I have not tested the 0506 myself.
But the 1206 doesn't measure too badly at all.
However it does exhibit a dip at about 10Khz in the FR when the 120V windings are tied in series.
I am not sure if this is caused by the limiting resistor in my test setup or how it will effect the system as a whole.
It seems that this dips corresponds to the peak in the impedance curve.
I will be looking at this a bit closer to verify it.
Posted is a picture showing these dips from the input/output ( I believe) of the transformer.
I forget what value of resistor I used.
The FR curve is flat when the 120V windings are open or in Parallel.
The Screen shot was done before I had the mishap and was measured in its stock form from the factory.
It was one of the very first measurements I did with it.
I am in the process of remeasuring it for about the 24th time and documenting my measurements and how I got them.
It has been a slow process as I want to be sure that I am getting consistent results and repeatability to verify my range of values.
I have posted some preliminary Impedance curves here for you to take a look at,
http://www.diyaudio.com/forums/planars-exotics/161485-step-up-transformer-design-6.html#post3404300
These curves were made with the secondary winding's (120V) left open and not connected.
Connecting them in parallel there is no change in the curve.
Connecting them in series will cut the high frequency impedance approximately in half as this doubles up on the secondary capacitance.
The addition of the capacitance from the ESL'panel will drop this part of the curve even more depending on the capacitance value of your panel.
On the low frequency side of things the impedance is quite low and the value of inductance of the primary winding (6V) determines this.
As I get going I will explore some ways that may to help improve this.
Removing the shields is very easy to do and doesn't effect the quality of the device as it is.
It is unfortunate that I damaged my part before I got to get a really good handle on what these shields were doing to my measurements.
But, I can just as easily add them back on once I get some base measurments with the basic core as it is now.
I was using my CrownDC300a at full power (115Vp-p) using test tones when it failed.
This is a very heavy test situation and most likely will never see this kind of abuse using your average amplifier playing music.
And even less likely using two or more cores.
The second picture shows the dip as well as THD from the output of the secondary at 40Vrms in to the primary of the transformer.
This is a extreme test and I am not sure how accurate the THD figures are as I later found out the the Realtek ALC892 on my motherboard is not very good at all by just using a standard loop back test.
The third picture shows the FFT of the output of the transformer at full power at 2400Hz this includes the amp of course.
At lower levels the THD is very low and much much more lower than this.
I will have more on this later as calibration is very critical for a very accurate result of the THD figures.
At normal levels in many cases I could not find any more added distortions that had any significance above about 600Hz to 1Khz or so and it got better as the frequency got higher.
I will take a closer and more refined look at this later.
Even as they are it is still much lower than most dynamic drivers at this very high voltage level !!
The last four pictures show the input and output voltages at the onset of core saturation.
They were at full power just before any flat topping of clipping from the amplifier at 330Hz, 304Hz, 270Hz and 240Hz.
I didn't get any screenshots of the primary currents and that was the next set of tests that I was doing when the transformer failed.
Thus I was watching the currents when I connected the electrostatic shield and had forgot to disconnected it when I started a sweep tests as it was in the saturation range when it failed.
Just for the record the primary currents did rise considerably when I connected the shield.
By as much as 30% to 50% or so but that is all I have on that for now.
This is solid indication that the shield adds unneeded capacitance to the transformer for ESL use.
All of these test were made with no extra capacitance added and was with only the transformers self capacitance.
FWIW
jer
