I have no idea whether it's blameless or not, but it's based on Renardson's April 1998 Wireless World article, Class B in a New Class, which Douglas called "first rate, innovative".
Amplifier Articles in Electronics World & Elektor
Hi Bonsai,
Bear in mind that the VAS is not always involved with the feedback of Miller compensation in a feedback amplifier, although Miller compensation is a good and popular choice. For example, lag compensation does not involve local feedback around the VAS. Also, at low frequencies, where Cdm no longer dominates, the VAS is not operating as a TIS. Those who build amplifiers with wide open-loop bandwidth may have the VAS operating not as a TIS across all or a large potion of the audio band.
My main point is that the term VAS is well established and understood, and that we have more important things to do than try to re-define its name.
Cheers,
Bob
This is nonsense. It was Douglas Self who invented the term "VAS", and by doing so it was he who was trying to incorrectly redefine an established and well understood term, namely the transimpedance stage (TIS).
You've clearly refused to read Solomon's seminal paper in respect of this vexed issue despite repeatedly being given links to it.
See below:
http://www.diyaudio.com/forums/soli...self-wants-your-opinions-104.html#post3534131
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Its VAS. If you don't like it, write your own book, full of your own "nonsense".
Cheers,
Bob
We refer to the collector of the second stage as "the gain node" since all the voltage gain of the circuit appears at this node (in the usual simple cases). The terminology does not confuse anyone, I see this as a tempest in a teapot.
Yes, I am writing a book, fully referenced; and NO; it isn't a "VAS": TIS it will be into perpetuity. Amen.
Perhaps you would be good enough to reveal the exact title? I wouldn't want to waste my money on the kind of triviality and bickering that seems to be typical of your output.
The only one who comes out of this thread with any credit is Douglas Self. Other than that there are a number of people with no apparent concept of personal dignity seemingly attempting to leverage or revive reputations on his coat-tails. No published or aspiring author should be so lacking in self-control as to intrude on his thread.
Try to appreciate what a sorry spectacle you are making of yourselves and how your behavior redounds to the discredit of the engineering profession and to the membership in general.
michaelkiwanuka,
There is no problem with having a civil discussion about a topic and that can be all well and good, but your ever lasting hashing of the term vas or tis is just for not. While the technical arguments are fine why are you so hung up on the simple terminology? In engineering for years we would see the term foot pounds instead of pound feet, but people knew what that meant even if the terminology wasn't correct. It didn't make a difference to the discussion, it was only a term used to describe an engineering phenomena, we didn't really care much that the terms were reversed, it didn't change the topic. You seem to be stuck on the terminology rather than the topic.
There is no problem with having a civil discussion about a topic and that can be all well and good, but your ever lasting hashing of the term vas or tis is just for not. While the technical arguments are fine why are you so hung up on the simple terminology? In engineering for years we would see the term foot pounds instead of pound feet, but people knew what that meant even if the terminology wasn't correct. It didn't make a difference to the discussion, it was only a term used to describe an engineering phenomena, we didn't really care much that the terms were reversed, it didn't change the topic. You seem to be stuck on the terminology rather than the topic.
One of my two major complaints about Mr. Cordell's book. It annoyingly blurs the border between the author's original and old (re)interpreted or adapted content.
The other is the lack of any consistent (across the book) stability analysis methodology (both in simulation and measurements) - foundation, specifics to audio, design trades, etc...
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Waly,
So if I am following you correctly here you are asking Bob to write his book as a text book rather than a general text covering a broad range of subject matter? Two very different styles of writing are required for two different audiences. I enjoyed Bob's book very much as it wasn't as heavy into the theoretical analysis and so I wasn't looking for a bunch of references to look up but at the same time I do appreciate the way that Doug writes also. These are very different writing styles and should be enjoyed for what they are.
ps. I would have to add that both of the authors write with personal preferences or biases that go with their personal opinion. So neither one of these authors is writing a straight forward classic textbook style of schoolbook where opinion is left out. That would be a very boring thing to read to me, I might as well just get a standard text book for an EE class on power amplifiers and read that if that was what I wanted with all the added problems that would be in there to solve.
So if I am following you correctly here you are asking Bob to write his book as a text book rather than a general text covering a broad range of subject matter? Two very different styles of writing are required for two different audiences. I enjoyed Bob's book very much as it wasn't as heavy into the theoretical analysis and so I wasn't looking for a bunch of references to look up but at the same time I do appreciate the way that Doug writes also. These are very different writing styles and should be enjoyed for what they are.
ps. I would have to add that both of the authors write with personal preferences or biases that go with their personal opinion. So neither one of these authors is writing a straight forward classic textbook style of schoolbook where opinion is left out. That would be a very boring thing to read to me, I might as well just get a standard text book for an EE class on power amplifiers and read that if that was what I wanted with all the added problems that would be in there to solve.
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Reversing terminology is wholly different from actually renaming something. Calling a transimpedance amplifier a voltage amplifier is not merely a case of "reversing terminology": it is entirely misleading, and does not lend itself to a vivid appreciation of how the amplifier works.
No, I am only expressing my personal preference towards books with a solid foundation, and one of the essential foundation pillars is the bibliography/references part. There's no good reason to lack quoting previous work, in fact this usually adds credibility to any published work (and also helps the author better settling the work flow).
I also prefer depth vs. width, for example the class D pages in Mr. Cordell's book would constitute, in my opinion, an excellent Wikipedia contribution, but otherwise those printed pages could be successfully re-used to address (or deepen) things like stability (with the audio amplifier, as a minimum phase system, specific), etc...
Depth vs. width is also one reason why I prefer Mr. Self's book on power amplifiers. Now, if Mr. Self would make the effort to bring his content more up to date and leave out any personal biases (which I find, with one glaring exception, are definitely and fortunately missing in Mr. Cordell's book)...
P.S. It would certainly not boring to me, but of course, YMMV. Efverybody is entitled to his own opinion.
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I've built two mono and two stereo boards of the simple Renardson Mosfet amplifier (without Feedfoward):
MJR7-Mk5 Mosfet Power Amplifier
This amp is really apart, its unconventional design delivering outstanding performances (I checked some).
Where did you get the mono boards? I built the stereo version using Mike's board, would be interested in mono boards...
Thanks for saying . I found his analysis of input stages wonderful to read . Like Mr Self very clearly explained and economical with parts . I was influenced by Bob Stewart who always seemed to advocate making an amplifier as simple as possible whilst being blameless .
My feeling is most of what is written is a journey that has nothing to do with music .The number one blameless requirement for me is distortion below 1 watt ? The old Hitachi MOS FET design showed graphs of 2 to 100 watts with curves to 50 kHz that read better than a NE5534 . Nothing special for an op-amp , not bad for a power amp . Why not below 2 watts ? In truth they are good . I wonder if Hitachi were hiding something ?
The old Quad 303 was close to being blameless . I think many disliked the fact it couldn't shake awful speakers into life . I will be building an amplifier for my new Magnaplanars . It is astonishing to hear a 303 with the Maggie's . It was meant to be for low level use whilst building something . They just love each other . To be frank I don't think one of the Audiophile amps of high repute often seen with them works as well ( too coloured , sounds dark and flabby ) . My 303 is a workhorse and friend . It has new outputs and many caps replaced . Bias is carefully set as is the centre voltage point . It is 100% standard . I do hit the current limiters sometimes so must press on with a bespoke amp . Dynamic range is colossal and music fades down forever it seems . The extreme top is a little soft which I am sure is only 25% the amp . In real life often the high frequencies are no greater . I should say I never thought of it as hi end and still don't . I now doubt it does anything wrong . I suspect the 405 is less good . Before you think I have never experienced hi end amps , I have . Most are wonderful . However not so much as to make me want one . The 303 has a transistor sound ? NO . A valve sound ? NO . Peter Walker I hope you can read this up there ?
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