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Old 18th June 2005, 05:02 PM   #11
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Buy Horowitz&Hill THE ART OF ELECTRONICS . . .
And read Appendix A, HOW TO DRAW SCHEMATIC DIAGRAMS, on page 1056.
No . . . ! ! ! Just go to a book shop, and read it, then return it into the shelf . . .
Or, stealing book for studying is no sin . . .


. . .

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Old 18th June 2005, 05:20 PM   #12
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Nope. Nelson draws his schematics using the Foresthills dialect of the language. In the local argot, a line that crosses straight over another line is a no connection. A line that connects is a dead end, such as the connection of R47 to the +input. Of course, there are incongruities just as in any language, in that C9 and R52 (can't read the number clearly) get a straight line connection instead of an offset one. That's the way it goes. It's a small hurdle that he puts in to test your commitment to building the circuit.
In any event, only the middle MOSFET (IRF610--Q?--number completely illegible, less than optimal scan) is active signal-wise. The upper one (IRF9610--Q?) and the lower one (IRF610--Q?) are current sources, and undriven ones at that, i.e. they are not Aleph current sources or anything of that nature. Nelson is just letting the collector of Q11 and Q12 connect via R46. How much AC goes across there, I couldn't say as I haven't built the circuit, but it might qualify as a sort of backdoor feedback. Note that the connection isn't part of the signal path, per se, as the ZTX parts only serve to set the current and tighten up the two current sources. They are DC servos that correct for AC signals across R44 (Q11) and R55 (Q12). Any deviation from pure DC gets passed back to the Gate of the MOSFET as a corrective signal, thus setting things right again.

Grey
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Old 18th June 2005, 05:44 PM   #13
Blues is offline Blues  United States
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Quote:
Originally posted by Nelson Pass


Maybe you are thinking about bleeder too much: Easy cure
for that - stop thinking and start experimenting.

Amp should die instantly? Amp might deserve to. Gets stake
driven right through heart!

We are fearless amplifier builders. Unafraid to stop simulating
and start building. What's the worst that can happen? You die?

No, amp dies! Maybe speaker, too!

Lose a couple of $$$!

MuuuuHahahahahahaha........!!!!


Moderators, please move this to the other thread...where amps need to be bled
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Old 18th June 2005, 06:38 PM   #14
MikeW is offline MikeW  United States
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Here is the schematic.
Attached Files
File Type: pdf pre-ampsch.pdf (83.3 KB, 121 views)
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Old 18th June 2005, 07:45 PM   #15
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Yes

The book says: "1. Wires connecting are indicated by a heavy black dot; wires crossing, but not connecting, have no dot . . . 2. Four wires must not connect at a point; i.e., wires must not cross and connect.


Ladies and gentle men . . . the one, the only . . . Starina . . .
wo! wo! wo! wo! wo! wo . . . ! ! !



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Old 18th June 2005, 08:10 PM   #16
MikeW is offline MikeW  United States
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Any other mistakes?
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Old 19th June 2005, 03:31 AM   #17
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One misprint. The size of R27

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jH
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Old 19th June 2005, 02:39 PM   #18
MikeW is offline MikeW  United States
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Default Thank you

I found that one 221K. I have one channel built. I still need to do some testing. Thanks for the help.
Do R44,59,55,70 have to be more than 1/2 watt? The prototype board has 2 watt, but it looks like they should only see .7 volts across them.
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Old 19th June 2005, 03:45 PM   #19
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1/2W will do just fine...or 1/4W if you want. You're correct, there's only a steady .65VDC across them.

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Old 19th June 2005, 06:19 PM   #20
MikeW is offline MikeW  United States
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Default single ended

Should the minus input and output be shorted for single ended operation?
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