Revisting an old thread.
The ZTX689B and ZTX789A deserve a close look.
ZTX689/ZTX851 comparative measurements in the third post: Moving Coil Phono Head Amp, Zetex AN-23, March 1996. - Pro Audio Design Forum
The ZTX851 rocks. It's awesome. Flat Balanced Input Moving Coil Phono Preamp Construction Information - Pro Audio Design Forum
The ZTX689B and ZTX789A deserve a close look.
ZTX689/ZTX851 comparative measurements in the third post: Moving Coil Phono Head Amp, Zetex AN-23, March 1996. - Pro Audio Design Forum
The ZTX851 rocks. It's awesome. Flat Balanced Input Moving Coil Phono Preamp Construction Information - Pro Audio Design Forum
diyAudio has been ablaze with ZTX851 discussion for the last five months
Richard Lee's Ultra low Noise MC Head Amp
Richard Lee's Ultra low Noise MC Head Amp
I've been testing the ZTX851 since January 10, 2016.
I may have made Richard aware of it back then: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851 - Pro Audio Design Forum
Brad Wood told me about it in December 2015 and rather than talk about it I melted solder.
EDIT: Mark I see you picked some up in early 2016 as well.
I may have made Richard aware of it back then: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851 - Pro Audio Design Forum
Brad Wood told me about it in December 2015 and rather than talk about it I melted solder.
EDIT: Mark I see you picked some up in early 2016 as well.
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It has been extensively covered in The Art Of Electronics Rev. 3.
Everybody in the field needs that book.
< https://www.amazon.de/Art-Electroni...qid=1573345541&sprefix=art+of+,aps,363&sr=8-1 >
regards, Gerhard
Everybody in the field needs that book.
< https://www.amazon.de/Art-Electroni...qid=1573345541&sprefix=art+of+,aps,363&sr=8-1 >
regards, Gerhard
I agree. A highly-recommended book. I have the First and Third Editions.
Horowitz and Hill didn't test the ZTX689B and ZTX789A which have a slightly higher rbb but have much higher gain and lower Cob. They're only 20V devices however which really isn't a problem in a MC or Mic preamp. The 689/789 also appear to have the low 1/f characteristics of the 851/951.
I don't know about the 689/789 but the ZTX851 Vbe match pretty easily.
We're lucky to still have these parts, particularly in through-hole, and I owe a huge debt of gratitude to Horwitz and Hill for finding them.
If we'd paid attention to Zetex we would have learned about these parts in 1996 when they wrote the first app note about them describing an MC head amp.
Horowitz and Hill didn't test the ZTX689B and ZTX789A which have a slightly higher rbb but have much higher gain and lower Cob. They're only 20V devices however which really isn't a problem in a MC or Mic preamp. The 689/789 also appear to have the low 1/f characteristics of the 851/951.
I don't know about the 689/789 but the ZTX851 Vbe match pretty easily.
We're lucky to still have these parts, particularly in through-hole, and I owe a huge debt of gratitude to Horwitz and Hill for finding them.
If we'd paid attention to Zetex we would have learned about these parts in 1996 when they wrote the first app note about them describing an MC head amp.
The Art of Electronics is actually two books.
Hah, it's actually two books! Despite the 1192-page length of the Art of Electronics, 3rd edition (which is mostly new material compared to the 2nd edition, which you should also have), it's incomplete. The book is filled with material and extensive cross references back and forth in the book. This is because so many topics are multifaceted and simply can't be dealt with properly completely in one place. So you may find yourself holding the page you're at with one hand, while flipping to a few other pages.
Once you get the book and start using it, you'll also discover hundreds of non-existent cross references. For example, in Chapter 3, section 3.6.2, on page 211, we're discussing current sources, and you're directed to "curves of measured current versus voltage (Figures 9.40 and 9.41) ^112. " The figures are on page 623, and show measurements of depletion-mode MOSFET circuits, in Figure 9.36, on page 622. Pretty good, lots of useful details. But wait, there was also footnote 112. That says you should go to "Chapter 3x (§3x.6), where we show tricks for raising the output impedance." Oops, there's no §3x.6 in the 3rd edition, and moreover, there's no Chapter 3x.
While writing the huge, detailed AoE3, we realized that much of the advanced material we wanted to include would really clog up the discussion, so we decided to create x-Chapters. For example, Chapter 3 would have Chapter 3x immediately following, before Chapter 4. And likewise, there'd be another x-Chapter, after Chapter 4. And naturally the x-Chapter cross references would all contain an x, like §3x.6. We also decided that the "x" in x-Chapter references needed to be lower case, to make the number easier to read (see how much easier it is to read 3x.6, than 3X.6). That meant the formulas, figure numbers, section numbers, chapter numbers, etc., all needed to contain lower-case x.
But, when you look at your new copy of AoE III, you won't find Chapter 3x, or §3x.6 either. That's because, as we worked, the book grew to over 1400 pages, and our hard-working editor at Cambridge University Press decided it was simply too big. We rejected the idea of omitting important reference material. We considered dividing the book into two pieces, a first half and a second half. Finally we decided to place all the x-Chapters in a new book, called, naturally, The x-Chapters. But sigh, it took Paul and me four more hard years of work to finish the x-Chapters. And the total two-book length grew to over 1700 pages. But finally it's done, and the second portion, a new 506-page book is available.
Well, OK, it's being printed and bound in the UK, a huge process that started in early September, but will be shipping to readers in December / January. You can look it over and pre-order copies at C.U.P., Art electronics x chapters | Electronics for physicists | Cambridge University Press or at Amazon, https://www.amazon.com/Art-Electronics-x-Chapters/dp/1108499945/ref=sr_1_1
Hah, it's actually two books! Despite the 1192-page length of the Art of Electronics, 3rd edition (which is mostly new material compared to the 2nd edition, which you should also have), it's incomplete. The book is filled with material and extensive cross references back and forth in the book. This is because so many topics are multifaceted and simply can't be dealt with properly completely in one place. So you may find yourself holding the page you're at with one hand, while flipping to a few other pages.
Once you get the book and start using it, you'll also discover hundreds of non-existent cross references. For example, in Chapter 3, section 3.6.2, on page 211, we're discussing current sources, and you're directed to "curves of measured current versus voltage (Figures 9.40 and 9.41) ^112. " The figures are on page 623, and show measurements of depletion-mode MOSFET circuits, in Figure 9.36, on page 622. Pretty good, lots of useful details. But wait, there was also footnote 112. That says you should go to "Chapter 3x (§3x.6), where we show tricks for raising the output impedance." Oops, there's no §3x.6 in the 3rd edition, and moreover, there's no Chapter 3x.
While writing the huge, detailed AoE3, we realized that much of the advanced material we wanted to include would really clog up the discussion, so we decided to create x-Chapters. For example, Chapter 3 would have Chapter 3x immediately following, before Chapter 4. And likewise, there'd be another x-Chapter, after Chapter 4. And naturally the x-Chapter cross references would all contain an x, like §3x.6. We also decided that the "x" in x-Chapter references needed to be lower case, to make the number easier to read (see how much easier it is to read 3x.6, than 3X.6). That meant the formulas, figure numbers, section numbers, chapter numbers, etc., all needed to contain lower-case x.
But, when you look at your new copy of AoE III, you won't find Chapter 3x, or §3x.6 either. That's because, as we worked, the book grew to over 1400 pages, and our hard-working editor at Cambridge University Press decided it was simply too big. We rejected the idea of omitting important reference material. We considered dividing the book into two pieces, a first half and a second half. Finally we decided to place all the x-Chapters in a new book, called, naturally, The x-Chapters. But sigh, it took Paul and me four more hard years of work to finish the x-Chapters. And the total two-book length grew to over 1700 pages. But finally it's done, and the second portion, a new 506-page book is available.
Well, OK, it's being printed and bound in the UK, a huge process that started in early September, but will be shipping to readers in December / January. You can look it over and pre-order copies at C.U.P., Art electronics x chapters | Electronics for physicists | Cambridge University Press or at Amazon, https://www.amazon.com/Art-Electronics-x-Chapters/dp/1108499945/ref=sr_1_1
Same. I bought the AoE recently and have been devouring it at every opportunity..but still over a thousand pages to go
Definitely an accessible book in terms of writing style and thanks from me too for all the hard work.
The world seems to be moving on to SMD.
A lot of stuff I used to get in TH are now SMD or no longer stocked.
I just checked the ZTX689B in my MC preamp.
The ZTX851 in that circuit indicates that they have an rbb' of about 1.75Ω and it makes a good test bed.
The ZTX689B in the same circuit comes in with an rbb' of 5.5Ω based on my initial measurements and has a noise density of around 600 nV√Hz.
Though the ZTX689 isn't quite as low in noise it has a much higher gain of 500 minimum and would be ideal for mic preamps. The Cob is also lower at 16 pF. Maximum collector voltage is 20V.
More data here: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851 - Page 50 - Pro Audio Design Forum
The ZTX689B and its PNP complement, the ZTX789A, are available in through-hole at Mouser.
The ZTX851 in that circuit indicates that they have an rbb' of about 1.75Ω and it makes a good test bed.
The ZTX689B in the same circuit comes in with an rbb' of 5.5Ω based on my initial measurements and has a noise density of around 600 nV√Hz.
Though the ZTX689 isn't quite as low in noise it has a much higher gain of 500 minimum and would be ideal for mic preamps. The Cob is also lower at 16 pF. Maximum collector voltage is 20V.
More data here: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851 - Page 50 - Pro Audio Design Forum
The ZTX689B and its PNP complement, the ZTX789A, are available in through-hole at Mouser.
Time to embrace 1980's technology!! SMT requires a few more tools, little breakout boards are great (I use these mainly for SOIC8 chips, but the approach will work for SMT transistors or sub-circuits if you want - differential pairs, current mirrors, etc)
soic adapters are $3 to $8 at farnell USA, down from $10 last time I looked. About 12 times what an IC costs. And those are soic to dip, takes another $2 adapter to break out to something with solder pads the iron tip won't bridge.
I'm laying in a supply of DIP and leaded passive & active components. If stuff gets any tinier I'm going back to wood piano actions. Don't tell me about Germany; took 17 days to get a package through customs UK - USA internal to Farnell.
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1. Lay them out yourself on a board that you send to the cheapest quote on PCBShopper – A Price Comparison Site for Printed Circuit Boards
2. Buy them from Futurlec
SMD Adapters
The ones you are most likely to want, cost $0.25 a piece when you buy 100 of them
8 Pin SOIC to DIP8 Adapter
2. Buy them from Futurlec
SMD Adapters
The ones you are most likely to want, cost $0.25 a piece when you buy 100 of them
8 Pin SOIC to DIP8 Adapter