Took off the magnetic shielding and flux band from both.
It's not the gapping, as putting vice pressure on both transformers increases the measurement of each about 5% -- no change in the ratio between the transformers.
Any other suggestions before I start taking apart the core? Seems to me I'd have to take apart both transformers so I can do continued comparisons until I get to a point where they measure the same...
It's not the gapping, as putting vice pressure on both transformers increases the measurement of each about 5% -- no change in the ratio between the transformers.
Any other suggestions before I start taking apart the core? Seems to me I'd have to take apart both transformers so I can do continued comparisons until I get to a point where they measure the same...
It can only be the gapping or the material... assuming the turns and layering are the same. Why take them apart? Do they meet your specs?
The buzzing bothers me. Also, they'll be used each for a monoblock. I'd hate to use transformers that differ in some respect.
Well... it is odd that the inductance varies by such a large amount. Did you compare the inductance of the secondaries?
Yeah, secondary inductance is proportional to the primary. Which of course makes sense, since I get the right voltages from both transformers.
Could one of the cores be partially magnetized? I'm not sure how to really test for that or fix it.
Could one of the cores be partially magnetized? I'm not sure how to really test for that or fix it.
hmmmm,
Let's try again in the morning. If both xformers meet spec... let it go. I know, it will always bother you... and one channel will always "sound" better.
Still, we should be able to explain such a difference... 20% goes with the game... 80%, something IS weird.
It might be your shield... it can't be the windings.
😕
Let's try again in the morning. If both xformers meet spec... let it go. I know, it will always bother you... and one channel will always "sound" better.
Still, we should be able to explain such a difference... 20% goes with the game... 80%, something IS weird.
It might be your shield... it can't be the windings.
😕
Hello,
every lamination has a strong nonlinear permeability value versus
magnetization for example:
100 Gauss 760u
1000 Gauss 2400u
10000 Gauss 2700u
16000 Gauss 5000u
So when You like to measure the inductance which the main "sees" You cannot measure with small voltage levels as you do!
Probably Your transformers don`t used equal core materials, which are with strong magnetization much more similar then with
the small (measuring) magnetization.
You can try to take out the laminations from both transformers
and put one half from transformer A to transformer B and one half from B to A
Regards
Heinz
every lamination has a strong nonlinear permeability value versus
magnetization for example:
100 Gauss 760u
1000 Gauss 2400u
10000 Gauss 2700u
16000 Gauss 5000u
So when You like to measure the inductance which the main "sees" You cannot measure with small voltage levels as you do!
Probably Your transformers don`t used equal core materials, which are with strong magnetization much more similar then with
the small (measuring) magnetization.
You can try to take out the laminations from both transformers
and put one half from transformer A to transformer B and one half from B to A
Regards
Heinz
Attachments
Yes, someone at rec.audio.tubes suggested the same thing, the cores being non-linear respect to the test signal's power level. He said the fact that both transformers draw the same mains current when unloaded is an indication nothing is basically wrong. Well, I guess I'll just leave them be, after I do a test running them overnight unloaded to see if any gets warm or fries itself.
I thank everyone for their help.
I thank everyone for their help.
Nixie,
I believe the variations in initial permeability explain all of this.... thanks to powerbecker.
Now just for fun... run a significant DC current through the one the secondaries of both transformers at the same time. Measure the inductance of the primaries.
I believe the variations in initial permeability explain all of this.... thanks to powerbecker.
Now just for fun... run a significant DC current through the one the secondaries of both transformers at the same time. Measure the inductance of the primaries.
Oh NOT that serious... that could be way too much current. A volt or less might do it. Remember, a steady DC current (and flux) is only limited by the resistance of the winding... all the inductance stuff falls out of the equation.
After running them for an hour and a half, the more buzzing (lower measuring) transformer is 15*C above room temperature, whereas the other one only 12*C above. Hmm.
Now they've settled, about 48*C and 45*C respectively. This is on the lowest tap of the primary (least turns for max output voltage) that causes most buzzing.
Hi,
running a primary with excessive mains voltage will cause the transformer to run hot.
When you increase the voltage, with open circuit secondaries, from a low start voltage you will find the primary current increases exponentially (or similar) and once past the safe maximum operating voltage it causing a lot of wasted power and excessive core heating. I suspect the manufacturers use this to determine the primary turns vs input voltage for each core size.
Are you measuring external surface temperatures or internal (core or winding) temperatures? There will be a big difference between internal and external (although not as bad as a toroid due to the exposed core of your EI).
edit, there was a thread a year or so back that discussed this primary voltage issue and also the suggestion that you can increase the output power (VA) by increasing the copper volume on both the primary and secondary windings. i.e. more turns and/or more wire diameter. I think this was less copper loss being converted to more output.
I think they also said that increasing the primary turns decreased the mechanical noise output (a year is a long time for my memory).
running a primary with excessive mains voltage will cause the transformer to run hot.
When you increase the voltage, with open circuit secondaries, from a low start voltage you will find the primary current increases exponentially (or similar) and once past the safe maximum operating voltage it causing a lot of wasted power and excessive core heating. I suspect the manufacturers use this to determine the primary turns vs input voltage for each core size.
Are you measuring external surface temperatures or internal (core or winding) temperatures? There will be a big difference between internal and external (although not as bad as a toroid due to the exposed core of your EI).
edit, there was a thread a year or so back that discussed this primary voltage issue and also the suggestion that you can increase the output power (VA) by increasing the copper volume on both the primary and secondary windings. i.e. more turns and/or more wire diameter. I think this was less copper loss being converted to more output.
I think they also said that increasing the primary turns decreased the mechanical noise output (a year is a long time for my memory).
The funny thing is the windings seem cooler than the core. I think part of the problem is mechanical heating due to vibration of the core.
Or heating of the core due to eddy currents? damaged oxide layers? especially as you scraped off the insulation and possibly burred over the edges hammering in the last few segments.
The oxide layers are indeed damaged, but there is nail polish on every lamination, so they are not touching.
Anyway, is it OK to just use them as is?
Anyway, is it OK to just use them as is?
My goodness, still workin this problem?
1. What is the cross section of the core?
2. How many turns is the primary?
3. What is the no load current of each tranny?
Cheers, John
1. What is the cross section of the core?
2. How many turns is the primary?
3. What is the no load current of each tranny?
Cheers, John
What does it matter, if both transformers have identical cores?jneutron said:
How should I know? As I said, I never touched the primaries; they are the original ones. And again, they are identical on both transformers.
I already answered this at least twice. Why reply if you didn't bother to read the thread?
Not paint, nail polish. I was adding them one by one after coating with nail polish, so it was still wet and would glue them to each other.poobah said:
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