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Old 2nd December 2016, 12:42 PM   #1
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Default Bootstrapped amps. DX/Aksa/RCA/etc...

Is there a current thread discussing the topology?
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Old 3rd December 2016, 10:05 AM   #2
AKSA is offline AKSA  Australia
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None that I have seen, though Bigun has done a lot of discussion of bootstraps.
Bootstrapped amplifier have lost a lot of sheen in recent years; the interest is in high quality constant current sources.

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Old 3rd December 2016, 11:09 AM   #3
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I built one that's very close in design to the Baby AKSA and was quite pleased with it. I'd like to do a larger version with 2 pair 21193/94 outputs.

Did you ever try a CCS on the Baby AKSA?
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Old 3rd December 2016, 11:34 AM   #4
AKSA is offline AKSA  Australia
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Yes. CCS sounds clean, a little surgical.
I like a simple resistor on the LTP and a bootstrap on the VAS.

However not everyone likes the same sound - audio is a bit like food/wine/clothes/architecture!

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Old 3rd December 2016, 11:40 AM   #5
JMFahey is offline JMFahey  Argentina
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Technology as old as can be.
Not dissing it, all my amps are bootstrapped and it has a unique advantage: it can swing beyond one rail, but certainly anything that can be said about it, was already said loooong ago.
Not that beating dead horses isnt popular at DIYA (and many other places )
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Old 3rd December 2016, 01:55 PM   #6
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The pile of dead horses is very high. There are also so many versions of this topology out there that it's very easy to get lost somewhere between horses and versions.

AKSA is surgical a good thing or bad thing? I prefer the sound of the bootstrap amplifier more then symmetrical designs.
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Old 3rd December 2016, 02:45 PM   #7
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The first amp I built was bootstrapped. Five transistors, and the output PNP was a germanium drift field type. The amp was in a Heathkit AR14 receiver, 20 watts, and wow that was a fun amp, back in 1966. Copied straight from RCA Transistor Manual, I think. I'll post the silly thing.

Bootstrapping has been studied for a long time. Today it is universally used in Class D amps on the high side N channel device, so it's not going away any time soon. Just another circuit topology to be used as needed by designers.
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Old 3rd December 2016, 02:54 PM   #8
Bigun is offline Bigun  Canada
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Quote:
Originally Posted by lazzer408 View Post
I built one that's very close in design to the Baby AKSA and was quite pleased with it. I'd like to do a larger version with 2 pair 21193/94 outputs.
I recently finished just such a beast....
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File Type: jpg PwrAmp-btm.JPG (845.8 KB, 929 views)
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Old 4th December 2016, 12:06 AM   #9
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Quote:
Originally Posted by Bigun View Post
I recently finished just such a beast....
How do you like the sound and performance? Which drivers did you use? Schematic available?
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Old 4th December 2016, 12:21 AM   #10
bimo is offline bimo  Indonesia
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My amplifiers that use bootstrap:
https://anistardi.wordpress.com/2015...rit-amplifier/
https://anistardi.wordpress.com/2014...alam-simulasi/
https://anistardi.wordpress.com/2014...tut-amplifier/

It is about how to make H2 dominant in THD and wide bandwidth amplifier.
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