I missed this comment initially and it's very helpful, thank you.
There may be (hopefully) an easy fix (at least on the 37x series): The shield connection is wedged between the bell cover and the EI laminations. I took the bellcover off and extended the lead to connect it on the outside. Good luck.
wanted to thank everyone for their input - there is clearly a lot of tolerance and ingenuity evident when facing this issue. I would like to see the mfrs respond with some specifications for noise (spectrum/db) that they stand by. My $0.02 is that mfrs should design, specify, advertise, and produce products that beat advertised noise maximums and consumers should be able measure and possibly reject at no cost to them those that do not meet those levels. Its not that hard to measure noise levels at various frequencies and frankly the mfrs should beat their specs by a wide enough margin so that it would make it pretty easy to agree when one is defective . Transformers are extremely expensive parts (especially shipping!) and so it seems like this is in everyone's interest. Also to be fair the mfrs can and should charge what ever the market will bear for any enhanced and guaranteed noise performance and we should pay for it without complaint 🙂
With all due respect to edcor, as I understand it their policy seems to be inherently unfair. There is no spec for noise, so if you get what you believe, based on purely subjective evidence, a noisy transformer, you have to pay return shipping and just hope that edcor agrees with you and will replace it. Again as I understand it, even if they agree that it is defective, you are still out shipping cost one way. If they decide it is not defective, you are out two shipping costs and still end up with a transformer you consider too noisy. Put another way, if they send you a defective xfrm you have to pay an extra shipping cost to get them to send you a working one. Especially if your time or attendent schedule delays are expensive, its hard to justify sending back a transformer under that policy. Utimately Edcor doesn't learn that perhaps they have a mfr or shipping problem and you have to assume that edcor transformers are too noisy to use in a design.
All of this just seems like good engineering practice - not exactly controversial.
I totally understand that their may be a lot of consumers who are unsophisticated with evaluating noise levels so its a big risk for Edcor to encourage returns. But the problem is their are many who are, and those are likely the ones who will spend more money over time. That is why having advertised specs and communicating carefully on this issue would be critical.
And I reiterate, that I in no way mean any disrespect to Edcor and would love for them to weigh in on this. If I have something wrong or there is a completely different way to look at this, I am all ears. I tried quite hard to understand their position over quite a few polite emails. Doesn't do me any good to spend $150 and many hours of time on a reject transformer and I am sure they don't intend for that to happen.
With all due respect to edcor, as I understand it their policy seems to be inherently unfair. There is no spec for noise, so if you get what you believe, based on purely subjective evidence, a noisy transformer, you have to pay return shipping and just hope that edcor agrees with you and will replace it. Again as I understand it, even if they agree that it is defective, you are still out shipping cost one way. If they decide it is not defective, you are out two shipping costs and still end up with a transformer you consider too noisy. Put another way, if they send you a defective xfrm you have to pay an extra shipping cost to get them to send you a working one. Especially if your time or attendent schedule delays are expensive, its hard to justify sending back a transformer under that policy. Utimately Edcor doesn't learn that perhaps they have a mfr or shipping problem and you have to assume that edcor transformers are too noisy to use in a design.
All of this just seems like good engineering practice - not exactly controversial.
I totally understand that their may be a lot of consumers who are unsophisticated with evaluating noise levels so its a big risk for Edcor to encourage returns. But the problem is their are many who are, and those are likely the ones who will spend more money over time. That is why having advertised specs and communicating carefully on this issue would be critical.
And I reiterate, that I in no way mean any disrespect to Edcor and would love for them to weigh in on this. If I have something wrong or there is a completely different way to look at this, I am all ears. I tried quite hard to understand their position over quite a few polite emails. Doesn't do me any good to spend $150 and many hours of time on a reject transformer and I am sure they don't intend for that to happen.
To add insult to injury, I waited 12+weeks for my standard power transformers from Edcor. I will attempt to spend my money elsewise - namely Monolith where I received great service, great product and help when I had questions (after the sale). Pricey - yes but worth the cost!
I stopped using Edcor a few years ago because they have ZERO quality control. I don't believe they test any transformer before they ship. Out of about a dozen transformers I've purchased, two were wound for 240V (purchased as 120V) primary and one was humming to the point it was unusable. That's a 25% fail rate. They are responsive when it comes to fixing their errors though, but that is a frustrating process for something that should have work to begin with. The whole premise of not testing I think is bad business practice, so I ditched Edcor for good. I've since purchased toroidal transformers from Antek. I've never had an issue so far after purchased 20+ transformers. Zero noise.
As other posters have said, loose laminations/shells or windings floating on the laminations can cause buzz. But if it's not that, it's magnetostriction caused by a poor core material. For low buzz, specify M6 core material and request operation at a slightly lower flux density than usual (to be further away from saturation). The downside is that you now require more (and more expensive) core material, which requires longer windings, which increases their resistance, which impairs regulation as another poster observed. So the resulting transformer is more expensive both to buy and to operate.
Dealing with transformer manufacturers is often frustrating. But to be fair to them, how could they possibly have an acoustic specification for buzz? It would depend on applied voltage, load, mechanical arrangements, and acoustic environment. If you're going to place continuing orders, it can be worth working with them, but for one-off orders it's simply not worth their time.
Dealing with transformer manufacturers is often frustrating. But to be fair to them, how could they possibly have an acoustic specification for buzz? It would depend on applied voltage, load, mechanical arrangements, and acoustic environment. If you're going to place continuing orders, it can be worth working with them, but for one-off orders it's simply not worth their time.
I had an Edcor power transformer that had a pretty loud buzz, tried using sound deadening material in the end bells, the core was tight so the popsicle stick trick didn't change anything so I took them back out. This transformer was not even near it's power rating either. I ended up mounting it on rubber isolators to even be usable, a year later the windings shorted and it started blowing fuses.
Since then I have been using Hammond, they have all been very quiet and I have had no issues with them.
Since then I have been using Hammond, they have all been very quiet and I have had no issues with them.
I received a buzzing PT from Edcor a couple of months ago. No DC offset. The thing is used at 66% of its rated capacity.
Installed butyl plates in the bells. Used expensive sorbothane washers to mount it.
It still buzzes.
It’s not very loud, so I have no hope it would be deemed faulty by an electrician.
But for an audio application, it’s inadequate and I won’t be using Edcor again.
At a time when some rage about “made in America”, this kind of outcome is counterproductive.
Installed butyl plates in the bells. Used expensive sorbothane washers to mount it.
It still buzzes.
It’s not very loud, so I have no hope it would be deemed faulty by an electrician.
But for an audio application, it’s inadequate and I won’t be using Edcor again.
At a time when some rage about “made in America”, this kind of outcome is counterproductive.
i used a 6mm layer of epoxy on the end bells of a 1 3/4 in power traffo, that quieted it down...
also a 6mm aluminum plate glued to the endbell helped too...
there are lots of means to clear these mechanical buzzing..
also a 6mm aluminum plate glued to the endbell helped too...
there are lots of means to clear these mechanical buzzing..
i will not remove that popsicle stick wedge once i stuck it in...
and i will dip the whole thing in a tub of polyurethane varnish, drip, then in again for several tries, drying in an oven, then repeating the procedure over until no more buzzing...
hey, this is diy folks, common, do not just give up.....try and try and you will be rewarded accordingly...
With all due respect, I prefer a PT that works as intended out of the box. That's why I'll stick with Antek from now on.
The only REAL problem with Antek is they are butt ugly. Especially if you are used to seeing pretty end bells.
Yeah so I'm currently on a build a Hammond PT and it buzzes starting about 70% of rated current. Noticed that if I clamped the end bells with a C-Clamp it went away. Going to look at filling end bells with Silicone or epoxy. Something just flashed in mind, maybe lead shot mixed in epoxy would dampen well.
I have the same buzz problem with an Edcor power transformer. When I squeeze the end bells it stops so it seems to be a mechanical vibration and my diy fix was to stick a couple of self adhesive felt furniture pads on both end bells and put a strong elastic band around them. Worked a treat - but ugly.
The problem existed when I purchased the transformer over 10 years ago and occurs when not even connected to a circuit. I had hoped by mounting on rubber it would stop but it didn’t.
I have decided to try a more permanent mechanical fix and intend putting the same type of furniture pads (small felt circles) inside the bells so they press on the coil.
The problem existed when I purchased the transformer over 10 years ago and occurs when not even connected to a circuit. I had hoped by mounting on rubber it would stop but it didn’t.
I have decided to try a more permanent mechanical fix and intend putting the same type of furniture pads (small felt circles) inside the bells so they press on the coil.
Antek sells transformer covers. Not cheap but maybe worth it in the end..
Antek you say? i had an Antek toroid sent to me that was DOA, the primary wire was broken, no wonder there was no continuity in the primary, from the looks of it, there were no signs of mishaps that could have made that, such as being dropped from a height....one of those China jobs eh? did they ever test that before shipping?
I've ordered probably a dozen Antek transformers for various projects and NEVER had a problem.