Stinius, your drawing isn't very clear, because it doesn't show where crossing lines connect. The JFETs may be paralleled, only it isn't clear.
Joshua_G said:
Joshua
It's not my drawing, it's the drawing from courage, the same one that you have been discussing in your posts.
Stinius
It is probably best not to parallel fets for current drive input, no matter what the Z is. It is also probably unnecessary as well.
When I make products that go down to 0.4nV/rt Hz or less, as I have done for the last 35 years, I MUST parallel devices, however the drive has never been about 40 ohms at most, from any MC phono cartridge source designed for the preamp.
If however, I was designing for MM cartridges, I would not parallel input devices, because the non-linear input C would intrude as added distortion.
When I make products that go down to 0.4nV/rt Hz or less, as I have done for the last 35 years, I MUST parallel devices, however the drive has never been about 40 ohms at most, from any MC phono cartridge source designed for the preamp.
If however, I was designing for MM cartridges, I would not parallel input devices, because the non-linear input C would intrude as added distortion.
John,
If I understand your comment, the Toshiba BL-type can be used as single devices without any problem (dissipation, etc) whatsoever, right?
What improvement do you suggest for the servo circuit?
Joshua,
Gates are connected to each other, Drains are connected to each other and Sources are connected to each other. Due to software limitations the connections are not that clear, I agree.
The schematic you posted recently, was drawn by me btw.
If I understand your comment, the Toshiba BL-type can be used as single devices without any problem (dissipation, etc) whatsoever, right?
What improvement do you suggest for the servo circuit?
Joshua,
Gates are connected to each other, Drains are connected to each other and Sources are connected to each other. Due to software limitations the connections are not that clear, I agree.
The schematic you posted recently, was drawn by me btw.
Joshua_G said:
Ok fine, but if you see it as a cascode how do you think the circuit would work, and what would the output look like?
Stinius
Joshua_G said:
They are drawn, drain to drain, gate to gate, source to source. Maybe there is a terminology misunderstanding, but I would call that in parallel.
Not that important, I agree that paralleling is only really useful at the lowest noise MC level. If you put a 100K pot in front of this as a line amp you could have an unnecessary component of level dependent distortion.
courage said:
So why not draw the new schematic with the same software?
Do you intend to actually build the circuit?
stinius said:
You can see examples of double cascoding on Borbely website, for instance.
The effect would be higher noise and distortion.
Joshua_G said:
You already mentioned this twice. Care to share some results showing increased noise and distortions in a cascode stage? If it's so bad, why do you thing people stubbornly use cascoding all over?
scott wurcer said:
That's a good thing. Like the desperation of war, it produces it's own momentum and impetus in the given areas of technology/physics. Mental breakdown of self erected barriers is necessary to produce results.
Taking physics 'as-is' as a model to perfectly predict the future of technology advancement and physics is absurd as saying that you have journey in front of you and you don't know at all where it will take you, but you are laying a stick down in the sand that points in the direction you want to go--and you will not alter that direction of and in your journey --at any cost-- whatsoever.
This is also the same nature of many comments here on this thread about how a given item, circuit or component, construction, or whatever will affect a given audio design when it comes to results that are heard.
Things that you do not understand will by their very nature appear as a giant unknown and be outside of your experience or capacity to recognize or evaluate. This point is most important to understand: It is the basic required mental condition of recognizing the fact of the existence of an unknown.
If the given reader of this post disagrees in some form with the basic statement or allusion in this posting, I would suggest you see a psychiatrist. I state this in all seriousness.
jneutron said:
That's all very impressive and I will not attempt to take anything away from it. I find it intriguing and if we spent some time, I daresay you would end up showing me a bunch of things I don't already know. To me, that is the best scenario I can hope for.
It is impressive, but it does not say in any way, shape, or form that you can design a great sounding piece of audio gear, whether or not you have your priorities straight with regards to human listening being a powerful tool in that endeavor---or if you can or do learn from the experience of others with regards to such.
KBK said:
It in no way has any bearing on whether or not I can make a great sounding piece of audio gear. It was a direct response to the statement that I only make coils for a living. What I do for a living is considerably more diverse than what a detractor would have people believe.
It describes experience which is consistent with the discussion. Nothing more, nothing less.
Cheers, John
Getting back to the latest circuit: I think that paralleling input devices to get higher operating current is a good idea, even if not ideal, because of the added nonlinear capacitance. The original schematic was very clear, and laid out like a flower, which I prefer. The parallel schematic was initially confusing, partially because of how the paralleled input devices were added and because there were no crossovers. Still, it is a useful schematic, once we look it over carefully.
john curl said:
Thank you.
What do you think would be better: using single V devices, or paralleling BL devices?
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