molybdenite?
http://www.diyaudio.com/forums/ever...lybdenite-transistor-new-wonder-material.html
Molybdenite transistor is a first - physicsworld.com
[I"...]molybdenite is an inherently two-dimensional material..."[/I]
(somewhere in the reading of this material about molybdenite, was the specific mention of the quality of the handling of micro transients -in such transistors)
http://www.diyaudio.com/forums/ever...lybdenite-transistor-new-wonder-material.html
Molybdenite transistor is a first - physicsworld.com
[I"...]molybdenite is an inherently two-dimensional material..."[/I]
(somewhere in the reading of this material about molybdenite, was the specific mention of the quality of the handling of micro transients -in such transistors)
Last edited:
Jan,
As several people have noted, you don't want to heavily forward bias the G-S junction. The change in drain current with gate voltage in a jfet is associated with the depletion region of the G-S junction modulating the resistance between D-S. For an n-channel jfet, a negative G-S voltage increases the depletion region and reduces the D-S current by decreasing the area for conduction between Drain and Source. A slight positive voltage (<300mv) shrinks the depletion region slightly and gives more current than the nominal Idss value. But if you keep raising the G-S voltage then you start turning on the G-S junction and further increases in source current don't give you any significant increase in drain current. And you run the risk of burning out the device if you raise Vgs too high, since the gate current will rise exponentially with gate voltage. So proceed with caution.
---Gary
You guys worry too much. I am NOT advocating overdriving the gate for an extended time, just time enough to charge any compensation caps so that they don't slow the design around. Many here apparently have little experience with fets and their 'limits'. I was first shown that you could show what happens when you OVERDRIVE the gate of of jfet, by Bascom King, a colleague then, as now, with a semiconductor curve tracer. It did not break the device and the Gm continued to rise above Idss with no real 'breaks' in the transfer function with reasonably low Z drive.
For some reason, everybody forgets that TRANSMITTER tubes have been driven this way way for close to a century.
For some reason, everybody forgets that TRANSMITTER tubes have been driven this way way for close to a century.
What I like in Jon's amp, it is not about "no forward bias" of jfets. What I like, diffstages bootstrap each other minimizing distortions such a way. And limit peak current as well.
What I don't like, JFETs are unpredictable in manufacturing. I still have that 30 years old habit thinking in terms of IC manufacturing, hard to forget...
What I don't like, JFETs are unpredictable in manufacturing. I still have that 30 years old habit thinking in terms of IC manufacturing, hard to forget...
Well, we have given the complementary differential fet input design a real, 40 year run, so far. We have many thousands of amps, and preamps out there, made by Levinson, Ayre, Parasound, Dennesen, CTC Blowtorch, etc. Somehow we have gotten away from the 'potential' problems. Many 'potential' problems, like input current overdrive, are over-blown by designers not as experienced, and we should discuss them here, in more detail in due time.
Last edited:
Hi,
I have found the precise same announcement at the Hong Kong, Shenzhen and Canton Tube, but not the Beijing one. It even had a british accent! talk about freaked out!
The Hong Kong MTR has "gap's" that make the worst I encountered in London look small (try University Station on the West Line). Most HK people are wee bit smaller and look like they could straight fall through gap (I'd get stuck, barely). The New Yawk Subway and Suburban trains also have some dodgy platforms!
So, laddies and gentlefolks, mind the (band) gap.
Ciao T
I have found the precise same announcement at the Hong Kong, Shenzhen and Canton Tube, but not the Beijing one. It even had a british accent! talk about freaked out!
The Hong Kong MTR has "gap's" that make the worst I encountered in London look small (try University Station on the West Line). Most HK people are wee bit smaller and look like they could straight fall through gap (I'd get stuck, barely). The New Yawk Subway and Suburban trains also have some dodgy platforms!
So, laddies and gentlefolks, mind the (band) gap.
Ciao T
Last edited:
I'm not worried Wavebourn. I am 'three score and ten' or 70 years old, and at the top of my design popularity. IF your output stage would give an advantage to audio quality, I would give you every acknowledgment that you would deserve. I am only here to serve making audio quality the best that it can be with existing components. Unfortunately, you have always seen me as a 'competitor' who you must 'compromise' when I could have been a colleague.
Input current overdrive is not a problem in 'your' input stage. It might be a problem when the JFET circuit is poorly designed. Anyway, it is good to point at this possible problem.
'Your' input stage had been analyzed (including distortions) here in deep about 2 years ago and one would hardly bring anything new.
You may want to add to that list Accuphase, Luxman and a miryad of Japanese home builders. I've seen this topology many times in "Musen to Jikken" magazine, first time somewhere around 80-81.
John, please define the term "'potential' problems".
Are you saying that:
a) there are no problems, or
b) there are problems, but they're not relevant to this type of topology or this particular design, or
c) the problems are of imaginative nature, put forth by designers lacking the years of experience with this particular topology?
Best,
Have you forgotten that Great Britain governed Hong Kong until some years ago?
Shenzen is a neighboring city to Hong Kong.
Which reminds me.
Prior to it's independence, Israel was governed by Great Britain. Naturally, in the first years of it's independence and many years afterwards, Israeli telephone and radio services were British ones and were maintained according to British standards.
Imagine what Israeli Post Service, Police, Military uniforms and trainings, municipality services and much more looked like in Israel's first years… all were direct continuity of the British legacy.
I've always seen you as a good collegue that thinks too good about his thelepatic abilities that are actually bad.
- Status
- Not open for further replies.