Bob Cordell's Power amplifier book
- Thread starter ihan
- Start date
The book arrived at my residence in California, Monday 24 June, shipped by Taylor & Francis. It looks great, congratulations Bob!
Good point. My first edition was available pirated shortly after it became available in Kindle format. The ISBN of the Kindle edition is the same as that on the pirated versions. The Kindle DRM has been broken, and there is software that will take an open Kindle file and convert it to a perfect PDF. Any book available in Kindle is vulnerable. I asked that my second edition not be made available in a Kindle version for that reason.
An aspect of hardcopy fakes is that Print on Demand (POD) makes it more practical and economical. In principle, if one has a pirate PDF of the book, they can publish fake copies in days using POD.
Cheers,
Bob
Dear Bob, Im re-reading the whole thing and I love it, I believe chapters 4 and 5 are true gems (that's where I am right now), I've noticed a couple of typos, mainly regarding component numbering, but nothing really serious. I have a question thou, in chapter 4 you used a Zobel network at the output of the VAS, in shunt really, is there any design criteria for this network values or is it not critical?
Once again, thanks for the great book!
Once again, thanks for the great book!
Hi Bob,
I received my copy a few days ago 3 business days after ordering from Routledge paid in local dollars by debit card AU$154 at this site Designing Audio Power Amplifiers: 2nd Edition (Paperback) - Routledge It was from their warehouse in Australia.
I really like the new Chapter 4 on 'Building an Amplifier' - good DIY basic stuff!
Looking forward to studying the new Chapter 5 on Noise.
I think the new sections in Chapter 13.7,8 on SingleCross (Doug's XDTM) and DoubleCrossTM are so good -- good to see such a helpful comparison of new ideas to audio power amplifiers. I hope we see lot's of DoubleCrossTM amplifiers made by members.
Then the new Section 9.10 gives level headed coverage on the Controversial Feedback Amplifier (CFA or Current Feedback Amplifier). You appear to favor the VFA because CFA's typically have lower loop gain and lower PSRR. A question follows: In the next section to the CFA you have a VFB type input stage and VAS - what would be its open loop gain if it had the same output stage as the CFA example in Figure 9.19?
I thought this would show us the likely difference in open loop gain between a VFB and the CFB input stage/VAS you gave.
Another query if I may. Did your DoubleCrossTM output stage measurements use ThermalTrakTM ? Your Figure 13.12 shows MJL3281 (non ThermalTrak IIRC)..
There's lot's more good new stuff I know but enough for now. Thanks for all your hard work. Well done!🙂 ...back to reading more.
Cheers,
IanHegglun
I received my copy a few days ago 3 business days after ordering from Routledge paid in local dollars by debit card AU$154 at this site Designing Audio Power Amplifiers: 2nd Edition (Paperback) - Routledge It was from their warehouse in Australia.
I really like the new Chapter 4 on 'Building an Amplifier' - good DIY basic stuff!
Looking forward to studying the new Chapter 5 on Noise.
I think the new sections in Chapter 13.7,8 on SingleCross (Doug's XDTM) and DoubleCrossTM are so good -- good to see such a helpful comparison of new ideas to audio power amplifiers. I hope we see lot's of DoubleCrossTM amplifiers made by members.
Then the new Section 9.10 gives level headed coverage on the Controversial Feedback Amplifier (CFA or Current Feedback Amplifier). You appear to favor the VFA because CFA's typically have lower loop gain and lower PSRR. A question follows: In the next section to the CFA you have a VFB type input stage and VAS - what would be its open loop gain if it had the same output stage as the CFA example in Figure 9.19?
I thought this would show us the likely difference in open loop gain between a VFB and the CFB input stage/VAS you gave.
Another query if I may. Did your DoubleCrossTM output stage measurements use ThermalTrakTM ? Your Figure 13.12 shows MJL3281 (non ThermalTrak IIRC)..
There's lot's more good new stuff I know but enough for now. Thanks for all your hard work. Well done!🙂 ...back to reading more.
Cheers,
IanHegglun
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There are companies with automated book scan machines that will scan any book for you for a dime per page. Don't even have to take the book apart.
This one does 2500 pages per hour. So if someone really wants to fake it, no big deal ...
It's an interesting technology, see the video here: Book scanner ScanRobot(R) 2.0 MDS - Videos of the automatic page turner
Jan
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Thanks for the kind words!
The values for the VAS output Zobel are not critical. Usually 100 pF in series with 100 ohms will do. One does not want to go too large on the capacitor, since it can at some point eat into slew rate capability of the VAS, since it takes some VAS current to charge and discharge it. With a single-ended VAS biased at 10 mA, the 100 pF capacitor alone would limit VAS slew rate to 100 V/us.
I'm collecting a list of errata to post on my web site. Anything you see, please post it here or send me a PM. If you like the book, a brief Amazon review would be deeply appreciated!
Thanks again for buying the second edition.
Cheers,
Bob
Before to long, AI machines will be able to comprehend 25.000 pages per hour. We are done for.
This is old stuff, decade or more. Yet here we are still. Nobody scanned my Linear Audio's ;-).
The main danger is from a guy somewhere in India (or anywhere else, not banging on India here) hand-scanning torn out pages and printing a bad copy. It happens a lot. I have several Crowhurst books from such a source. Very bad quality, yet it sells.
Jan
Jan, your articles are also great stuff, I already own the whole series
Hi rsavas,
There is hope. Did you see Mark Johnson's post here?
John Broskie's TubeCad blog 177 CCDA & Class-AC
My circuit here sim'd distortion 0.0004% (4ppm) at 100W and 20kHz with 500mA bias. My Rush OPS has voltage gain which allows lower voltage and lower power faster driver transistors and lower voltage and faster VAS transistors with less quasisaturation issues. Power transistors are current driven and non-switching.
BTW I compared my Rush CFA with the Rush VFA forms here and got lower loop gain with the CFA form (same as Bob found). My comparison was as close as possible to 'apples-to-apples' with the same OPS and same VAS etc.