Markus,
I guess you speak about http://www.dself.dsl.pipex.com/ampins/dipa/dpafig33.gif
which is the blameless amp. VAS is constituted by TR12 and TR4, Cdom is 100pF.
I guess you speak about http://www.dself.dsl.pipex.com/ampins/dipa/dpafig33.gif
which is the blameless amp. VAS is constituted by TR12 and TR4, Cdom is 100pF.
Hi ChocoHolic,
The true D Self 'Blameless' amplifier has 100pF C.dom, Darlington VAS, and output choke. It is further down the page you link.
The C.dom current becomes a much higher fraction of differential input stage tail current at high audio frequencies; this requires large differential sensed error to establish NFB loop controlled VAS drive, i.e. a greater high audio frequency distortion at the output terminal.
Maybe you are looking at D Self's generic amplifier which is shown for illustration purposes. This actually has an open loop which is flat to higher frequencies, but less NFB. Here the C.dom induced differential stage current error is relatively low.
Cheers ........... Graham.
The true D Self 'Blameless' amplifier has 100pF C.dom, Darlington VAS, and output choke. It is further down the page you link.
The C.dom current becomes a much higher fraction of differential input stage tail current at high audio frequencies; this requires large differential sensed error to establish NFB loop controlled VAS drive, i.e. a greater high audio frequency distortion at the output terminal.
Maybe you are looking at D Self's generic amplifier which is shown for illustration purposes. This actually has an open loop which is flat to higher frequencies, but less NFB. Here the C.dom induced differential stage current error is relatively low.
Cheers ........... Graham.
Hi Graham, PMA....
thanks.... I was refering to the first and very basic design
on that page....
Now I found the right one :
http://www.dself.dsl.pipex.com/ampins/dipa/dpafig33.gif
OK., here my points do not apply and I can also understand how
you state a gain of 3000 for the VAS. Thanks.
Well, philosophy seems to be a very high gain at low frequencies,
but integration with Cdom already starting at low frequencies...
...in general more critical for TIM distorsion...
but the high values of degeneration resistors (200mV...300mV drop)
of the input stage should make the design quite tolerant also in this regard and DC-offset as well....
Well, I did not hear it.... but I do not see many obvious inconviniences...
Bye
Markus
thanks.... I was refering to the first and very basic design
on that page....
Now I found the right one :
http://www.dself.dsl.pipex.com/ampins/dipa/dpafig33.gif
OK., here my points do not apply and I can also understand how
you state a gain of 3000 for the VAS. Thanks.
Well, philosophy seems to be a very high gain at low frequencies,
but integration with Cdom already starting at low frequencies...
...in general more critical for TIM distorsion...
but the high values of degeneration resistors (200mV...300mV drop)
of the input stage should make the design quite tolerant also in this regard and DC-offset as well....
Well, I did not hear it.... but I do not see many obvious inconviniences...
Bye
Markus
Mikeks,
Have you checked ?
i.e. do you know what you are writing about ?
Do a Sim with a meter in series with the differential inpt transistor to measure current flow at 10 to 20kHz when the amplifier load is a virtual loudspeaker system.
You will find the results matching what Destroyer hears, the input currents, and therefore NFB loop control become sharply non-linear,
Remember the current through the C.dom is 90 degree leading wrt signal voltage, this causes distortion at output stage voltage crossovers !!!!
Cheers ............. Graham.
Have you checked ?
i.e. do you know what you are writing about ?
Do a Sim with a meter in series with the differential inpt transistor to measure current flow at 10 to 20kHz when the amplifier load is a virtual loudspeaker system.
You will find the results matching what Destroyer hears, the input currents, and therefore NFB loop control become sharply non-linear,
Remember the current through the C.dom is 90 degree leading wrt signal voltage, this causes distortion at output stage voltage crossovers !!!!
Cheers ............. Graham.
Graham Maynard said:
As a result of degeneration first stage distortion in Self's design is negligible...although the current demanded of the input stage increases with frequency.....
Graham Maynard said:
Graham...surely, you (in the UK), can have no way of knowing what Destroyer in Brazil 'hears'....or not as the case may be....
There are many good technical reasons why Self's design isn't entirely blameless....but this is most certainly not one of them...
Graham Maynard said:
The phase shift is to be expected of an integrating loop....and of itself, causes no distortion in the output stage.....whatsoever....
Let me give some inputs to you all
I am not an enginneer, so, C dom and those things have small meaning to me, it is alike a computer to an ape.... but i am very skilled related hearing things, compare equipments, ressonances, frequencies and more than 4036 amplifiers constructed... cannot say better words to you put in equations, but i can be helpfull with my example:
I was a ham, and a CBer to.... radio was one of my hobbies since 1969, and i learned one thing:
Despite of expensive enormous ham radios, one simple radio transceiver, called cobra 148 GTL beated all them, some of them 25 times Cobra price, from Dynascam Corporation. Not standard, already modified radio to 10 meters band, this when re adjusted 1 Megahertz up related to standard frequencies, and still works very good... silent radio, good audio and in special
When hearing three persons talking some time, same frequency, you making efforces, with attention you can separate them.... hear what one is talking and the others are there talking to...but those audios do not mixed one each other in a "beat" frequency way... they not confused into a fourth confused sound.... i could separate them.
Also i perceive too much high frequency, and not so good bass related its precision.... audio poor.... worst than very cheap chip amplifiers, with condenser coupled output... i was frustrated.
Sorry to say, i am not an animal always...but i give a 12 gauge shot and the circuit is already vaporized.... also i spell the worst words i could find in my memory in 5 languages.
I read the hell amplifier text, and i suppose, so experienced doctor, and so many tests... at least a good audio.... alike common amplifiers audios.... not outstanding... but clear, not crispy and sametime mufled in highs.
If this can help you..... you will have to translate to Long tails, C dom, CCS, output coils and understand what i say.
But i thank all of you efforts, my dear friend Chocoholic trying to save the circuit.... this is kind Chocoholic....but i think if you hear this circuit... you will go klimbing your mountains and will throw them away, the amplifier, when reached the top highs.
I am already a little bit damned with that amplifier.... my ears are not a trash box!
Carlos
I am not an enginneer, so, C dom and those things have small meaning to me, it is alike a computer to an ape.... but i am very skilled related hearing things, compare equipments, ressonances, frequencies and more than 4036 amplifiers constructed... cannot say better words to you put in equations, but i can be helpfull with my example:
I was a ham, and a CBer to.... radio was one of my hobbies since 1969, and i learned one thing:
Despite of expensive enormous ham radios, one simple radio transceiver, called cobra 148 GTL beated all them, some of them 25 times Cobra price, from Dynascam Corporation. Not standard, already modified radio to 10 meters band, this when re adjusted 1 Megahertz up related to standard frequencies, and still works very good... silent radio, good audio and in special
When hearing three persons talking some time, same frequency, you making efforces, with attention you can separate them.... hear what one is talking and the others are there talking to...but those audios do not mixed one each other in a "beat" frequency way... they not confused into a fourth confused sound.... i could separate them.
Also i perceive too much high frequency, and not so good bass related its precision.... audio poor.... worst than very cheap chip amplifiers, with condenser coupled output... i was frustrated.
Sorry to say, i am not an animal always...but i give a 12 gauge shot and the circuit is already vaporized.... also i spell the worst words i could find in my memory in 5 languages.
I read the hell amplifier text, and i suppose, so experienced doctor, and so many tests... at least a good audio.... alike common amplifiers audios.... not outstanding... but clear, not crispy and sametime mufled in highs.
If this can help you..... you will have to translate to Long tails, C dom, CCS, output coils and understand what i say.
But i thank all of you efforts, my dear friend Chocoholic trying to save the circuit.... this is kind Chocoholic....but i think if you hear this circuit... you will go klimbing your mountains and will throw them away, the amplifier, when reached the top highs.
I am already a little bit damned with that amplifier.... my ears are not a trash box!
Carlos
A little extreme, but I LIKE IT!
Quite right, Mr. Ape sir. Your slide-rule might like the amp for it's paper design but it's your ears that are the dependable judge.
Knows, not nows... why did you put this "K"...we do not pronunciate
Is this "k" to the "scoppers".... the MR. Metering..... i am thinking when in love.
Stop my dear!
Why darling?
I will measure how much excited you are!
Carlos
Is this "k" to the "scoppers".... the MR. Metering..... i am thinking when in love.
Stop my dear!
Why darling?
I will measure how much excited you are!
Carlos
The scratch show some idea, of how we can be maniac
This is an audioholic, audiomaniac, audiolover, full of passion, alike some of us, whe go to sleep and so crazy that goes with their measurement instruments.
I cannot be responsable of poluted mind thinking, they are wrong!
If you misunderstood, ask me, do not go on creating ghosts or bad things.
If Exterminators kick me out, i will promiss, i will be back with a 100, a hundred, a hundred thanks to you all.
Carlos
This is an audioholic, audiomaniac, audiolover, full of passion, alike some of us, whe go to sleep and so crazy that goes with their measurement instruments.
I cannot be responsable of poluted mind thinking, they are wrong!
If you misunderstood, ask me, do not go on creating ghosts or bad things.
If Exterminators kick me out, i will promiss, i will be back with a 100, a hundred, a hundred thanks to you all.
Carlos
Attachments
Yes, naturally i made a lot of checkings and diferent tests.
I changed bias to try better reproduction, reduce more the bias too, change some resistor values, i changed also differential current, i increase the supply voltage, reduced the off set (very big 130 mV first time), changed some transistors to hi speed ones, changed speakers too, are there 5 under my bed... 3 pairs is industrial brands, and two hand made, removed the output coil, reduced the condenser... the 100 pf one, changed the input condenser, try to reduce this one too. use it with 16 ohms and 4 ohms, plugged headphones with charge resistors, and some resistance in series with headphone... when sure.... give a shot into the board, because no doubts a non good sounding amplifiers.
regards,...maybe something i forgot could do better result, i always think this way.... so, not to loose more time in my life, because never could transformed so bad sound into some reasonable sound i finish with it...but curious if someone could make it sound very good...ot at least good.
As a reference for you, i like some old Macintosh tube models, and i love the jlh class A designs.....not more is comparable, always less then JLH....those last 7 years, a reference to me...could not find better than.... always worst than.
Carlos
I changed bias to try better reproduction, reduce more the bias too, change some resistor values, i changed also differential current, i increase the supply voltage, reduced the off set (very big 130 mV first time), changed some transistors to hi speed ones, changed speakers too, are there 5 under my bed... 3 pairs is industrial brands, and two hand made, removed the output coil, reduced the condenser... the 100 pf one, changed the input condenser, try to reduce this one too. use it with 16 ohms and 4 ohms, plugged headphones with charge resistors, and some resistance in series with headphone... when sure.... give a shot into the board, because no doubts a non good sounding amplifiers.
regards,...maybe something i forgot could do better result, i always think this way.... so, not to loose more time in my life, because never could transformed so bad sound into some reasonable sound i finish with it...but curious if someone could make it sound very good...ot at least good.
As a reference for you, i like some old Macintosh tube models, and i love the jlh class A designs.....not more is comparable, always less then JLH....those last 7 years, a reference to me...could not find better than.... always worst than.
Carlos
"What Destroyer is hearing arises when you loudspeaker load a Miller VAS C.dom stabilised bipolar class-B amplifier circuit, like the D Self Blameless. The change in reproduction is caused by load angle PLUS C.dom shift.
The output stage reverse commutates through a fraction of its crossover bias potential in order to create the differential stage error necessary for the input stage to lead-charge the C.dom."
A "Miller VAS C.dom stabilised bipolar class-B amplifier " covers a lot of territory. Way beyond just Self and his Blameless. Is all three factors individually?
--- Miller VAS C.dom stabilised
--- bipoloar
--- class-B
Or is it the combination of the three? How about "Miller VAS C.dom stabilised MOSFET CLASS-A amplifier "?
Could you provide some examples (with at least generic/public domain schematics) you feel good about that avoid the faults listed above. I'm not being contentious, it's genetic/environmental; my grandmother came from Missouri where they have the saying: "I'm from Missouri, show me."
The output stage reverse commutates through a fraction of its crossover bias potential in order to create the differential stage error necessary for the input stage to lead-charge the C.dom."
A "Miller VAS C.dom stabilised bipolar class-B amplifier " covers a lot of territory. Way beyond just Self and his Blameless. Is all three factors individually?
--- Miller VAS C.dom stabilised
--- bipoloar
--- class-B
Or is it the combination of the three? How about "Miller VAS C.dom stabilised MOSFET CLASS-A amplifier "?
Could you provide some examples (with at least generic/public domain schematics) you feel good about that avoid the faults listed above. I'm not being contentious, it's genetic/environmental; my grandmother came from Missouri where they have the saying: "I'm from Missouri, show me."
Interesting Mikek, your University where very good
And maybe the others had not so many good chances as you have, or, they did not studied hard to go deep in electronics, i was starting to have one little idea, that i could see you with different ideas related others..... many times having reverse ideas, this is interesting, i will be more atention in your threads and the place you are, to learn more, because if you do not agree with so many people, normally do not agree, is because you knowledge is deeper, if i am not wrong... this way, following the leader!
Or the artist of the controversy....hummmmm i think not...yes, not, yes, not..... i am having the bacteria of controversy too.
Carlos
And maybe the others had not so many good chances as you have, or, they did not studied hard to go deep in electronics, i was starting to have one little idea, that i could see you with different ideas related others..... many times having reverse ideas, this is interesting, i will be more atention in your threads and the place you are, to learn more, because if you do not agree with so many people, normally do not agree, is because you knowledge is deeper, if i am not wrong... this way, following the leader!
Or the artist of the controversy....hummmmm i think not...yes, not, yes, not..... i am having the bacteria of controversy too.
Carlos
Forget measurements, it wasn't my concern. It is easy to measure subjective preference while still eliminating psychological bias -- it's called blind testing. It is the failure of blind tests to show differences between amplifiers, cables, etc. that is the damning of Subjectivists.
/ Bobby -- can't really hear a difference so I had to come up with other excuses to myself for using seven dollar resistors.
/ Bobby -- can't really hear a difference so I had to come up with other excuses to myself for using seven dollar resistors.
Prune said:
Not exactly. I am doing blind tests and they bring pretty nice results. Depends how you do them. The switchbox changing between "A" and "B" every 5 seconds is not the way how to do it.
BTW, I hate dividing between subjectivists and objectivist. To be a good designer, you must do both. The blind designer only measures.
"It is easy to measure subjective preference while still eliminating psychological bias -- it's called blind testing. It is the failure of blind tests to show differences between amplifiers, cables, etc. that is the damning of Subjectivists."
You want to start a really bitter fight in Audiophiland just mention ABX. You would get more respect if you were a child molester. 🙂
Nonetheless you might find www.pcabx.com interesting
You want to start a really bitter fight in Audiophiland just mention ABX. You would get more respect if you were a child molester. 🙂
Nonetheless you might find www.pcabx.com interesting
I never mentioned ABX. There are various ways to do blind testing (and actually it should be double blind). ABC/HR for example may be better for audio use.
(BTW there's ABC/HR software to compare sound files, such as compressed/decompressed with different codecs, at http://ff123.net/abchr/abchr.html)
(BTW there's ABC/HR software to compare sound files, such as compressed/decompressed with different codecs, at http://ff123.net/abchr/abchr.html)
Hey, guys, I split out all this stuff into the "Yardstick" thread in Everything Else. That took me some time and effort. Please use that other thread for ABX and related discussions.
we were moved guys, because we change too much the mains subject...
And we made that too long... this way, friend Sy moved us...lets go ahead in everything else, this way, we can scape more freely.
no problems, he is a friend, i like him.
Carlos
And we made that too long... this way, friend Sy moved us...lets go ahead in everything else, this way, we can scape more freely.
no problems, he is a friend, i like him.
Carlos
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