SJEP120R063 SiC JFET Modeling
I will like to know if any one could find out how to get the parameters for this SiC JFET as I am currently undergoing a project on this device.
I will like to know if any one could find out how to get the parameters for this SiC JFET as I am currently undergoing a project on this device.
Interesting thread and DD sounds exotic, I would however like to reconnect to the original question for a moment.
Driving a hybrid ESL with a tube amp and a small ratio step-up trafo.
I've just started my own ESL project and I don't have any irl data so for now it'll have to be an academic exercise on my part.
Circlotron seems like an interesting OTL solution.
Would it be a good idea to go for a circlotron with medium-high voltage output tubes and a low turn-ratio step-up transformer?
Any candidates that spring to mind?
I guess they should at least manage 250V output for it to be interesting?
I'm just being curious...
My own circlotron that I'm currently building is much less spectacular with 6CG7 tubes.
Driving a hybrid ESL with a tube amp and a small ratio step-up trafo.
I've just started my own ESL project and I don't have any irl data so for now it'll have to be an academic exercise on my part.
Circlotron seems like an interesting OTL solution.
Would it be a good idea to go for a circlotron with medium-high voltage output tubes and a low turn-ratio step-up transformer?
Any candidates that spring to mind?
I guess they should at least manage 250V output for it to be interesting?
I'm just being curious...
My own circlotron that I'm currently building is much less spectacular with 6CG7 tubes.
Hi,
as any amplifier circuitry the circlotron has advantages as well as disadvantages.
A great Pro is that it works fairly stable into complex loads.
Another Pro is that since its output devices are connected as followers, its output impedance is low, which is good for driving transformers and the trannies behaviour.
As a Con the burden of large signal amplitude lies not only on the output stage but also on the driver stage.
A further Con is the need for two power supplies, which needs to be floating.
Creating the symmetrical signals for the driver stages might not be trivial.
So it might be an easier alternative to use bridge-connected SE-amps with added output buffers? If You use two power supplies here it would even be possible to have a ground referenced DC-free output.
jauu
Calvin
as any amplifier circuitry the circlotron has advantages as well as disadvantages.
A great Pro is that it works fairly stable into complex loads.
Another Pro is that since its output devices are connected as followers, its output impedance is low, which is good for driving transformers and the trannies behaviour.
As a Con the burden of large signal amplitude lies not only on the output stage but also on the driver stage.
A further Con is the need for two power supplies, which needs to be floating.
Creating the symmetrical signals for the driver stages might not be trivial.
So it might be an easier alternative to use bridge-connected SE-amps with added output buffers? If You use two power supplies here it would even be possible to have a ground referenced DC-free output.
jauu
Calvin
I'm hoping someone will pick up the ball and run with it.
Since my panels are in the initial stages (still gathering building materials) I can't do anyting worthwile myself.
At best I can do some theoretical exercises but beeing a tube n0ob the outcome would probably be less than optimal. Trying to stay possitive...
You are spot-on conerning the cons, maybe I'll get adventurus when the panels are done? Hopefully someone else will have come up with something long before that.
Since my panels are in the initial stages (still gathering building materials) I can't do anyting worthwile myself.
At best I can do some theoretical exercises but beeing a tube n0ob the outcome would probably be less than optimal. Trying to stay possitive...
You are spot-on conerning the cons, maybe I'll get adventurus when the panels are done? Hopefully someone else will have come up with something long before that.
Calvin, how important is this DC-free output? If I DC couple an SRPP-type amp, with say 2kV no-signal output to the stators, is that a problem? Aren't the stators insulated anyway for the high signal levels?
jan didden
Hi,
as long as both parts of the bridge remain balanced the DC-offset is of no interest signal-wise. Both stators would see equal potential, hence no potential difference. It must be ensured though that the potential difference remains zero under all circumstances, such as ageing and temperature.
Looking at the ESL-behaviour alone, a DC-Offset on both stators wouldn´t make a difference in the working of it (Diaphragm Bias Voltage should be re-thought). Looking at the ESL in a practical surrounding, the stators would exhibit a much higher voltage swing (it would aquire higher voltage potentials) with regard to earth potential. Since the stators don´t float with regard to earth potential, but are referenced via the amplifier towards earth potential. This puts much higher stress on the insulation. Besides the safety aspect, increased voltage stress leads to higher risk of flashover, speeded ageing of insulator materials and earlier breakdown.
I´m not completely sure about the effect of a constantly charged stator/insulator system, but on the surface of the insulation layer of the stator charge will accumulate, waiting on a leakage path to bleed away. This could be a any approaching object like a probing finger or the membrane. In case of the membrane touching the stator, it´ll most probabely keep attached till the charge has bleeded away. The recovery time will be high because the DC-offset of the amp constantely recharges the stator and its surface. A ground referenced stator´s recovery time may be just a fraction of a second long, depending on the insulation layers resisitivity and as such it´d be barely listenable.
But the most important deficiency remains the safety issue.
One might think about symmetrical power supply lines so that the DC-offset is at, or at least close to 0V.
jauu
Calvin
as long as both parts of the bridge remain balanced the DC-offset is of no interest signal-wise. Both stators would see equal potential, hence no potential difference. It must be ensured though that the potential difference remains zero under all circumstances, such as ageing and temperature.
Looking at the ESL-behaviour alone, a DC-Offset on both stators wouldn´t make a difference in the working of it (Diaphragm Bias Voltage should be re-thought). Looking at the ESL in a practical surrounding, the stators would exhibit a much higher voltage swing (it would aquire higher voltage potentials) with regard to earth potential. Since the stators don´t float with regard to earth potential, but are referenced via the amplifier towards earth potential. This puts much higher stress on the insulation. Besides the safety aspect, increased voltage stress leads to higher risk of flashover, speeded ageing of insulator materials and earlier breakdown.
I´m not completely sure about the effect of a constantly charged stator/insulator system, but on the surface of the insulation layer of the stator charge will accumulate, waiting on a leakage path to bleed away. This could be a any approaching object like a probing finger or the membrane. In case of the membrane touching the stator, it´ll most probabely keep attached till the charge has bleeded away. The recovery time will be high because the DC-offset of the amp constantely recharges the stator and its surface. A ground referenced stator´s recovery time may be just a fraction of a second long, depending on the insulation layers resisitivity and as such it´d be barely listenable.
But the most important deficiency remains the safety issue.
One might think about symmetrical power supply lines so that the DC-offset is at, or at least close to 0V.
jauu
Calvin
I have seen a working amp using 2 resistance loaded, (10mA springs to mind), pl509 (7kv anode max) running out of phase to drive a quad 57 panel directly, HT was around 4Kv IIRC, generated by a shoe box size capacitive multiplier, absolutely lethal. Sounded surprisingly clean and tight, especially low down, tops a bit down, could have been the amp or less than healthy old 57s, not sure, not very loud. If I was going to do something like this would use a switching PSUs, like 4 1kV sections in series to get the HT, as could use smaller caps, have current limit etc.
h
h
Hi,
I don´t know agree with "The best Cap is no cap".
First, a DC-blocking cap is just one cap. It works and works and works. It blocks DC from the very first moment till the very last. A DC-Servo is a bunch of parts among those typically 3 or more caps and an working behaviour that may lead to an indifferent status at power-up or power-down.
jauu
Calvin
I don´t know agree with "The best Cap is no cap".
First, a DC-blocking cap is just one cap. It works and works and works. It blocks DC from the very first moment till the very last. A DC-Servo is a bunch of parts among those typically 3 or more caps and an working behaviour that may lead to an indifferent status at power-up or power-down.
jauu
Calvin
Well, I started to read some but there are obvious errors there ... Caveat Emptor!
jan didden
Calvin,
You've got me convinced. The safety issue should get priority.
I have reworked my amp design for a zero volt no-signal on the stators. I dont think I need a differential servo, after all a stator DC difference of a few volts or even a few 10's of volts won't make much difference in the world of 4-7kV static bias to the diafragm I would think.
So I will go with a dual hv psu of +/-2700V or so. I'm talking to Pieter from Tribute transformers for heater & screen supply xformers that can swing 2.6kV and that have 50pF or less from secondary to RoW (Rest of the World).
Just simmed a hv regulator with current limit. Thank IXYZ for hv mosfets ;-)
Thanks for your advise guys,
jan didden
No that's not a good solution. The amp should have low enough offset designed-in. Adjustments are prone to error, drift etc.
jan didden
Maybe not a good solution for a conventional commercial product but this is "driving ESL with valves/tubes"
in "Planers and Exotics" at "DIY Audio"! So you gatta tweek some knobs, big deal!
A great man (I think it was Eistein?) once said: You should make it as simple as possible but not any more simple than that.
I've been wrestling with the same problem but in a smaller scale and in the end it would appear to boil down to two options.
Either go with output caps or opt for a servo?
I've been wrestling with the same problem but in a smaller scale and in the end it would appear to boil down to two options.
Either go with output caps or opt for a servo?