AB100 Class AB Power Amplifier

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drjbf1

drjbf1

Member
Joined 2007
Nelson Pass said:
Yes, I have added a 20 pin dual inline connector and designated
standard pin connections for a front end to serve numerous applications,
making for modular amplifiers.

Tentatively:

+V +D +O +IN G G -IN -O -D -V
Click to expand...

Intriguing. The AB100 looks to be single ended input. But I can see the +in and -in, but the D+ and D- suggest balanced outputs. Could this possibly be a possible new BA4 Class A/B output stage?
 
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Nelson Pass

Nelson Pass

The one and only
Joined 2001
Paid Member
This is being designed as a standard OS for the store, with up to 12
output devices mounted in the UMS pattern. Follower or voltage gain /
bipolar, fet, lateral or vertical, single-ended or balanced input, with
plug-in front ends and probably separate plug-in bias circuits.
 
F

FYC

Member
Joined 2001
Just start to look at this design. Very interesting. When trying to walk through the parameters I noted 1 point that I cannot understand. The current through the driver stage seems to be unbalanced in the positive and negative half? On the positive half, the current should be controlled by R6, hence 0.6V/33R=18mA. On the negative half, the current is controlled by R13, hence 0.6V/68R=8.8mA. Where will the extra 10mA flow to?
 
Extreme_Boky

Extreme_Boky

Member
Joined 2003
east electronics said:
Here comes i time that i prove my self wrong and right at the same time

Wrong since a commercial that features more than one pair of darlingtons exist in the market actually just showed up in the shop today for repair .

Right because this amplifier was totally blown for the known reasons ( i expect ) but i will look into it and get back to you .

In between enjoy the schematic ....This is a commercial design existing in the market for a number of years and also features a patch of 150Pf in the upper side Only ! relatively low next to known other schematic . It could be also interesting to see how the amplifier will perform with and without the patch

Since i am way too busy and constructing the AB 100 will take some time I will grab the opportunity and measure and listen to this amplifier after repaired since i think its a look alike .
I will enjoy working with Tip 142-147 after 20 some years passed from the time i was blowing a few .
Click to expand...

I like the input stage...degenerate it and re-adjust the quiescent current...
 
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Nelson Pass

Nelson Pass

The one and only
Joined 2001
Paid Member
FYC said:
Just start to look at this design. Very interesting. When trying to walk through the parameters I noted 1 point that I cannot understand. The current through the driver stage seems to be unbalanced in the positive and negative half? On the positive half, the current should be controlled by R6, hence 0.6V/33R=18mA. On the negative half, the current is controlled by R13, hence 0.6V/68R=8.8mA. Where will the extra 10mA flow to?
Click to expand...

The current through R6 and R13 is essentially equal. The voltage drive
to those transistors is different by about .3V
 
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