From your link:
VFA: Two gain stages (LTP+TIS) = higher OLG
CFA: One gain stage – 2nd stage TIS/TAS = lower OLG
I don't agree neither. You can give some gain to the first transistor in the loop (that subtract feedback from input signal), or not, it is always (IMHO) a CFA because it don't change the way it works.
ex, from this forum:
https://www.diyaudio.com/forums/att...al-mosfet-amplifier-vssa-mosfet-amplifier-jpg
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No I do not agree with you. But remember I was at the time talking about mainstream CFA and VFA to try to capture the essence of what the differences were which was a large part of the original discussion here in DIY audio.
But, given the history of the discussions around this subject, I can tell you it will quickly descend into hell.
Let each believe in what they feel makes them happy (like religion!) but never discuss it publicly.
You can PM me.
But, given the history of the discussions around this subject, I can tell you it will quickly descend into hell.
Let each believe in what they feel makes them happy (like religion!) but never discuss it publicly.
You can PM me.
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The stupidity of some humans will always surprise me ;-)
VFAs and CFAs can both achieve excellent results, as you perfectly know. Some people believe the two topologies can bring a slightly different sonic character, others not, some can prefer one, others the other.
I greatly appreciate my friends are not in love with my girl friends ;-)
On my side, I use and design both for what i believe (or feel) they are best. Blondes or brunettes.
I feel sad it is impossible to discuss of the ways to design each at its best, avoiding errors, understanding the way they both work. That is quite simple, in reality.
[edit] I will not PM you about this subject for a reason you can understand. It seems you design both amps since enough time and knowledge to know what you are doing and the ways you prefer to take. A discussion about the good practice of a religion is, for me, like discussing about the angel's sex. ;-)
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Good!
Some famous people round here won't consider to answer you in private, but they are the first to fire you publicly in a very sustained and aggressive manner.
They need to show who's the Alpha male here and then they'd invite you in private only for others to see once again what favours they made for you but i'm sure it's not what you intended.
If you are talking of me, I don't see where i was agressive at all, and specially against Bonsai (who is one the contributors I always read with interest and sympathy) .
To disagree about a technical point is agressive, in your way to see the things ? What could-we speak of in this forum, if we cannot exchange ideas ?
(The most funny is I did not realized at all he was the author, following the link of Richard, answering to *him*.)
And if you are referring to Bonsai (your message is not so clear), he was not neither agressive at-all, while he said, as i did , he disagreed. That a simple way to say we... do not agree about something ;-)
By the way, about male alpha and aggressivity, what do you think of your intervention ?
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🙂
Sorry, about the Alpha male... i'm listening to Flashdance right now so i'm penetrated by the 80's spirit.Relax!
Sorry, about the Alpha male... i'm listening to Flashdance right now so i'm penetrated by the 80's spirit.Relax!
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I hope you guys do realize that the moderators of diyAudio banned Michael Kiwanuka, the most ferociously (viciously!) loud advocate of the idea that Current Feedback Amplifiers most definitely are X, and most certainly are NOT Y. I suggest you look at his final 200 posts to find out "how to get banned forever".
see https://www.ovationhifidelity.com/w...-Introduction-to-CFA-Amplifiers-for-Audio.pdf
tells it all, accurately. .
-RM
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A joke or a wink: ;-)
Attachments
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No offence, neither. Just a strange idea you had, if I was your target, that a cartoon character could be concerned by its virtual image ?
I was asking myself (and still ask) why my post could be seen by you as agressive, while it was totally friendly in my purpose.
No this wrong, and easily shown by simulation as he says. The H-bridge amplifier has a fixed gm set by the bridge resistor and input transistors gm and hence constant GBW.
You're the only one to feel anything about it! That's actually a good thing.The others are just waiting for your mistakes.You're hunted now.Be silent and wait for your enemies to get sick 🙂
Just reminded me when talking about filtering inputs and bipolar or fet ---
Plus, many people hear the affects/effects of interconnects ---
A lot of trouble and variation between listener could be minimized by just having the proper cable construction and its grounding.
I wrote an Audio article in Feb/1988 and this was a part of it: cable rejection characteristics;
View attachment Cable rejection char.pdf
THx-RNMarsh
Plus, many people hear the affects/effects of interconnects ---
A lot of trouble and variation between listener could be minimized by just having the proper cable construction and its grounding.
I wrote an Audio article in Feb/1988 and this was a part of it: cable rejection characteristics;
View attachment Cable rejection char.pdf
THx-RNMarsh
I think we misunderstand what each is referring to.
But, without even trying to untangle it.... I generally agree with Bonsai on his description of how a CFA works which is different from VFA.
-RNM
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Give example, swapping the bridging resistor for each gain is not on the table. The comment was the IC industry insists on calling them VFA's but that's how they are sold. The same holds for bringing out internal pins for custom compensation of a VFA. Once the designer has all the options the distinctions seriously blur.
I'm only talking about H-bridge here, both input are high impedance there is no current in the feedback network entering the inputs. This topology adds slew enhancement a large signal property, GBW and stability are small signal properties.
I challenge anyone to categorically prove that a certain level of THD vs. power, for instance, can not possibly be achieved with either topology.
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In electronic, my mistakes are usually charged by my friend Murphy and paid cash with holly smoke. More disturbing, if you see what I mean ;-)
Not a challenge - just asking... Is there a difference in the IMD spectrum between the topologies?
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