AB100 Class AB Power Amplifier

[Karl vd Berg]

From OnSemi and ST manufacturers' datasheets, I see slightly different internal schematics from each TIP142 and TIP147 (resistors)...

Which of them is preferable?

 

[osscar]

For me ON semi seems little better..

 

[Mark Johnson]

Build Left channel with ST devices and Right channel with On Semi devices. Listen to each (in mono). If you have a strong preference, implement that in both channels. If you don't have a strong preference, leave the amp alone and start listening in stereo.

 

[Karl vd Berg]

Thanks, Osscar!

Mark Johnson, very interesting idea! Could also mix the 2 manufactures' parts.

 

[prasi]

most probably you wont be able to detect any differences in sound

 

[Freecrowder]

So Osscar, I have not built a stereo pair yet to listen to in my system. I will compare the A40 to the AB100 when I do. I have had the A40 for over 10 years and it is the best amp I own right now. I also have the Honeybadger and it is a close second. I need the power though for running maggies.

 

[osscar]

thank you for information.

 

[osscar]

Build Left channel with ST devices and Right channel with On Semi devices. Listen to each (in mono). If you have a strong preference, implement that in both channels. If you don't have a strong preference, leave the amp alone and start listening in stereo.

Sorry for late answer, but as NP said (if I remember correctly), darlington transistors with lower value internal resistors are better ...higher driver current - less distortion...obsolete Lambda PMD parts even better...

 

[Freecrowder]

Would like to discuss what it would take to replace the Darlington output stage with just a power BJT. Particularly looking at Sanken devices. Will the existing driver stage have enough gain to drive this? Or will it take another driver stage after the existing. I have no idea if what I'm asking will work or not.

 

[RSK]

Would like to discuss what it would take to replace the Darlington output stage with just a power BJT. Particularly looking at Sanken devices. Will the existing driver stage have enough gain to drive this? Or will it take another driver stage after the existing. I have no idea if what I'm asking will work or not.

+1👍
And what will be the maximum rail voltage?

 

[Mark Johnson]

I would advise against making radical modifications to a Nelson Pass design, especially if you have no idea whether they will work or not. Build his amplifier as he designed it; if the final result is lackluster in your opinion, THEN make changes.

_

 

[mpmarino]

sheesh, $0.82 ?? What vendor is that, Mark?

 

[carsten.witt]

@Eugene L. - Singapore (I don't remember your nickname),
please send me a PM, your boards are back to me (incorrect / Insufficient shipping address)

@manniraj,
that lets hope!

 

[manniraj]

@Eugene L. - Singapore (I don't remember your nickname),
please send me a PM, your boards are back to me (incorrect / Insufficient shipping address)

@manniraj,
that lets hope!

Oh so his has reached back but mine no trace of it so far. Lets hope if it reaches me and unfortunately I will be in Frankfurt for a week or 2 in the 2nd week of October. So if mine as well returned within that time frame then surely can request you to ship it to FK.

Thanks

 

[Freecrowder]

So my thoughts on replacing the Darlington stage are aimed at building a 300W/chan power amp to drive magnepans. they are very inefficient as everyone knows. I'm currently pushing a little over 200W/Chan with the four 142/47. That puts it just over the SOA of the outputs. So what I was thinking was using BJT outputs rated higher and still using just 4 pair so that I can utilize the same board as is. Looking at rails between 50-60vdc.

 

[Nelson Pass]

If they are not darlingtons, then you will need follwer driver transistors, as the
current gain of big power transistors is less than 100, and the front end is
good for whatever its DC bias point is, 20 mA or so.

 

[Freecrowder]

So then the question becomes are there Darlingtons with higher output capabilities so that I can use just four still. In my search I haven't come across them. Sankens aren't any higher that I can see. Anybody know of any.

 

[gaborbela]

Take a look at MJ11015/MJ11016
https://www.onsemi.com/pub/Collateral/MJ11012-D.PDF
I don't know if it is OK to use it in this project, I know some DIY-ers used it in the A40 as a replacement for the Lambada.

 

[Mark Johnson]

AB100 is an exercise in getting maximum watts per dollar. Its TIP142/7 output transistors are half the price of comparable Sanken devices (2SB1647) and one ninth the price of the massive, brutal 300W TO-3 devices (MJ11033). If you want to increase AB100's output by a factor of N, increase the number of TIP142/7 devices by that same factor of N. Or design a new amplifier with different goals.

 

[Karl vd Berg]

+1

Out of curiosity: what's the fT of TIP142/147? I'm asking this because I checked 2SB1647 datasheet, showing an fT of 45MHz, but couldn't find that parameter for the TIPs...

2SD2560 (complement to 2SB1647) is even faster at 70MHz...