For what it's worth most odd harmonic problems are caused by electronic devices within the home. Anything with a microprocessor such as a refrigerator, microwave, dishwasher, washing machine, cloth dryer, furnace, ect. Variable freq drive on a furnace can cause big time harmonics back on the mains.

Dimmers are terrible. They can even radiate RF through the air several feet, not to mention on the wiring in the home.

Check this video out.
>https://www.youtube.com/watch?v=OCK5W9vlAE0


CFL and LED lights that screw into a regular 120V socket have an electronic transformer that put crap back on the mains. Do you have a lot of them in your home?

The list just goes on and on. But many people have these device in their homes and are not experiencing the problems you are.

Sorry for the detour, back to the test.....
Plug in just one piece of audio equipment directly into the wall receptacle outlet and check for the louder than normal hum from the power transformer of the piece of equipment. Best to pick one of the piece's of equipment you took down to the local hifi shop.

If no abnormal hum, start to turn on one breaker in the electrical panel at a time. Check the piece of audio equipment each time after a breaker has been turned back on. Continue until you find the circuit that is feeding the culprit causing the problem. Next check the loads that are connected to that circuit. Isolate the problem.

IF, with all the breakers turned off you still have the louder than normal hum go outside and look up at the utility transformer that is feeding your house. You should be able to follow the secondary side wires of the transformer and see what others houses are fed by the same transformer.

Are they just houses? Any small commercial or garage businesses? Are you fairly close to any commercial or industrial facilities?

If just houses, no businesses, do you know any of the neighbors that are fed from the same utility transformer as your house? If so see if they will let you plug the piece of audio equipment in a wall outlet in their home. Check for any abnormal Hum? No abnormal hum? If no abnormal hum your problem is somewhere after the power leaves the transformer and your house.

If you take the time to do the tests I outlined, post back your findings.

Here is some stuff I found searching the Net. You will have to copy and paste. For some reason the Agon [url] xyz [/url] thingy wouldn't work right.
.
http://www.soundonsound.com/sos/jul03/articles/mainsproblems.asp

http://powerelectronics.com/site-files/powerelectronics.com/files/archive/powerelectronics.com/mag/410pet20.pdf

http://www.psihq.com/iread/harmonic.htm
Jim

Great information as always,

Link 1

Link2

Link3

Good Listening

Peter
I posting in this thread to save it for myself... Great info here so far. Thank you.