Out of two Hammond 272JX PT I use, one buzzes little more than the other. The buzz reduces just little when I press the mid point of bell cover with my fingers even though the screws are tight. If there's loose lamination, should varnish be used? But how? Do I have to remove the bell covers, dip the PT in varnish or do I keep the covers and pour the varnish in, then drain it?ThSpeakerDude88 said:
I've also had extremely frustrating levels of stray flux from my Hammonds, even running at 110V primary. Line output transformers picking up quite a bit of hum, even up to 6 inches away. Electraprints were much better in this area.
Anyone notice also that their filament transformers are being manufactured in China ? Nothing against China, but Hammond has been producing in Canada for quite a while. Hope quality doesn't change - I use Hammond all the time for filaments and auxiliary power supplies.
Lundahl, Sowter, or Electraprint are my preference for B+.
Anyone notice also that their filament transformers are being manufactured in China ? Nothing against China, but Hammond has been producing in Canada for quite a while. Hope quality doesn't change - I use Hammond all the time for filaments and auxiliary power supplies.
Lundahl, Sowter, or Electraprint are my preference for B+.
I have been using Hammond or Allied (made by Hammond) power transformers for a long time. I have not had problems with them buzzing.
I have lived in the same house for 30 years. The same pole transformer has provided power to this and 8 other houses for all of those 30 years, until last week. The line voltage in this house has crept up over the past. It ran 122 to 124 volts, until last week.
Last Monday one of Florida's famous lightning bolts blasted that transformer into the scrap heap. After 10 hours of darkness FPL replaced that rusty old transformer with a shiny new one. Now the line voltage is a very average 118 volts, and the previously quiet Hammond 272JX that is connected up on my bench has a faint buzz to it. The test amp on the bench has not been touched. I have not yet had the time to fire up some of my other previously quiet amps.
Could the buzz or lack of buzz be related to power quality? I had been planning to do some FFT testing of our power line, but I never got around to it. Now I have nothing to compare my new power to.
I have lived in the same house for 30 years. The same pole transformer has provided power to this and 8 other houses for all of those 30 years, until last week. The line voltage in this house has crept up over the past. It ran 122 to 124 volts, until last week.
Last Monday one of Florida's famous lightning bolts blasted that transformer into the scrap heap. After 10 hours of darkness FPL replaced that rusty old transformer with a shiny new one. Now the line voltage is a very average 118 volts, and the previously quiet Hammond 272JX that is connected up on my bench has a faint buzz to it. The test amp on the bench has not been touched. I have not yet had the time to fire up some of my other previously quiet amps.
Could the buzz or lack of buzz be related to power quality? I had been planning to do some FFT testing of our power line, but I never got around to it. Now I have nothing to compare my new power to.
For sure. My place has some dirty power, it causes the transformers to buzz significantly more (not just the Hammonds) than when I take my gear to a friends place. Installing DC traps on my amps helped substantially. It would make sense that harmonic distortion on the mains could be a contributer too (I think the DC on the mains is a byproduct of Harmonic distortion). I'd be curious to see what the FFT shows of your power if you ever get around to it.
The Buzzing is caused from the windings not properly VARNISH IMPREGNATED.....
Lately Hammonds are notorious for this....just poor QC....
They don't seem to care and keep producing this stuff....
Having a nuetral with more than 500mV DC off ground is a problem that power company should be aware of... But DC off-set will not cause the transformer to buzz..... DC offset will just push the BH loop higher by just a hair...not enough to saturate or even come close, unless yor talking over 5 volts!!!
Chris
Lately Hammonds are notorious for this....just poor QC....
They don't seem to care and keep producing this stuff....
Having a nuetral with more than 500mV DC off ground is a problem that power company should be aware of... But DC off-set will not cause the transformer to buzz..... DC offset will just push the BH loop higher by just a hair...not enough to saturate or even come close, unless yor talking over 5 volts!!!
Chris
Are you sure? .5V seems like it would be significant given the amount of current it could cause through a low DCR winding. It really seems like it would be significant if your running the transformer near it's VA rating. A lot of the toroid guys have problems with buzz and many of them use DC traps with good results.
Tubelab,
You are a smart guy, I have no doubt you will figure this out. Still, I have amps I built 20 years ago that have lived in many houses and apartments. As such, they never buzzed, not even in my current house. It doesn't seem to have mattered before across different houses, states etc.... on other transformers. My $0.02. The hammonds buzz... I've just learned to accept it.
Oh BTW, my hammonds do NOT have the common over voltage problem that many people say theirs have. Mine are pretty spot on, even with my slight over voltage line (121-122).
So who knows, the classic your mileage may vary is in full effect.
-Sean
You are a smart guy, I have no doubt you will figure this out. Still, I have amps I built 20 years ago that have lived in many houses and apartments. As such, they never buzzed, not even in my current house. It doesn't seem to have mattered before across different houses, states etc.... on other transformers. My $0.02. The hammonds buzz... I've just learned to accept it.
Oh BTW, my hammonds do NOT have the common over voltage problem that many people say theirs have. Mine are pretty spot on, even with my slight over voltage line (121-122).
So who knows, the classic your mileage may vary is in full effect.
-Sean
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