The viewers, public are our friends. Sorry about the confusion.
Glad things worked out ok.
Cheers Michael.
Hey both Michaels and All,
This is an interesting thread from the delve into the black box called an output transformer point of view. Often we pay more attention to plate curves than flux leakage. The first post asked the question. It was not a hypothetical what if question. It was a real world what is the difference between A and B question that provoked a head scratching, “What is going on in there” rethink of single end output transformers.
Thanks guys.
DT
This is an interesting thread from the delve into the black box called an output transformer point of view. Often we pay more attention to plate curves than flux leakage. The first post asked the question. It was not a hypothetical what if question. It was a real world what is the difference between A and B question that provoked a head scratching, “What is going on in there” rethink of single end output transformers.
Thanks guys.
DT
if someone were to ask me to build those two types of OPT's i'd probably make then the same.....after all it is the turns ratio that determines what primary impedance is reflected at the primary side.....
You can usually get away with mis-applying a P-P OT (ie, wrong absolute Z but same Z ratio) since they have adequate design space, but the SE OTs do not have any room for error. Notice that the GXSE does not even meet its own specs when properly applied. Only 4 Watts max for the same max flux as the GXPP uses (8 Watt at the higher flux where saturation sets in), and only 80 Hz to 18 KHz response. Mis-apply one of the GXSE's and you will end up with just 160 Hz low end at 4 Watts. It takes a 3x to 4x bigger/heavier SE OT than the equivalent P-P OT to get the same specs. GXSE's are the same size as the GXPP's.
With a CXPP-25 P-P on the other hand for $10 more, you get 6x the power rating, 4x the low freq. rating (and they actually have interleaved windings versus none in the GXSE, so a real 20 KHz top end), 48x lower magnetizing current (and hysteretic distortion). No contest in my book. SE OT's are banned here.
With a CXPP-25 P-P on the other hand for $10 more, you get 6x the power rating, 4x the low freq. rating (and they actually have interleaved windings versus none in the GXSE, so a real 20 KHz top end), 48x lower magnetizing current (and hysteretic distortion). No contest in my book. SE OT's are banned here.
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I dont understand
I thought you would always use a higher wattage OT than the actual output of the design
I thought you would always use a higher wattage OT than the actual output of the design
"I dont understand"
Understand what?
Generally it is a good idea to use a little larger OT than the amp design to stay out of the saturation regime?
The GXSE-15 would be useful for a 4 or 5 Watt SE amp due to its limitations, not due to conservative design.
The CXPP-25 would obviously be overkill for a 5 Watt design, but using it in an anti-triode type setup (in order to use a P-P OT for SE emulation) automatically doubles the power output over the SE design for a given tube, so is not too far-fetched. It's well matched to a 10 or 12 Watt output tube (for 20 or 24 Watt out in anti T mode).
Understand what?
Generally it is a good idea to use a little larger OT than the amp design to stay out of the saturation regime?
The GXSE-15 would be useful for a 4 or 5 Watt SE amp due to its limitations, not due to conservative design.
The CXPP-25 would obviously be overkill for a 5 Watt design, but using it in an anti-triode type setup (in order to use a P-P OT for SE emulation) automatically doubles the power output over the SE design for a given tube, so is not too far-fetched. It's well matched to a 10 or 12 Watt output tube (for 20 or 24 Watt out in anti T mode).
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For a given frequency voltage on which the core saturated is directly proportional to the number of turns. For a given voltage frequency on which the core saturated is inverse proportional to number of turns. That means, the tranny with twice number of turns will saturate on twice higher voltage when frequency is the same, or on twice lower frequency when the voltage is the same.
Gentlemen, I am disappointed, no one did the calculations.🙄
smoking-amp cheated, he looked the page with the solution.
Wavebourn hit the nail from the beginning, well, is all in his head.
The other mere mortals, we have to do the math.
But in the forum it is ready to use here
http://www.diyaudio.com/forums/tubes-valves/181072-designing-transformers-j-c-maxwell.html
Data
T1: Zp1 = 10 KOhm, Zs1 = 16 Ohm
T2: Zp2 = 5 KOhm, Zs2 = 8 Ohm
Unknowns
Np1, Np2, Ns1, Ns2, Lp1, Lp2, R1, R2
A reasonable starting point is that both transformers have the same lower frequency roll-off, then from Eq.(53)
Lp1 = 2 Lp2
From Eq.(37)
Np1 = √2 Np2
From Eq.(50)
Ns1 = √2 Ns2
Winding resistance is given by
R = (N l σ) / (π r^2)
σ is the resistivity of the wire, r is the radius of the wire.
So that the turns entering the window must be satisfied
√2 (r1)^2 = (r2)^2
Then
R1 = 2 R2
Very close, right? RadioWhat?😎
I always tell my students read to Maxwell.
Lie, just kidding, I'm just a TV repairman.😀
This is correct, honestly I do not know how you do.
If I'm not looking at Eq.(22) I get lost!
smoking-amp cheated, he looked the page with the solution.
Wavebourn hit the nail from the beginning, well, is all in his head.
The other mere mortals, we have to do the math.
But in the forum it is ready to use here
http://www.diyaudio.com/forums/tubes-valves/181072-designing-transformers-j-c-maxwell.html
Data
T1: Zp1 = 10 KOhm, Zs1 = 16 Ohm
T2: Zp2 = 5 KOhm, Zs2 = 8 Ohm
Unknowns
Np1, Np2, Ns1, Ns2, Lp1, Lp2, R1, R2
A reasonable starting point is that both transformers have the same lower frequency roll-off, then from Eq.(53)
Lp1 = 2 Lp2
From Eq.(37)
Np1 = √2 Np2
From Eq.(50)
Ns1 = √2 Ns2
Winding resistance is given by
R = (N l σ) / (π r^2)
σ is the resistivity of the wire, r is the radius of the wire.
So that the turns entering the window must be satisfied
√2 (r1)^2 = (r2)^2
Then
R1 = 2 R2
Very close, right? RadioWhat?😎
I always tell my students read to Maxwell.
Lie, just kidding, I'm just a TV repairman.😀
This is correct, honestly I do not know how you do.
If I'm not looking at Eq.(22) I get lost!
😛 That is hillarious.
Cool post Pop.
Thanks Positron! You are so positive.😀
IMHO. Sometimes the best tools are paper and pencil...
I'm not a fan of math, well, almost; happens that words are not my thing.
Once, I wrote a poem to my wife, and she asked me if it was a greeting card or something.🙄
You see?
Sorry Michael, I don't know if to thank or apologize.😱
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Sorry, from one TV repairman to another; All your equations are exactly correct and your assumptions are exactly what one would be given to assume starting from only the impedance specs.
🙂
i hate maths myself but the math involved here is straightforward and simple....
applied to output transformers:
10k:16ohms = 5k:8ohms......no math can disprove this....
primary inductance is directly related to number of turns, nothing to do with turns ratio...
primary inductance is directly related to size and permeability of the core under the windings....
the size of wire used in the primary winding is limited by the winding window, so is the number of turns that you put into it...
frequency response is limited by core saturation at low frequencies and leakage inductance/shunt capacitance at high frequencies.....
have i missed something?
me to was a TV repairman a long time ago......
applied to output transformers:
10k:16ohms = 5k:8ohms......no math can disprove this....
primary inductance is directly related to number of turns, nothing to do with turns ratio...
primary inductance is directly related to size and permeability of the core under the windings....
the size of wire used in the primary winding is limited by the winding window, so is the number of turns that you put into it...
frequency response is limited by core saturation at low frequencies and leakage inductance/shunt capacitance at high frequencies.....
have i missed something?
me to was a TV repairman a long time ago......
"have i missed something?"
The size of the wire. The 10K has smaller wire and 1.41 X as many turns (both primary and secondary, ratio stays the same). And 2X as much DC resistance (smaller wire and longer wire).
The size of the wire. The 10K has smaller wire and 1.41 X as many turns (both primary and secondary, ratio stays the same). And 2X as much DC resistance (smaller wire and longer wire).
That's what I thought before the deduction of equations, then I saw the light ... I mean, I think so slowly, that it was dawning.😀
True, this arises from applying Eq.(50)
You're wrong, if you look at Eq. (37), primary inductance is related to the square of number of turns.
This also says Eq.(37)
This is already covered, the corresponding window area is given by
A = N(2r)^2 ==> √2 (r1)^2 = (r2)^2
Core saturation at low frequencies is covered by Eq.(22) , having established the parameters, leakage inductance can be minimized using multiple windings, shunt capacitance also depends on insulating materials (ε) not only of geometry, equations I owe you.
Do not dare to look at least one equation.🙄
You missed the best part of the movie.
BTW. The murderer is the dentist.😀
My father was a U.S. Army Signal Corp radio and camera Repair Man, does that count? I did remove , test and replace the tubes more than once.
In your calculation remember to include the connected load and the output of the amplifier, including feedback.
DT
No. Only the spec'd minimum performance is the same. It could be that when used for the 5K application the performance is much better than spec'd
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