Hi,
in the light of post220 and similar revelations, it looks like I am going to revisit my slightly modified Sugden P128s and incorporate some/many of Bob's teachings. Come in Amazon. I am waiting for my Christmas present.
in the light of post220 and similar revelations, it looks like I am going to revisit my slightly modified Sugden P128s and incorporate some/many of Bob's teachings. Come in Amazon. I am waiting for my Christmas present.
Hi Bob,
Is there anything in your book about enhanced compensation techniques? Specifically, is there anything to improve upon TMC (transitional miller compensation).
I have on the bench a design using TMC that gives 0.004% at 20kHz - it is essentially a blameless with a mosfet output stage. I wonder if there is anything in your book regarding compensation that would help me improve it.
By the way, I have ordered a copy of your book!
I've also ordered Jan's book that includes Douglas Self's latest on inclusive compensation. It will be interesting to see if Self can add anything to what has already been posted here.
Best Regards,
Ian
Is there anything in your book about enhanced compensation techniques? Specifically, is there anything to improve upon TMC (transitional miller compensation).
I have on the bench a design using TMC that gives 0.004% at 20kHz - it is essentially a blameless with a mosfet output stage. I wonder if there is anything in your book regarding compensation that would help me improve it.
By the way, I have ordered a copy of your book!
I've also ordered Jan's book that includes Douglas Self's latest on inclusive compensation. It will be interesting to see if Self can add anything to what has already been posted here.
Best Regards,
Ian
delayed...delayed...although I've ordered the book before ya bunch did, amazon has delayed shipping by additional four weeks. 🙁
regards
regards
uuh yes, you're right! And they have broadened the delivery corridor, must have confused me.
Anyway, I want my book now! 🙁
Anyway, I want my book now! 🙁
Not really.
Hi Edmond,
That's disappointing news.
Am I right in thinking you first brought TMC to this forum's attention? If so, I hope Self gives you the credit.
Cheers,
Ian
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Self addresses both input-inclusive and output-inclusive compensation, citing work by Baxandall, Linsley-Hood and Leach among others. The article discusses pros and cons of each concept.
On the TMC side he also references a series of posts by Edmond, Bob Cordell and others on the forum.
jan
On the TMC side he also references a series of posts by Edmond, Bob Cordell and others on the forum.
jan
Hi Ian,
I have a chapter that discusses advanced compensation techniques, including TMC. In that chapter I also cover Miller Input Compensation that I used in my original MOSFET power amp. Although I don't think I discussed it, I have simulated designs that combined TMC with input compensation - i.e., where the TMC compensation signal is brought all the way back to the input stage instead of just back to the input of the VAS. Apart from that, I don't think I have improved on TMC.
I am a big fan of TMC. I don't know if what Doug talks about in his up-coming article is TMC or not, but my understanding is that Baxandall and Edmond deserve the credit and I think Edmond coined the term TMC.
Cheers,
Bob
Thanks for the clarification Jan - I look forward to receiving my copy (perhaps tomorrow or Friday).
Rebirth of TMC?
Hi Ian,
That's right.
Well, only in a very indirect way (no names). I had expected to get more credit as it was me who brought this technique (again) under his attention AND brought it to the public domain as well. A few years earlier (in the year he died?) it was Baxandall (as it seems) who also informed Douglas Self about the same trick.
To my amazement Self wasn't 'exited' about TMC, while he did get good results from TPC, which should give a similar reduction in distortion. (see also: http://www.diyaudio.com/forums/soli...erview-negative-feedback-252.html#post1694515 )
So I was looking for an explanation for his mediocre results and told him that TMC only reduces distortion from the OPS. I also told him that if the distortion from the VAS or IPS is higher (normally that's not the case), then the improvement from TMC is masked, i.e. 'not exiting'. Regrettably, I never got an answer to my suggestions.....
Funny enough, now he speaks in terms of: 'simple but devastatingly effective' and 'Possibly one of the best bargains in audio!'
Thank you, Mr. Self!
BTW, the TMC caps in his article (2x220pF) are far from optimal.
Cheers,
E.
Hi Ian,
That's right.
Well, only in a very indirect way (no names). I had expected to get more credit as it was me who brought this technique (again) under his attention AND brought it to the public domain as well. A few years earlier (in the year he died?) it was Baxandall (as it seems) who also informed Douglas Self about the same trick.
To my amazement Self wasn't 'exited' about TMC, while he did get good results from TPC, which should give a similar reduction in distortion. (see also: http://www.diyaudio.com/forums/soli...erview-negative-feedback-252.html#post1694515 )
So I was looking for an explanation for his mediocre results and told him that TMC only reduces distortion from the OPS. I also told him that if the distortion from the VAS or IPS is higher (normally that's not the case), then the improvement from TMC is masked, i.e. 'not exiting'. Regrettably, I never got an answer to my suggestions.....
Funny enough, now he speaks in terms of: 'simple but devastatingly effective' and 'Possibly one of the best bargains in audio!'
Thank you, Mr. Self!
BTW, the TMC caps in his article (2x220pF) are far from optimal.
Cheers,
E.
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Hi Edmond,
First of all, thank you for bringing TMC to our attention. I had been completely unaware of it until you brought it up right here. I happily gave you credit in my book.
Doug has been late to the party on a couple of things if you have watched the evolution of his book from the first edition to the fifth. Two of these are DC servos and the Locanthi T circuit.
Nevertheless, he has blazed a trail for many of us. After having written over 600 pages, I can assure you that I have even higher respect for those who went before me like Doug, Randy Slone and Ben Duncan. I have never worked so hard in my life.
Even if we don't agree with everything that another author wrote, we learn by having the issue brought to the table for debate. I'm sure that there will be errors and things that people disagree with in my book 🙂. No matter how hard we try, we don't get everything right.
Cheers,
Bob
Hi Juergen,
My understanding is that the current publication date is September 17. This is a one-week slip from what it was quite awhile back. This is when physical books are available at McGraw-Hill.
What I don't know is how much time it takes to get from MGH to, e.g., Amazon, through Amazon, and then be shipped to your address. I would not have guessed that the end-to-end time for this would be more than a month, or even a month, but I know little about the publishing mechanics.
I'll have copies to sell at RMAF, BTW.
Cheers,
Bob
Hi Bob,
All I need to know is that the book is coming. I can't make it come any faster, so it'll get here when it gets here. Never worry about things you can't change.
The main reason I brought this up are the "no feedback" type amps that crop up. The ones that drive mosfets with either a tube, or a pair of TO-92 transistors.
Thank you for your reply on that though, it was more than I expected.
-Chris
All I need to know is that the book is coming. I can't make it come any faster, so it'll get here when it gets here. Never worry about things you can't change.
I'll have to look at that next time. I do normally run at 1 KHz, but then it's tried again at either 10 KHz or 20 KHz. Depends on how I'm feeling at the time. I have to click another switch to go from 10 KHz to 20 KHz. Isn't this a case of pulling the majority carriers out of the base? I'd be surprised that this would be a problem unless you're using the original 2N3055 (hf cutoff around 19 KHz). Or could it be related to the circuit you are driving it with? The same issues that mosfets suffer from, but weaker. I haven't noticed a problem, so I'm asking so that I have a direction to go in.
Although low distortion is almost everyone's goal, that amount of dissipation doesn't make me very happy at all. Once you run up to 50 VDC and two pairs, your looking at 30 watts of heat per channel. Everything just gets uglier as you go higher and more pairs appear. At this point, fancy begins to look better and better as long as odd things don't begin happening to the music.
The main reason I brought this up are the "no feedback" type amps that crop up. The ones that drive mosfets with either a tube, or a pair of TO-92 transistors.
Thank you for your reply on that though, it was more than I expected.
-Chris
Bob,
You can not place a 600 page book on the shelf these days without a good proof read. Who was chosen for this laborious job? It would have had to be someone you trust as an intellectual semi-equivalent.
Tad
You can not place a 600 page book on the shelf these days without a good proof read. Who was chosen for this laborious job? It would have had to be someone you trust as an intellectual semi-equivalent.
Tad
Volume 1
Also about subjects which have already been discussed on forums or published on my website?
If that's not a problem, perhaps about ETMC together with CMCL, as these two techniques lend themselves well to combine. They are born for each other, so to speak.
Another subject might be the new auto bias circuit + error feedback. But in all cases it will not be substantiated or confirmed by real measurements.
Please let me know what you think about it.
Cheers,
E.
Also about subjects which have already been discussed on forums or published on my website?
If that's not a problem, perhaps about ETMC together with CMCL, as these two techniques lend themselves well to combine. They are born for each other, so to speak.
Another subject might be the new auto bias circuit + error feedback. But in all cases it will not be substantiated or confirmed by real measurements.
Please let me know what you think about it.
Cheers,
E.
Hi,
is this an invitation to restrict information to the Forum, so that a commercial interest can become involved?
is this an invitation to restrict information to the Forum, so that a commercial interest can become involved?
credits
Hi Bob,
You were not the only one and the few who know about it dismissed it, until........Well, you know the story.
Thank you!
Sure! BTW, I've learned a lot from Douglas Self. As a matter of fact, his articles in WW/EW have revitalized my interest in power amps.
Cheers,
E.
Hi Bob,
You were not the only one and the few who know about it dismissed it, until........Well, you know the story.
Thank you!
Sure! BTW, I've learned a lot from Douglas Self. As a matter of fact, his articles in WW/EW have revitalized my interest in power amps.
Cheers,
E.