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AB100 Class AB Power Amplifier
AB100 Class AB Power Amplifier
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Old 18th June 2019, 06:06 PM   #531
osscar is offline osscar  Latvia
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A few days ago I got such a nice "donor" , each side heat-sink to-3 pre-drilled, but only for one pair.
think I could get in there smaller AB100 - let's call it AB 60 as ZM suggested .
I will have to paint it white and make a new aluminum or wooden front panel.
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My DIY so far: two Leach amps, Pass AB100, Pass F5, B1 buffer, Hiraga le monstre, two LM3875, LM1875, OPA549, 6C33C SE, GU32 PP, 6p3c-e PP, Marsh headphone amp.Phono - OBH-8se, Pacific RIAA, inDiscreet Phono, MF A1 Clone, Whammy headphone amp.
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Old 18th June 2019, 07:45 PM   #532
Skylar88 is offline Skylar88  South Africa
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Interesting history. Thanks for posting it, Papa.

I'm glad that the design made it's way to diyAudio, but sorry that you never made anything on it.
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Old 18th June 2019, 07:58 PM   #533
Freecrowder is offline Freecrowder  United States
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AB100 Class AB Power Amplifier
So would like to purchase some boards! Do I understand correctly that no more are available. Any other US group buy in process or planning?
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Old 20th June 2019, 06:07 PM   #534
Freecrowder is offline Freecrowder  United States
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AB100 Class AB Power Amplifier
So I have inquired about Gerber files for this design? I was told they exist. Not sure where. Anybody have any info on this. Thanks in advance.
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Old 20th June 2019, 06:36 PM   #535
gdan is offline gdan  Greece
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AB100 Class AB Power Amplifier
See post #463

AB100 Class AB Power Amplifier
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Old 22nd June 2019, 12:31 PM   #536
carsten.witt is offline carsten.witt  Germany
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@Mr. Pass,

little questions ....

where is R35 on your boards
C9=0pF - what means that?
means 2210=221R / 4751=4k75R

Thanks!
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Old 22nd June 2019, 01:25 PM   #537
carsten.witt is offline carsten.witt  Germany
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Edit was not working ....
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Old 22nd June 2019, 01:44 PM   #538
Mark Johnson is offline Mark Johnson  United States
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AB100 Class AB Power Amplifier
C9=0pF is a synonym for DNI. Do Not Insert.

It means that there is a "footprint" for C9 on the PCBoard layout, but your assembly technician is told not to stuff or solder any component in that footprint. The amount of capacitance we want in this position is: zero. No capacitor at all.

One reason you might put this in your design is: for future flexibility. If, God forbid, WhizBang Semiconductor stops making the BL74JSK device, or if they accidentally let their inventory pipeline go empty*, you have a plan. You'll buy the almost-as-good M44D74GN from ErsatzPLC, and compensate for its imperfections by stuffing an 8.2pF capacitor in position C9. This reduces the amplifier bandwidth by 15% but you're still in production. Now instead of 0.25dB from 2 Hz to 110 kHz, the modified amp is "only" 0.25dB 2 Hz to 93 kHz. Still quite listenable.

*because your fierce competitor Panasony paid 10% more to buy up every last part in existence

_

Last edited by Mark Johnson; 22nd June 2019 at 01:46 PM. Reason: Panasony
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Old 22nd June 2019, 02:05 PM   #539
carsten.witt is offline carsten.witt  Germany
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Hello Mark (hope it ok),

thanks for your answer for C9!

Sorry, my english is not the best ... what I understand is: flexibility and if C9=8.2pF then is the bandwidth "only" 0.25dB 2 Hz to 93 kHz.
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Old 22nd June 2019, 02:15 PM   #540
Mark Johnson is offline Mark Johnson  United States
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AB100 Class AB Power Amplifier
There is only one person who knows exactly why Nelson Pass included C9 in his PCB layout, and that person is not me.

I offered a hypothetical scenario including fake names of semiconductor companies, nonexistent part numbers, and completely bogus bandwidth specifications, to illustrate one possible reason why someone MIGHT include C9. It was a hypothetical scenario. A work of fiction. A story from the land of make-believe.

The good news is: you don't need to know why there is a footprint for C9 on the PCB. Just be sure not to stuff and solder anything there, and live a happy life.
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