Greetings all. I just joined this group. My background is researching designing toroidal transformers and have extensive knowledge of same. From what I have read so far, there seems to be some misinformation. Pls post any toroid questions and I will do my best to answer them.
This type of forum is full of misinformation, usually due to opinions and not fact.
Many engineers supply factual answers to find many readers disagree and post absolute rubbish and snake oil.
Welcome to this forum.
Many engineers supply factual answers to find many readers disagree and post absolute rubbish and snake oil.
Welcome to this forum.
There have been questions around how to make toroidals handle standing DC currents, as in single ended output transformers or in power supply chokes. EI or C-core get a gap, how does that work for toroidals? A cut in the core?
Hi Brian,
Great that you joined, Im also fresh here, just a month old member. Thanks for your offer!
There is one thing about toroids thats utterly annoying, a buzz, horrible noise worse than any other. Here people design - 120db noise circuits for power amps, what's worth when toroids just buzzes.
The shop where I was buying my transformers was over sizing the core for about 20% of nominal power, then vacuum lacquer it and then double bake it. Result is much better but sometimes it still does very quiet, but horrible buzzz.
Can we get rid of it all together? Make completely silent trafo in 300 to 1000w range, is that feasible?
Great that you joined, Im also fresh here, just a month old member. Thanks for your offer!
There is one thing about toroids thats utterly annoying, a buzz, horrible noise worse than any other. Here people design - 120db noise circuits for power amps, what's worth when toroids just buzzes.
The shop where I was buying my transformers was over sizing the core for about 20% of nominal power, then vacuum lacquer it and then double bake it. Result is much better but sometimes it still does very quiet, but horrible buzzz.
Can we get rid of it all together? Make completely silent trafo in 300 to 1000w range, is that feasible?
Hello Brian,
Please take a look at this thread:https://www.diyaudio.com/community/threads/no-electrostatic-screen-on-toroid.408993/#post-7596055
Please take a look at this thread:https://www.diyaudio.com/community/threads/no-electrostatic-screen-on-toroid.408993/#post-7596055
Should I expect a toroidal transformer to always have higher winding resistance than an equivalent VA EI core transformer?
I would expect a donut xfmr to have less winding resistance than an EI of the same voltage / current capabilities simply because mean length of ture will be shorter in the donut.
What does it mean about the quality of the transformers if I found the opposite? Very badly made toroidal?
FYI I am talking about the effective output resistance of the transformer, not just the resistance of one winding.
FYI I am talking about the effective output resistance of the transformer, not just the resistance of one winding.
Hi Brian
Thanks for your offer. I'm interested in your view on potential issues that might arise when using a toroidal power transformer with a split primary winding (120-0-120v) as a pushpull output transformer using, in my case, an 8v secondary to give around 7k2 ohms pp with an 8ohm sec load. Possibly a similar query to post #3.
Thanks for your offer. I'm interested in your view on potential issues that might arise when using a toroidal power transformer with a split primary winding (120-0-120v) as a pushpull output transformer using, in my case, an 8v secondary to give around 7k2 ohms pp with an 8ohm sec load. Possibly a similar query to post #3.
I am curious what you have there. I am attaching the PDFs of two isolation transformers I have been considering for tube amps.
One is EI (2.5kgs), the other toroidal (1.6kgs), with similar VA ratings. The EI has a regulation of 25%, the toroidal 8%, so the output resistance of the toroidal is clearly lower than that of the EI?
https://eu.mouser.com/datasheet/2/410/VPS230_760-781512.pdf
https://eu.mouser.com/datasheet/2/410/VPS230_760-781512.pdf
Voltage drop on (especially split bobbin) EIs is far worse than what the winding resistance will do to it. Leakage reactance is crazy high on split bobbins, low on most toroids. Concentric wound EI somewhere in between.
Hi Brian,
Hope you are good, I see you posted something but never answered. If you are at it, Pls see my post #4, buzz from higher power toroids is issue, at least me I could never get this issue completely solved, I'm sure many are struggling with it too.
Cheers,
Drazen
Hope you are good, I see you posted something but never answered. If you are at it, Pls see my post #4, buzz from higher power toroids is issue, at least me I could never get this issue completely solved, I'm sure many are struggling with it too.
Cheers,
Drazen
I'm not the missing expert, but may help a little.
If your transformer is sometimes silent and sometimes makes noise (buzz, hum), this is your mains having a DC component. This is a common problem. Sometimes you can even notice the noise getting louder and disapear, periodical or very randomly. This is because not only nice loads use the electicity net. Some say, since inducing solar made electricity is injected into the net it got worse. There may be quite some noise during the day, but solar is down at night, while random glitches continue.
Audiophiles have build the most expensive toroids you can think of, but with no effect. Anly solution is to live with it (simply turn on some music, it helps!) or put the transformer in a well isolated box. Even putting it on some soft, absorbend material will reduce noise a great deal. Most anoying are resonating cases. You got to do some thinking to keep the transformer floating, but still hold it in place when you move your gear. Usuall no real problem for a smart engineer, as you only need a very small gap to isolate from the housing.
If you do not run permanent high levels like in a live concert, heat with the usual overdimensioned toroid for HIFI should be no problem, even in a closed metal case, hidden in a cabinet.
Anyway, please don't wrap your whole transformer in any foam or whatever. You don't want to isolate it for heat, but for noise! At least the radius should be exposed to free air. Top and bottom can rest on some elastic material, like neopren. If unsure, check temperatures after a few hours.
You can even heat fuse it.
If you want to get 100% rid of noise, you can use a quite simple diode-capacitor DC blocker. Some say it is taking away sound quality, but this is more a mental problem than technical. Some high end amps have such a device build in.
If your transformer is sometimes silent and sometimes makes noise (buzz, hum), this is your mains having a DC component. This is a common problem. Sometimes you can even notice the noise getting louder and disapear, periodical or very randomly. This is because not only nice loads use the electicity net. Some say, since inducing solar made electricity is injected into the net it got worse. There may be quite some noise during the day, but solar is down at night, while random glitches continue.
Audiophiles have build the most expensive toroids you can think of, but with no effect. Anly solution is to live with it (simply turn on some music, it helps!) or put the transformer in a well isolated box. Even putting it on some soft, absorbend material will reduce noise a great deal. Most anoying are resonating cases. You got to do some thinking to keep the transformer floating, but still hold it in place when you move your gear. Usuall no real problem for a smart engineer, as you only need a very small gap to isolate from the housing.
If you do not run permanent high levels like in a live concert, heat with the usual overdimensioned toroid for HIFI should be no problem, even in a closed metal case, hidden in a cabinet.
Anyway, please don't wrap your whole transformer in any foam or whatever. You don't want to isolate it for heat, but for noise! At least the radius should be exposed to free air. Top and bottom can rest on some elastic material, like neopren. If unsure, check temperatures after a few hours.
You can even heat fuse it.
If you want to get 100% rid of noise, you can use a quite simple diode-capacitor DC blocker. Some say it is taking away sound quality, but this is more a mental problem than technical. Some high end amps have such a device build in.
Buzzing toroids? Possible only with low quality ones, never mind if manufacturer claims great quality, or with high DC at mains.
I’ve bought, so far, 6 audio grade toroidal transformers from toroidy.pl and have never heard even the slightest sound form them.
https://sklep.toroidy.pl/en_US/c/Toroidal-transformers-AUDIO-GRADE/75
I’ve bought, so far, 6 audio grade toroidal transformers from toroidy.pl and have never heard even the slightest sound form them.
https://sklep.toroidy.pl/en_US/c/Toroidal-transformers-AUDIO-GRADE/75
This only shows you are living in a region with low DC contamination of the AC mains. Nothing more.
Hello people,
Thanks for reaction!
I was ordering my trafos with 20% oversized core, vacuum varnished several times (once for core, for primary and then for secondary).. This reduces buzz to minimum, but it's still there. Nevertheless it's much better than all commercial audio trafos I have bought.
This is OCD issue, with slightest music it's not hear able, but hate the buzz....
I tried DC blocker at mains input, no difference where I live.
I also sealed many trafos in epoxy,and this is very liquid epoxy with 24 hrs settling time, this penetrates deep, first I removed outside wrapping. This also helps, but still it's not zero buzz. Here are examples
Then we have commercial Amp Trafos, mostly EI core welded on corners, and the buzz is even lover than with crazy effort I put in toroids, what's the catch?
Thanks for reaction!
I was ordering my trafos with 20% oversized core, vacuum varnished several times (once for core, for primary and then for secondary).. This reduces buzz to minimum, but it's still there. Nevertheless it's much better than all commercial audio trafos I have bought.
This is OCD issue, with slightest music it's not hear able, but hate the buzz....
I tried DC blocker at mains input, no difference where I live.
I also sealed many trafos in epoxy,and this is very liquid epoxy with 24 hrs settling time, this penetrates deep, first I removed outside wrapping. This also helps, but still it's not zero buzz. Here are examples
Then we have commercial Amp Trafos, mostly EI core welded on corners, and the buzz is even lover than with crazy effort I put in toroids, what's the catch?
My question: If you could design a transformer that would couple the widest spectrum of noise from the mains to the secondary. Would not a toroidal be the transformer of choice?
There is something in the quality of transformers. Usual DC in my mains swings below +-1 V. Mostly about 0.5 V.
Last edited:
NOT, absolutely not, but we have LC filters to cure that.
My issue and question is the noise from transformer itself, not electrical noise passed through it, or electromagnetic al induction..
How to stop transformer making noise all together, without Amp attached to it?
And here problem is only with 200VA + pieces.