Bob:
WOW - that's a lot!
So much so that it looks like you're not planning to write sequels.
thanks in advance for all the work. i'm looking forward to reading it.
mlloyd1
WOW - that's a lot!
So much so that it looks like you're not planning to write sequels.
thanks in advance for all the work. i'm looking forward to reading it.
mlloyd1
Hi Bob,
Impressive to say the least.
As for things you haven't delved into in great detail, I'm sure there are members here and your own contacts that may already be working on these issues. Any threads that come out of this could be extremely fruitful as ideas are exchanged between everyone. I can only hope it stays as clean as your threads tend to be.
As mlloyd1 said ...
Bob, I have a feeling that that you have a classic on your hands sir.
-Chris
Impressive to say the least.
As for things you haven't delved into in great detail, I'm sure there are members here and your own contacts that may already be working on these issues. Any threads that come out of this could be extremely fruitful as ideas are exchanged between everyone. I can only hope it stays as clean as your threads tend to be.
As mlloyd1 said ...
Maybe not. After all, when the next rev of the book comes out, it's simply a refresh of what was there originally. It is built on, not rebuilt. Otherwise I can't see a clean way to deal with these topics unless a totally different book is published. But, how to divide the information logically, and now there are two book titles that must be revised as better information becomes available.
Bob, I have a feeling that that you have a classic on your hands sir.
-Chris
Bob:
WOW - that's a lot!
So much so that it looks like you're not planning to write sequels.
thanks in advance for all the work. i'm looking forward to reading it.
mlloyd1
Hi mlloyd1,
You're more than welcome - writing the book is something that I've wanted to do for quite some time and it has been a labor of love.
I'm sure my wife will not let me write another book for awhile, although I would like to. Although there will not likely be a sequel as such, I will at some point be asked by McGraw-Hill to write a second edition.
Cheers,
Bob
Hi Chris,
First, I'm sure that there will be errors and things that I should re-think that people will point out, and I will encourage that on my web site. That alone will be a source of improvement in the next edition.
Secondly, I think you are right about the discussions that the book will generate - that will also provide inspiration for new or refined material to go in the next edition.
Hi Soldering Guy,
Thanks for your interest and good luck with your learning about power amplifiers. One of the goals of my book is to ease people with less experience into amplifier design while still subsequently going deep for the more experienced.
I'm sure there will be enough to go around, although if there were not, it would be a nice problem for me to have
. McGraw-Hill told me that one of the factors they use to size the print run is the number of pre-orders they've gotten, and that has apparently been a good number. As far as I know, publication is still scheduled for this Friday, but I don't know how long it takes to percolate through the retail channels like Amazon and B&N.Cheers,
Bob
Website information for book
Hi guys,
For those of you interested, my website at CordellAudio.com - Home has been fully updated and contains quite a bit of information on the book, including the Preface, the back cover and three versions of the TOC (varying degrees of detail, starting with just a simple chapter list).
Cheers,
Bob
Hi guys,
For those of you interested, my website at CordellAudio.com - Home has been fully updated and contains quite a bit of information on the book, including the Preface, the back cover and three versions of the TOC (varying degrees of detail, starting with just a simple chapter list).
Cheers,
Bob
Hi Bob,
Okay. I'm not going to look.
It's bad enough that I'm already wound up waiting for the book to arrive, and I normally don't allow myself to look forward to anything that much. The information you've released in this thread so far is enough to strongly recommend your book!
You're teasing an addict now buddy!
-Chris
Okay. I'm not going to look.
It's bad enough that I'm already wound up waiting for the book to arrive, and I normally don't allow myself to look forward to anything that much. The information you've released in this thread so far is enough to strongly recommend your book!
You're teasing an addict now buddy!
-Chris
I joke a lot, especially for 70 €cent a pop selected.
Cgd of Toshibas is not exactly pretty either, in particular for the junior versions that i've often used for economical reasons.
All things relative : http://www.diyaudio.com/forums/pass-labs/129040-mosfet-output-stage-capacitance.html#post1599135
(admit i still have quite a number of power Laterals for a simple minded. For a scary moment, check out Cgd/Cgs of the NEC J135)
As I've posted many times in many different threads, VERTICAL MOSFETs have a very high and a very NON-LINEAR input capacitance. Nelson's linked post simply supports my position. (I have no idea why he continues to use the silly things.)
But don't make the mistake of confusing a 2sJ135 for a 2sK135. The former is a VERTICAL MOSFET, while the latter is a LATERAL MOSFET.
Lateral parts typically have at least 10x lower Cdg than do vertical parts. Pay closer attention -- it's a good way to learn.
Last edited:
Semelab is still making improved replacements for the Hitachi lateral output devices under the Exicon, Magnatech, and Class-D brand names. The only thing going away are the small TO-220 driver parts. Semelab doesn't make anything like this.
Last edited:
WHAT!!??
Doug Self finally admitted that a triple was better than a double??? Will wonders never cease?
Marshall Leach expounded the Locanthi T-circuit in his series of articles in Audio magazine. On his website he says that he has never found a superior output stage.
We agreed and have been publicly using (a slightly improved) T-circuit in our power amps for nearly ten years now. One reason I stopped buying Self's books was because he kept making the same mistakes. He would create some circuitous argument about not using a triple because it "only cut the distortion in half" (and this was INSIDE his silly feedback loop) and then he would go on to attempt to justify a front end that was twice as complex because it reduced the distortion 2% (in relative amounts).
Hi Bob,
I've had your book on pre-order for sometime now and am anxious to dig into it.
I was wondering, you mentioned some problems with the Fairchild KSA3503 SPICE model here in this thread:
http://www.diyaudio.com/forums/software-tools/101810-spice-simulation-58.html#post1544197
Did you determine what was wrong with the model and how to fix it. I noticed problems with it a long while back and also the KSC2690 - well actually seems I find more models with problems than good ones, LOL!
I'm using the 2000-03-30 CREATION date version and have to check if there is a newer version.
I've had your book on pre-order for sometime now and am anxious to dig into it.
I was wondering, you mentioned some problems with the Fairchild KSA3503 SPICE model here in this thread:
http://www.diyaudio.com/forums/software-tools/101810-spice-simulation-58.html#post1544197
Did you determine what was wrong with the model and how to fix it. I noticed problems with it a long while back and also the KSC2690 - well actually seems I find more models with problems than good ones, LOL!
I'm using the 2000-03-30 CREATION date version and have to check if there is a newer version.
But i did, up close to a kx-r with a magnafying lense. (the launch countdown TVC timer is a nice touch)
It was just a funny example that popped up in my head, for some awkward reason i kept swapping the J and K numbers in the Hitachi Lateral highlight days.
(still do, so i use the mnemo patch that the P-channel is the lower number part of a complementary pair)
The NEC 2SJ135 is illustrative though, if compared to the J76-J79 Hitachi series, 13 times more Cgd/Cgs for 30 times more Gm.
(WB to the trenches, btw, been wondering how things are in the Bolder part of CO on both the physics and physical frontier)
Hi Bob,
Okay, I peeked. Darn you jacco!
I see you have my favorite question there. "When is a ground, not a ground?". Probably one of the most important and least asked questions.
-Chris
Hi Chris,
Yes, the whole thing about grounding is often difficult and sometimes overlooked. I have been guilty myself. One even needs to be very mindful of where to connect the scope ground when poking around inside a circuit. It is remarkable how many millivolts can develop across a seemingly heavy stretch of ground.
Cheers,
Bob
Hi Charles,
Its good to see you here.
You are absolutely right about the gate-drain capacitance of vertical MOSFETs. It gets quite large when the effective reverse bias from gate to drain gets small, as when an amplifier swings near the rail. With a 2SJ201 it gets up to about 1500 pF at 1V, while it is only about 220 pF at 50V.
However, we can't let the BJTs off the hook; they suffer a similar problem, and their Ccb is nearly as big and nearly as nonlinear. Ccb for an NJL1302 is about 1500 pF at a reverse collector-base bias of 1V, while decreasing to about 200 pF at 50V.
At 5V reverse bias, the 2SJ201 Cgd is about 950 pF, while the NJL1302 Cbc is about 700 pF.
That the vertical MOSFET Cgd and BJT Cbc behave similarly, even though they derive from different physical processes, is interesting.
The bottom line here is that we must not be complacent about the drive requirements for power MOSFETs; they need to be driven with almost as much gusto as BJTs when the signal slew rate is high. That is one reason that I never recommend driving the MOSFET directly from the VAS.
Cheers,
Bob
