I'm sure you are all aware that the Third edition of Self On Audio was published a few weeks ago, so please do not consider this an advertisement.
(Though I will say it has a lot of new material I have never published before) Quite the opposite, in fact.
When I write a book I do my best to get everything right. I fail.
In this case there is a most embarrassing error in Chapter 19. The diagrams for Figure 19.1 and Figure 19.11 (but not the captions) were transposed at the publishers. 1 is the same as 11, right? Thus the generalised RIAA response on p209 should be on p200, and vice-versa.
I absolutely failed to spot this when I checked the proofs, so the ultimate responsibility is mine. Unfortunately it occurs in one of the more closely-reasoned chapters and it can only make it harder to understand. I am sorry.
I therefore thought I had better put up a public warning to save furrowed brows. I will add an errata section to my website at Self On Audio: The Book. If you find any other errors do please let me know.
(Though I will say it has a lot of new material I have never published before) Quite the opposite, in fact.
When I write a book I do my best to get everything right. I fail.
In this case there is a most embarrassing error in Chapter 19. The diagrams for Figure 19.1 and Figure 19.11 (but not the captions) were transposed at the publishers. 1 is the same as 11, right? Thus the generalised RIAA response on p209 should be on p200, and vice-versa.
I absolutely failed to spot this when I checked the proofs, so the ultimate responsibility is mine. Unfortunately it occurs in one of the more closely-reasoned chapters and it can only make it harder to understand. I am sorry.
I therefore thought I had better put up a public warning to save furrowed brows. I will add an errata section to my website at Self On Audio: The Book. If you find any other errors do please let me know.
The original LA article is indeed correct. You are a much better publisher than the global big boys.
Hi Guys
There are those who nit-pick about everything, but I think it is safe to say that Mr. Self's articles and books have enlightened anyone who reads them. I know I've learned a lot so THANKS!
At the risk of discussing APAD - a different book series of yours - it is disappointing to see errors persist from one edition to the next. One that bothers me (because I am a fan of nested feedback, the subject of the figure) is the "internal" data of APAD5 fig.8-8 where the output stage data in the A and B sections is reversed, and remain reversed in APAD6 Fig.13-28.
Doug, you know my views on "editions" versus "volumes", and I guess we will agree to disagree, yet I must commend you on some of the re-organisation in the latter edition compared to the previous. One detail that could have been incorporated is to mention "new" information earlier so that obsolete methods or values are not read as valid. The specific example is the electrolytic capacitor value in the standard PA feedback loop.
In the Wireless World articles that became the core of the books, this cap value was rather low, typically 220uF. Readers of your website see this old free info and assume this is a good cap value. Your later writing states quite explicitly that larger values reduce THD at low frequencies and your latest kits use an improved value of 1mF (even though you tested a 4m7 cap). THD at 1kHz is affected by this cap, too, as a simulation or measurement readily shows, leading some like myself to use much larger values over 10mF. Contrary to what some people believe, this capacitor has no influence on the settling time of the amplifier; other issues are at play if settling is slow.
I also know the difficulty of editing one's own work. It seems to be only truly possible to do once the pressure to print is off?
Happy New Year
There are those who nit-pick about everything, but I think it is safe to say that Mr. Self's articles and books have enlightened anyone who reads them. I know I've learned a lot so THANKS!
At the risk of discussing APAD - a different book series of yours - it is disappointing to see errors persist from one edition to the next. One that bothers me (because I am a fan of nested feedback, the subject of the figure) is the "internal" data of APAD5 fig.8-8 where the output stage data in the A and B sections is reversed, and remain reversed in APAD6 Fig.13-28.
Doug, you know my views on "editions" versus "volumes", and I guess we will agree to disagree, yet I must commend you on some of the re-organisation in the latter edition compared to the previous. One detail that could have been incorporated is to mention "new" information earlier so that obsolete methods or values are not read as valid. The specific example is the electrolytic capacitor value in the standard PA feedback loop.
In the Wireless World articles that became the core of the books, this cap value was rather low, typically 220uF. Readers of your website see this old free info and assume this is a good cap value. Your later writing states quite explicitly that larger values reduce THD at low frequencies and your latest kits use an improved value of 1mF (even though you tested a 4m7 cap). THD at 1kHz is affected by this cap, too, as a simulation or measurement readily shows, leading some like myself to use much larger values over 10mF. Contrary to what some people believe, this capacitor has no influence on the settling time of the amplifier; other issues are at play if settling is slow.
I also know the difficulty of editing one's own work. It seems to be only truly possible to do once the pressure to print is off?
Happy New Year
There has been little opportunity to tut-tut a publication that Amazon UK has been late in delivering.
Their despatch advice seems to be derived from PowerBall results so I'm expecting a revised delivery date of the 40th of January - or perhaps any day now
When I read this I wondered what the heck? In this neck, flog means to promote or sell. I had to look up your meaning and sure enough...
You never stop learning.
There has been little opportunity to tut-tut a publication that Amazon UK has been late in delivering.
Their despatch advice seems to be derived from PowerBall results so I'm expecting a revised delivery date of the 40th of January - or perhaps any day now
Maybe they're busy packaging the 'revised text labels' that they (used to?) send out when reference materials had errors back in the day.
I've always taken Doug's examples as illustrative rather than prescriptive, and always used the largest value practical in my projects, up to 33mF. But then again I've also adopted the low impedance philosophy, usually with a 100R shunt resistor, so a very large series cap is almost mandatory.
Never experienced any settling difficulties on startup.
I assume you mean that 0.1% and 1% are transposed in APAD6 Fig.13-28. Quite right, though if I've ever been informed of this one I must admit I've forgotten. I have recorded it for correction in APAD7, and will add it to the errata page on my site here:
The Audio Power Amplifier Design Handbook
You'll have to remind me about editions/volumes.
It is quite true that there are a few inconsistencies in the older diagrams, and they could benefit from being redrawn and generally tidied up. You will appreciate this is a lot of work, and it never seems to get to the top of the to-do list.
I do not believe the last statement is true, from my tests with ordinary electrolytics. If so it must be sub-0.0003% and in the noise.
Last edited:
Hi Guys
"I assume you mean that 0.1% and 1% are transposed in APAD6 Fig.13-28."
Also that the B portion has a pole at 10MHz not 1Mhz.
In the simulations I've done, the electrolytic in the feedback loop has an effect on 1kHz THD, which caused me to go from a standard value of 10mF to 33mF. For as accurate as the sims may or may not be, I aim for the lowest number possible - as you do - and 3ppm is on the high side of the target and is still measurable with an AP.
In LTspice the error log shows six decimal places for the THD. Like most here who have followed the example in Bob Cordell's book, it is set to check the first ten harmonics. The ideal is all zeroes: 0.000 000% which indicates <10ppb. I must say the first time I had a sim with this result I was pretty happy! But then you get spoiled... And then I wish I had a tenth of your math skill...
Doug, when it comes to making mistakes you are an amateur compared to me. I make lots of them! ... although it probably isn't the sort of thing one brags about... oh well.
Happy new year
"I assume you mean that 0.1% and 1% are transposed in APAD6 Fig.13-28."
Also that the B portion has a pole at 10MHz not 1Mhz.
In the simulations I've done, the electrolytic in the feedback loop has an effect on 1kHz THD, which caused me to go from a standard value of 10mF to 33mF. For as accurate as the sims may or may not be, I aim for the lowest number possible - as you do - and 3ppm is on the high side of the target and is still measurable with an AP.
In LTspice the error log shows six decimal places for the THD. Like most here who have followed the example in Bob Cordell's book, it is set to check the first ten harmonics. The ideal is all zeroes: 0.000 000% which indicates <10ppb. I must say the first time I had a sim with this result I was pretty happy! But then you get spoiled... And then I wish I had a tenth of your math skill...
Doug, when it comes to making mistakes you are an amateur compared to me. I make lots of them! ... although it probably isn't the sort of thing one brags about... oh well.
Happy new year
This has now been added to the errata page of APAD6
file:///C:/webimage/ampins/books/errata-apad6.htm
Member
Joined 2009
Paid Member
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.