John Curl's Blowtorch preamplifier

[EUVL]

and one more :

 

[EUVL]

> Does it work?

Apparenty as ICs .....
It was from a patent that belongs to Intel.

The cascode transistors are MOSFETs, I think.


Patrick

 

[jan.didden]

I could be mistaken but I get the feeling that some here believe that their ears are sensitive enough to hear any alteration to an audio signal.
The fact is, human hearing has limits, and there are real (measurable) differences in audio signals that no one can hear.

To get a better sound, knowing what you can't hear could be just as important as knowing what you can hear.

Agree 100%.

Jan Didden

 

[john curl]

PMA that looks like the JC-1 input stage. Is it?

 

[jan.didden]

Which high rated audio product has Douglas Self designed?

Self doesn't require that his name is put on his products. I do know that he has designed lots of amplifiers for different customers. The latest I am aware of is the XD-series like the Cambridge Audio XD-840 cross-over displacement amps.

www.cambridgeaudio.com/assets/documents/840Awhitepaper8-2-06web.pdf

Basically doing to a class-B OPS what you guys always do to an opamp output stage.

Jan Didden

 

[john curl]

Jan, I don't recall my insisting of having my name or initials connected to a power amp since the Levinson JC-3 days. It seems that manufacturers find it useful in promoting the product and chose to do it without my advance permission.

 

[PMA]

Probably something like this, but drain resistors made all equal (possible as long as the VAS not connected yet).

 

[john curl]

I am posting the JC-1 input stage through SY. There are a few small changes, but it is much the same.

 

[PMA]

I was not sure if it would be appreciated. Anyway, it is interesting to see folded cascode influence, especially after closing feedback.

 

[john curl]

Auplater, do you know why superconductivity would bypass the 'residual resistance' of normal wire?

 

[john curl]

My real question about 'residual resistivity' is: Does it change with voltage level or current flow?

 

[john curl]

PMA, I am always interested in your input. Also what about that circuit that EUVL showed. What is its transfer function?

 

[PMA]

I would wait what SY is posting. The drawing I have has basic mistake - VAS cascodes have source and gate reversely connected, it would never work. Probably drawing mistake.

 

[jan.didden]

Jan, I don't recall my insisting of having my name or initials connected to a power amp since the Levinson JC-3 days. It seems that manufacturers find it useful in promoting the product and chose to do it without my advance permission.

John,

I didn't mean that in any negative sense. On the contrary, as a designer it makes sense to proudly connect to your product. I just mentioned it because of PMA's question. Some designers like Self work in the dark, so to say, so we don't know what they design and for whom.

Jan Didden

 

[PMA]

I get this ampl. plot, with VAS and FB (single ended input):

 

[Wavebourn]

I would wait what SY is posting. The drawing I have has basic mistake - VAS cascodes have source and gate reversely connected, it would never work. Probably drawing mistake.

Some MOSFETs are very symmetrical, so in reality it may work.

 

[PMA]

Not source vs. gate, I would guess.

 

[john curl]

I don't think there is a mistake. It is just the lettering.

 

[PMA]

How about the amplitude plot posted? Does it make sense?

 

[john curl]

Looks OK to me, because there is no local feedback.