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Nelson Pass 10th January 2013 10:29 PM

AB100 Class AB Power Amplifier
4 Attachment(s)
AB100 Amplifier - Micro Article by Nelson Pass

Since villagers armed with pitchforks and torches have begun camping
out my front door demanding a Class AB power amplifier, and

Whereas, I am inclined to demonstrate my goodwill in this manner and
do in fact have a 13 year old piece laying around unpublished,

I Hereby Present the AB100 Class AB Bipolar power amplifier.

Salient Specifications:

Rails: +/-50V or so

Gain: 36 dB (this was the request of the people who commissioned
this but did not want to pay for it)

Bandwidth: 5 Hz to 100 KHz (-3 dB)

Damping Factor: about 500

Maximum power: 100 Watts 8 ohms, 200 Watts 4 ohms

Slew Rate: 30 V/uS

Bias Current: about 0.08 A per channel

Following are several graphics. (Unfortunately I scanned them in the
distant past, so the quality is not up to my usual standards)

Let It Not Be Said: That I never did anything for you....


AudioSan 10th January 2013 10:37 PM

wow. it's a hard acupation:P
do i see a little aleph with a extra stage, inspiration in the front end there?
the TIP 142/147 are To220 right?

6L6 10th January 2013 10:42 PM

Very cool.

Or at least less rejected heat than 100WPC class-A. :) :) :) :) :)


Ok, which of the smaller transistors need to be mounted on the main heatsinks for thermal tracking?

TIP-142 and -147 are available in TO-247 -- hooray!

What can be substituted for the 2SA1110 and 2SC2590? (If anything...)

Zen Mod 10th January 2013 10:43 PM

after enough staring , everything is Aleph lookalike

I know .......


AudioSan 10th January 2013 10:43 PM

6L6. heat is a GOOD thing:D:D atleast up here close to the north pole:D:D (santa is freezing)

AudioSan 10th January 2013 10:44 PM


Originally Posted by Zen Mod (
after enough staring , everything is Aleph lookalike

I know .......


yes i know:) wee agree agein:D

Zero Cool 10th January 2013 11:06 PM


6L6 10th January 2013 11:20 PM

Looking at it a bit more...

Is 100uf necessary on the input? Or is that just insurance against the rest of the world?

Does the pot adjust bias or output DC offset?

Are the neg gate diodes 4004's and the positive rail 4001's, or is that a typo? Should they all be 4004's?

Is everything, as currently drawn in the schematic, an electrical junction? Specifically, look to the right of R4.

Approx. how many VA, per channel, is required of the power transformer?

AudioSan 10th January 2013 11:24 PM

i bet they all should be 4004. 4001 will burn very fast:)
the pot seams to be for bias.

eyoung 10th January 2013 11:36 PM

Oh my...


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