Darkshy, take a stress pill and think things over! ( Who said that? Hmm..)
Seriously, I agree CFB is the champ, normally. Usually simpler topology but used asymmetrical, the DC may be an issue.
As I see it, the high SR is a side effect of a high NFB and that usually reduces THD. Of course, to get a high SR you will also have stages that can deliver high current.
But.... High SR if of no use in itself. The audio signal can never provoke the amp to maximize the SR if it's too high.
But.... It's intersting to watch how an amp recovers from the saturation ( square wave for example ). I think it says something about it's stability.
I made a mosfet amp some years ago. It measured quite well. The square wave response was good but not extreme ( lika with a no NFB amp ).
Then I tweaked it a bit and inserted a capacitor from the VAS output to the LTP. That did only affect the behavior above 300khz.
But.... the square wave response went stratospherical. A 20khz wave and with a 1uf load and there were no ringings what so ever, and that's not usual.
And furthermore, the soundstage opened up, but that might have been imagination but I don't think so. For some absurd reason it seems that the behavior abover 200khz has a very powerful effect on the subjective impressions. The amp sort of opens up.
But.... I admit, I think it is great, but I think my later amps is much more satisfying, so I donated it to some people in need for a good power amp.
Here it is:
www.diyaudio.com/forums/solid-state/281519-ndh-mosfet-amplifier-explained-detail.html
Seriously, I agree CFB is the champ, normally. Usually simpler topology but used asymmetrical, the DC may be an issue.
As I see it, the high SR is a side effect of a high NFB and that usually reduces THD. Of course, to get a high SR you will also have stages that can deliver high current.
But.... High SR if of no use in itself. The audio signal can never provoke the amp to maximize the SR if it's too high.
But.... It's intersting to watch how an amp recovers from the saturation ( square wave for example ). I think it says something about it's stability.
I made a mosfet amp some years ago. It measured quite well. The square wave response was good but not extreme ( lika with a no NFB amp ).
Then I tweaked it a bit and inserted a capacitor from the VAS output to the LTP. That did only affect the behavior above 300khz.
But.... the square wave response went stratospherical. A 20khz wave and with a 1uf load and there were no ringings what so ever, and that's not usual.
And furthermore, the soundstage opened up, but that might have been imagination but I don't think so. For some absurd reason it seems that the behavior abover 200khz has a very powerful effect on the subjective impressions. The amp sort of opens up.
But.... I admit, I think it is great, but I think my later amps is much more satisfying, so I donated it to some people in need for a good power amp.
Here it is:
www.diyaudio.com/forums/solid-state/281519-ndh-mosfet-amplifier-explained-detail.html
How to believe that everything is well researched when engineers go very deep and more Mathematical than needed ?
1.41 3.1415
Also nothing is well explained.(simple)
Every information I have readt on the internet is a total bulshit that confuses the newbies. I wanted to learn by myself but i didn't had the time and the patience so I decided to skip this for a while. Then I found only confusing info that kills your inspiration and moved to the SMPSes.
I found a time and learned by myself as I planned to do so.
There weren't another variant as nothing is explained at all.
And I learned everything with tricks, not the deep way 3.14+sin*cos/53
Our brains are not CFB's with high SR
Well researched means to not think too much about it and to let the knowledge arrange itself as it happened to me.
I have always understanded electronics (ultimate simple) but the audio part was very difficult one(and the most interesting when the fb circuits kicked in)
and I paused the learning because the balance of my interest moved more to the SMPS circuits, I didnt managed to get a good SMPS from 12V but managed to get one from 220 that worked very good and made it also a PCB which was the biggest pleasure in my life
there is nothing new under the sun, always there is smth new under the sun...
always different - always the same
People think there is nothing to improve but this is not true, they are hallucionating and flying in the future, living in a pink world.
Its not true because for example: almost every stage must be driven with an EF stage because EF stages are killing the bad capacitors faster.
the stages must be high current ones
...
Im in a very freaked condition now because I learned 10000 good things at the same time and now see the picture clear.
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multiple post spam because Im in very hurry and didnt have time.
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You shouldn't search an issue of the-best the-best (the champagne as you said) because the perfect thing has no issues. Search and this means you're not sure.
The my latest design has a 2mV offset and drive an unbiased stage like its biased
OH MY GOD BROO, its the half effect (not the side) with the linearity the other one and there are a 3rd effect also which is the fb effect, the combination of these to effects. Look how deep the engineers went in. Very sad.
Ofcourse it reduces THD, it gives a speed to the linearity.
High current stages are needed everywhere because they have only benefits.
Its better to have a reserve for just in case, especially when you dont lose something. CFB beats with 2 pluses, people prefer VFB more
My favourite is the single transistor opamp:
npn inverter+cfp vas loaded with css,bootstrap,resistor combo
Yes the stability and that it can drive an unbiased output stage like its biased
dont hallucinate
There is a circuit representation on the MC33078 Datasheet. Alternatively see that for LM833P (as distinct from LM833N).
C'mon guys,
he has already proven his way of thinking in 'alternative facts' very well in this posting he started another thread with: http://www.diyaudio.com/forums/solid-state/305696-single-transistor-op-amp-circuit.html#post5029873
His circuitry shows one transistor, and another one, and finally yet another one, while he claims this to be a 'Single transistor Op-Amp circuit'.
I remember an old Medicine Head song from the early 1970ies, called 'One and One is One'. Now, does 'One and One and One is One' still hold true?
Best regards!
he has already proven his way of thinking in 'alternative facts' very well in this posting he started another thread with: http://www.diyaudio.com/forums/solid-state/305696-single-transistor-op-amp-circuit.html#post5029873
His circuitry shows one transistor, and another one, and finally yet another one, while he claims this to be a 'Single transistor Op-Amp circuit'.
I remember an old Medicine Head song from the early 1970ies, called 'One and One is One'. Now, does 'One and One and One is One' still hold true?
Best regards!
To me it looks like MR is to invert the phase and reduce the output impedance due to the local feedback loop. That is not necessary with a BJT output stage.
Also the current drive for a MOSFET is modest in comparison to that required for a BJT as in my asc where the CCS loaded NPN driver operates in single-ended Class A.
My a.s.c file shows for an output standing current of c.160 m.A. the emitter current for the driver transistor is c. 50 m.A.
I have chosen the values to keep heat dissipation low - I will be using the regulated power supply of +/- 22 volts for my Linsley-Hood 1996 amplifier. This is bulky and generates a lot of heat - so much so I put the supply in a separate case with a plug in connection for an umbilical cable to the amplifier.
Up until recently I had intended building a directly coupled version of Linsley-Hood's 1970 Class AB amplifier which also uses a Class A driver which I also modeled. The lead up article to this was "Class Distinction in Audio Amplifiers" which was controversial at the time but well worth reading the three parts which can be accessed here The Class-A Amplifier Site - JLH Class-AB Amplifier
Darkshy.
Diyaudio is a harsh environment. It you do something crappy and but are passionate, people will ridicule you.
If you do something good, people will ignore you ( and probably steal the idea ).
If you do something totally crappy, people will love you and the thread will live on for eternity.
The only amps that will get attention are the blameless "Douglas Self approved" ones, since he has the science on his side.
Of course we have the Passlabs section where audiophiles of all types may find an asylum, but it's exclusively for Nelsons designs.
Darkshy, you will sooner or later come up with a good amp, but you need to chill down. Experience takes time to gather.
Diyaudio is a harsh environment. It you do something crappy and but are passionate, people will ridicule you.
If you do something good, people will ignore you ( and probably steal the idea ).
If you do something totally crappy, people will love you and the thread will live on for eternity.
The only amps that will get attention are the blameless "Douglas Self approved" ones, since he has the science on his side.
Of course we have the Passlabs section where audiophiles of all types may find an asylum, but it's exclusively for Nelsons designs.
Darkshy, you will sooner or later come up with a good amp, but you need to chill down. Experience takes time to gather.
I modeled the Linsley-Hood 1970 Class AB as a direct-coupled circuit with a Constant Current Load for the Voltage Amplification Transistor.
The asc file for this, and the Cordell-Models txt where the .models for the transistors were found, are attached.
The value of R20 sets the output dc offset - in practice a trim-pot in series with a resistor and R9 sets the output stage standing current - also a trimpot in series with a low value resistor.
I was considering this circuit as lower dissipation replacement for my Linsley-Hood 1996 Class A amplifier with options to run in Class A or Class AB.
However the driver transistor Q4 runs at a fixed current level of 70 m.A. for an output stage standing current up to 200 m.A.
Although less efficient than a push-pull circuit, in Class AB the overall heat dissipation will still be less than the 1996 Class A amplifier.
The asc file for this, and the Cordell-Models txt where the .models for the transistors were found, are attached.
The value of R20 sets the output dc offset - in practice a trim-pot in series with a resistor and R9 sets the output stage standing current - also a trimpot in series with a low value resistor.
I was considering this circuit as lower dissipation replacement for my Linsley-Hood 1996 Class A amplifier with options to run in Class A or Class AB.
However the driver transistor Q4 runs at a fixed current level of 70 m.A. for an output stage standing current up to 200 m.A.
Although less efficient than a push-pull circuit, in Class AB the overall heat dissipation will still be less than the 1996 Class A amplifier.
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