Thank you .
PS - You did know VFA/CFA would merge , RN . Did you design/build
this already .... and dropped the hint just to see how fast we would
catch on (up) ?
OS
What? Who me? Get my hands dirty building something!? This is just an intellectual concept/idea. Now I suppose you'll have to name it after me or your first born son after me.
No. This is just like when I told Walt Jung to dc-servo his phono preamp because the coupling cap removal would lower cost and size and give better sound and lower group delay etc. His comment was... but what about the DC offset and drift at the output..... [phono stages have high LF/DC gain to make matters worse]. I had recently been reading about servo control systems so I said, 'servo it'. He asked what that meant. Then he went on and figured a circuit to do it and published it in TAA and the rest is history. No mention of me in it -- here I get a Thank You, at least. It was John Curl, who knew this dc servo was my idea and last year pointed it out to DIYAudio members on his forum.
It's only my concept/idea for you but you had to implement it on your circuit/design. How you do this is up to you and who am I to say that I would have the #1 best way. Others will find ways to do similar with thier circuits and produce variations.
I took a test once of my 5 top strengths. The test results for each of the top 5 characteristics all said the same thing. "Intellectual". I read and study a lot... jack of all trades and master of none.
Recently, two power amps I designed (but had others build) lasted me 10 years but recently I smoke tested them...blew them up. I am going to pay someone to fix them.
You guys hurry up and make me a great CFA design that I can buy to replace them (200W/chnl). I see a few very good ones here but still too much building involved so far. Some assembly work would be Ok, I guess.
Thx-RNMarsh
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I read of what you have done (achieved) , that was enough. Edmond and Zan
are "guru" level ... I can almost "wrap my mind" around their contributions.
But , they want to hit that "anal" level with 50 device masterpieces.
I have my Indian and Indonesian friends already making EF3's and my first
CFA + VFA. My track record for a perfected amp is written (BADGER).
My CFA will be just as "idiotproof"... and just as DIY friendly.
OS
Simplify where possible -
Enough of what? I'm just getting started.
_____________________
A couple years ago, I needed a buffer stage only to drive low Z headphones. I had a very nice buffer design (breadboarded) and it kept growing in number of transistors. When I reached 12 devices per channel... just for a buffer and had more additions in mind.... I said.. STOP. It is 24 devices for 2 channels and still growing?! For just a buffer?
That is when I took a fresh look at things and made a nice little headphone amp with just 8 transistors... gain with a buffer. Simple but very clean. With this result:
The moral to this story is... After you understand enough of what you are doing... go back and simplify where ever possible while keeping what is important.
You can also do this by distortion cancellation methods and with much less fb for removing the residuals..... with this approach there is a large possibility to have few devices and simpler circuits and still have very low distortion. I should think. Any takers?
Thx-RNMarsh
Enough of what? I'm just getting started.
_____________________
A couple years ago, I needed a buffer stage only to drive low Z headphones. I had a very nice buffer design (breadboarded) and it kept growing in number of transistors. When I reached 12 devices per channel... just for a buffer and had more additions in mind.... I said.. STOP. It is 24 devices for 2 channels and still growing?! For just a buffer?
That is when I took a fresh look at things and made a nice little headphone amp with just 8 transistors... gain with a buffer. Simple but very clean. With this result:
The moral to this story is... After you understand enough of what you are doing... go back and simplify where ever possible while keeping what is important.
You can also do this by distortion cancellation methods and with much less fb for removing the residuals..... with this approach there is a large possibility to have few devices and simpler circuits and still have very low distortion. I should think. Any takers?
Thx-RNMarsh
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Enough of what? I'm just getting started.
_____________________
A couple years ago, I needed a buffer stage only to drive low Z headphones. I had a very nice buffer design (breadboarded) and it kept growing in number of transistors. When I reached 12 devices per channel... just for a buffer and had more additions in mind.... I said.. STOP. It is 24 devices for 2 channels and still growing?! For just a buffer?
That is when I took a fresh look at things and made a nice little headphone amp with just 8 transistors... gain and a buffer. Simple but very clean. With this result:
View attachment 395689
The moral to this story is... After you understand enough of what you are doing... go back and simplify where ever possible while keeping what is important.
You can also do this by distortion cancellation methods and with much less fb for removing the residuals..... with this approach there is a large possibility to have few devices and simpler circuits and still have very low distortion. I should think. Any takers?
Thx-RNMarsh
That IS my "MO" , as well ... sometimes my lust for perfection will grow
to a "medusa" level circuit topology. Then I take out the trimmers and "chop".
DIY builders will be overwhelmed by special considerations concerning
a specific design(topology). I try to simplify these considerations to include as many
hobbyists as I can.
I was just as uninformed as they were, 5 years ago , ..... so to augment
a new DIY "experience" (for them) is a pleasure
. OS
My personal point of view is a careful trade off between complexity and reliability. Thing must always be as simple as possible. This is also why I have a hard time understanding the battle between believers of VFA/CFA are in contradiction.
Signal path must always be as short and with as few junctions as absolutely possible.Where look more lose on the component count is in the housekeeping.
I do like the distortion cancellations as pointed out by Richard, I like thinking in the concept of making something straight with the use of curves.
Signal path must always be as short and with as few junctions as absolutely possible.Where look more lose on the component count is in the housekeeping.
I do like the distortion cancellations as pointed out by Richard, I like thinking in the concept of making something straight with the use of curves.
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I sure do not want lots of parts
What I want is that simplicity that comes when you really understand a problem.
Low parts count from maximum efficiency.
It's kind of Zen that real cleverness can be in subtlety.
And I don't want to add parts to achieve utterly irrelevant "improvements"
I am with Andrew on this.
Best wishes
David
I am looking at the servo you put up OS and I am seeing another way to implement AFEC . . . .
Might an interesting way to inject the error signal into the system. The benefit here is not the distortion reduction you will get, but you get your DC offset correction and fantastic PSRR - 120 dB up to many 10s of KHz . . .
Might an interesting way to inject the error signal into the system. The benefit here is not the distortion reduction you will get, but you get your DC offset correction and fantastic PSRR - 120 dB up to many 10s of KHz . . .
I sure do not want lots of parts
What I want is that simplicity that comes when you really understand a problem.
Low parts count from maximum efficiency.
It's kind of Zen that real cleverness can be in subtlety.
And I don't want to add parts to achieve utterly irrelevant "improvements"
I am with Andrew on this.
Best wishes
David
Ostripper ,be carefull when you choose your current sources ,For example Q6 and Q5 is the worst CS in therms of stability with the temperature .With the supply voltage and the load the stability is very good compared to other topologies .This CS being the one which supplies the first stage is important also to have a small temperature drift .
I am looking at the servo you put up OS and I am seeing another way to implement AFEC . . . .
Might an interesting way to inject the error signal into the system. The benefit here is not the distortion reduction you will get, but you get your DC offset correction and fantastic PSRR - 120 dB up to many 10s of KHz . . .
Whoa.
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This is exactly why I advocate the floating central CCS- if you thermally bond them to the input-pair then thermal drift is compensated in a very good and simple way
BTW i think the current on demand feature of the CFA is the reason why it seems to sonically outperform the corresponding VFA's The gain structure is expansive in nature. a little like bjt-outputs also seems sonically expansive when compared to the corresponding FET's
Yes , the 2Q CS leaves a lot to be desired in the tempco arena. LED CCS's
are way better in this regard.
At under 2ma/device , ambient is the only consideration -
I'm working on this now.
OS
even Sterophile has printed a skeptical view of the idea: Euphonic Distortion: Naughty but Nice? | Stereophile.com
would you guys like to take the discussion to another thread instead?moved posts here:http://www.diyaudio.com/forums/everything-else/10653-listening-tests-2.html