Because the phase angle should be negative.
Look at this as a reference: https://www.mennovanderveen.nl/imag...SE_______/3050-SE_vs02_290321_datasheet-2.pdf
Look at this as a reference: https://www.mennovanderveen.nl/imag...SE_______/3050-SE_vs02_290321_datasheet-2.pdf
You put a boubt
I restart with test and I made a previous error, stupid!
Wrong connection on AP!
Many thx for your observation even I had to put better attention
In attach the right graph
The shape is the same but revers
Also graph of phase on post 18 is wrong
Walter
The intention is to offer a list of trafos. Only nano iron
But at the moment it is time only for test.
Also potting them is a goal.
Probably are involved also my project of amps done during the years
Walter
The ratio is around 25 times
And I use always one single secondary at 5 ohm.
80 H are at 100 Hz
Soon I will test it with DC current inside a power stage with 300B
Walter
Nano cores -1.25T- (and amorphous too) has less saturation limit, that average Fe cores.
Practically never used its over 1T (for example 0.5T BDC, 0.5T BAC).
Too high exctitation (or too low air gap) delimits the maximum power at the low side, so at higher frequency available the desired distortion at given power.
Practically never used its over 1T (for example 0.5T BDC, 0.5T BAC).
Too high exctitation (or too low air gap) delimits the maximum power at the low side, so at higher frequency available the desired distortion at given power.
I haven't heard of this nano core but the fact that you measured 80H at 100Hz is appreciable and I think it will be an exceptional OT. However, the inductance should also be measured in the presence of direct current of 60-100mA
Of course but I wait the end of the offline test so then I can play with the final circuit
As usual I do
Walter
waltube,
Keep going. I am sure it will be a good SE transformer.
Exciting to hear about.
By the way, the graph phase reversal was, and is not, a big issue. I spotted it, but I did not consider that it needed to be mentioned.
Only in a complete amplifier does it have to be paid attention to.
Low frequencies alway lead, and high frequencies always lag.
When you have DC in the primary, if the phase lead is 26 degrees, that will be the -1dB low frequency.
Keep going. I am sure it will be a good SE transformer.
Exciting to hear about.
By the way, the graph phase reversal was, and is not, a big issue. I spotted it, but I did not consider that it needed to be mentioned.
Only in a complete amplifier does it have to be paid attention to.
Low frequencies alway lead, and high frequencies always lag.
When you have DC in the primary, if the phase lead is 26 degrees, that will be the -1dB low frequency.
Was an stupid error by me
I have ready the basic hw to run the test amp after finish the offline test
Walter
@6A3sUMMER , I not agree.
In the past i saw several output transformer with “big” differances measured in phase or out of phase, including a brand as Tango.
There could be also a difference if the transformers is grounded or not. Just my cup of tea.
The measurements of Walt looks promising but are incomplete. No test set up….
In the past i saw several output transformer with “big” differances measured in phase or out of phase, including a brand as Tango.
There could be also a difference if the transformers is grounded or not. Just my cup of tea.
The measurements of Walt looks promising but are incomplete. No test set up….
Ternopil, . . . and all you readers of this thread
There are so many tests you can run for an output transformer. All good tests tell you something about the transformer.
For most tests, you can run the transformer forward or backward, and get the same results.
There are Tubes / Valves threads that show some of waltube's test methods.
I used to have access to a Rohde & Schwarz $50,000 vector network analyzer and $10,000 precision cal kit.
I tested input to output ratio, primary inductance, primary distributed capacitance, leakage inductance, phase, insertion loss, and of course used a DMM to measure the primary and secondary DCRs.
For SE 300B output transformers, I used a 700 Ohm driving resistance (just like a 300B's rp), and an 8 Ohm non inductive load on the 8 Ohm output tap.
The most often applications of an SE 300B output transformer, does Not use global negative feedback.
Therefore, the one dual test that tells you about 90% of what you need to know . . . is the input to output test of amplitude versus frequency, and input to output phase versus frequency.
The known driving impedance and load impedance, plus the input to output amplitude and primary DCR and secondary DCR allows you to calculate the primary impedance when the secondary is properly loaded.
Of course if you are winding your own transformers, and trying to get them to work more closely to your goal, before you modify the transformer design, you need to measure the input to output amplitude, primary inductance, primary distributed capacitance, leakage reactance, and primary DCR and secondary DCR.
Doing that will permit you to come closer on the next design results of:
Input to output ratio, and input to output phase.
Of course, the SE transformer's end bells and laminations need to be grounded in a real amplifier, and the primary B+ end is effectively at AC ground, and the secondary Common is to be grounded.
Safety First!
Yes . . . Grounding one primary lead, versus grounding the other primary lead, will give different results;
and grounding the primary common lead, versus grounding the primary output tap will give different results.
That is because of the capacitance between the primary to secondary, primary to laminations, and secondary to laminations.
Consider that those capacitances are different at the two ends of the primary, and thos capacitances are different at the two ends of the secondary.
Therefore, when you test the transformer, you need to ground those same items in the exact way you will use them in the amplifier, so that the tests are fair (just like the tranformer will be used in the real amplifier).
I hope some of the readers of this, my Post, can read through it all the way to the end.
There are other tests, but I will not mention those in this thread.
Art and Science.
Have Fun!
PS: Notice that the input to output phase of waltube's graph is Zero Degrees at Mid Range Frequencies. And that is where our ears are most sensitive (Yes, at mid frequencies). Nice!
There are so many tests you can run for an output transformer. All good tests tell you something about the transformer.
For most tests, you can run the transformer forward or backward, and get the same results.
There are Tubes / Valves threads that show some of waltube's test methods.
I used to have access to a Rohde & Schwarz $50,000 vector network analyzer and $10,000 precision cal kit.
I tested input to output ratio, primary inductance, primary distributed capacitance, leakage inductance, phase, insertion loss, and of course used a DMM to measure the primary and secondary DCRs.
For SE 300B output transformers, I used a 700 Ohm driving resistance (just like a 300B's rp), and an 8 Ohm non inductive load on the 8 Ohm output tap.
The most often applications of an SE 300B output transformer, does Not use global negative feedback.
Therefore, the one dual test that tells you about 90% of what you need to know . . . is the input to output test of amplitude versus frequency, and input to output phase versus frequency.
The known driving impedance and load impedance, plus the input to output amplitude and primary DCR and secondary DCR allows you to calculate the primary impedance when the secondary is properly loaded.
Of course if you are winding your own transformers, and trying to get them to work more closely to your goal, before you modify the transformer design, you need to measure the input to output amplitude, primary inductance, primary distributed capacitance, leakage reactance, and primary DCR and secondary DCR.
Doing that will permit you to come closer on the next design results of:
Input to output ratio, and input to output phase.
Of course, the SE transformer's end bells and laminations need to be grounded in a real amplifier, and the primary B+ end is effectively at AC ground, and the secondary Common is to be grounded.
Safety First!
Yes . . . Grounding one primary lead, versus grounding the other primary lead, will give different results;
and grounding the primary common lead, versus grounding the primary output tap will give different results.
That is because of the capacitance between the primary to secondary, primary to laminations, and secondary to laminations.
Consider that those capacitances are different at the two ends of the primary, and thos capacitances are different at the two ends of the secondary.
Therefore, when you test the transformer, you need to ground those same items in the exact way you will use them in the amplifier, so that the tests are fair (just like the tranformer will be used in the real amplifier).
I hope some of the readers of this, my Post, can read through it all the way to the end.
There are other tests, but I will not mention those in this thread.
Art and Science.
Have Fun!
PS: Notice that the input to output phase of waltube's graph is Zero Degrees at Mid Range Frequencies. And that is where our ears are most sensitive (Yes, at mid frequencies). Nice!
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Which R&S did you had access to in the past, this is very nice equipment but lots of them is not for audio frequencies.
In the case of Walters transformer as AE already mentioned , the 80H is very high and the dc (i guess the standerd 60-80mA) will probably saturate the core before any audio signal is applied. That's why it is important to know the set-up, how it is measured.
Ternopil, and baudouin0,
The Rhode & Schwarz vector network analyzer I used covered from 10Hz to 4GHZ.
It had the External Input and Output option, which allowed the use of an external Bridge.
I had a special Bridge that worked from 10Hz to the multiple MHz range.
Each different test setup, was first calibrated using the precision cal kit, before making the measurement(s).
The dynamic range was at least 80dB.
I tested interstage and output transformers, input to output 2 stage single ended amplifiers, speaker cables, capacitors . . .
and the combination of an amplifier driving real loudspeaker loads.
If I wanted to spend the $60,000, and had the energy, I might purchase that test equipment, and start up a measurement services company.
But I am having too much fun in retirement, and I am keeping too busy to do that.
Let's wait until waltube has the final version of his transformer and tests it with a 300B driving it.
I expect it will work very well with the Quiescent DC current.
I fondly remember seeing Jack Elliano adjust the Air Gap on a SE transformer, testing for inductance, etc. (Jack of Electra Print Audio).
Every Good engineering design is a series of Tradeoffs, and Synergistic results.
Have Fun!
The Rhode & Schwarz vector network analyzer I used covered from 10Hz to 4GHZ.
It had the External Input and Output option, which allowed the use of an external Bridge.
I had a special Bridge that worked from 10Hz to the multiple MHz range.
Each different test setup, was first calibrated using the precision cal kit, before making the measurement(s).
The dynamic range was at least 80dB.
I tested interstage and output transformers, input to output 2 stage single ended amplifiers, speaker cables, capacitors . . .
and the combination of an amplifier driving real loudspeaker loads.
If I wanted to spend the $60,000, and had the energy, I might purchase that test equipment, and start up a measurement services company.
But I am having too much fun in retirement, and I am keeping too busy to do that.
Let's wait until waltube has the final version of his transformer and tests it with a 300B driving it.
I expect it will work very well with the Quiescent DC current.
I fondly remember seeing Jack Elliano adjust the Air Gap on a SE transformer, testing for inductance, etc. (Jack of Electra Print Audio).
Every Good engineering design is a series of Tradeoffs, and Synergistic results.
Have Fun!
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