Of course if you were going to swap out the OT in your amp for one with litz wiring, and post comparison results in the next day or two then
Why would I need more than 100 kHz on full power?
Why need more than 20kHz, or 50kHz, ... or a rabbit hole to go down. Perhaps let the OP present his technical data, rather than your own if it has no relevance to the thread, otherwise the thread gets polluted by non-related amp data from anybody passing by.
No problems, I am passing away from this site, thanks to you! Feel free to discuss directional wires and wooden cable stands!
to Wavebourn
you post is not in line with this topic for a simple reason, because you gave us the results for the entire amp feedback included.
Is not complicate to get the a wide freq. answer if we use feedback but we have also to understand in which way the TDH vs. frequency is changing, for example (this is a very important test, in my opinion).
In addition here, in my opinion, we aren't discuss about snake oil but under tests that everyone can replay; this is must be clear.
Is very difficult to see the tests related ONLY to a O.T trafo; we think that the test set we propose is, at the moment, the best one available.
Every suggestion is welcome, of course.
I am working, with Fabrizio, to understand how much is better the Litz ot Trafo or is not convenient to build it under the costs/performances aspect .
We think that Litz is better for a simple reason ( just to tell one) because the point of resonance is moved at higher frequency.
But we have, with next prototype, to have a better L at low frequencies; soon I have to test a new one that is coming for a s.e. project.
you post is not in line with this topic for a simple reason, because you gave us the results for the entire amp feedback included.
Is not complicate to get the a wide freq. answer if we use feedback but we have also to understand in which way the TDH vs. frequency is changing, for example (this is a very important test, in my opinion).
In addition here, in my opinion, we aren't discuss about snake oil but under tests that everyone can replay; this is must be clear.
Is very difficult to see the tests related ONLY to a O.T trafo; we think that the test set we propose is, at the moment, the best one available.
Every suggestion is welcome, of course.
I am working, with Fabrizio, to understand how much is better the Litz ot Trafo or is not convenient to build it under the costs/performances aspect .
We think that Litz is better for a simple reason ( just to tell one) because the point of resonance is moved at higher frequency.
But we have, with next prototype, to have a better L at low frequencies; soon I have to test a new one that is coming for a s.e. project.
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Checking my stock of litz wire, I have two types that could function as primary and secondary of an output transformer.
First type has 45 x 0.05 mm wire; total diameter of this litz wire is a little over 0.4 mm.
Second type has 30 x 0.10 mm wire; total diameter of this litz wire is 0.7 mm.
With these wires I could wind a typical SE output transformer.
For comparison, I could wind the same output transformer with 0.4 mm (primary) and 0.67 mm (secondary) using normal magnet wire.
Important for a fair comparison is using the same bobbin and core type and dimensions for both transformers in order to have the same coil build up (numbers of turns, interleaving, numbers of primary and secondary sections).
However, when calculating the DC resistances of both coils, it appears that the DC resistances for the litz wire transformer are about 1.4 times higher than for the magnet wire transformer.
In other words, the magnet wire transformer would have some 80 ohms of primary DCR, and the litz wire transformer would have some 115 ohm of primary DCR. DCR's of the secondaries would show the same difference.
Copper loss, which can also be expressed as insertion loss, is therefore worse for the litz wire transformer.
In my experience this copper loss is a very important parameter wrt sound quality. In other words: wind two transformers with the same winding ratios but different wire gauges (so different DCR's), and hear the difference!
I can imagine that litz wire transformers shift HF resonance higher up (because of less capacity) but this is only one property. Other properties (DCR, winding technique, core material and dimension) might prove to be more important.
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Walter... you tested same bobbin (litz wire?) on different cores (that's correct?)... with such a test what did you measured? Litz wire performances?
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I liked that waltube showed a lab bench test circuit which does NOT depend on amp used but measures *only* the DUT (device under test).
Of course any transformer will eventualy be used in an amplifier, that´s its purpose, but precise measurement changing one variable at the time clears waters.
That´s why I would also have liked to see 2 exact same transformers compared, exact same core, turns, etc; only varying wire type. 🙂
PS: which is the actual magazine issue discussing this test?
The link only shows a main page with a dozen different issues, don´t want to go through all of them searching, please post a direct link.
Of course any transformer will eventualy be used in an amplifier, that´s its purpose, but precise measurement changing one variable at the time clears waters.
That´s why I would also have liked to see 2 exact same transformers compared, exact same core, turns, etc; only varying wire type. 🙂
PS: which is the actual magazine issue discussing this test?
The link only shows a main page with a dozen different issues, don´t want to go through all of them searching, please post a direct link.
Because of phase shift at higher frequencies.
50 KHz -3dB or resonant frequency is really mediocre unit.
To Pieter:
The ohms you liste are measured or not?
The theoretical difference in DCR in not so important as the parasitic at high frequencies.
If the 30 ohm of differences are reals we have a partition as the pdf in attach.
This a picture from Radiotron of a equivalent circuit at mid frequencies ( just for simple explanation); RL is a load reflected, in my case the ratio is 20:1 so the RL is 2400 ohm ( because I fix the ratio with 6 ohm of load, if I connect 8 ohm I reach 3200 ohm).
Rw is the winding dc resistance, in this case we consider 30 ohm , the difference between the two values you post.
The loss is around 0,1 dB!
In you opinion it is a problem?
Walter
The ohms you liste are measured or not?
The theoretical difference in DCR in not so important as the parasitic at high frequencies.
If the 30 ohm of differences are reals we have a partition as the pdf in attach.
This a picture from Radiotron of a equivalent circuit at mid frequencies ( just for simple explanation); RL is a load reflected, in my case the ratio is 20:1 so the RL is 2400 ohm ( because I fix the ratio with 6 ohm of load, if I connect 8 ohm I reach 3200 ohm).
Rw is the winding dc resistance, in this case we consider 30 ohm , the difference between the two values you post.
The loss is around 0,1 dB!
In you opinion it is a problem?
Walter
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to JMFahey
it is www.audioreview.it it is italian magazine on paper, the site is a general description
We will moving to have a better test set ( more easy than 4.900 volts!!! 🙂 )
for OT trafos
Walter
it is www.audioreview.it it is italian magazine on paper, the site is a general description
We will moving to have a better test set ( more easy than 4.900 volts!!! 🙂 )
for OT trafos
Walter
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So...
1) first transformer: EI core + standard wire bobbin
2) second transormer: double C core + Litz wire bobbin.
test: transformer #1 vs transformer #2
That's correct?
I imagine and hope the same geometry for the standard wire bobbin and the Litz wire bobbin.
Ok... with such a test you worked out that Litz wire is better 🙂
Ok... with such a test you worked out that Litz wire is better 🙂
I think so.
But we are workin on it
In next two months we have some other protitype to show with project.
Walter
But we are workin on it
In next two months we have some other protitype to show with project.
Walter
The DCR's are measured and are in line with calculations.
So it is not a "theoretical" difference but a practical difference, causing higher insertion loss when using litz wire.
I wrote "in my experience" which means that quite some time ago I was investigating the importance of DCR. It was quite apparent that the lower DCR transformer sounded better than the higher DCR one, and the difference in DCR is about what happens when replacing magnet wire by litz wire on the same core, same bobbin dimension and so on.
So my experience is not based on a prehistoric (but still useful by the way) RDH circuit, but on direct comparison done in the actual amplifier, a SE 300B in this case.
Please note I am not suggesting that litz wire does not make sense, but you can only draw meaningful conclusions when your test set up is good, and checking how you tested it is not a good set up.
Same cores, please, that is double C cores only in all prototypes.
Nice the reversed TUD (transformer under test) method in test setup. I have to apply it.
Preistoric???
Is is hard to define preistoric the RDH!!! 🙂
This a basical theory still valid.
Walter
Is is hard to define preistoric the RDH!!! 🙂
This a basical theory still valid.
Walter
Please try to read Walter.
I said RDH is still useful.
But better still is practical experimentation with modern materials, based on the basic theories.
I said RDH is still useful.
But better still is practical experimentation with modern materials, based on the basic theories.
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