Paul Barker wrote:Can you summarise them and show your conclusions and how they prove your case please?
Please answer the above questions?
I don't have a case, I don't need or wish to prove anything. I was just commenting that the C that you were describing was not the C that Andrew was refering to. Nothing more nothing less.
You asked me for a in depth article, I found one, I you then ask me to summerise!!!
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
Paul Barker wrote:I can't read the legends is the red line the capacitor and the other line the transformer?
He seems to have plotted current, red is I, C1; green is I, L2. Dotted lines are the phase for same
What therefore is the relative amplitude of the two (and therefore can the capacitor contribute when the transformer is coupled as a transformer)?
Can't read the numbers! Scale is decibels BTW
i.e at 20hz what db down is the transformer curve and what db down is the capacitor curve and what db down is the combined effect.
Sweep seems to start at 1 Hz, hence a significant roll-off shown, L1/2 are only 33 Henries. I'm guessing (wildly) -3 dB @ 10 Hz?
Now if you put your leakage inductance in the sim
Yes needs extra coils added to the ends that are not inductively coupled, also extra small caps joining those together. Then need to know what their values are ~ starts getting complicated!
Then sweep it up into ultrasonic or even RF and see what that does to them, could have some interesting effects.
I agree with Paul in that I envisage two coupled bifilar windings as each being like a series of coils, with capacitors at each of a multiple set of junctions, coupling across to the equivalent junctions of the other series of coils.
As far as I know the LTspice coil coupling function does not take any account of capacitances between the windings (so far as I have noticed), although it is possible to vary the inductive coupling between (i.e. adding leakage inductance) so to create anything like a bifilar would need something like the abovementioned.
In Andrew's model the coupling ('K' directive) is at maximum or 'perfect' at '1', changing it to e.g. 'K1 L1 L2 0.995' will add leakage and that might produce some interesting behaviour.
HTH
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
Hmmmmm.... looks like a perfect swamp, with alligators on point and eager..... here's some fresh cut chad in the water....
Interesting argument about bifilar windings and was that also silver coil wire and amorphous double C core?
I am not a fan of the sound of bifilar windings. The capacitive coupling is fine, so long as the wires are bound together in a ribbon. The flux transform from marginal angle crossed adjacent layers, of the typical device, leave me hearing multiple threads in pure tones. The capacitive stack settling time, I assume, provides my ear with an aura of ringing, as the E Field moment collapses into B Field current flow. I do assume that strict layer to layer Z winding would help with some of this.
But then, I don't like the low level "garble" I hear in autoformers either.
After all of the math's have been done, and you have to actually make something, means to me that you take off from the first order approximation models and go looking for storage of energy. In non linear flux transform, B max saturation hysteresis, minimization of leakage inductance, minimization of distributed capacitance, that is doing appreciable amounts of "work" and the ideal number of primaries and secondary's. These are where my time has been invested. To say nothing about spotted speaker pox and Litz wire cables, just so I could hear the subtle differences in those many categories.
Storage of energy, with two free general hints.
In the core this arises primarily from magnetostriction induced eddy currents. The worst of this magnetostriction arises in lamination legs adjacent to gaps. So, 1 X 1 E/I laminating schemes might not be the best use. C cores are interesting, but would be far more interesting as J cores. Amorphous core is wonderful stuff, but the LCR relationships don't allow any amount of capacitive coupling to be used, (at least in my trials) due to frequency response peaks.
In the coil, the use of uniform capacitance, with a typical dielectric constant value of 3.4 to 6 causes signal print storage, probably due to the charge and release times for materials with this much electron concentration per cubic centimeter. Differential capacitance, with non film winding to winding dielectrics, and a constant under 2.5 and vacuum impregnated polyester resin with a constant of 4, seems to work best.
Non linear flux transform, with one slight hint.
In the core this arises from hysteresis, eddy currents, magnetostriction, poor match of annealing to chemistry and large burrs on material edges.
In the coil, between antennas of primary and secondary windings appears worst, from two sources. The disruption of planar magnetic fields within the window, due to any number of factors, with gap adjacent ripples being the worst. The radial field structure between parallel, concentric, outside boundaries of blocks of primary and secondary antennas.
Minimization of leakage inductance.
In the coil due to unavoidable gaps in between wires and any sort of layer insulation. The spaces around the windings are also a problem, but use of any core material that does not have extended frequency range for power transform, will make this a moot point. The use of Nickel, mu metal and metallic glass materials means you need to consider this.
Minimization of distributed capacitance.
In the coil due to uniform dielectric constants of the materials chosen, to match a lumped capacitance model that is very misleading.
I have found solutions for these and all of them come from specific construction techniques, not endless analysis of ideal models. Those models, the tests run to find out how close to reality they fail and materials sciences applied to bringing the real thing closer to the failure point of the models, are very useful activities. They just don't teach you how to avoid making a power transformer, when you meant to make an audio transformer.
Somewhere deep down in the mix there is a distortion which isn't there for the louder instruments/parts of the music ???
(If it is this its interesting as intuitively I associate distortion with the loud sounds not the quiet ones and I have heard this with .... well just an example. You knwo when you have a knackered pair of Lowthers when although they might sound fine when they are putting out the SPL but when there is just very very quiet music you don't hear clarity, you hear mush coming, in this example, from the magnet actually brushing the no longer aligned voice coil.
And I've heard a couple of solid state amps produce the same sort of sound electronically - again with the tiny quiet bits where the difference between the signal and the noise floor is minimal.)
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
Thanks for coming over Bud - great to see you visit our great little forum !
I would guess that 'garbled' in Bud's parlance would be a general loss of musical intelligibility , reducing the immediacy of the sound.
I would say I've used autoformers at speaker level and heard a slight loss of tonal colour and 'life' ( dynamics at low-mid level I think ) which made me seek other solutions to the system level matching .
I don't expect Bud will come back and answer each and every question here - he's either building transformers or fielding ( often aggressive ) questions at DIYAudio .
I was hoping Paul and Nick might offer something more than 'Thank you' in resonse to the info that Bud provided
"Once you find out ... the Circumstances ; then you can go out"
I have nothing to critique about what Bud said. I thanked him for the information he has provided. He knows far better than I, it would be arrogant of me to apply my ignorance to any of what he posted there, but as it happens I have similar views, though my views compared to his are worthless.
In regard to the autoformers i have never used them. To comment on what i haven't done would be pointless.
What were you doing with autoformer Mark? Parafeed?
I have a couple of pairs of ONetics transformers - I like them. Bud's advice to me was good when I asked
OTOH I didn't understand much of what Bud said in his posting and would love to know more. Let's see eh! This is a much better forum!!! I mean, do we ever argue - aren't we always helpful, polite and mutually supportive!? we don't even sarcasm, do we? okay a little irony but that's healthy...isn't it
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
Paul, autoformers were for padding-down the GPA compression drivers by 8-10 dB to match the Onken bass box .
One thing I can glean for certain from Bud's post is the avoidance of things like Kapton/polyester film for separating winding layers , due to large amounts of surface charge interfering with low-level signals . This would agree with Pieter's T's comment about use of organic materials like waxed paper ( I think ) when I sat next to him at ETF 2004 ( 2005 ? ) during Per Lundahl's talk . Sorry, was this too much name-dropping ?
Looking forward to getting two pairs of 2A3-spec transformers soon from Bud .
"Once you find out ... the Circumstances ; then you can go out"
