A DC Blocker to help stop transformer HUM

[ToKillTime]

I'am a complete newbie in this field and confronted with the same issue that my toroidal trafo is humming. I saw the Block on ATL and I wanted to ask what is the difference between both versions (1.4 V vs 2 V), since they cost the same. Hence, which one should I try?

Thanks in advance!

 

[solderdude]

I'am a complete newbie in this field and confronted with the same issue that my toroidal trafo is humming. I saw the Block on ATL and I wanted to ask what is the difference between both versions (1.4 V vs 2 V), since they cost the same. Hence, which one should I try?

Thanks in advance!

Does the hum change during the day/night ?
Most transformers (especially big ones) hum. This is normal, not desired but some do (toroid/EI/Rcore) and may reach audible levels.
I would not use a DC blocker unless the hum varies in loudness during a day.
It probably won't be a solution when the hum does not change (note at night your hearing is more sensitive).
It might help if it sometimes hums or suddenly hums louder at certain moments.

 

[ToKillTime]

The hum changes only when I switch on the TV. Without TV on, there is no hum audible. Interesting is that the hum is getting louder/quieter when the picture of the TV is darker/brighter. I have a LG OLED and my intensive troubleshooting identified that the TV is polluting my housegrid.

Therefore the question, which version should I give it a try?

 

[vco1]

Most transformers (especially big ones) hum. This is normal, not desired but most do.

It might be normal, but it can be really annoying. It's a bit strange too imho. We're striving for the best (inaudible) SINAD measurements, while on the other hand transformers in our rig make a lot of noise by themselves.
In the case of my CA amp I could hear the hum with my headphones on from about 1,5m distances. And across the room when no music was playing. It took away the fun of listening to music. In the end I was basically just focusing on the hum.

As for @ToKillTime 's question: I'd go for the 2V version if the hum is loud. That's what I did.

 

[Geert]

Especial cheap transformers hum, meaning at a level that's potentially disturbing. My previous amp did, my new amp in the same setup doesn't (and has about the same size of transformer but is a lot more expensive). So I wouldn't just call it normal. For the old amp I fixed it with an ATL DC blocker.

I do agree that when the level of hum differs during the day or modulates their's a higher change it is DC that's causing the issue, and that a DC blocker might solve the issue.

The difference between the ATL 1.4 V vs 2 V version is the maximum level of DC it can block. 1.4 V is usually enough.

 

[ToKillTime]

Alright, thank you!

But when the 2V is more "powerful", why do they both cost the same?

 

[Geert]

Because all that's needed to block more DC is a few diodes, which cost close to nothing.

 

[ToKillTime]

Ok, thanks. Yesterday I ordered the following DC Blocker:

DC BLOCK - audiolab Deutschland

DC BLOCK Gleichspannungsfilter Die typische Netzversorgung ist diversen Arten von Störungen und nichtlinearen Lasten ausgesetzt, die die Wellenform verzerrt. Asymmetrische Lasten verursachen eine Verschiebung der Wellenform und führen zu dem, was als "Gleichstrom im Netz" bekannt ist. Die...

audiolab-deutschland.de

I'm from Germany and hence shipping is more beneficial in this case. I will try this one and share my feedback. If this one won't bringt any improvements, I will get the blocker from ATL.

 

[solderdude]

When this one doesn't work the ATL won't help either.

 

[sergeauckland]

Ok, thanks. Yesterday I ordered the following DC Blocker:

DC BLOCK - audiolab Deutschland

DC BLOCK Gleichspannungsfilter Die typische Netzversorgung ist diversen Arten von Störungen und nichtlinearen Lasten ausgesetzt, die die Wellenform verzerrt. Asymmetrische Lasten verursachen eine Verschiebung der Wellenform und führen zu dem, was als "Gleichstrom im Netz" bekannt ist. Die...

audiolab-deutschland.de

I'm from Germany and hence shipping is more beneficial in this case. I will try this one and share my feedback. If this one won't bringt any improvements, I will get the blocker from ATL.

I very much doubt whether the ATL would work where the Audiolab didn't. There's so little inside a DC blocker, that except for something really cheap on eBay, one DC blocker from a reputable manufacturer is like another. If the Audiolab doesn't work, then I'd look elsewhere for a solution, not another DC blocker.

S.

 

[pma]

Because all that's needed to block more DC is a few diodes, which cost close to nothing.

Yes. It works and it is the perfect think to be made as DIY. No expensive purchases needed.

 

[Anterantz]

This is the second arcam that I have the first one I returned it because it hummed too much, this new unit went silent 5 months and now it has started ringing sometimes.

At night it seems to do it more but it is not very random, right now
I haven't heard it for a week.

Now it only sounds a slight audible whisper only if you put your ear close, but that slight hum is not there when I take it to my parents' house and I had it plugged in for 6 hours.

I will try the atl and find out what it can
cause this.

 

[Geert]

Now it only sounds a slight audible whisper only if you put your ear close

That's what I would call normal, so no reason to install a DC blocker.

 

[Anterantz]

That's what I would call normal, so no reason to install a DC blocker.

So why sometimes it sounds and sometimes it doesn't? It seems as if at times the network is contaminated.

 

[Geert]

I meant there's no need to install a DC blocker if you can't hear the transformer humming from your listening position. Unless "only if you put your ear close" is your normal listening position (like a desktop amplifier).

 

[Anterantz]

I meant there's no need to install a DC blocker if you can't hear the transformer humming from your listening position. Unless "only if you put your ear close" is your normal listening position (like a desktop amplifier).

I wanted to say that it is barely audible at about 50cm but when it sounds like the video that I attached yesterday if it is audible even at 2 meters but it sounds a little and disappears at 10s and comes back when it feels like it.

It is not something periodic!

 

[restorer-john]

Transformer hum that is audible is simply not remotely acceptable in high fidelity equipment. I don't care about lamination buzz/hum in a car battery charger, a cordless drill charger or other non-critical devices, unrelated to audio.

Distorted/DC on mains can and does cause transformers of various types to make noise they shouldn't. A DC blocker may solve it, but poor transformers will hum and buzz nonetheless. Get rid of them.

Many quality manufacturers spend considerable time, effort and expense ensuring transformers are dead quiet. Buy those products instead of cheap ones.

 

[Anterantz]

Transformer hum that is audible is simply not remotely acceptable in high fidelity equipment. I don't care about lamination buzz/hum in a car battery charger, a cordless drill charger or other non-critical devices, unrelated to audio.

Distorted/DC on mains can and does cause transformers of various types to make noise they shouldn't. A DC blocker may solve it, but poor transformers will hum and buzz nonetheless. Get rid of them.

Many quality manufacturers spend considerable time, effort and expense ensuring transformers are dead quiet. Buy those products instead of cheap ones.

The toroid comes from an arcam avr20 and it is not cheap to say ... so either they use cheap transformers or they are more susceptible to hum

 

[restorer-john]

The toroid comes from an arcam avr20 and it is not cheap to say ... so either they use cheap transformers or they are more susceptible to hum

Toroidal transformers are more susceptible to DC on the mains causing physical noise.

Have a look at what's involved with toroid manufacture:

 

[Anterantz]

Hello, do we know if removing a ground from the plug to a screw on the chassis could solve this?

Greetings